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electricpete (Electrical) (OP)
12 Jul 07 20:53
This thread is not about temperature or the possible link between man-produced CO2 and global warming.

It is about the simple question:  Has burning fossil fuels caused a measurable increase in greenhouse gases?

I thought this was a simple answer (yes... dramatic and irrefutable evidence in the ice cores that our CO2 has increased 25% in the last 150 years and is increasing at rate higher than any previous time in the 600,000+ year  history available to us through ice cores.).  But in another thread someone said it is absurd to claim that fossil fuels contribute to increase in greenhouse gases.

Opinions?

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

zdas04 (Mechanical)
12 Jul 07 21:28
That "someone" would be me.  My contention is that if you order the "greenhouse gases" by the magnitude of their impact on the environment, CO2 comes pretty far down the list, and the amount of that component that is from combustion is miniscule so my contention remains that it is absurd (i.e., the changes are not in the round-off error).

I came across an interesting bit of data about the ice cores--when folks say they prove anything in particular it is only after a huge amount of screening.  For example, they delete any data that includes a major volcanic erruption because those natural events that seem to happen about once a decade spike the data so much as to make all other years approach zero.

A motivated researcher can make any data say anything they want it to say.

David
GregLocock (Automotive)
12 Jul 07 21:53
I'd argue that burning fossil fuels (or making cement) probably increases CO2 concentration in the short term, but that the contribution is small in the overall context of the carbon cycle, and mostly increases the carbon cycle rate (GT/yr), as the feedback loop sets itself to a higher level. This is just standard chemical equilibrium equations at work.

As carbon dioxide concentration increases in the atmosphere, more plants grow, more plankton grow, more chalk gets laid down, more coral gets laid down, the concentration of carbon dissolved in the seas increases.

So what you need to know is whether the gain of the system, that is the lay down rate of carbon out of the atmosphere per increase in CO2 in the atmosphere, is sufficient to end up in equilibrium, or whether there is a run away effect.

Superimposed over this is that the CO2 concentration will affect the earth's albedo, to some extent, and the temperature change caused by this will cause a change in the capacity of plants, sea, and plankton, to absorb the CO2 and lay it down in carbon sinks.

But, generally, across the world, increasing temperatures increases the rate of uptake of CO2 by plants and plankton, so this is still part of the negative feedback loop. On the downside, increased temperatures will reduce the percentage of CO2 dissolved in the oceans.

This is fine in isolation, but it ignores three vital factors (1) water is by far the biggest greenhouse gas (2) solar activity varies  (3) the distribution of CO2 and water vapour vertically through the atmosphere has a crucial effect on the albedo.

As a matter of interest I saw "The Great Global Warming Swindle" on TV last night. It was book-ended by a lot of huffing and puffing from the usual suspects, since it was shown on our national socialist TV channel (grin). Neither side covered themselves in glory, in my opinion. The film maker himself had an agenda, and the fundamentalists looked as dodgy as fundamentalists usually do. The steam coming out of the interviewer's ears as the film-maker wound him up was the best single thing. Logic was in short supply.

Cheers

Greg Locock

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Ashereng (Petroleum)
12 Jul 07 22:23
I don't really know much about global warming, greenhouse gases, burning fossil fuel (actually, I do know this one, just not its effect on world climate change), etc.

So, I take a simplistic approach.

There are probably lots of reasons why green house gases are increasing:

1) we burn more fossil fuel, we creat more green house gas,
2) we cut down more trees than are grown, we do not get rid of as much green house gas

I see that the total crude consumption is going up, and I also hear green peace saying we are losing forests. I would guess then that green house gas levels are rising.

But, alas, your OP askes, is this measureable. I would guess probably not really measureable in the exact cause and effect way that I think your are asking. I think the whole issue probably has lots of factors - and I am not versed enough in them to know.

My uneducated opinion. smile

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
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mls1 (Electrical)
12 Jul 07 23:51
electricpete - thanks for starting this thread.  I think the liveliness of the discussion is evidence that we are all trying to sort this thing out.

". . mls1... I read your comments and apparently you also think it is absurd to claim any link between fossil fuels and the observed increase in CO2?"

No, I don't think that is an absurd claim.  Do I think it's true?  I'm not sure.  I think, as Ashereng says, there are many factors and it's not as simple as "we burn, level goes up, a -> b".  That does not prove causality.  

The ice core samples show CO2 levels constantly changing.  Some say CO2 lags temp others say it leads.  One thing seems certain, they are correlated.  But is it possible, for example, that there is an equilibrium with CO2 absorption in the ocean that shifts when temperatures change resulting in changes in the atmospheric concentration?  Thus, temperature causes CO2 levels not the other way?  Not saying this is the case but it seems plausible.

One possible flaw in the ice core data is that it assumes that entrapped air bubbles are perfectly preserved.  i.e. the measured CO2 concentration is exactly what the atmospheric concentration was during the period of entrapment.  Some dispute this assumption.

Another classic example of obvious logic that isn't so obvious is the deforestation claims.  I live in the US Pacific Northwest where from satellite images you can see vast swaths of clearcuts, so clearly we are suffering from deforestation, right?  Not exactly, the patterns seen from above are forests at different stages.  We clearcut the old growth many years ago and now have dense young forests.  So in reality we have denser forests than before resulting in massive forest fires that are getting worse each year.  

My last point, burning fossil fuels can not be good for the environment.  Even more importantly, hydro carbons are necessary for such things as the rubber in our car tires and the asphalt on our roads so some day we will realize it's too valuable to burn.  Nuclear, hydro, wind, wave, PV, etc. are the future and will become economically feasible.  So there are plenty of reasons to get off our addiction, but I'll continue to question conventional wisdom on climate change until causality is actually proven.
Tomfh (Structural)
13 Jul 07 1:20

Quote:

The steam coming out of the interviewer's ears as the film-maker wound him up was the best single thing. Logic was in short supply.

I had to turn it off. Good rational explanations were being offered, e.g. the nerdy bloke explaining why CO2 lags, and all the skeptics could manage was their usual gobbing off and name calling - going on about "how it's all a fraud".
jmw (Industrial)
13 Jul 07 6:03
In the rush to biodiesel, one eager country (which already has a very high CO2 contribution because of their deforestation, smoke from which causes severe problems to their neighbours)desperately wants to clear more of it for palm oil production.
Of course, these plantations would compete with other land use needs and also have a very deleterious affect on the wildlife. Indeed, the Orang Utang is already under threat from the original activities.
How will these plantations be established? by more slash and burn creating more CO2.
Why biodiesel? because it is "carbon neutral" Or is it?
If CO2 were unequivocally the major cause of AGW then is this the right answer? I don't think so.

In any event, we have plenty of arguments presented by both sides of the equation and each side persists in their viewpoint.

We are reminded that "He who is persuaded against his will is of the same opinion still." Can't remember who said it, but I guess it applies here since we have the same protagonists on each side  (me included)reduced to nothing more than presenting the same arguments as before as if repetition will win the day.

JMW
www.ViscoAnalyser.com

PSE (Industrial)
13 Jul 07 9:02
Personally, I would rather breathe the exhaust from trees rather than the exhaust from fossil fuel burning.  "Experts" still argue about the data supporting or refuting greenhouse gases and global warming.  Living here in the US even though I try to conserve, I undoubtedly (compared to others in the world) consume in comparison, an inordinate amount of the earth's resources in general.  Though I did just pull this up and am a bit surprised.

http://www.nationmaster.com/graph/ene_com_ene_use-energy-commercial-use

Granted, the US is the most populous of the nations in that "top ten".

This is more expected though not necessarily the second link.

http://www.nationmaster.com/graph/env_co2_emi-environment-co2-emissions

http://www.nationmaster.com/graph/env_pol_car_dio_fro_fos_fue_200_pergdp-fossil-fuels-2000-per-gdp


My larger concern is the nastier toxins that can be released in burning fossil fuels.  They have to go somewhere.  I live in a state where it is now recommended to eat a fish about once a month caught in native waters.  Clean the toxins out of the waters and then what do you do with it?  My concerns are more about our poisoning ourselves rather than overheating.

Regards,
KENAT (Mechanical)
13 Jul 07 11:50
Greg, one point I saw in I think it was National Geographic was that while plants are mostly made of Carbon, hence CO2 is the main ‘ingredient’ there are other minerals/chemicals they (including plankton) need to thrive.

Just increasing CO2 without providing adequate amounts of these other minerals won’t increase the rate of carbon absorption as much as you might otherwise expect.

If I recall they actually did some experiments where they determined which mineral was lacking and added additional.  This caused a slight growth increase but then turned out lack of another mineral limited it and so on and so forth.  

Also on the deforestation issue, while I’m inclined to be generally against if for numerous reasons there is an argument that a mature forest is pretty much carbon neutral.  The rate of decomposition of dead flora approximately matches the rate of growth of new.  So unless the conditions are such that a significant amount of the dead flora is being fossilized or harvested and turned into wooden goods with a significant life expectancy, the mature forests aren’t a massive long term carbon sink.

Now replacing them with deserts obviously would be a loss of carbon sink.  Even burning them down to replace with crops/grazing which don’t absorb as much net CO2 per acre is also reducing the sink.

KENAT, probably the least qualified checker you'll ever meet...

Comcokid (Electrical)
13 Jul 07 11:53
When talking about greenhouse gas increases and using fossil fuels, you always have to be clear about exactly which "fuel" you are talking about.

Burning coal, oil, or natural gas release carbon sequestered in past eons back into the environment and atmosphere. This is essentially new carbon into the environmental carbon cycle.

Burning bio-diesel, peat, or wood only slightly accelerates the return of carbon already in the active carbon cycle back into the environment. Some say that rising temperatures could cause large amounts of methane ice on the sea bottoms to boil back into the environment, but even this represents carbon that has been out of the loop only a short time in geological terms.

One other complication of all the fossil fuel consumption and potential global warming impact which has only been realized in the past few years is - - - soot. Burning fossil fuels, especially coal, diesel, or wood through inefficient means releases soot and particles into the atmosphere. However recent studies have shown such atmospheric particles are very effective at blocking sunlight and re-radiating infrared radiation back into space! This effect may be almost totally offsetting potential warming effects of greenhouse gasses.

No doubt, there are other secondary effects that need more study that could affect warming one way or the other. The media and politicians look for simple sound-bytes or two word slogans (Greenhouse Gasses! Fossil Fuels!). Some scientists are now caught up in the emotional frenzy and have left scientific methods behind. But the actual issues are complex and don't surrender easily to quick statements.
jmw (Industrial)
13 Jul 07 12:15
Re particulates, see Global Dimming
http://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_prog_summary.shtml
http://www.globalissues.org/EnvIssues/GlobalWarming/globaldimming.asp
It is alleged that this is masking the full effects of global warming. (unfortunately, we are more successful at reducing particulates than we are CO2-- SOX from fossil fuels at one time contributed 33% to the atmospheric SOX. In the last 10 years or so we have reduced that significantly through using low sulphur fuels.
This is relevant to the Global Dimming report since dimming effect is said to be created by fossil fuel burning.

JMW
www.ViscoAnalyser.com

dcasto (Chemical)
13 Jul 07 16:15
PSE, don't be concerned about the fish and pollutants, those warnings are to protect the government from being sued, like warning lables on hot coffee.  Swordfish 100 miles out have more Hg than any tuna and man is not dumping free Hg 100 miles offshore.  

I have the same signs on lakes where I live and the problem is from the errosion from the streams leaching out heavy metals during the normal cycles.  Some want to blame 100 year old mines and such, but the rock is still exposed whether from man, machine or nature.  The real problem is that the toxins have always been there, its just that we have the technology to find them now.  It's like the tornado thing in Denver.  Growing up we had no tordanos but today we have them, must be man building things, Nope, there were always tornados, but until we built an airport in Kansas (or so it seams), we now have "found them".

I entered a study in 1974 to see what Moly-be-dam has on humans because our water was downstream of mines.  We are all fine.

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