Via Stephen Hayward at Planet es word of another scientist off the “consensus” reservation. According to David Evans (who, according to his bio, is a genuine rocket scientist – sweeeet…), “… in 1999 the evidence that carbon emissions caused global warming seemed pretty conclusive, but since then new evidence has weakened the case that carbon emissions are the main cause. I am now skeptical. As Lord Keynes famously said, ‘When the facts change, I change my mind. What do you do, sir?'”

Evans does a great job of laying out why the science on the issue of climate change is not settled, and also notes the potential dangers of the current “consensus”:

The evidence is not currently conclusive either for or against any particular cause of global warming. I think that it *is* possible that carbon emissions are the dominant cause of global warming, but in light of the weakening evidence I judge that probability to be about 20% rather than almost 90% as estimated by the IPCC.

I worry that politics could seriously distort the science. Suppose that carbon taxes are widely enacted, but that the rate of global warming increase starts to decline by 2015. The political system might be under pressure to repay the taxes, so it might in turn put a lot of pressure on scientists to provide justifications for the taxes. Or the political system might reject the taxes and blame science for misinforming it, which could be a terrible e for science because the political system is powerful and not constrained by truth.

Some people take strong rhetorical positions on global warming. But the cause of global warming is not just another political issue that is subject to endless debate and distortions. The cause of global warming is an issue that falls into the realm of science, because it is falsifiable. No amount of human posturing will affect what the cause is. The cause just physically is there, and after sufficient research and time we will know what it is.

Perhaps the best thing about this post is that es as part of a civil, rational debate about the merits of climate science, something that is sorely lacking in the current highly politicized climate. This sort of exchange is an encouraging sign that rationality may win out over hysteria in the end.