Regarding the falsifability of the CAGW theory, the major tenet of the theory is the energy imbalance that is empirically demonstrated through satellite observations. We also know the outgoing long wave radiation is lower at wavelengths associated with CO2 absorption
(Harries 2001) and radiative surface forcing has increased at wavelengths associated with CO2
(Evans 2006). We also know the global temperature has risen since the industrial revolution (yes, with a slow down over the last 16 years, I’ll get to that). Neither of these are points of contention for scientists in the field, on BOTH sides of the fence (it’s the magnitude of the effect that CO2 has on the temperature, or climate sensitivity, that is point of contention).
If the greenhouse gas theory was overturned, then the CAGW theory would be falsified. However, it is important to note the difference between the greenhouse gas theory and how it affects the complex global climate, climate sensitivity. The former can, and has, been tested, and verified, in laboratory (physical, not model) simulations as well as through satellite spectroscopy.
The CAGW theory can also be falsified if the premise that the greenhouse gas effect, caused by anthropogenic CO2 emissions, is not a significant driver in the global climate change. Now, many here will jump on this and say “ah ha, it has been “proven” to not be a significant driver; therefore you’ve admitted the CAGW theory is falsified”. This is not true. When discussing a subject that cannot be easily proven or disproven by a simple lab experiment, a consensus is formed through a body of evidence resulting from years of research and hundreds (or thousands) of papers and the theory is not falsified by an equally robust body of evidence. If, for example, the argument that “it’s the sun” gains a body of evidence explaining the recent warming more accurately than the CAGW theory, then it could become the leading theory. However, as it currently stands, that is not the case.
If you argue that “the consensus shouldn’t matter, it’s what nature shows that is important (and insert the Feynman quote)”. As I stated above, the scale and complexity of the problem means that you can’t create an experiment to test the theory. Our only test is what is actually happening around us. Again, many will jump on this and say “ah ha, it hasn’t warmed in X years; therefore, by your very definition, nature has proven the CAGW theory wrong”. Again, this is not true. Surface temperatures have not raised that much in the past 16 years, true. However, we (1) still have an energy imbalance and (2) we are starting to do more research into ocean temperature changes which show that deep oceans appear to be heating up. We’ve also continued to see Arctic ice extent, ocean acidification as well as a slew of other environmental affects predicted by CAGW.
I would also argue, as Brad1979 has, that although there has been a recent slowdown in the rate of warming as of late, it still falls within the IPCC predicted range. Just because you refuse to click the link, doesn’t make it go away. If you’re so fussy about Skeptical Science, here’s from
another site or a link to the paper
Foster and Rahmstorf 2012. And no one is arguing that these models are perfect, as more research comes in and our understanding grows, the models improve. However, no body of evidence has completely reversed the temperature trend, they just push the slope of the line up or down a bit.
On a closing note, TGS4, I agree that “denier” is a rather “charged” term, I think it just further polarizes the debate. However, I’m also fed up with terms like “believer”, “alarmist”, “AGW religion” and “bow to the altar of AGW”.