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Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It
12

Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
Ah yes, it’s that time again folks. A paper is released, in this case Lewis and Curry 2014, that says climate sensitivity is on the low end of the spectrum and the “skeptic” community starts banging pots and pans claiming the ACC theory is dead. Well, like most things in the field of climate science, it's not nearly that simple. Let's look at the entire story.

Equilibrium Climate Sensitivity (ECS) and Transient Climate Response (TCR)
Equilibrium Climate Sensitivity (ECS) – the amount the planet will warm in response to a doubling of atmospheric CO2 concentration (the base is usually taken from preindustrial levels of 280 ppm). ECS includes both fast and slow feedbacks, so ECS is not fully realized for decades or centuries after CO2 is held constant.

Transient Climate Response (TCR) – similar to ECS but only includes fast responding feedbacks. In other words, TCR is the temperature rise at the time atmospheric concentrations hit 2x the baseline, not where it will settle out to. As slow responding feedbacks tend to be positive, TCR is smaller than ECS.

These two are not the same and should not be confused. Many “skeptic” arguments prey on this confusion, be careful.

The Body of Knowledge on Climate Sensitivity
First, here’s a good list of the spectrum of peer reviewed literature addressing climate sensitivity. If you actually want to understand the topic (instead of cherry picking things that fit your viewpoint), it’s import to look at the body of work, that’s kinda how science works. Here’s a graphical representation, from AR5 WG1 Fig Box 12.2-1:


To claim that a single paper can definitely set climate sensitivity, is false. While on the low side, Lewis and Curry 2014 does sit within the spectrum of other estimates.

Lewis and Curry 2014
Now to the paper itself. Lewis and Curry 2014 (LC14) is very similar to Otto et al 2013 (they both take the energy balance model approach), just with different heat uptake rates and reference periods.

LC14 has a heat uptake rate (0.36 Wm^-2) that is almost half of Otto et al 2013 (0.65 Wm^-2). The uptake rate used in LC14 comes from a single model, not an ensemble mean, and is, surprise, surprise, a very low value (which leads to lower ECS).

The ending reference period (1995-2011) was selected to “avoid major volcanic activity”. Although this seems odd considering Vernier et al. 2011 found that volcanic activity greatly affected the 2000’s. Furthermore, it is well known that the last decade has been a La Nina dominated period which would further add a cooling bias to their ending reference period, and thus artificially lower their ECS and TCR estimates.

Now new evidence (Durack et al 2014) suggests that “observed estimates of 0-700 dbar global warming since 1970 are likely biased low. This underestimation is attributed to poor sampling of the Southern Hemisphere”. Using the results of Durack et al 2014, the ECS would rise (15% according to a tweet from Gavin Schmidt).

The paper makes no mention of Cowtan & Way 2013 which demonstrates and corrects the cooling bias in HadCRUT caused by a lack of coverage in the heavily warming Arctic. Therefore, much of the recent warming which is occurring in the Arctic is unaccounted for in this paper. This would cause an artificially lower value of ECS and TCR.

The paper also ignores Shindell 2014 and Kummer & Dessler 2014 (most likely because they are too recent). Both of these papers highlight the inhomogeneities in aerosol forcing which may cause energy balance models to underestimate ECS and TCR.

Finally, the rather simplistic technique used in LC14 (and Otto et al 2013 as well) ignores all non-linearities in feedbacks and inhomogeneities in forcings. The exclusion of these elements leads to a lowering bias in TCR and ECS. Due to the fact the sample period and technique used introduce lowering biases into the results, LC14 may be useful in establishing the lower bound of sensitivity but in no way offers a conclusive value for the median or best estimate.

It should be noted that the results of Lewis and Curry 2104 implicitly accept and endorse the core of the Anthropogenic Climate Change theory; namely that increases in atmospheric CO2 will result in increases in global temperatures and that feedbacks will amplify the effect. For example, if you feel that the recent rise in global temperatures is due to land use changes and not CO2, then the TCR and ECS to a doubling of CO2 should be near zero. Or, if you feel that "it's the sun" and not CO2 then the TCR and ECS to a doubling of CO2 should be near zero. The recent change in climate is "just natural" and not CO2 you say? Well then TCR and ECS should, again, be near zero. So, if you've found yourself claiming any of the preceding and now find yourself trumpeting the results of LC14 as proof for your side, then you, unfortunately, are deeply confused. If you want to accept LC14's value for TCR of 1.33 K as THE value for TCR (which it isn't), then you also accept that majority of global warming is due to anthropogenic CO2 emissions.

What About Other Papers that Claim Lower Sensitivity?
As I stated from the outset, Lewis and Curry 2014 is hardly the only paper to address climate sensitivity. Beyond that, it’s hardly the only paper to suggest that climate sensitivity is on the lower end of the IPCC spectrum. I’ve addressed a few already but there are more (Lindzen 2001, Spencer & Braswell 2008, etc.). However, almost all of these papers have been found to have some significant flaws that cast doubt on their conclusions. Various peer reviewed rebuttals to these papers are listed below. I’d welcome readers to review the rebuttals and the original authors response to them.


...But What if Climate Sensitivity WAS Lower Than Expected
Let’s ignore all this for a second and pretend that, with Lewis and Curry, we can definitively say that climate sensitivity is lower than expected. Then what? Does this completely debunk the ACC theory? Does this mean rising CO2 levels really aren’t a concern? Well, many “skeptics” would say “YES!” but they do so without ever actually examining the issue.

According to Myles Allen, head of the Climate Dynamics group at Oxford:

Quote (Myles Allen)

A 25 per cent reduction in TCR would mean the changes we expect between now and 2050 might take until early 2060s instead…So, even if correct, it is hardly a game-changer…any revision in the lower bound on climate sensitivity does not affect the urgency of mitigation
.

The issue is that, with atmospheric CO2 levels rising as quickly as they are, a lower TCR does not mean anything significant. It just means that the effects will be delayed slightly. So even if “skeptics” were correct in saying that climate sensitivity is definitely at the lower end of the IPCC range (which they’re not), it would have no substantial impact on future global temperatures or the need to control CO2 emissions.

So, Lewis and Curry 2014 is:
1) Inconclusive to definitely say that climate sensitivity is on the low end of the IPCC spectrum
2) The results are suspect and appear to include numerous biases that would lead to lower TCR and ECS
3) Even if it were conclusive and accurate, it would still not suggest that reductions in CO2 emissions are unnecessary. In fact, it adds to the scientific body of knowledge that temperatures will continue to rise to unsafe levels if we continue with the status-quo, just maybe a decade later than other estimates.

(Note: I’ve started this new thread to discuss climate sensitivity specifically. It is an important topic that popped up in another thread and I felt it merited its own discussion. I would, as much as possible, like to keep the conversation on this subject…although this is likely wishful thinking)

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Oh rconnor - your ideology has blinded you. Why do I say that?

Quote (rconnor)

So even if “skeptics” were correct in saying that climate sensitivity is definitely at the lower end of the IPCC range (which they’re not), it would have no substantial impact on future global temperatures or the need to control CO2 emissions.
You are so fixated on the supposed need to control CO2 emissions that you have missed the blatantly obvious: time. More specifically, time to adapt. The time to adapt to change whatever the cause. Because that's the issue here. If we were to be struck by an asteroid or comet tomorrow (and not be amongst the instantly incinerated), the ensuing nuclear winter/ice age would kill many people because of the rate of change - we wouldn't have time to adapt. Compare that to a slow-onset ice age, due to some other natural slow cause. In the face of a slowly oncoming wall of ice, I would certainly move rather than be "crushed". Well, I could anyway if I were not poor.

So, if the sensitivity is low, then the impetus for mitigation action is likewise low while the incremental cost for adaptation is also low. It is only when the sensitivity is high that the rate of change becomes incompatible with adaptation and mitigation is a cost-effect approach.

The challenge in all the sensitivity calculations is to tease apart the natural (cyclic or otherwise) warming and cooling from that directly attributable to humans, and specifically human emissions of CO2. Certainly not an easy task. One t the things that I will give Lewis and Curry huge credit for is putting some real effort into identifying and calculating their error estimation. So many previous studies have done a very poor job of that task.

What I find most interesting is how, over time, the estimates are reducing. Certainly there is a lower-bound estimate: the laboratory value of (give or take) 1 deg C per doubling. Any value above that relies on feedbacks that amplify that effect.

From a time-value-of-money perspective (economics), the lower the sensitivity, the lower the incentive to do anything. The slower effects happen, the better off we are. Of course, the richer we, the easier it is to adapt. So, maybe it would be better to make everyone in this planet richer with greater access to energy - which would allow them to easily adapt to whatever change comes out way; be it natural or human-induced. Unfortunately, whatever action is taken to reduce CO2 emissions will have pretty much the opposite effect. Even if it mitigates a human-induced change, such a move weakens our ability to adapt to any other change - and that's trally a bad thing.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

"More specifically, time to adapt."

That presumes that there is no tipping point, and that the cost to repair is no worse than linear. Ironically, Western Civilization came up with, "A stitch in time saves nine," and pretty much in any industry, it's well recognized that the sooner a problem is solved, the lower the cost. So, yes, we may, or may not, be richer in the future, but the problem will be progressively worse, and the proportional cost to bring things back will be more than linearly more expensive. How many engineering problems have you done a cheaper job of solving by waiting for it to get worse? There's already a trend of high tides that are going to cost millions, if not billions, of dollars to mitigate in the next 50 yrs. So, we are already paying for not solving the problem. Given the large percentage of the world's population that lives near an ocean coastline, there will likely be massive displacements of population and damage to property and ground water tables from salt water intrusion.

TTFN
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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

2
Does any of this justify spending 8 billion dollars to avert 0.02 degrees of rise instead of preserving an area of rain forest the size of Uruguay?

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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

one model, whatever it's results, will not make, or unmake, the argument (debate is way too gentle a word, and pissfight is too inelegant); and if sketics are claiming such (as claimed) then they aren't helping the argument (they're just chucking gas onto the fire).

but taking the concensus for a bunch of different models seems (IMHO) to be hokum. if different models prodcue radically different results, then either some of them are "wrong" or they are optimised for different climate inputs/effects (like a linear FEM will do a pretty good job, a non-linear model will do a better job ... if the structure had significant plasticity effects then the linear model would be "nonsense" but at least it tells the analyst this (if he listens carefully to what the model is telling him).

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

You'd think after doing this for 20 years, the estimates for climate sensitivity would be zooming in to the 'right' answer instead of diverging wildly.

Maybe, just maybe, CO2 isn't the only thing that's warming the planet.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

nahhhh, it cannot be ...

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

This is what I actually said, "a) the sensitivity of the global surface temperature to CO2 seems to be falling, as it is more rigorously analysed, away from the funny numbers that were being used to scare people back down towards the number you'd expect from lab measurements."


That set of papers is selected from a website that has a tab labelled "Anti-AGW papers debunked", so forgive me if I suspect that there might be a bit of cherrypicking going on. As it is your confusing and mislabelled graph makes the point that two thirds of those datapoints come in as less than 3.2 deg C per doubling, the IPCC 4's official scary number http://www.ipcc.ch/publications_and_data/ar4/wg1/e...



Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

NOW I know what apathy feels like...

If we need a new Climate Change thread every time a paper comes out, this is going to go from tedious to stupid.

Not one of you has ever switched sides from what I can gather.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

CEL - actually the opposite of apathy. There is some serious passion on both sides of the discussion. While I completely disagree with rconnor, I do admire his passion and tenacity. The likelihood of his mind being changed is quite low, yet for some bizarre reason I keep trying. You can't do that while being/feeling apathy.

While I try my best to convert him and others with the same misguided beliefs, I also try to show fence-sitters how ridiculous the alarmist/warmist mentality/approach is. I can try to influence undecided engineers - and if I have then I have succeeded.

I have a fundamentally positive outlook on humans and human ingenuity. I don't see mankind as a plague (virus) on this planet, but rather the greatest thing to ever occur. I am so full of optimism, that I will fight the pessimists until my last breath!

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

I meant myself. I've tried to read these debates, but I'm out of steam and no longer care.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

The human existance is the universe attempting to under stand itself. Models and debate is part of that process, and should be encuraged. To not do so is to place us back in the dark ages, with the king telling us what to believe.

Apathy is what the non-thinkers do, as a way to make life simpler, as they waste there lives, freedom, money, and our resources.

So if there is a cause of any climite change, it is apathy. Because apathy has no ideas, or solutions, and dosen't care.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

As the book I am reading at the moment says, human are always in a rush to change things because our lives are so short. If the models that inspired the AGW lucrative panic religion are correct, in their long term implications, but cannot handle the 50-60 year cycle length short term variations, then they have a problem, because we have good data for 30-odd years, and reasonable data for 150, ie 3 independent datapoints. So you need to decide how many to use to train the models (they aren't physics based, they are trained models) and then how many to use to validate the models. With only 3 independent datapoints that doesn't give you a whole damn lot to work with.



Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Climate change has become religion. Nobody knows anything with any degree of certainty, except that everyone else is wrong.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
TGS4, I will address your point regarding mitigation v adaptation only as it relates to sensitivity. I will not discuss the economic analysis of mitigation v adaptation as this is off topic. However, I will note that numerous studies indicate that mitigation is much more cost effective than adaptation in the long run.

TCR is the amount the planet will warm at the point when atmospheric CO2 levels reach twice that of the baseline (usually 280 ppm). ECS is the amount the planet will warm, in total, if atmospheric CO2 levels reach twice that of the baseline and then are held there indefinitely. However, without any reductions in CO2 emissions, CO2 levels will continue to rise far beyond that point. RCP8.5 (which is close to a “business-as-usual” scenario) leads to a CO2 level of close to 940 ppm in 2100. So reducing the TCR from 1.8 K to 1.33 K means very little when you’re sitting at 940 ppm - you’re still experience dangerous increases in temperature.

It’s important to realize that when we talk about a TCR of 1.8 K or 1.33 K, this DOES NOT tell us the amount of warming we will see in the future. That amount is dependent on where we limit atmospheric CO2 levels. All that a lower TCR and ECS means is that the % reductions in emissions per year required to keep future global temperatures at a safe level (most say +2 deg C is that level) is lower, but it still requires mitigation to achieve that. Furthermore, as Myles Allen pointed out (which you’ve seem to have missed) is that taking a TCR of 1.33 K instead of 1.8 K, all you do is shift the effects out by 10 years. A TCR or ECS value at the lower end of the range does nothing to reduce the threat of future temperature rises without mitigation. .

But beyond all this, you’ve completely ignored (so has every other poster) the fact that LC14 includes numerous biases in the reference period and technique used that creates an artificially lower TCR and ECS. So while it is ok at establishing a lower bound, it is wrong to treat it as the “best estimate”.

Quote (TGS4)

What I find most interesting is how, over time, the estimates are reducing.
What are you basing this statement on? Well, I’ll do the leg work for you. Below is a graph of ECS estimates from various papers over time. I made sure to include LC14, Lewis 2013 and Otto et al 2013 and didn’t even bother including more recent, high ECS studies…still doesn’t matter. You’re guess is at best unsupported and at worst is flat out wrong and the inverse is correct.


While the values seem to continually come in within the IPCC range (as LC14 did), some come in at the higher end of the scale, some come in at the lower end. However, there is nothing to suggest that the sensitivity is increasingly or definitively found to be at the lower end. Some studies point to the exact opposite conclusion. Sherwood et al 2014 concludes that models with lower climate sensitivity do not accurately reproduce observed climate dynamics. Based off the assumptions they make, some techniques have inherent biases that tend to lead to higher or lower values. Simple energy balance models used in LC14 and Otto et al 2013 are known to introduce lowering biases, LC14 much more than Otto et al 2013.

Now, what I will say is that the values don’t seem to be homing in on a singular value. This is why sensitivity remains an important open question. However, one cannot conclude that the results are trending to the lower end as this is unsupported by the data (in fact the inverse is supported by the data). If nothing else, the results trend, more and more, within the IPCC range. This supports the ACC theory. Most importantly, even if the true TCR and ECS are closer to the lower bounds, this still means that mitigation is required to limit future temperature rise.

GregLocock, see above. There’s nothing to support the assertion that “more rigorous” studies (LC14 would be the exact opposite, it’s a simplified technique that, due to its simplicity, has inherent biases that lead to lower values of TCR and ECS) have been causing the sensitivity estimate to fall. The only reason it may seem that way to you is because, as I stated, when any paper with lower sensitivity comes out, the “skeptic” community begins banging pots and pans together and draws the attention of media.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

How very typical warmist of you to draw a straight line through a mess of data. I see a sinusoid through that data with a definite decrease in the more recent years. But, I guess when everything in your world is linear, I guess all you see are lines. And you certainly couldn't see cycles...

TCR or ECS, while they may be correlated to a low base value of CO2 concentration - 280ppm, they ought to be valid throughout the range of concentration values. Therefore, your assertion that concentration will reach 940ppm by the year 2100 is a 1.175 doubling over the current value of (to round numbers) 400ppm. Therefore, if TCR is on the order of 1.33K, then the global average temperature (and you know how much I detest that abomination of a quantity) should be expected to increase by 1.56K above current levels. Meh.

Of course, to get to 940ppm from our current 400ppm, the concentration will have to increase by 540ppm in the next 85 years. That's a rate (linearized, I know - so shoot me) of 6.35ppm/yr. It's currently at about 2ppm/yr. So, to achieve your number, the rate of increase will itself have to be tripled. Business-as-usual indeed...

While you may not want to discuss the economics of adaptation vs mitigation, it really is the heart of the matter. And to start, you have to start identifying costs and benefits. I know that it's hard for many warmists to accept, but there truly are benefits of warmer temperatures. Not to mention the agricultural benefits of a higher CO2 concentration. Since the end of the little ice age, according to NASA GISS, global average temperatures (gawd, I hate this metric) have increased by almost 0.8K. In that time, the worldwide GDP has gone up (in constant dollars) between 30-fold and 40-fold. Wow - maybe warming is really really good for us!

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

First test with time based data , split the data into two equal time periods, apply the same method (linear regression) to both.


Also you should plot the confidence limits. ow did you select the papers?






Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

"How very typical warmist of you to draw a straight line through a mess of data. I see a sinusoid through that data with a definite decrease in the more recent years." ... all i see is a pellet pattern from a shotgun, though it'd be nice to see the regression coefficients of the straight line ... and whether a curve has a higher regression; but this is just "counting angels".

@ rconnor, would you admit that another paper saying that warming is increasing is met with the same type of sensationalism ("the end is nigh") ... there's too much sensationalism from both sides ... it might as well be a political debate ?

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

The regression coefficient will be misleading.

Almost all physical and thermal processes are proportional to a power of absolute temperature. That means that the temperature projections are actually all on the order of 3xx ± 2.5 K, which is a range of less than ±1%. So, the predictions are not "wildly" divergent, it's the consequences that are wildly divergent. To that degree winky smile, almost all of the predictions show at least a 1 K increase, which will certainly lead to some significant climatic changes, which still include glacier melting, sea level rise, etc. Whether the sea level rise ends up to be 3 m or 10 m, is simply a matter of degree; the financial cost of even the lowest rise will be in the 10s or 100s of billions of dollars.

TTFN
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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

If I was presenting that data (rconnor's most recent plot), I'd probably draw a circle around all the points and give parametric equations for it. Then point out that 100% of the points correlate with being "inside" it. That straight line is a joke.

- Steve

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
Granted, it was silly of me to put on the linear trend. After an hour of digging through ECS estimates, I was growing a little tired and wrongly slapped it on. My mistake. But you've all missed the point.

TGS4 ("What I find most interesting is how, over time, the estimates are reducing") and GregLocock ("sensitivity of the global surface temperature to CO2 seems to be falling") pull comments out of their butts, based on absolutely nothing other than a hunch, and use it as the basis to question the ACC theory. Apparently no one has an issue with these unsupported statements. When you actually do the research, it, in no way, supports their assertion. So while you are correct to attack the usefulness of a linear trend, you should also be asking them to retract their guess that sensitivity is dropping OR provide evidence to support it. But you don't, because it falls in line with your beliefs on the issue and such gets a free pass from any skepticism.

Furthermore, their false hunch that sensitivity estimates are decreasing is likely based on recent energy budget model studies such as LC14 and Otto et al 2013, which have known biases that lead to lower estimates. They have completely ignored this fact. So even if LC14 is on the lower end, it in no way provides a comprehensive reason to think that the actual TCR and ECS are on the low end of the IPCC spectrum.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Eyeballing the data, since the IPCC First Assessment Report came out (1990), the trend is downward. If you would care to post the data from that plot (although in keeping with warmist tradition - "why would I share my data with you, when all you want to do is prove me wrong"...).

You want to critique the low-ball estimates. Fine - I critique the high-ball estimates as being based on exquisitely complex computational models that are a complete waste of electrons.

IRStuff - your throw-in numbers of $10-$100 billion dollars. Is that in today dollars? Where do those numbers come from? And sea level rise of 3-10m. Puleeze - warn me before you say such absolutely outrageous things - I now need to clean up my phone screen. Again - we saw 0.8K increase in the last ~100-120 years, coincident with a 30-40 fold increase in worldwide GDP. Even if your numbers are believable (and they are not, BTW), if in 85 years we see a similar increase in worldwide wealth, your numbers will be puny - the cost of doing business really. Sorry, your economics fails.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

2
I have no issue with debate; I enjoy a good, productive, debate. I take issue with the same debate occurring ad nauseum. I come to eng-tips for interesting discussion with peers and betters... I hope to have my mind opened, to change my opinion, to expand my skill set and knowledge. I have frequently had my position on a matter changed, with pleasure. Let me call such a spirit of exploration and participation "honest posting". Once in a black while, I find myself in an argument. I always regret being in one, let alone my statements themselves.

I do not believe that any more than the occasional (possibly even accidental) participant brings honest posting to these climate debates. You are, however, quite right to chastise me for airing my distaste for your discussion. If I don't like that you aren't playing nicely in the sandbox, I should just go chat with the adults who are discussing technical work.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

An R^2 of 0.055 seems to have been omitted from your plot.

The choice of start date is rather important, let's pretend the IPCC has been issuing scary numbers since 1988



Oh, whoops.

you can even try the last ten years or twenty years.

There may be slight errors in that data, obviously working back from a screen grab is a bit noisy, and my graph from blobs routine is not perfect.



Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

CEL, you should have known that not everyone plays nicely in the sand box. And yes you will find cat terds there. But throwing sand is much better than many other things that could be happening.

Maybe it is the same thing over and over, but soon you will figure who's posts are not worth reading, because they don't respond to anything that dosen't fit there agenda. And yes some people are so hard line that they may not even relise they have an agenda.

The more recent comment about that there maybe more advantages to warming probally won't see any comments from warmests, because there agends block them from even consitering that.

The sad truth is if we were not debating about the climate, we would be debating about another topic. And no solution would be found to that, and it woden't matter because the goverment overloards woulden't lissen to us anyway.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

From http://en.wikipedia.org/wiki/Climate_sensitivity#E...

For the ECR as defined above,

1990 IPCC: equilibrium climate sensitivity to CO2 doubling lay between 1.5 and 4.5 °C, with a "best guess in the light of current knowledge" of 2.5 °C

1996: IPCC Second Assessment Report found that "No strong reasons have emerged to change" these estimates

2001: The IPCC Third Assessment Report (TAR) said it was "likely to be in the range of 1.5 to 4.5 °C".

2007: IPCC Fourth Assessment Report (AR4), which said it was likely to be in the range 2 to 4.5 °C with a best estimate of about 3 °C, and is very unlikely to be less than 1.5 °C. Values substantially higher than 4.5 °C cannot be excluded, but agreement of models with observations is not as good for those values.

2014: As estimated by the IPCC Fifth Assessment Report (AR5) "there is high confidence that ECS is extremely unlikely less than 1°C and medium confidence that the ECS is likely between 1.5°C and 4.5°C and very unlikely greater than 6°C

So it appears that the IPCC estimate is a range, not a number, and has stayed relatively flat except for a bump of 0.5C in 2007.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
GregLocock, yes it certainly is skewed by starting point and also by the fact that the last 3 papers I included were Lewis 2013, Otto et al 2013 and Lewis and Curry 2014, all of which are energy budget models which, as we've said, includes numerous biases that lead to lower sensitivities. Regardless of the starting point or specific papers you choose, the correlation in any direction would be weak. As I said, "if nothing else, the results trend, more and more, within the IPCC range. This supports the ACC theory. Most importantly, even if the true TCR and ECS are closer to the lower bounds, this still means that mitigation is required to limit future temperature rise."

btrueblood, you are correct. Sensitivity remains a key question. However, LC14 does not provide anything close to a definitive answer. Furthermore, even if it did, it would still indicate that future temperatures will rise and mitigation is required to prevent that. This is a key point that some skip over. They feel that a lower sensitivity means that the whole theory is put into question. However, in reality, a sensitivity on the lower end of the IPCC range merely means that mitigation measures need to be slightly less aggressive. While this is a very good thing, it may not be true.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Rconnor - you throw out the "ACC theory" like its something so obvious that it need not be defined. If this so-called theory (more like a junior hypothesis to me) includes for an ECS of 1.5-4K/doubling, well yoy might as well blame everything on ACC Theory, because it is so broadly-defined that anything and everything can fit in it.

So, define your damn terms. For this discussion, what, exactly, is this so-called ACC Theory? Don't point me to references, or links, or any of the such. I want to see it in your own words exactly what this apparition we are swinging it is.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

"The more recent comment about that there maybe more advantages to warming probally won't see any comments from warmests, because there agends block them from even consitering that."

"Again - we saw 0.8K increase in the last ~100-120 years, coincident with a 30-40 fold increase in worldwide GDP."

Sure, arbitrary and random correlations work wonders. Why not also correlate that to the 6x explosion of world population that came with that? So by that correlation to temperature rise, the world population should grow another 7x. 50 billion people on Earth? Think GDP will really grow 30x to 40x with that much pressure on all resources?

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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

If wind energy were to make a dent in the world energy consumption, would the drag on wind speeds cause climate change?

What if we use these wind towers to put cell phone trancivers on?


IR are you suggesting global warming causes increased population, or increased GDP? It's hard to understand which.

I was suggesting that global warming would make more food production land available.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

I'm simply extrapolating on TGS4's claim that 0.8-K rise in temperature resulted in 30x to 40x increase in global GDP in the last 100 yrs or so, and pointing out that this was also correlated to a 6x increase in population in the same time frame. His argument appears to be that another 0.8-K temperature rise would result in another 30x to 40x increase in global GDP that would swamp out any costs associated with that temperature increase. So, by extension, we would also have another 7x increase in population, which would put us at 50 billion people.

While increasing the temperature may make currently non-producing land arable, some of the currently arable land will become not so. Considering that the Sahara is in one of the hottest temperature bands on Earth, and is completely inarable, one can pretty much assume that this will be a zero-sum result, i.e., total arable land will at best remain at about the same acreage. Additionally, there is an unstated assumption that access to usable water is unchanged, but that's a big if, given that places like California's Central Valley are currently being allocated zero water. I don't think that make the Rockies arable is going to better than keeping our current set of arable lands. Hilly terrain is not conducive to large agriculture, and will increase transportation and labor costs. Will Montana as the new breadbasket be better than ditching the mid-West?

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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

IRstuff - thanks for asking a very thought-provoking question. I wonder if anyone more than 100 years ago asked the same question?

Hmmmm. Yup. Thomas Malthus. (Actually more than 200 years ago, but his acolytes have been beating (wrongly) on the same drum ever since then. The dear Reverend, in 1798, proposed a that the earth (and more specifically his homeland of Great Britain) could carry no more people. His current acolyte: Paul Erhlic, has been also besting the drum of some forthcoming doom due to population growth. Malthus and all of his followers have been absolutely wrong. And I see no reason why they wouldn't continue to be wrong into the future. But, then again, I have faith in humanity and especially the resourcefulness of engineering brethren, to find solutions to feed whatever our population is. Of course, the more wealthy people are, and the more they have a steady and reliable supply of energy, they inevitably slow their population growth.

W.r.t. Your comment about the Sahara... In fact, as CO2 concentration increases, plants become more drought tolerant, because their stomata don't need to open as wide to admit CO2, but losing water vapour in the process. So, with a nominally warmer planet (and remember, it's the poles that are getting warmer, not the tropics and other mid-latitudes), I predict a more green planet. In the last 30 years, the Sahara is shrinking (here I provide a link to an article from a thoroughly-denier organization please note the source...: http://news.nationalgeographic.com/news/2009/07/09...)

Indeed, water needs for agriculture in a warmer planet coincident with higher CO2 are less than they are now.

But please, carry on with more examples of how things would be better with a warmer planet with higher CO2 concentrations. These are the benefits of which is write.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
TGS4, the anthropogenic climate change theory is the theory you’ve been fighting against for years on these forums, I’m pretty sure you know what it is. Nevertheless…

The Anthropogenic Climate Change theory (ACC theory) in a nutshell:
1) Humans emit large amounts of CO2
2) Leads to increases in atmospheric CO2 concentrations
3) Leads to a positive forcing
4) Leads to increased energy accumulation
5) Leads to climatic changes and increased global temperature
6) More of 1 in the future will lead to more of 5 in the future
7) More of 5 in the future will adversely impact human societies

(Note that this discussion, on climate sensitivity, deals with point 6.)

I can’t see how any of this would be new to you or anyone remotely familiar with this topic. Is this what you were looking for? I feel that you are searching for something specific, in which case why not ask it directly?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

" a sensitivity on the lower end of the IPCC range merely means that mitigation measures need to be slightly less aggressive."

Back that train up. Why mitigate a 2 C rise? Because some beachfront properties might get washed away? I think adaptation where needed is probably a better option, as cost of the structure is a pretty good predictor of the owner's ability to fund adaptations. Furthermore, before I sign off on even revenue-neutral carbon tax strategies, I want to see that the rest of the world is doing similar. Oh, by the way - have you read about the upcoming sales of BC gas and coal causing their carbon emission numbers to rise, and the possibility that they may need to abandon the revenue neutrality of their carbon tax in order to stay carbon neutral?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

rconnor - that is the weakest bunch of cr@p that I have seen from you yet. Numbers, man, numbers!! And for the love of all that is right in this world - how about some details? What EXACTLY are the NUMBERS that reflect your theoryhypothesis? What you have written is about as pseudo-science as I have seen.

Unless you put numbers in there, we are going to be arguing around in circles. You seem to have sorts of numbers and graphs and what-have-you to attempt to back up whatever you are claiming, and yet THIS is what I get for your theoryhypothesis? I'm beginning to think that you yourself don't even know what it is you are defending.

I will note, however, that aside from you appalling lack of numbers, there's nothing that you wrote (up to and including 6) that I disagree with or deny. I guess that doesn't make me a denier smile

(Still waiting on the source numbers for your (ECS vs time) graph that you claim makes a liar out of me, yet as GregLocock has shown, actually makes a liar out of you. Your integrity is really on the line here... Are you going to act like your warmist brethren and obfuscate and stall and eventually not produce the data or will you provide the actual data and be shown that you were wrong?)

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

" I wonder if anyone more than 100 years ago asked the same question?"

One hundred and fifty years ago, the US wasn't even occupying its current borders, and its population was less than 1/10 of the current population. There was no need to ask the same question because no one was pushing the limits on any resource, other than the bison and passenger pigeon, and even those weren't recognized until it was too late to do anything.

44% of the world's population lives near a sea coast: http://coastalchallenges.com/2010/01/31/un-atlas-6...

So, it's not just about rich people. Certainly, most of the people caught up Sandy's mayhem weren't in the rich category. By some accounts, the majority of people potentially impacted by rising seas are at the exact opposite extreme of wealth: http://www.npr.org/templates/story/story.php?story...

The world seems to be stuck in a "Manifest Destiny" mode, wherein we can plunder and pillage forever and not pay the piper. We have already found that such behavior can result in irreversible effects and consequences, like the extinction of the bison and passenger pigeon. To believe that everything can be "fixed" at a later time is naive and has been historically proven to be just simply wrong. We've got piles of permanently contaminated soil and land because of those attitudes.

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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
Ah, when you asked me to define ACC theory, it sounded like you wanted a description. However, you know full well the amount of research behind each one of those statements. Just because I gave a summary (which is what you asked for) doesn't make it "weakest bunch of cr@p". If you want numbers, then ask for numbers. And it helps you tell me which numbers you want to know. I’m guessing ECS and a “safe” temperature threshold:

ECS – 3 deg C
I agree with the AR4 range of 2 C to 4.5 C. The reason why I don’t accept the more recent dropping of the lower bound in AR5 is because it does so due to the recent energy budget model techniques. The IPCC took the conservative approach to lower the bound but included caveats with regards to these new techniques (my emphasis):

Quote (AR5)

…this change reflects the evidence from new studies of observed temperature change, using the extended records in atmosphere and ocean. These studies suggest a best fit to the observed surface and ocean warming for ECS values in the lower part of the likely range. Note that these studies are not purely observational, because they require an estimate of the response to radiative forcing from models. In addition, the uncertainty in ocean heat uptake remains substantial. Accounting for short term variability in simple models remains challenging, and it is important not to give undue weight to any short time period that might be strongly affected by internal variability
I feel that these techniques introduce biases that lead to lower values (see above) and the new literature that they ignore or pre-date (Cowtan and Way 2013, Durack et al 2014, Shindell 2014 and Kummer & Dessler 2014) furthers my doubts in these studies. While energy budget model techniques might be ok at establishing an ultimate lower bound, I don’t feel they should drop the likely lower bound.

”Safe” Temperature Threshold – +2 deg C
Based off my reviews of the literature on the subject, I feel that keeping future temperature rise at or below +2 deg C is important. I feel that +2 deg C will still have adverse effects on certain areas/industries (unfortunately, mostly in the poorer parts of the planet) but the effects get much worse as you approach +3 deg C. While building a sea-wall around New York might be practically possible, doing so around the islands in Indonesia might not be. The resulting displacement is much more of a humanitarian issue than an economic issue (mass/forced immigration never goes smoothly). Furthermore, rapid large scale shifts in temperature have always been “taxing” on the biosphere in Earth’s geological past. While humans will not go extent (by a long shot), some species will and the resulting change to the biosphere will have major effects on human societies. I find it funny that people that argue that a climate tax will destroy the world's economy (with no source to back that up) also feel that the world's economy can pay for adaptation with no issues (with no source to back that up). (and for the record, here's a few sources for my point of view - 1, 2, 3, 4, 5, 6...etc...but this is taking us off topic)

In general, I agree with the IPCC numbers. I feel that reviewing the body of evidence is important and no one does a better and more thorough review of the body of evidence than the IPCC. While it is completely appropriate to question the IPCC (I don’t agree with everything in the reports, see above), anyone that dismisses the IPCC outright cannot be taken seriously in a conversation on climate change. Not only is it comprised of members with vastly more experience in the area than I (or you) but they also review many more papers than I (or you) have. To think that I (or you) know better than the IPCC, such that we reach drastically different conclusions, would require some damn strong evidence (certainly not some random blog). When it comes to understanding the best science surrounding climate change to date, nothing comes close to the IPCC (certainly not some random blog). For anyone that feels that this is an “appeal to authority”, it’s not. If you go ahead and do a review of the 1000’s of published papers, you’ll be doing the same thing that IPCC did and will likely reach the same conclusions. If instead you cherry pick which studies you want to read and which you don’t, you’ll end up with the same conclusion as some blog site. I don’t doubt that this will start a flame warm of (unsupported) anti-IPCC ideology but that matters little to me.

But speaking of lack of numbers to support your statements…

Quote (TGS4)

(and remember, it's the poles that are getting warmer, not the tropics and other mid-latitudes)
Source? Seriously TGS4, you already made this comment (13 Jan 14 14:12) and I already corrected it(16 Jan 14 1:20) (thread). While the poles are warming faster, the tropics are still warming as well.

NASA GISS data per zone per year
or graphically

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

thx, I find that really interesting. what FF burning strategy gets us to stabilise at +2deg (presumably at the end of the century) ? and you're so confident that by employing this strategy we'll avoid the "disasterous" +3deg.

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

IRstuff - and yet, those very questions were being asked - see my examples. Remember the concern about sperm whale oil and the potential elimination of the species if we didn't find an alternative to that oil. Thomas Malthus was talking about the ability of Great Britain to handle ~8 million people - current population is 64.1 million. Ehrlich has been going on about "The Population Bomb" since 1968 - we are coming up to its 50th anniversary. And it's been demonstrated over the last 46 years to have been wrong.

Perhaps if your concern is with climate change (regardless of the source) affecting "poor people", maybe we should enrich them? We could start by providing them with efficient, reliable, non-polluting (in the common sense of the term, not the carbon pollution bs) sources of energy. In the west, that meant electricity - usually by coal, but I'm fine with whatever gets the reliable and consistent power to them.

rconnor - well at least we finally have some numbers to go along with your assertions. Thank you (still waiting on the ECS graph data...). This supposed threshold of temperature rise - what's the reference temperature - or should I say what is the ideal temperature of this planet? And of course, your acceptance of the IPCC idea that they are the be-all and end-all of the review of the scientific literature (of course, there's a little investigative journalism by Donna Laframboise - http://nofrakkingconsensus.com/my-book/ - that might disagree with that assessment) is very telling. But yet you reject their most recent lowering of the ECS numbers. Interesting...

That brings up the issue, yet again (and it is on-topic) of averages. So, if the planet (on average) warmed up less than 2°C, yet ALL of the warming took place at the poles, melting the polar ice caps - you'd still be OK with that? What if the poles didn't warm at all, saving the world from the inundation of meltwater, but the tropics and mid-latitudes warmed, all so that the average were less than 2°C - you'd still be OK with that? I've reviewed the literature, and other than IRstuff's concern about sea level, all of the other supposed harms are either computer-model-generated (and you know what I think about that), or are simply hysterical grant-money-pleadings. Exactly what harms kick in after 2°C that wouldn't otherwise occur in ecosystems that experience diurnal fluctuations of 5-25°C and seasonal fluctuations of 5-70°C? And what could we NOT adapt to?

I'm not fundamentally-opposed to taxation. If there are harms, then we should figure out the best way to pay for it. However, for me it's the mitigation vs adaptation issue that I have trouble with. I would much rather adapt to a specific harm than mitigate the potential of one - the potential of which has only been posited by computational models, the track-record of which has been dismal.

rconnor - you are correct on the poles vs tropics, and I was wrong. I should have said that the poles were heating, as you said, faster, than the tropics. The GISS baseline (is that the same as your 2°C baseline??) is 1951-1980. On that basis, in 2013 the S20° to N20° tropics are at +0.49°C, while the poles are up 1.26C in the North and 0.64C in the South (both 64°-90°) - source http://data.giss.nasa.gov/gistemp/tabledata_v3/Zon... Of course, the data shows a fair bit of year-over-year fluctuation of almost the full 2013 anomaly... I'm sure that if you plotted that and drew a straight line through the data, which you have been known to do, you would probably see catastrophe.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

The fundamental issue about using earlier models in the straight line fit is that they have equal weighting with the later data. So the 1968 study is accorded equal weight to one made almost half a century later. That'd be OK if nothing had been learned in that time, but one would hope that later studies were better informed than earlier ones, otherwise we seem to be spending a great deal of money and making no progress.







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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

"Perhaps if your concern is with climate change (regardless of the source) affecting "poor people", maybe we should enrich them? We could start by providing them with efficient, reliable, non-polluting (in the common sense of the term, not the carbon pollution bs) sources of energy. "

Not my issue, but not relevant either. Not all of the people going to be affected by climate change are even remotely contributing to the problem. Bangladesh, while most likely burning fossil fuels, is probably a relatively small problem, compared to the US and China. Yet, Bangladesh's climate warming problems will probably make ours look insignificant.

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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

IRstuff - your response, to me, represents all that is wrong with the alarmist/warmist perspective. When there is "blame" for a issue such as this, the focus is on blaming and restitution and not actually solving the problem. The real solution is to set the conditions for the Bangladeshis to enrich themselves and therefore better able to handle whatever is thrown at them. Your solution is to punish the West, make energy more expensive for everyone, keep the Bangladeshis poor and somehow this is "better".

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

I was merely answering your point "providing them with efficient, reliable, non-polluting (in the common sense of the term, not the carbon pollution bs) sources of energy" which you apparently ignored to make your your own agenda point, which is apparently some sort of orphaned, paternalistic "trickle down" concept.

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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Let me sum up this discussions two points.

1 GHG will warm the planet and cause unknown but potentially catastrophic changes to our currently built out civilization and population
and it would be prudent to curtail entertainment consumption of fossil fuels at this point until we know what will happen and how to manage it.


2 GHG will warm the planet and cause unknown but potentially catastrophic changes to our currently built out civilization and population
BUT it will harm our economy and standard of life to do any meaningful reductions in carbon fuel usage so it seems prudent to gamble on the
optimistic outcome materializing.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

IRstuff - so what exactly is your point then? That you don't want the poor to have reliable abundant energy? You don't want to enrich them so that their communities are more robust to handle any weather calamities? What's paternalistic about wanting people to succeed on their own and able to support and sustain themselves? It's paternalistic to require them to stay poor and dependent on the West as we "pay for our sins".

2dye4 - it's probably best that you stay out of the discussion - these are grown up concepts that you apparently cannot fathom or comprehend. Your ideology also blinds you to reality. If the sensitivity (ECS or TCR) is low, then there is no catastrophe (there's always the potential for catastrophe - celestial objects crashing down, vulcanism, infectious diseases, etc). Of all you can contribute is the precautionary principle, then it's best that you leave the adult discussion to the likes of rconnor.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

A few unprintable words for you TGS4. Use your imagination.
I also don't think much of your input but I will withhold juvenile insults.

I simply though this perspective is lacking in much of the discussion. Participants mostly
belong to one or the other camp depending on how they WISH to view the probabilities and likely outcomes
with skeptics being by far the most emotionally entangled and illogical.

I would ask you what in my post you take issue with but then again I could not possible care less.

I think instead of quibbling over minor scientific details that we are not in any way qualified
to judge as well as the scientists who actually do this for their day job , we might just
think about the boundaries to the what ifs and how much we would be willing to sacrifice for
a given quantity of peace of mind.

Remember the USA uses 2X per capita fossil fuel than many other first world nations. I don't think
it is so terrible to live in these other places, do you.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

2dye4 - your simplistic approach/summary is unbecoming and engineer. If the ECS/TCR a is low, then the timeframe for adaption is much longer and the potential for catastrophe is so much less. What can you not grasp of that?

And, no, I am not buying the authority of these so-called scientists. I suspect that I know more about computational modeling than the vast majority of them, so I think that I am eminently qualified to render an opinion, especially on their use or misuse of computational models. And you - what do you bring to the table?

That you think that these are minor scientific quibbles shows your total lack of understanding. At least rconnor understands and appreciates some of these subtleties. This disagreement about ECS/TCR is part of the heart of the discussion. If you have nothing technical to add to the discussion, then I say "good day".

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
Temperature baseline period – pre-industrial, 1851-1900.

“Investigative journalists” op-ed disagrees with the thousands of peer-reviewed papers and NASA, NOAA, National Academy of Sciences, Royal Society, etc… - you don’t say! I never knew that Donna Laframboise thought otherwise! Compelling argument!

What will happen at 3 deg C that won’t happen at 2 deg C? – For a very good explanation, read this report published by the National Academy of Sciences. IPCC reports also detail this descriptively and graphically. It’s important to note that it’s a scale, not an “on/off” issue.

Diurnal/seasonal fluctuations vs average fluctuations - …sigh...you know the answer to this (at least you ought to). This is likely just Gish Gallop. Diurnal and seasonal fluctuations have been happen for a little while now on Earth. The biosphere is quite well adjusted to it. Furthermore, the Holocene has not experienced a long term, significant change in temperature. However, in the Anthropocene we will experience long term, significant changes in temperature that the biosphere will likely not have time to adapt via evolution. Furthermore, you know the whole “it’s changed before” argument? Well when climate went through significant changes in average temperature, the biosphere went through large scale changes (and extinctions). You know ice ages and such. Periods that were warmer than pre-industrial levels were great for lizards and not great for mammals…and likely not great for humans that have evolved and developed through the Holocene.

Furthermore, areas have been quite dependant on a consistent climate from year to year. One year you might get a drought, which affects agriculture and other aspects. Another year, you might experience flooding which affects cities and agriculture. Normally you can ride out the short term extremes, as it usually balances out over the long term. However, when you consistently have more draughts (of greater severity) in some areas and consistently have more floods (of greater severity) in other areas, it begins to have a serious impact.

mitigation v adaptation – you think (i.e. believe based off very little evidence) adaptation will be better. Just like you thought the tropics weren’t warming. Just like you thought humidity wasn’t increasing. Just like you thought BC carbon tax had not reduce emissions. Just like you thought sensitivity estimates were definitively dropping. And just like in all those other cases, I’ve presented some evidence (6 papers…and there are many more) that says otherwise.

Quote (TGS4)

If the ECS/TCR a is low, then the timeframe for adaption is much longer and the potential for catastrophe is so much less.
Without mitigation, the time frame is pushed out by ~10 years if we assume a TCR of 1.33 K (LC14 value) instead of 1.8 K. That’s not significant.

Without mitigation, atmospheric CO2 concentrations will be ~940 ppm in 2100. Using a TCR of 1.33 K or 1.8 K, it really doesn’t matter – the warming will be very severe.

Quote (TGS4)

actually makes a liar out of you. Your integrity is really on the line here...
YOU made the assertion, YOU need to support it. That should be the end of this story. However, instead of just asking you to support your position through evidence, I’ve dug up the evidence for you (list of papers below). Why my “integrity is really on the line” is baffling.

While one cannot definitively say that the trend is increasing (and admittedly my linear trend should never have been included), neither can one definitively say that the trend is decreasing. The correlation is far too weak. Furthermore, three of the latter data points are based off simplistic energy balance models which introduce assumptions and inherent biases that lead to artificially lower sensitivity values. This skews the end of the data series downward while not being reflective of the body of various techniques. Therefore, there is even less confidence in the accuracy or usefulness of the trend. As it stands, there is almost no valid support of the assertion that climate sensitivity estimates have been decreasing as our understanding grows.

Before any evidence was brought forth or analyzed, both GregLocock and TGS4 made such statements. This was done based off a narrow review of recent simple energy budget model techniques. I’ve demonstrated issues with these techniques and have yet to hear any defense of them. The fact that the basis of their assertion is in question seems to cast more doubt on its accuracy.

Of key importance to climate change policy is the question is there substantial evidence to suggest that the sensitivity is outside the lower bound of the IPCC range? Nothing in the body of evidence suggests that answer is yes. A single study, ripe with assumptions and biases that lead to artificially lower values, proves nothing. A single technique, with inherent biases that lead to lower values, proves nothing. The body of knowledge, across numerous techniques, numerous sample periods, numerous data sources and numerous authors, suggests that the IPCC range is valid. You must prove otherwise or drop the argument.

But anyways, see the list of papers I used below. It certainly is not all-encompassing but it’s arguably representative. If you want to add papers, feel free to do so.
Manabe and Wetherald 1967
Manabe 1971
Rasool and Schneider 1971
Sellers 1973
Sellers 1974
Weare and Snell 1974
Manabe 1975
Manabe and Wetherald 1975
Ramanathan 1975
Temkin and Snell 1976
Augustsson and Ramanathan 1977
Ohring and Adler 1978
Manabe and Stouffer 1979
Manabe and Wetherald 1980
Idso 1980
Ramanathan 1981
Chou et al. 1982
Hall and Cacuci 1982
Nicoli and Visconti 1982
Gilliland and Schneider 1984
Hansen et al. 1984
Washington and Meehl 1984
Wetherald and Manabe 1986
Wilson and Mitchell 1987
Mitchell et al. 1989
Noda and Tokoika 1989
Schlesinger et al. 1989
Washington and Meehl 1989
Wetherald and Manabe 1989
Oglesby and Saltzman 1990
McAvaney et al. 1991
Boer et al. 1992
Hoffert and Covey 1992
Mahfouf et al. 1993
Manabe and Stouffer 1993
Lambert 1995
Thompson and Pollard 1995
Chen and Ramaswamy 1996
Gordon and O'Farrell 1997
Hegerl et al. 1997
MacKay et al. 1997
Schlesinger et al. 1997
Bertrand 1998
Delworth et al. 1999
Roeckner et al. 1999
Wolbarst 1999
Boer et al. 2000
Washington et al. 2000
Dai et al. 2001
Wetherald et al. 2001
Boer and Yu 2003
Shaviv and Veizer 2003
Stern 2005
Sumi 2005
Goosse et al. 2006
Hegerl et al. 2006
Schmittner et al 2011
Hargreaves et al. 2012
PALAEOSENS Project 2012
Bitz et al. 2012
Masters 2013
Lewis 2013
Otto et al. 2013
Lewis and Curry 2014

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Typical warmist obfuscation rconnor. You plotted data (and I am actually taking your word that you gathered the information correctly) and I asked for the data. You replied with a list of papers. Not the data that you used - should be in an excel file (unless you don't know how to use that like Phil Jones...) that can be easily uploaded. Actually, you said that I was wrong to say that recent studies were driving the ESC/TCR values down. You produced data to support that, except your data doesn't support that. Either you were wrong or I was wrong. But sure, I certainly see why you wouldn't share the data when I can use it to demonstrate that you're wrong. This little back-and-forth, for me, demonstrates all that is wrong with the scientific discourse on this topic. You are so obstinate that you can't admit to even once being wrong. Whereas I can man-up and admit where and when I am wrong. Now, whose the man of science and who looks more like a man of religion in that interaction?

You might as well add another paper to that list: Harde 2014 which says 0.6°C/CO2 doubling.

Re Donna Laframboise - have you even read her work? Her critique is about the integrity of the people and the papers involved in the IPCC (she makes no claim about the "science"). It's a corrupt organization that has been infiltrated with biased NGOs. But, better to plug your fingers in your ears than to actually listen to dissenting voices.

Re diurnal and seasonal fluctuations - are you really going to go all hockey-stick again? Our recent history has been filled with rapid and severe fluctuations in the average - and what we have experienced thus far is well within the range of what has happened in the past. Indeed warmer might be worse for warm-blooded creatures if the temperature exceeds their normal temperature. However for mankind, we have little inventions, like air conditioning and other refrigeration. Have you ever wondered how people live today in places such as the middle eastern deserts - air conditioning. I guess, however, if you want us all to live a subsistence lifestyle without reliable energy, then maybe we'll have to go without those modern conveniences. I have zero concern that mankind will survive and thrive in any environment - we already do!

And where does this 940ppm come from? As I said before:

Quote (tgs4)

Of course, to get to 940ppm from our current 400ppm, the concentration will have to increase by 540ppm in the next 85 years. That's a rate (linearized, I know - so shoot me) of 6.35ppm/yr. It's currently at about 2ppm/yr. So, to achieve your number, the rate of increase will itself have to be tripled. Business-as-usual indeed...

Speaking of the BC carbon taxes and emission, is there any updates on the data? I can only find data to July 2012. sad

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

YOU should all drop the sand and play nice...

I think I'm going to have to stop reading these threads. Useless bickering and responses which are clearly ignoring half of what other posters say is all I seem to find here.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

I think that you're right CEL. I'd have better luck converting ISIL militants to Judaism. I see why zdas04 took a hiatus. Not that our bickering back and forth will change any outcome at the global or country level, but the stakes are huge. If I'm right, yet they destroy the economy for nothing, that's a bad outcome. If they're roght, yet we do nothing, they see that as a bad outcome, too. If they're right, and we destroy the economy we just might trade one bad outcome for another. And if I'm right and we do nothing, we're fine. This is why Dr. Curry refers to this as a wicked problem.

That said - 2dye4: I apologize for insulting you.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Quote:

Let me sum up this discussions two points.

1 GHG will warm the planet and cause unknown but potentially catastrophic changes to our currently built out civilization and population
and it would be prudent to curtail entertainment consumption of fossil fuels at this point until we know what will happen and how to manage it.


2 GHG will warm the planet and cause unknown but potentially catastrophic changes to our currently built out civilization and population
BUT it will harm our economy and standard of life to do any meaningful reductions in carbon fuel usage so it seems prudent to gamble on the
optimistic outcome materializing.

3 GHG will warm the planet and cause unknown but potentially catastrophic changes to our currently built out civilization and population,
but the chances of it being *only* caused by fossil fuels and none of the other vast array of ways mankind affects our environment are fairly small, so any climate strategy that focuses entirely or even primarily on fossil fuels is doomed to failure anyway.

Which is why we can't craft policy around science that can't get the sensitivity numbers right.

Carbon is probably about a third of the problem. That's why the low end models have a sensitivity of about a third of the high end models. The high end models are erroneously attributing other anthropogenic warming effects to carbon, while the low end models are attributing the correct impact to carbon without specifically explaining the other warming sources.

And we go round in circles, while nobody talks about anthropogenic changes in land cover.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

i'm good with we add "other vast array of ways mankind and nature (ie non-mankind) affects our environment"

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Nobody said *only*

Do you people realize how silly you sound with this never ending picking at the theory. It's like birds picking at an elephant to try to move it.

Hey if any of you skeptics really have something solid and substantial to say about climate change theory weakness then write up a proposal
and send it to BP, Exxon, Haliburton...They would fork over half a million dollars in less than a few hundred milliseconds for science solid
enough to cast some doubt. So get to work....

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

for me it's a central tenet of the "global warming" "argument" ... that AGHG are solely responsible for climate change being experienced.

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Quote:

Nobody said *only*

The policy is crafted around a presumption of "only."

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

"never ending picking at the theory"

Oh, well as rconnors has failed, perhaps you could write 'the theory' down, including numbers. Sadly the scientists involved have been unable to write 'the theory' down. What we have at the moment is a bunch of hypothesese.

Incidentally you obviously don't believe the more extreme predictions since you calculated that your carbon footprint is twice as large as that that would maintain the status quo, and seem content with that.

Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
“and I am actually taking your word that you gathered the information correctly” – Please don’t. Do your own independent research, which you should have done prior to making such an assertion such that you could actually support that assertion.

However, I’ve listed the papers I used which you're welcome to use by going to the abstracts, grabbing the numbers and creating your own plot. You have all the necessary information to double check my plot, now you just need to put in the effort. Or not. I certainly could send the excel file but the only added good it would do would be to save you the time and effort of double checking the numbers. While in the past I’ve allowed you to lean on me to do put in the time to do the research for you, after you called me a liar, I’m not willing to be so generous this time.

Harde 2014 – Oh boy. Firstly, tell me whether it’s ECS or TCR? Actually don’t bother, the model is so grossly simplistic that it can’t discern a difference between ECS and TCR. It says it incorporates feedbacks but then it makes assumptions and simplifications that negates all positive feedbacks. Cloud feedbacks are assumed to be strongly negative (based on what I’m not sure…wait! I looked at the references and, as expected, it’s based off Lindzen’s discredited Iris effect. Very fitting.). Furthermore, a sensitivity around 0.6 deg C means that past climate changes could never have happened (at least to nowhere near the scale they did). Unfortunately, they did happen, as many “it’s changed before”ers will tell us (including yourself…in the very same post) and, you know, the entire field of paleoclimatology.

So this paper has completely flipped climate sensitivity on its head, undoes all the research suggesting a strongly positive water vapour feedback, rewrites the book on cloud feedbacks and completely dismantles paleoclimatology (and, in doing so, silences the “it’s changed before”ers). Wow! What a paper! Where would such a landmark and momentous paper get published? Nature? No, too small! Science? No way, too obscure! The only journal suitable for such a grandiose paper is…ah, let me make sure I get this right…Open Journal of Atmospheric and Climate Change (sound trumpets!)! The only other place I’ve seen this publisher (Scientific Online) mentioned is Jeffrey Beall’s list of Predatory Publishers (#403).

Interesting, related article.

Donna Laframboise – If I linked you a bunch of Moon Landing Hoax books, articles and website by “investigative journalists”, does that mean they have something valid to say?

”I have zero concern that mankind [sic] will survive and thrive in any environment - we already do!” – because the biosphere can sustain us (for now). I have no doubt that humankind will survive a 3 deg (or higher, for that matter) increase in temperature. My concern is that effects on the biosphere will create hardships for humans. You continually stress the economic turmoil that mitigation will cause (without any numbers or supporting evidence) while completely ignoring any practical economic, social or moral issues that will result if we wait to adapt. For example, sea level rises and coastal cities in developing regions are forced to relocate. Physically that’s no problem. Economically, socially, culturally, politically and morally it is. Mass forced immigration is a massive problem that has historically lead to huge, lasting issues. These issues may not show up in any cost/benefit analysis as they are mainly social/moral issues. Again, I’ve provided sources that state the cost/benefit of mitigation v no mitigation. You’ve just kept responding by saying “we’ll adapt!”. I don’t doubt that but at what cost? (economically, socially, morally)

”where does 940 ppm come from?” – RCP8.5. ppm per year is increasing over time. Using the old emission scenarios, CO2 emissions trended closest to A1F1 which leads to an atmospheric CO2 concentration of ~960 ppm. And note that A1F1 assumes that emissions/year will slow down in 2050 and decline in 2080. RCP8.5 assumes that emissions/year will rise until 2060, when they being to slow down and eventual plateau around 2090. Without mitigation efforts, both these pathways are realistic.

Also, it is odd that on one hand you'd argue that China and India are going to continue to increase their CO2 emissions and then on the other hand say that CO2 emissions won't continue to rise. Which is it?

BC Carbon tax new numbers – Can’t find an updated (2013) report either.

GregLocock wrt “well as rconnor has failed, perhaps you could write “the theory” down, including numbers” – What are you looking for? I keep answering this question and then you folks keep going “nope, that’s not what I wanted” but never state what, specifically, you want. I’ve provided some numbers, do you want others? If so, which ones? Ask me to “define the theory” and I’ll do, and have done, just that. Ask me to “provide numbers” (without specifying which ones) and I’ll do, and have done, just that. Provide me with a specific question and you’ll get a specific answer.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Have you even read Laframboise's work on the IPCC? Before dismissing it out-of-hand?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Just went on Laframboise's website:
http://nofrakkingconsensus.com/

That website is exactly the sort of thing I expected. I accidentally bought a Washington Times one time thinking it was a real paper. It doesn't take long to pick out the difference between partisan screeds and reasonable journalism.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Sure. let's start with the definition of a scientific theory

"A scientific theory
A scientific theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation."

In my opinion the theory of climate change does not exist, what you have is a ragbag of hypothesese, some may turn out to be accurate, some won't.

So, if you really think there is a theory of anthropogenic climate change, it needs to be well substantiated, repeatedly tested, and confirmed in the real world.

E=m.c^2 is a theory. "The polar bears are all going to die because Al Gore flies in bizjets" is not.

Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
GregLocock,

e=mc^2 is a formula. Special Relativity is a theory.

You seem to suggest that all theories must have a singular equation that expresses the theory mathematically, otherwise it’s not a theory in your mind. In which case, I can only assume that makes you a creationist (i.e. this would negate the theory of evolution as a “theory” in your mind).

Beyond that, your expansion of the Wikipedia definition of a scientific theory is certainly not that used by many scientists. Do you consider string theory to be a theory? M-theory? Pretty much every theory in cosmology? If climate change doesn’t satisfy your definition of a “theory”, then certainly neither would any of these. This would put you at odds with pretty much the entire physics community. While many may disagree with the string theory and m-theory, they nevertheless see no qualms with calling them theories. The same is true for the anthropogenic climate change theory.

But all of this is rather silly semantics aimed to discredit the ACC theory. At the end of the day, you can call it whatever you want. I’ll call it a theory, which is certainly consistent with how the term is used in other areas of science.

That aside, you’ve failed to answer my question on what numbers you want me to provide to aid in my definition of the ACC theory. So I’ll try and repeat myself:

Anthropogenic Climate Change Theory states that the rise in global average temperature observed during the latter half of the 20th century is primarily (75%-100%) due to anthropogenic CO2 emissions (note that >100% is possible due to cooling affects of aerosols and other forcings). Continued increases in atmospheric CO2 concentrations will lead to more warming. A doubling of atmospheric CO2 concentrations (using a baseline of 280 ppm) is expected to result in a future rise of 3 deg C (using a baseline of 1851-1900).

Testing the Theory
Firstly, it is the only theory capable of describing and reproducing the observed changes in the latter half of the 20th century. The sun, “force X”, geothermal flux, land use changes, orbital/tilt variations and natural ocean cycles have been examined but fail to explain the climatic variances noticed. I’d welcome readers to review the scientific literature or my previous posts for more information on this. Again, I’d remind readers that the strength of the ACC theory is not that there is no other theory that explains the 20th century changes but that anthropogenic CO2 does explain the changes so well.

Now to the accuracy of the ACC theories predictions, which is the bone of contention for most. The climate models have done a good job at predicting temperature trends as long as stochastic and unpredictable factors such as ENSO events, volcanoes and aerosols match the predictions of the models. The recent short term divergence between models and observations is primarily due to the short term effect of ENSO events and higher than predicted aerosols. The divergence does not appear to be because sensitivity estimates are too high, land use forcings are incorrectly estimated, solar forcing has been under represented, etc. In other words, climate models have failed to predict that which they were never expected to predict and that which (other than increasing anthropogenic aerosols) will have no long-term climatic effect. Nothing core to the ACC theory is threatened by this short term divergence. (my post at 4 Apr 14 17:45, Kosaka and Xie 2013, Schmidt et al 2014, Foster and Rahmstorf 2011, England et al 2014, Rigby et al 2014, Huber and Knutti 2014). Despite the heavy influence of short term variability recently, observations do lie within the range of models.


Furthermore, when you account for the the short-term variability, model accuracy improves even more.


Impacts and Policy
I consider the resulting impact of a 3 deg C rise as separate extension to the ACC theory, as is the policy regarding mitigation and/or adaptation. These are more economic, political and social issues which are separate to, but also the result of, the question of climate change. So while they are part of the same conversation, I don’t lump these in with what I consider the ACC theory. However, there is much research on both these topics. The majority of which suggests that mitigation is required to avoid future economic losses and social, political and moral hardships. I’ve included papers and research supporting this position above. I’ve heard almost nothing but unjustified opinions from those here that express an alternative viewpoint. Your welcome to reference Tol’s papers…although, given the amount of evidence discrediting his papers, I’d recommend against it.

All,
Is this a satisfactory definition of the ACC theory? Well, I expect you disagree with the statements but is this what you were looking for me to explain, from my perspective? Can we now go back to discussing LC14 and climate sensitivity? Perhaps TGS4 would care to defend his inclusion of Harde 2014? I’m sure he applied equal skepticism to Harde 2014, after reading about it at WUWT, then he does to other aspects of climate science which he is skeptical of.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It


E=m.c^2 is testable, confirmed and well substantiated.

"You seem to suggest that all theories must have a singular equation that expresses the theory mathematically". I did not. Straw man.

I'm afraid your spaghetti plots aren't a theory, any more than this exercise in curve fitting is. They aren't based on physics, or more accurately, they have gains in them that are used to improve the fit away from what straightforward physics would say. These gains are supposed to account for unknown feedback effects, but of course since they account for unknown effects, they are merely tunable eye candy.




















Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
You called E=mc^2 a theory which seemed to suggest you confused equations with theories. I can't really be accused of a straw man when I'm doing my best to work off your errors.

Feedbacks are based on physics. To say otherwise is just plain false and nothing more than a deliberate attempt to swear some dirt onto climate science. There is tremendous amounts of research that goes into them and how they are modeled. For example, the AR5 WG1 chapter on radiative forcings has 10 pages (two columns per page) of references. Clouds and aerosols chapter has 22 pages of references. This is not just blind tuning as you have been lead to believe and attempt to lead others to believe.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

We've already established they are adjustable gains. If you are fitting a model and allow yourself adjustable gains then you don't have a theory, you have eye candy. Sure there are attempts to quantify these feedbacks, but at the moment they have a wide variety of positive and negative feedbacks to choose from, and can select which are used for a model by adjusting the gain of each. While, eventually, that may work, it will need a lot more data with signal than we have, given the parts of the total system that are currently incalculable.

Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
And we’ve also already established they are adjustable only within a range that is consistent with observations and research. Furthermore, while the end goal is better matching of historic temperatures, the parameterization is already locked prior to running a GCM. Therefore, the tuning is only to represent the subsystem more accurately and is done before they know how well they will reproduce historic temperatures.

Granted, if a model diverges wildly from historic temperatures, it will be considered a failure and require reanalysis. However, the model is examined to pick out which subsystem contained errors which lead to the divergence and that subsystem is examined to see if it can be represented better.

For example, cloud parameterization, an area with high uncertainty, is not adjusted blindly such that it produces a more accurate temperature reconstruction. It is adjusted such that it represents the physics of cloud formation and dynamics as close to observations and research literature as possible. An example of this is [link Sherwood et al 2014, which analyzed how cloud formation was represented in models as compared to observations. They concluded that models which used stronger convective mixing, which leads to higher sensitivity, agreed with observations. Whereas, models which used weaker convective mixing, which leads to lower sensitivity, did not agree with observations. Again, there is 22 pages of such literature that goes into cloud parameterization. It is far from a guessing game but certainly not perfect.

You falsely characterize climate models as some sort of blind “curve fitting” exercise out of ignorance of the actual process (not out of lack of knowledge on modeling in general, I should note).

I would like to stress that climate models are far from perfect. For anyone to believe that I think otherwise, that would be a mistake. It’s an incredibly complicated process to model climate and they contain many simplifying factors and assumptions that lead to errors and uncertainty. Frankly, given the complexity, I’m continually surprised at how well the models do when you account for the unpredictable factors such as ENSO, volcanoes and human aerosols. This is a testament to the amount of research that has gone into this area. Yet more is to be done and the accuracy of the models and the predictions is likely to continue to improve. However, even near the lower end of the bound of uncertainty it still shows that increased levels of CO2 will lead to higher temperatures in the future.

In order for the skeptic’s “do nothing” position to be satisfying, there needs to be a drastic change in the current scientific understanding, not just hoping it to be on the low end of the uncertainty. This was a key point to draw from LC14 which I’ve pointed out (…bringing us back on topic…). Even making every assumption possible to push the sensitivity down as far as they could, LC14 still leads to a TCR of 1.3 K, which is high enough to require mitigation efforts to limit future temperature rises. Using LC14’s value for TCR instead of the IPCC value, future impacts would be pushed out by 10 years. While this would make mitigation efforts more manageable, it still requires mitigation efforts.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Can either side of this argument help me out? I have never seen timeline data sampling that statisticians would consider significant. The Earth is 4.5 billion years old, yet we argue about data from the last 50-150 years to prove both sides of this argument. This is such a small sampling, it is ludicrous. Does anyone have better data that would show longer term trends? We have ice core samples that go back 800,000 years. This is still insignificant statistically, but it is better that what I have seen. I am not aware of any other method to get reasonable data further back from that. What else is out there?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
Hawkaz, although it is off topic, I appreciate you asking a sincere question. I will provide an answer but I hope it doesn’t derail the conversation away from sensitivity.

The question you have to ask is: is it relevant to the problem at hand? Are temperatures from >800,000 years ago relevant to how changes in climate will affect humans today?

The issue is not whether the planet can handle higher temperatures or rapid temperature swings (it can, it has and it will continue to), the issue is whether humans and the modern biosphere, which humans are dependent upon, can. So temperatures from well before the evolution, development and prosperity of humans are rather unimportant. Furthermore, Earth was a volatile place in its infancy. The relevancy of Earth’s climate 4 billion years ago to today is about as strong as the relevancy to Mercury’s climate today. What is important is that major climatic changes in Earth’s history are accompanied by mass extinctions and drastic changes in the biosphere and topology of the planet.

As I’ve said before, a 3 deg C increase in temperature (from pre-industrial levels) is not be unheard of in Earth’s past. However, while these temperatures were great for lizards, they were not great for mammals. Furthermore, I don’t believe that the dinosaurs were too terribly concerned with coastal flooding damaging their cities or changes in climate threatening their agricultural productivity. Less sarcastically, we’ve built up an impressive and complex civilization that is dependent on a stable long term climate to support it. So the data that matters, is the data that is relevant to humans – namely the Holocene. During the Holocene, where humans developed and civilizations began to flourish, we’ve had a fairly stable climate. The recent observed changes are unlike anything observed during the Holocene. Many feel that we are entering a new climatic epoch, dubbed the Anthropocene.



If your question is gauged more towards the idea that “if climate has changed before, how do we know this isn’t just natural climatic changes?” then that’s a different story. First things first, climate doesn’t magically change. “Natural” climate change is often treated as random, uncaused change. This is obviously untrue but nevertheless appears to be appealing to some. Natural climate change has a cause – historically that cause has been orbital/tilt changes. However, orbital/tilt changes have a very small, very slow impact on climate. So, while these changes would initiate large scale, lasting changes in climate, they were not responsible for most of the change in terms of magnitude. CO2 release was a positive feedback, spurred by orbital/tilt changes, that lead to other positive feedbacks (water vapour, albedo changes, etc) that was responsible for the bulk of the warming in Earth’s past. It’s important to note, as it is relevant to this thread, that if Earth is not that sensitive to changes in CO2 (i.e. low ECS and TCR) then we cannot explain the past changes in Earth’s history. However, with higher values of ECS and TCR, we can accurate explain past climatic changes.

Below is a graph from Shakun et al, 2012 which illustrates how stable the Holocene has been coming out of the last glacial-interglacial transition. It also notes the relationship of CO2 (yellow dots) and global temperatures (blue line). Note that a 3.5 deg C rise occurred over a period of ~8,000 to ~10,000 years.


With regards to recent changes in climate, orbital/tilt changes are far too slow an far too weak (and not expected to have an impact for thousands of years) to account for the rate and extent of the observed changes. Furthermore, solar activity has been moving in the opposite direction of global temperature since ~1960. Other factors, such as geothermal flux, land use changes and oceanic cycles (AMO/PDO), have also been studied but fail to explain the recent changes.

Does this answer your question? Let me know if you’d like me to clarify anything.

TL;DR – temperature variances in Earth’s early history are irrelevant because the question at hand is how will future temperature changes affect the biosphere that modern humans are dependent upon and built their civilization around during the Holocene.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

i think rconnor glossed over the moderately obvious point that we don't have a temperature record for much more then 20+ years (satellite records ... land based temperature records are somewhat suspect). beyond that you're using proxies (ok, he does show a graph with "proxy global temperature" on it). what this means is we're deducing the temperatures based on some other measurement (be it tree rings, oxygen isotopes, ...) and this deduction is not fully accepted (ok, the skeptics argue about it; the scientists doing the math argue about it with much more insight and knowledge, most everyone else accepts it as gospel). we might have a better record of CO2 levels , but i haven't thought about it, or researched it, that much.

an observation from rconnor's graphs would be that they seem to downplay what we know of the middle age warm period (when they settled Greenland, grew grapes in England) and the little ice age (when they were skating on the Thames). ok, there are small changes ... but Greenland today doesn't look very hospitable, although the global temperature is higher ...

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

The reason I stopped looking at whetehr ENSO affected global temps over the last 500 years is that most of the ENSO record is proxies, and most of the global temperature record is proxies ,and you guessed it, some of the same proxies are used in both series. So ultimately any attempt to find a signal in their relationship was a long winded way of seeing how many of the same proxies had been used, which was a long way from what I was interested in.

The 'historical temperature record' should always be called a reconstruction, or a model, it is not a historical record. Even HADCET is a model.

Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

I described the IPCC graph as a spaghetti graph, that is a little unfair as it confounds three different sets of variability.

Firstly it shows some predictions from the first (FAR) second (SAR), and third (TAR) reports, and then 3 scenarios from the 4th report (AR4).

So, first you have the models, which will have been trained over different sets of data in their hindcast or training period, then you have the period where the models run free, using measured levels of CO2 etc to drive them, in which we can examine the correlation , and then finally the models response to various estimates of the future CO2.


Actually it is a spaghetti graph as it is impossible to determine which model is in which portion of its hindcast/correlation phase.

it's p63 in the 363 MB download http://www.climatechange2013.org/images/report/WG1...

Anyway, here is a much better graph from the same paper, p87.








Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

whilst i can't make too much out of the RCP side of the graph (other than the obvious, models are predicting higher than observations), my 2c ...

1) why do we call it "temperature anormaly" ... when we know it's really temperature increasechange relative to some datum?
2) why isn't there a standard datum ? ... 'cause every report wants to set itself apart from the others ?
3) whilst it's hard to see individual model predictions, i see a much more dynamic graph on the left compared with the reasonably monotonic right side ?
4) how quick untill someone mentions ... "the pause" ?

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
“we don’t have a temperature record for much more then 20+ years…beyond that you’re using proxies”

If you meant to say, “Anything before 1994 is a proxy”, you are wrong. Very wrong.

Most modern instrument records date back to 1850, however the accuracy of the 19th century data is suspect. Regardless, to call temperature data prior to the use of satellites (which was in the 70’s not the 90’s by the way) “proxy” is rubbish. It’s simply a case of “skeptics” going “I don’t like the facts, they must be false”. Despite claims made at a weather man’s blog, UHI does not have a significant impact on the temperature record as demonstrated by Berkley Earth and Space Team (BEST) and Li et al 2004, Jones et al 2008, Hausfather et al 2013, etc. Regarding the imprecision of measurements, this article explains how the size of the data set helps the overall precision.

The only thing I’ll say about the “hockey stick” is Mann et al 1998 was shown to have some issues with the statistical method used but, and the point that “skeptics” conveniently forget, the major results were still confirmed. Numerous paleoclimate studies have been conducted since Mann et al 1998 and they are in general agreement with each other – the recent rise in temperature is unlike anything seen in the Holocene. So, toss out Mann et al 1998 if you like, it doesn’t change a thing.

At this point, some may point to HadCET as a counter point. CET stands for Central England Temperature and that’s exactly (and all) that it is. While HadCET roughly agrees with BEST data, it contains wild year-to-year variability which is what you’d expect (and the problem with) taking such a small regional sample. For example, 2010 was the hottest year on record globally but it was the coldest year since 1986 for HadCET. So, while HadCET may have shown warm temperatures in the MWP, it is not indicative of the global temperatures. Furthermore, the warming during the MWP coincides with natural warming factors. The same natural factors were in a cooling phase during the recent warming. So not only was the MWP not as warm as today globablly, even if it was it would fail to explain the recent warming. In fact, it would suggest that the recent warming is even more anomalous.

I agree with Greglocock that paleoclimate temperature sets from earlier in the Holocene should be called “reconstructions”.

rb1957,
1) It’s an “anomaly” compared to the baseline. So it’s the exact same thing as a “change relative to some datum”.
2) I do agree there should be a standardized baseline period but it usually doesn’t matter because people talk about temperature change within some period. For example, when someone says “there’s been an X degree rise since 1970”, it doesn’t matter whether the data uses a baseline of 1951-1980 (used by NASA normally) or 1961-1990 (used by IPCC normally). Furthermore, the baseline selected does not influence the shape of the graph, which is really the important aspect of climate change. When people talk about temperature rise “since the pre-industrial period”, where the baseline does matter, the baseline is usually 1851-1900.
3) Left (hindcast) models have unpredictable elements such as ENSO, aerosols (anthropogenic and natural) input into them. Right (forecast) models do not and estimate what those might be. In the long run, these effects have little impact as they are either short term (volcanoes) or oscillate between warming and cooling (ENSO/PDO). So the “dynamics” you see in the hind cast is internal variability, while that is smoothed out in the forecasts.
4) The real question is How long until someone actually tries to substantiate or defend the “pause” as a valid argument against the 15+ times I’ve detailed why it’s not valid?…I’m not holding my breath on this one.


This takes us further away from the topic at hand, so let me repeat myself:

Quote (rconnor)

In order for the skeptic’s “do nothing” position to be satisfying, there needs to be a drastic change in the current scientific understanding, not just hoping it to be on the low end of the uncertainty. This was a key point to draw from LC14 which I’ve pointed out (…bringing us back on topic…). Even making every assumption possible to push the sensitivity down as far as they could, LC14 still leads to a TCR of 1.3 K, which is high enough to require mitigation efforts to limit future temperature rises. Using LC14’s value for TCR instead of the IPCC value, future impacts would be pushed out by 10 years. While this would make mitigation efforts more manageable, it still requires mitigation efforts.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

I misused hindcast in my previous. The three phases are learning/training, where the gains etc in a neural network or other adaptive system are being trained to follow the real data, hindcasting/testing, where the performance of the model is tested using data that was not part of the training set, and then forecasting/extrapolation, where the model is being used to predict some future state on the basis of modelled inputs.

If a model is stable and robust then it is useful to explore the sensitivity of the model to the break between learning and hindcasting. I'll do that on Tuesday on my silly curve fit to illustrate how it works. There is a more robust solution which I was taught as k-fold, in which you break the data set into k subsets, and then use various permutations of the k subsets for learning and testing.

That may not be appropriate for a model which relies on the previous years state as a basis for the current year, obviously the only memory in my silly curve fit is the year and the current co2 level, so it doesn't need to know what happens in the previous year. That is it will give an estimated temperature anomaly for any given date and co2 ppm.

Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

So to answer your question "3) whilst it's hard to see individual model predictions, i see a much more dynamic graph on the left compared with the reasonably monotonic right side ?"

Up until 2005 they are in their training and possibly hindcast phase. Due to the obfuscation of the chart you can't tell which, which is crucial. My guess is that they are training right up to 2005. from 2005 onwards they are using various predictions of CO2 levels.

If someone displays good correlation in the training phase it means either their model is good, or that they had enough knobs to turn. It is not in itself a guarantee of usefulness.

If someone displays good correlation in the hindcast or testing phase then they are demonstrating that the model is good at predicting outcomes for a given input set, and hence may be useful for predictions.

Therefore it is vital to differentiate between training, hindcast and forecast modes. Note what happens if you run no hindcast -you have no independent test of the model.


RCPs are different projections for CO2 etc concentrations, so they've driven eacch model with 4 different RCPs during the forecast phase. That's why the spread increases from 2005 onwards, up until then they use one set of historical record, then each is run for each of 4 scenarios. The danger is when people get a thick texter and draw a line through the middle of the spaghetti. GIGO.




Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

As to whether HADCRUT4 etc are data or models, let's read the very first para of the paper

http://www.metoffice.gov.uk/hadobs/hadcrut4/HadCRU...


Recent developments in observational near-surface air temperature and sea-surface temperature
analyses are combined to produce HadCRUT4, a new data set of global and regional temperature
evolution from 1850 to the present. This includes the addition of newly digitised measurement
data, both over land and sea, new sea-surface temperature bias adjustments and a more
comprehensive error model for describing uncertainties in sea-surface temperature measurements.


and a bit later on

with land data in unobserved regions reconstructed
using a method known as empirical orthogonal teleconnections


Which doesn't sound like JimBob went to his stephenson screen and wrote down the max min readings every day, to me

I'm not actually fussed by this aspect of it, but it does mean that any claims of a data driven temperature record back to 1850 should be taken with a large pinch of salt. Perhaps we merely differ in our definitions, by a model I mean data +assumptions, whether it is homogenizing, rebaselining, or as in the second quote, calculated from surrounding data.

This para also indictaes that swallowing the dataset whole might bite you

The differences in temperature analyses resulting from the various approaches is referred to as
“structural uncertainty”: the uncertainty in temperature analysis arising from the choice of
methodology [Thorne et al., 2005]. It is because of this structural uncertainty that there is a
requirement for multiple analyses of surface temperatures to be maintained so that the sensitivity of
results to data set construction methodologies can be assessed. The requirement for any given
analysis is to strive to both reduce uncertainty and to more completely describe possible uncertainty
sources, propagating these uncertainties through the analysis methodology to characterize the
resulting analysis uncertainty as fully as possible.


and of course there's this. This is good honest stuff, they've made some choices, and they need to understand what the resulting errors are

The assessment of uncertainties in HadCRUT4 is based upon the assessment of uncertainties in the
choice of parameters used in forming the data set, such as the scale of random measurement errors
or uncertainties in large-scale bias adjustments applied to measurements. This model cannot take
into account structural uncertainties arising from fundamental choices made in constructing the data
set. These choices are many and varied, including: data quality control methods; methods of
homogenization of measurement data; the choice of whether or not to use in situ measurements or
to include satellite based measurements; the use of sea-surface temperature anomalies as a proxy for
near-surface air temperature anomalies over water; choices of whether to interpolate data into data
sparse regions of the world; or the exclusion of any as yet unidentified processing steps that may
improve the measurement record. That the reduction of the four data sets compared in Section 7.4
to the same observational coverage does not resolve discrepancies between time series and linear
trends is evidence that choices in analysis techniques result in small but appreciable differences in
derived analyses of surface temperature development, particularly over short time scales.




Figure 8 here

shows what I'd expect to see, modern estimates have small error bounds, but even as recently as 1910 the total 95% confidence interval across both data sets is +/- 0.4 deg C for some years. It would be terrific to see the same graph back to 1850, and I wish they'd use an 11 (or more) year moving average rather than annual, I am not bothered by annual errors in the least.

Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

If nothing else, it pisses me off when someone states the debate is over, and congress debates and concludes for that time that it isen't so. And then to continue as if congress dosen't matter in the enacting of the laws. I just don't like some of these behind the scenes movements that can state the debate is over before the debate has even started.

How many of these posts have happened after the "debate" was declared over?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

"How many of these posts have happened after the "debate" was declared over?" ... pretty much all of them, IPCC delcared "game over" back in 2007.

"temperature anormaly" ... i queried this term based on the onomatopoeia of "anormaly" ... there's nothing anormal with temperatures changing, but the word anormaly suggests there's something wrong, anormal.

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
it's "anomaly" not "anormaly".

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

duely noted, without changing the sense of the observation ... anomaly suggests something abnormal, "something that deviates from the norm or from expectations".

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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)

Quote (rconnor)

It’s an “anomaly” compared to the baseline. So it’s the exact same thing as a “change relative to some datum”.
If you still don't like the use of the term "anomaly", what can I say, write a letter to the IPCC.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

I guess the debate is over, it's an "anomaly".

Like the theory that the world is round, there needs to be a time for inspection of the evedence, and counter theory, before you consiter any actions. And this just seems to be a rush because someone just noticed it.
And despite all the figures and facts given, I don't see all the other theories defeted yet.

I do see this Winter is seeming different from the last, so I buy that things might be changing. But is it better or worse, I've heard both.

I hear lava is flowing, will that make a difference?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)

Quote (GregLocock)

Perhaps we merely differ in our definitions, by a model I mean data +assumptions, whether it is homogenizing, rebaselining, or as in the second quote, calculated from surrounding data.
Fair enough. While each temperature data set makes certain assumptions and uses different methods to address infilling and other uncertainties, all data sets are in very close agreement with one another. I will note that the BEST data set was aimed at addressing “issues” with the other data sets from a skeptic point-of-view (Muller and Curry) and their results were also in-line with other data sets. So much so, that it erased many doubts in Richard Muller’s mind surrounding anthropogenic climate change. So if this is an attempt to discredit temperature data sets, it’s misguided. If it’s merely an attempt to highlight the uncertainty, ok.

Quote (crank108)

I guess the debate is over, it's an "anomaly".
What debate! Anomaly = change from the baseline. Who’s debating this? What’s confrontational about it?

Quote (cranky108)

I do see this Winter is seeming different from the last, so I buy that things might be changing.
That’s not how this works. Year to year changes mean nothing on their own. Saying “this Winter was warmer/colder than last winter. Therefore climate change is true/false” is nonsense in either direction. Weather variance and climate change are two different things.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

"I guess the debate is over, it's an "anomaly"." ... just because there's no counter post in something like 2hrs doesn't mean acceptance; just because there's no counter post mean imply acceptance (it probably indicates apathy).

anomaly would be the correct term if the graphs plotted temperature change compared to a non-CO2 enhanced atmosphere ... which would be pretty undefinable (unless we had an alternate universe to play with). to call "temperature change relative some arbitary datum" an anomaly just ascribes a negative context to the change ... but then i guess that's the intended message, so i'll leave this red herring where it is

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

If you are say the debate is not over, then you must not trust that 'Al Gore' is telling the truth.

I contend it may not be an "anomaly", but is unusual, or unexpected, or difficult to explain (Does that make you feel better about it)? So what!!!

This whole thing still seems to be a rush to a conclusion.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

damnit, that red herring has come back to life !

i think you've missed my point ... about calling a change from a datum as an anomaly. it is more correct IMHO to say "delta temperature" rather than "temperature anomaly".

does anyone know how to kill a zombie ? (for anyone who knows D&D, and i believe there's quite a few of you out there, i know it's a trick question; you can't kill a zombie)

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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Zombies are already dead.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

"Zombies are already dead." ... exactly, that's why you can't kill them.

"The guys on "Walking Dead" ..." ... yeah, but that's just hollywood ...

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

yeah, but it's all Hollywood

In any case, zombies aren't dead either, otherwise there would be no need to keep them from biting you. Rocks are dead, and they generally don't run down the street trying to clobber you.

TTFN
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Of course I can. I can do anything. I can do absolutely anything. I'm an expert!

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

what about the rock monster from (the original) star trek ?

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

You mean the "Horta?"

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

i think so, sounds right

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

I don't know about zombies being dead. I've seen a few out begging for money to feed their drug habit.

I've also seen a few rocks tumbling down the highway.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
Can I ask if anyone is willing to provide a defense of the usefulness of Lewis and Curry 2014 as a "better" estimate for sensitivity? Numerous people used it as the basis for arguing that sensitivity is not as high as expected. Upon closer inspection it contains significant biases (some I would say were done purposefully, while others are just inherent to the method used) that lead to artificially lower sensitivity values. Since that point, no one has offered a word in defense of LC14 (and Harde 2014, for that matter) or their original assertions.

Furthermore, there remains no evidence to support assertions that because sensitivity estimates are dropping over time, the "true" values are at or below the lower end of the IPCC range. Yes, recent energy budget model techniques have lead to lower values but that is mainly due to inherent cooling biases in the technique. Subsequent research only further solidifies the point that these techniques and papers are not appropriate to establish a "best estimate" for sensitivity. The bulk of estimates show no strong correlation of dropping or increasing overtime. What appears true is that estimates are continually in the IPCC range.

Beyond all of this, even if we take LC14's sensitivity as THE value for sensitivity (which is most certainly not true), it actually supports the need mitigation. Using LC14's value for TCR would mean that affects expected to occur in 2050 would, instead, occur in 2060. This is insignificant. Not only does this not, in any way, support the skeptic "do nothing" position, it actually works against it.

However, I feel that this too will be a "zombie" argument. One that has been debunked, never defended, but continually brought up again and again. I'm not asking for agreement, I am asking for a rational defense prior to repeating the same argument. If none exists, then it's possibly time to revisit your original assertions.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

how do you "defend" one estimate of a quantity over another ? they are "just" two estimates of an unknown. come back in 30 years and we might have a better idea

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
rb1957,

I would agree that the sensitivity estimate should not be argued paper-to-paper, method-to-method. When discussing sensitivity, you should incorporate all valid papers and all valid methods. That is exactly what the IPCC has done. That is not what "skeptics" have done. They pick papers like LC14 that match their beliefs and use that single (flawed) paper and single (flawed) method as the basis of their argument that sensitivity is lower than expected. You seem to disagree with this just as much as I do.

But given the fact that some want to use a single method as the basis of their argument, they must demonstrate why that method is superior to all the other methods out there. They must demonstrate why we should throw out the higher estimates and replace it with these lower estimates. They have done no such thing. In fact, the inverse has been demonstrated – that this single method (and single paper) is less valid than other methods for establishing a “best estimate” for climate sensitivity.

Not only have they not supported their viewpoint, they have not defended their (unsupported) viewpoint from criticism. Frankly, I don’t care if they choose to defend their viewpoint or not but it would be disingenuous of them to provide no defense now but then, in the next thread, bring back up this same argument. This would be a “zombie argument”.

(This doesn’t even touch on the fact that even if we accepting the LC14 value, it would not only not support the skeptic “do nothing” position, it would actually work against it. This “zombie argument” is wrong on so many levels…but nevertheless, I fully expect to hear it again and again and again.)

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Do you not also need to look at why the higher estimate models also have biases?

In your first analysis you gave just as much weight to a 1970s paper as to the result of 40 years with better data and better techniques. If you could tell me which of those data points was L&C I'll knock it out of the study and repeat it.

A point made previously still stands. if two analyses show estimates that do not overlap, they are not agreeing, they are disagreeing. At best one of them is right, it is possible that neither are right, what can't happen is that they are both right.

Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
You are arguing that the sensitivity is on the lower end of the scale because recent energy budget model techniques say so. What evidence have you brought forth to support that? Keeping in mind your evidence also needs to demonstrate why other techniques, which lead to higher values, are unsupported.

If I was saying the paper X says that TCR is 3.5 deg C, therefore sensitivity is higher than the IPCC expects, then you’d have a point. I’d have to explain why this method is more valid than the other methods.

However, I am not. I’m arguing that there is no evidence to suggest that the sensitivity should definitively be on the lower end of the scale. I’ve demonstrated this by showing that the estimates over time show no strong correlation of trending up or down. I’ve also gone one step further to demonstrate that the single technique you cling to that supports your position is flawed.

With regards to removing LC14 from the analysis (and Otto et al and Lewis 2013), it would do very little to improve the correlation, which is the crux of the matter. We’d still be left with a clump of data, some lower, some higher, most of which sits well within the IPCC range. This would continue to work against your assertion.

No, we don't have two equally valid estimates. What we have is a single technique that has been shown to contain significant flaws that lead to an artificially low sensitivity vs. the hundreds of other studies, spreading over numerous different techniques that, when taken together, support (well form, really) the IPCC range. The latter is much more valid than the former.

But your post was nothing more than an attempt to dodge the question. Do you have anything to defend your assertion that LC14 and other papers using the same energy budget model technique are superior to other techniques and papers such that it would suggest that climate sensitivity is definitively lower than previously estimated?

Your assertion, your requirement to support it.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

but does it matter ? if the lower estimate delays the world's doom by 10 years then i'd say the difference is pretty negligible.

but, personally, a average a bunch of estimates is not a very "scientific" thing to do. they are all determined by well meaning and humanly biased scientists (rconnor has suggested the L&C mayhave "nudged" their numbers to suit their opinion; having introduced that concept, is it unreasonable that other's may have also ?). each makes assumptions on a whole host of factors. none are "right" ('cept possibly one by superior intuition on the part of it's maker).

but if the range of the projected "doom" varies only by a few years then it really doesn't matter, IMHO. The accuracy on any estimate of "doom" can't by much less than a couple of decades. If the low end of the ramge suggested that "doom" might be postponed almost indefinitely then you'd have something to argue over.

in any case, it quickly won't matter what the US or Europe does. I expect CO2 output from China, India, and Brazil will dominate the US's and we won't a a rat's chance to affect their behaviour. Particularly if we've already committed economic suicide.

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Not too worry... WWIII will trump all concerns about climate change (aka global warming) and other extinction events... IMHO.
G-Pa Dave
pipe

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

I said I'd repeat the analysis for a variety of start years. Just for fun I've increased the projected CO2 content for 2100 to 740 ppm, approx, which is perhaps towards the high end of what the IPCC projects, and on the low end of what a capitalist would predict looking at SE Asia.

The major outcome is that a curve fitting technique based on 1850 onwards is remarkably insensitive to the precise fitting date, from 1960 to 2000, and the resulting anomaly varies only between 2.5 to 2.9 K at 2100 AD.

The estimated CO2 sensitivity is higher as more of the later data is incorporated into the model, curve fitting from 1850 to 1960 gives 2.1 K/doubling CO2, whereas curve fitting from 1850 to 2000 gives 2.3 K/ doubling. If the ENSO/PDO theory is right (not currently a good look, NASA says the upper half isn't warming enough, and the lower not at all) this will decrease as the 50/60 year ocean cycle takes effect over the next 30 years, we shall see. (More annoying data from NASA, average cloud cover has increased over temperate regions in the last 40 years, albedo effects tba)

It's interesting that the long term cycle seems to settle on 75 years, that is not a number I've come across in the literature. That may be a bias in my model, which explicitly assumes a K/doubling +sinusoid with a longish period .



I'll point out yet again, this is an exercise in curve fitting, not physics. Would that the the knob twiddlers would admit the same.

Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

isn't this how engineers approach a problem ? how accurately do we need to know various data ? which data have a strong impact on the result ?

from greg's graphs it looks like the sensivity can vary between 2.3 and 2.06 without much change in the output ... yes?

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)

Quote (rb1957)

but does it matter ? if the lower estimate delays the world's doom by 10 years then i'd say the difference is pretty negligible.
Replacing “world’s doom” with “negative impacts of climate change”, this is exactly my point, and one that skeptics ignore when talking about low sensitivity papers. Without mitigation, lower TCR estimates means very little in the grand scheme of things – we still have substantial increases in temperature and substantial impacts on the biosphere.

Quote (rb1957)

but, personally, a average a bunch of estimates is not a very "scientific" thing to do
You’re correct, that’s why the IPCC doesn’t do that. The “best estimate” from the IPCC (in AR4) was NOT the mean value between the various studies and techniques. It was established after evaluating the various studies and techniques. It’s also important to note that, outside of very simple climate models, sensitivity is an output, not an input.

Quote (rb1957)

If the low end of the range suggested that "doom" might be postponed almost indefinitely then you'd have something to argue over.
Yes, exactly (again, replacing “doom” with “negative impacts of climate change”).

Quote (GregLocock)

The estimated CO2 sensitivity is higher as more of the later data is incorporated into the model, curve fitting from 1850 to 1960 gives 2.1 K/doubling CO2, whereas curve fitting from 1850 to 2000 gives 2.3 K/ doubling.
You are attempting to calculate TCR, not ECS, with this simplistic (yet appreciated) technique. Values of 2.1 K or 2.3 K would be substantially higher than the usual “consensus” value of 1.8 K. Should I call up the Huffington Post and get them to write an article stating “Skeptic Analysis Shows Warming Worse Than We Thought!”? It would be fitting after the ceremonial parade LC14 got on skeptic blogs and right wing tabloids certain media outlets. However, we both know that this technique is far too simplistic to establish anything close to a “true” sensitivity value. That aside, I appreciate the work you put in.

But GregLocock, I do have to ask again, especially after your own analysis showed a TCR higher than the expected value, what evidence do you have to support your assertion that sensitivity is likely at or below the IPCC range?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
You're going to hang your hat on that correlation? R^2 of 0.08 (and ignoring the fact you changed the start period)? That's your evidence?

Even if we ignore the incredibly weak correlation, what does this correlation actually say about the "best estimate" of sensitivity?

Even if we ignore the jump in logic that an incredibly weak correlation means sensitivity estimates are trending towards a more valid, lower sensitivity, why are they more valid than other estimates and techniques that lead to higher sensitivity?

Forget more valid, are energy budget model techniques, on their own, valid at establishing a "best estimate"? How do you resolve the issues with the technique demonstrated in the original post?

How do energy budget model TCR estimates (1.3 K) match with your TCR estimates (2.1 K or 2.3 K)?

All-in-all, if your argument hinges on an R^2 of 0.08 (found AFTER you made your assertion, by the way) and offers nothing to link an incredible weak correlation to any form of explanation, I'm going to remain skeptical on the validity of your assertion.

But let's say I banged my head against my desk and woke up believing that LC14 contains the "best estimate" for TCR and agree with your assertion. What would change then? Nothing, really. Using a TCR of 1.3 K instead of 1.8 K, impacts would be pushed out by ~10 years. We'd still require mitigation efforts to reduce future temperature rises and negative impacts on the biosphere.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Good. Be skeptical. Be very skeptical. That's what this all about.

However you seemed to have swallowed holus bolus the idea that an increase in average global temperature is a bad thing. Apply some skepticism to that.


Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Incidentally wittering on about TCR and ECS in the context of this one line equation model is meaningless, there is no dynamic component in the long term model at all, so TCR=ECS.

Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
"Remain skeptical on the validity of your assertion" was a euphemism for "you have absolutely nothing to support your assertion".

(1) A correlation that is at best ridiculously weak (R^2=0.08) and at worst weakly opposite of your viewpoint (R^2=0.055 if using the original start date) is evidence of nothing. (2) It is evidence of nothing when there is no explanation to link the correlation to the assertion that sensitivity is at the lower end of the scale. (3) It is evidence of nothing when energy budget models that lead to the (ridiculously weak) negative correlation have been shown to contain significant flaws. (4) It is evidence of nothing when it is counter to your other analysis which shows that TCR is higher than the IPCC estimate (although I feel it is also flawed). (5) It is evidence of nothing when even if it were correct (which it's not) it would do nothing to support the "do nothing" position (in fact it would further emphasize the need for mitigation to limit future temperature rise).

You attempted to dodge the (five) issues with your assertion again. As it stands, you have no evidence to support your assertion. Beyond that, I have provided evidence that counters your assertion. Your assertion requires saving...or dropping. I can't stop you from dodging or ignoring the issues but it would be disingenuous to do so then repeat the same thing later on.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

here's why the R^2 of the straight line fit is so low. This is the average CO2 sensitivity for papers published in each decade , 1967-76 etc, plotted at the centre point of that decade. the error bars show the range of results in that decade.


Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
And how does this salvage your assertion or address any of the 5 issues with it? If anything it reinforces the fact that the correlation is far too weak, far too dependent on the start period and heavily influenced by flawed energy budget models at the end of the plot to establish anything credible.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
And when that stupid (and incredibly weak) straight line fit is apparently all the evidence you have to support your assertion, where does that leave you?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)

Quote (rconnor)

And how does this salvage your assertion or address any of the 5 issues with it?

Another attempt to steer the topic away in order to avoid addressing criticism of your assertion.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
Allow me to rephrase:

Another attempt to steer the topic away in order to avoid addressing criticism of your assertion. As I said before...

Quote (rconnor)

how does this salvage your assertion or address any of the 5 issues with it?

I should note that GregLocock needn't be the only one on the hook to attempt to salvage the assertion that "sensitivity estimates are likely lower than the IPCC range". Numerous people made this claim, none have offered a defense.

I'll outline what aspects need defending:

  1. GregLocock's own analysis leads to TCR values higher (2.1-2.3 K) than the IPCC best estimate of 1.8 K and much higher than the LC14 value of 1.3 K. So what are you arguing? That TCR is higher or lower than the IPCC estimate? (Should I assume "lower" and that you'll just forget about the other analysis?)
  2. There is no strong evidence to support a statement that "sensitivity estimates are dropping over time" (a R^2 of 0.08 is evidence of nothing...especially when the start date was adjusted to give a negative correlation)
  3. Even if a strong correlation existed, it does not logically follow that sensitivity estimates are trending towards a more accurate and lower value. Evidence is required to demonstrate how these lower estimates are "more valid" than other estimates and techniques. Nothing has been brought forward. Just because you like lower values more because they fit your ideological preferences doesn't make them more valid.
  4. Building on #3, evidence has been brought forward that demonstrates that LC14 (and other energy budget model techniques) are actually less valid. They are over simplistic models that contain numerous biases that lead to artificially low sensitivity values. While these methods may be applicable to establishing a lower bound, they are not valid as a "best estimate".
  5. Even if TCR was definitively 1.3 K (which it's not), it would mean that IPCC estimates for temperature rise would still be correct but would just be ~10 years early (i.e. impacts expected to happen in 2050 would, instead, happen in 2060). This is not a deal breaker and would still require mitigation to avoid future temperature rise.
Note that all of these issues are independent from the previous, so a defense of the assertion that "sensitivity estimates are likely lower than the IPCC range" needs to address all 5 points.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Your analysis only stands up if you assume that later models are no more accurate than earlier ones, and that the addition of more data does not improve the accuracy.

My analysis was not a physics based model, as I said, it was a curve fit. Unfortunately the models you are so keen on are also curve fitted.

Re you second point, yet you were quite happy to use an R^2 of 0.055 to prove you were right! I agree R^2<0.8 is dodgy. My decadal plot shows why using a straight line fit was stupid in the first place. You can't fit a straight line to a parabola like it shows.

You continue to assume that global warming would be a bad thing.

You continue to assume that keeping 6 billion people in poverty is defensible. Oddly enough they don't agree and are burning as much coal as they can.







Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)

Quote (GregLocock)

Your analysis only stands up if you assume that later models are no more accurate than earlier ones, and that the addition of more data does not improve the accuracy.
Again, you miss the point. I’m not arguing that TCR should be 2.3 K instead of 1.8 K. I’m arguing that the assertion “sensitivity is lower than the IPCC range” is wrong. My analysis shows that there is no substantial evidence to suggest that the true sensitivity is below the IPCC range (issue #2). That's all it needs to show.

Your entire argument is predicated around energy budget models (Otto et al 2013, Lewis 2013, Lewis and Curry 2014) being right and other methods being wrong. Not only is there no evidence to support this (issue #3) but there is evidence to support the antithesis of this (issue #4), namely that energy budget models are LESS accurate than other methods due to inherent biases and over simplifications that lead to artificially low values of TCR. Again, I’ll note that energy budget estimates are not straight up wrong – they could be a good double check of the ultimate lower bound. However, they cannot establish a “best estimate”.

Furthermore, using the most up-to-date data from Cowtan and Way 2013, Shindell 2014, Kummer & Dessler 2014 and Durack et al 2014, energy budget estimates would be much higher. Using Durack et al 2014 alone would increase the LC14 TCR value to 1.5 K. Applying Cowtan and Way 2013, which captures the warming in the Arctic that is missed by the poor coverage in that area by HadCRUT, would further up LC14’s TCR value. So your “up-to-date data” argument actually works against your assertion.

And none of this even begins to deal with issue #5, that even if issues #2 to #4 are defended, and the "true" TCR value is likely 1.3 K, it STILL doesn't support skeptic's "do nothing" position.

Quote (GregLocock)

My analysis was not a physics based model, as I said, it was a curve fit.
I agree that your curve fit to get a TCR of 2.3 K is flawed (mainly because it is overly simplistic). No argument here.

Quote (GregLocock)

Unfortunately the models you are so keen on are also curve fitted.
Wrong and off-topic. (...but...Parameterization is done and locked prior to running the GCM. Parameterization is therefore not done as a curve fit to past temperature. Parameterization is tuned to better match the physical representation of the system. “Tuning” cannot be done such that forces the system to react in ways that is inconsistent with observations and the reviewed literature, even if it were to lead to a more accurate temperature fit.)

Quote (GregLocock)

yet you were quite happy to use an R^2 of 0.055 to prove you were right!
Wrong. Purposefully ignoring what I’ve repeatedly said and replacing with nonsense. Here’s what I’ve said:

Quote (rconnor 13 Oct 14 14:13)

Regardless of the starting point or specific papers you choose, the correlation in any direction would be weak. As I said, "if nothing else, the results trend, more and more, within the IPCC range.

Quote (rconnor 15 Oct 14 17;46)

While one cannot definitively say that the trend is increasing (and admittedly my linear trend should never have been included), neither can one definitively say that the trend is decreasing. The correlation is far too weak.

Quote (rconnor 7 Nov 14 14:27)

The bulk of estimates show no strong correlation of dropping or increasing overtime.
I’ve continually stated there is no evidence to support a rising or falling trend. I don’t need to conclude the trend is rising as I’m not arguing that TCR is worse (higher) than the IPCC thinks, only that the IPCC range is accurate (which you are arguing against). All I need to show (and have shown) is that there is no evidence to suggest otherwise. But I’ve gone one step further to demonstrate that the papers that you cling to support your ideological preferences assertion are not valid as “best estimates”. Remember, it is your assertion that must be defended.

The last two lines are off-topic and just unsupported nonsense. If you are willing to admit that your assertion is wrong and sensitivity is likely in the IPCC range, then we can begin to talk about the consequences of a warmer planet. Alternatively, you could stop dodging the topic at hand and address the criticisms of your assertion.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

No this is what you actually said abut the graph when you posted it

"one cannot conclude that the results are trending to the lower end as this is unsupported by the data (in fact the inverse is supported by the data)"

So you claimed your data which should never had a straight line drawn through it in the first place, with an R^2 of 0.05, 'supports' your argument.


Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
I have since retracted the statement in parentheses in 3 subsequent posts, all of which I quoted again for you.

You continually pick the most minor, most irrelevant aspects of these posts to comment on and completely ignore the heart of the discussion. Now either address the criticism or quit wasting my time with this charade.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

The whole assertion that this is all merely "curve fitted," is belied by the very thing that some complain about, namely, the rather large spread in the predictions. If it were merely curve fitting, then this left-wing, pinko, commie conspiracy would simply agree on the value of temperature rise, and everyone would curve fit their way into the same predicted values. The fact that they don't, and can't, come up with the same answer points to the fact that it's not curve fitting, and that it's probably too complicated to do that anyway, even if they could.

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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)

Quote (GregLocock)

I think we’ve reached the end
Ok.

Disappointingly, you’ve offered nothing but attempts to obfuscate the argument and left us here:
  1. GregLocock's own analysis leads to TCR values higher (2.1-2.3 K) than the IPCC best estimate of 1.8 K and much higher than the LC14 value of 1.3 K. So what are you arguing? That TCR is higher or lower than the IPCC estimate? (Should I assume "lower" and that you'll just forget about the other analysis?) GregLocock has stated that his curve fit analysis is likely flawed. I would agree with him.
  2. There is no strong evidence to support a statement that "sensitivity estimates are dropping over time" (a R^2 of 0.08 is evidence of nothing...especially when the start date was adjusted to give a negative correlation)
  3. Even if a strong correlation existed, it does not logically follow that sensitivity estimates are trending towards a more accurate and lower value. Evidence is required to demonstrate how these lower estimates are "more valid" than other estimates and techniques. Nothing has been brought forward. Just because you like lower values more because they fit your ideological preferences doesn't make them more valid.
  4. Building on #3, evidence has been brought forward that demonstrates that LC14 (and other energy budget model techniques) are actually less valid. They are over simplistic models that contain numerous biases that lead to artificially low sensitivity values. While these methods may be applicable to establishing a lower bound, they are not valid as a "best estimate". Especially when incorporating the most up-to-date data and research (Durack 2014, Cowtan and Way 2013, etc.), the sensitivity estimates for LC14 (and other energy budget models) would be higher.
  5. Even if TCR was definitively 1.3 K (which it's not), it would mean that IPCC estimates for temperature rise would still be correct but would just be ~10 years early (i.e. impacts expected to happen in 2050 would, instead, happen in 2060). This is not a deal breaker and would still require mitigation to avoid future temperature rise.
As I stated, GregLocock is not the only one that’s argued “sensitivity is lower than the IPCC thinks!” Now that this argument has been shown to have serious and fundamental flaws, it’s not solely on GregLocock to defend it. Of course, no one HAS to defend it but it would be disingenuous to not do so but then parrot this argument again in a future thread (i.e. use a “zombie argument”). Furthermore, given that low sensitivity is crucial to the skeptic position, not having any proof supporting low sensitivity would be quite damaging to this position.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

OH, you can't stop

My summary is that since the IPCC was formed in 1988 the 10 year average peer review reported CO2 sensitivity has dropped consecutively since then. rconnor wishes to ignore the later findings, which of course makes any discussion of trends moot.

Irstuff- the whole point about the curve fitting is that the climate models are trained using some of the historical data.

The end.

Cheers

Greg Locock


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RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
GregLocock,

I was simply restating what you had been ignoring in case someone else wanted to take up a defense of the assertion that sensitivity is lower than expected. If you would like to leave the conversation, please feel free to do so. I would like to continue to discuss the topic as I feel it is important and central to the climate change debate.

Unsurprisingly, GregLocock’s latest response continues on the trend of ignoring the criticism put forth against your viewpoint:
“My summary is that since the IPCC was formed in 1988 the 10 year average peer review reported CO2 sensitivity has dropped consecutively since then” – See issue #2. This statement hinges on a R^2 of 0.08, which is evidence of nothing. Furthermore, GregLocock himself has stated “a straight line fit was a stupid idea”. I would agree that it is was a stupid idea by me in the first place (and have said so repeated after making the initial mistake). A linear trend without understanding the data points and what they mean is useless (see issue #3). But he then took that “stupid idea”, changed the start date and now uses it as his only support for his assertion.

”rconnor wishes to ignore the later findings” – See issue #4. There is a massive difference between ignoring findings (as GregLocock has done) and demonstrating that some findings are not as valid as others (as I have done, see the first post). LC14 and other energy budget model techniques are not valid for establishing a “best estimate”. Even without correcting for their inherent cooling biases (Shindell 2014, Kummer & Dessler 2014), if you incorporate up-to-date data (Durack et al 2014, Cowtan & Way 2013), these estimates are higher than first calculated.

”which of course makes any discussion of trends moot.” – See issue #3. In general, a blind trend is be evidence of nothing, unless you understand the data points and the larger context behind the data/trend. Specific to this case, an absurdly weak trend, skewed by flawed papers at the end of the trend, says NOTHING about the best estimate of sensitivity. So discussing (incredibly weak) trends in isolation of anything else (as GregLocock wants to) is moot because it’s unscientific and illogical. You need to introduce a broader understanding of topic in order to understand the trend. The second you do that (see issue #3, #4 and #5) it becomes clear that there is NO logical link between “Since 1988, sensitivity estimates have fallen with an R^2 of 0.08” to “sensitivity is lower than the IPCC estimates, so climate change will have no negative impacts in the future”.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
And yet more evidence to suggest that energy budget models are incapable of developing a best estimate for climate change – Andrews et al. (2014) (AMS Journal of Climate).

Overly simplistic energy budget models can only assume linear feedbacks. This assumption is inconsistent with the best understanding of the science at the moment. Andrews et al. (2014) demonstrates that feedbacks in GCMs are nonlinear and increase over time. From the abstract:

Quote (Andrews et al. (2014))

The nonlinearity is shown to arise from a change in strength of climate feedbacks driven by an evolving patter of surface warming. In 23 out of the 27 AOGCMs examined the climate feedback parameter becomes significantly (95% confidence) less negative – i.e. the effective climate sensitivity increases – as time passes.
Therefore, any method that assumes linear feedbacks, which all energy budget models do, would appear to lead to an artificially lower sensitivity value. This paper can be added to issue #3.

Now, Andrews et al. (2014) alone cannot definitively quantify the impact that (incorrectly) assuming linear feedbacks has on energy budget models. Optimistically, the impact of (incorrectly) assuming linearity could be negligible on the actual sensitivity value. I would expect that the assumption would have less impact on TCR (shorter time scales) than ECS. Also, if the word “model” or “GCM” causes your eyes to go blood shot with rage, you can completely ignore this paper. In any case, we are still left with issues #2 to #5 and nothing to support the assertion that sensitivity is lower than the IPCC range.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

"Overly simplistic energy budget models can only assume linear feedbacks. "

That itself seems an overly simplistic statement, but perhaps you mean to define the term "overly simplistic energy budget models" thereby?

I have built and run a number of models, using energy methods, which included a variety of non-linear dissipation variables. It's not rocket science, except when it is.

"Andrews et al. (2014) demonstrates that feedbacks in GCMs are nonlinear and increase over time."

Without some more in-depth reading into what drove that statement, it sounds like "my model is nonlinear, so it must be better". Wouldn't the real goal be to base those feedbacks on real physical phenomena? I.e. something you could model in laboratory scale.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
btrueblood, your points are well taken. I will expand upon some of those statements you question to hopefully address your comments. You can find LC14 here (full paper).

LC14 use the following formulas to calculate ECS and TCR:


These equations are, essentially, what all energy budget methods work off of. The paper states (on page 3, right below the TCR equation): “Both equations (1) [ECS] and (2) [TCR] assume constant linear feedbacks”.

Regarding your comment “my model is nonlinear, so it must be better”, that is not quite accurate. Paleoclimatology supports nonlinear feedbacks as well as GCMs. You cannot explain past climate changes if you assume linear feedbacks. So, linear feedbacks are not supported by our current understanding of the science, they are used as an assumption to simplify the problem.

As I stated, this might not have a great impact on TCR but it would seem to have an impact on ECS. However, I’m not 100% sure of how much impact it has. So, at best, assuming linearity is probably not correct but probably not that impactful on TCR values. At worse, it leads to artificially lower sensitivity values.

And remember, in order for the skeptic assertion to be comprehensive, the asserters need to demonstrate why energy budget estimates, which lead to lower sensitivity estimates, are more valid than other methods, almost all of which lead to higher sensitivity estimates. If nothing else, Andrews et al. (2014) (and Vernier et al. 2011, Durack et al. 2014, Cowtan & Way 2013, Shindell 2014, Kummer & Dessler 2014, etc…) put that into question, if not support the exact opposite.

(I do have a contention with your last point regarding a laboratory scale model. As it is off topic, and I’ve addressed it before (7 Mar 14 16:52, 11 Mar 14 14:25 and 12 Mar 14 12:58, look for comments directed to GregLocock ), I’ll just leave you with this question – how would you create a laboratory scale model to study the interdependent effects of ocean/atmosphere dynamics, prevailing wind patterns, changes in prevailing wind patterns, ocean currents, changes in ocean currents, cloud formation, changes in albedo, etc, such that the can adequately capture the dynamics of the earth’s climate system AND find a way to speed up those interactions such that you can see the impact in 100 years? I don’t believe it can be done. Instead, you’d attempt to break those systems up into subsystems, study them by analyzing observed behavior (past and present) and then take that knowledge into a model. That’s exactly what climate scientists are doing.)

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

"how would you create a laboratory scale model to study the interdependent effects of ocean/atmosphere dynamics, prevailing wind patterns, changes in prevailing wind patterns, ocean currents, changes in ocean currents, cloud formation, changes in albedo, etc, such that the can adequately capture the dynamics of the earth’s climate system" ... it's been done, or rather conceived of, in a rather amusing book (HHGTTG).

as for energy budget predictions vs GCM predictions, as an engineer I immediately like energy budget and if GCMs are incompatable with an energy budget i'd ask "where's the energy coming from ?". and as btb posted, those are very simple models, quite possibly too simple, and there's nothing (much) stopping someone from using a more complex model.

another day in paradise, or is paradise one day closer ?

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

Well, to argue the opposite, notice that the uncertainty band for the GCM's is ridiculously large, back up there in your first post. That the LC14 estimates (including the error band) of the ECR overlap the worst case error bands of the GCM's means you can't throw it out just because it gives a different (lower) number.

"You cannot explain past climate changes if you assume linear feedbacks." Based on, presumably, GCM's? And what database do you use to evaluate the models against these past climate changes, etc. etc. and on and on, off topic, ok I know, I'm raining on your parade and you'll p%55 all over me for it. But please just answer this: when the only argument that it must be nonlinear is because the competing computational method says it must be...is circular reasoning to some extent, is it not? Would not the best thing for the GCM advocates to do, would be to build an energy balance model that includes these nonlinear terms, to show us poor plebes how its done? There are ways to break an energy balance solution into smaller chunks, and evaluate the changes over smaller temperature intervals to see if the nonlinear terms show up again. But no, it's pointless, since the experts agree with you.

In the meantime, energy prices in places like the UP are skyrocketing, because utilities are not allowed (by Federal law, in order to maintain grid reliability) to shut down older, inefficient (and presumably high CO2 output) power plants, even though Federal law mandates, or will mandate, these shutdowns per the new EPA rules. I listened to a smarmy environmentalist saying it's the utilities fault, that they should have spent money to upgrade the power plants instead of fighting the new mandates...and thought "spoken like somebody who hasn't a clue how capitalism works". Yeah, I'm really ready to see how the new carbon taxes and/or cap & trade schemes work for me. Meanwhile, I still see an awful lot of BC tags down here in WA state, usually in line at the Costco station, filling up on gas.

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
LC14 uncertainty range overlaps with some GCMs - Yes, I've said from the beginning, while LC14 is on the low end, it's not entirely outside the IPCC range. Also, as I've said before, LC14 isn't inherently wrong IF your goal is establishing an ultimate lower bound. However, it is not applicable to establishing a best estimate due to the numerous issues raised in the first post. It’s important to note that these issues don’t simply introduce uncertainty, they introduce known and notable cooling biases.

Linear vs Nonlinear Feedbacks – It would be incorrect to say that nonlinear feedbacks are purely the outcome of GCMs. Nonlinearity of feedbacks can be easily observed in albedo. Recent observations of loss of sea ice are compared against paleoclimate reconstructions and, in both cases, the feedback of albedo change starts weak (little warming, little sea ice loss) and then strengthens (more rapid sea ice loss) before stabilizing at a higher point. Another example would be destabilizing of ocean currents that is noted as a key player in past climate changes and there are many more. While you need models to calculate the exact value of the forcing, you do not need models to know that it will be nonlinear.
Again, I stated that Andrews et al. (2014) highlights this but does not enable us to quantify the impact. So, the simplifying assumption that feedbacks are linear could have no notable impact or a notable cooling bias on LC14’s TCR value. I’m fairly confident, though not positive, that it does have a notable cooling bias on the ECS value as the nonlinearity of feedbacks is more noticeable further in the future (as per Andrews et al. (2014) and other studies).
Remember, the linear feedback assumption is only one of the many issues with LC14.
Also remember that if you have an issue with climate models, then you have an issue with LC14 in the first place as it too is dependent on models.
”There are ways to break an energy balance solution into smaller chunks, and evaluate the changes over smaller temperature intervals to see if the nonlinear terms show up again.” – This is difficult because one of the problems with an energy budget model is that it is greatly impacted by the reference period. Energy budget models are, more or less, about finding the slope of a straight line between two end points. The shorter the period, the more impactful the short term variability is and the greater the uncertainty. However, the longer the period, the less accurate the “straight line” assumption is. In either case, your choice of start “point” (it’s actually the average of a period) and end “point” greatly impact your results. As discussed, LC14 seems to pick points that lead to a lower sensitivity (anomalously low end point affected by aerosols and ENSO). One could just as easily pick points that lead to higher sensitivity (anomalously low start and anomalously high end) which would be equally invalid.
I completely agree with you that having a simple energy balance model that worked would be a great double check. However, they have problems. These problems may be minimized in time but LC14 is just too error-ridden with cooling biases to be valid as a best estimate. If LC14 fixed some glaring issues (incorporate Cowtan & Way and Durack, as well as fix the end point) then I wouldn’t be as dismissive of it, even though it would still have other issues (linear feedback assumption being one).
(Future Statement)”But GCMs have great amounts of uncertainty as well!” – Absolutely. But there are other methods for determining sensitivity than the output of GCMs and energy budget models. So wouldn’t the best way forward to take all the different valid techniques, across numerous reference periods, using different data sets to establish the most likely range for sensitivity? …kind of exactly like what the IPCC is doing?
And, as you have all ignored (except for rb1957), even if we take LC14 or the low end of the IPCC range at the “true” value for sensitivity, we are still left with temperatures approaching +3 deg C above pre-industrial periods without mitigation measures.

BC Tags in WA - Ya, been discussed a while back (21 Nov 13 16:57 and 27 Nov 13 15:37). TGS4 and I dug through quite a bit of data. Cross boarder trips were way up in BC but fuel consumption in WA actually went down over that same period. This pretty much disproves the anecdotal hypothesis that reductions in BC can be accounted for by increases in WA (or at least provides much more solid evidence than the “I see lots of BC plates” statement does).

RE: Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It

(OP)
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