In a forthcoming paper in the Quarterly Journal of Economics, Meghan Busse and her co-authors ask if weather conditions affect car purchasing decisions. They find that the choice to purchase a 4x4 or convertible is highly dependent on weather conditions at the time of purchase, which is inconsistent with classical utility theory. Psychological biases such as projection bias and salience seem to explain their findings. The paper is available here.
The Berkeley Earth Project , an independent study of global warming, has found that the earth has become a degree warmer over the past half century. However, the statistical uncertainty surrounding pre-1920 estimates makes it very hard to say much about long-term trends - click here for graph . This is one of my concerns with the global warming debate - we simply don't have trustworthy long-run data which looks at temperature changes over the last millennium (or two). My second concern with the global warming debate is that it is very hard to prove any sort of casual link between global warming and human activity. The scientists may be able to show correlation between global warming and our production of carbon dioxides etc., but correlation is not causation. My third concern with the debate is that those who are sceptical or agnostic are stereotyped as flat-earthers or intellectually-challenged crackpots. This only stifles debate and the progress of science itself.