Look: Trying to argue that AGW does not exist puts you on the wrong side of current science. Is there a possibility it’s wrong? Sure. Science is never a closed book. We could discover a new mechanism tomorrow that better explains temperature changes over time, and be forced to revise the models. But that’s true for anything in science. You must always keep your mind open.
However, the data we have as of this minute very strongly suggests that CO2 is a significant driver of climate, and we have hard measurements showing that CO2 levels are rising fairly rapidly.
i spent last night going to the actual GISS data and some of the other datasets, and plotting them against Hansen’s original climate models. Do they diverge from time to time? Yes. In fact, they are diverging right now - I could post the graph I’ve got here, where I took the recorded measurements since the 2005 article that was linked above and added them to the graph, then plotted 5-year, 7-year, 9-year, and 11-year means across the data to smooth it a bit.
Right now, the climate appears to be trending more towards Hansen’s ‘C’ curve, which he says could only happen there were drastic cuts in CO2. So that would appear to refute his model. And lots of anti-AGW people are using the cooling seen in the past five years as a refutation of global waming. However, there’s a deviation at least as large in the period between 1991 and 1995, but it eventually corrected itself and by 1996 the temperature predicted by the model was again very close to the measured temperatures.
My conclusion from this is that the model has not been refuted, but that there is so much noise around the trend lines that it hasn’t been confirmed, either. But we have to be honest and say that with the data we have so far, the model is at least holding up reasonably well.
If the temperature continues to fall or remain steady for the next five years, the model will be in big trouble, because the spread between the model and the measured data will be so large that it can’t be explained by annual variance. Right now, it can.
My concern is that the response of pro-AGW people has been essentially to treat all the data as confirmation. When a glacier would show signs of melting, that was trumpeted as proof of global warming. If a glacier was found to be growing in size, someone would trot out a study saying that global warming could increase glacier size in some places, so it was proof of global warming. When it became clear that there has been no warming for the past few years, the term itself was dropped in favor of ‘climate change’. If changing climiate is proof of global warming, it’s unfalsifiable, and therefore not science. Climate always changes.
What I’d like to hear from the AGW side is what data they would accept as proof that global warming models are wrong. If it’s cooler ten years from now than it was in 2000, would that be proof? If not, how come the fact that it was warmer in 2000 than it was in 1990 was considered to be proof that AGW exists? Bad science exists on both sides of the debate (not necessarily among the scientists in question, but by the more politically-oriented boosters or naysayers on both sides).
Finally, here’s my biggest problem with the global warming movement - there is a HUGE excluded middle in the debate. The way the debate has shaped up, it seems that the only question is whether or not AGW exists. If it does, then that is taken as all the justification needed for radical changes to our industrial economy. But there is a large gap between, “AGW exists”, and “what should we do about it?”
Both sides seem to have a vested interest in avoiding that debate. The anti-AGW side doesn’t want to concede that the problem even exists, so they have no desire to talk about solutions. the pro-AGW side wants to maintain a direct linkage between the fairly solid evidence that AGW exists and any policy they might want to implement, and would rather not talk abou things like the real effects of global warming, whether fixes cost more than the problem, how much money should be spent today to fix a problem 50 years down the road, etc. Because once you get past the basic claim that AGW exists, the science gets a lot more fuzzy and some of the claims scientists and politicians are making are on much weaker ground. So the pro-AGW side would rather treat the debate as binomial - either AGW exists, in which case any policiy floated to stop it is a good one, or it doesn’t exist.
We should get past that debate. The anti-AGW people should stop fighting what is fairly solid science, and start engaging on the much more complex and nuanced issue of what a rational policy towards it should be.