http://mises.org/daily/2571

Let's call this exhibt A in My argument.

David Evans a mathmetician by definition a scientist had this to say:

I devoted six years to carbon accounting, building models for the Australian government to estimate carbon emissions from land use change and forestry. When I started that job in 1999 the evidence that carbon emissions caused global warming seemed pretty conclusive, but since then new evidence has weakened that case. I am now skeptical.


This evidence was not conclusive, but why wait until we are absolutely certain when we apparently need to act now? So the idea that carbon emissions were causing global warming passed from the scientific community into the political realm. Research increased, bureaucracies were formed, international committees met, and eventually the Kyoto protocol was signed in 1997 to curb carbon emissions.

The political realm in turn fed money back into the scientific community. By the late 1990s, lots of jobs depended on the idea that carbon emissions caused global warming. Many of them were bureaucratic, but there were a lot of science jobs created too.

I was on that gravy train, making a high wage in a science job that would not have existed if we didn't believe carbon emissions caused global warming. And so were lots of people around me; there were international conferences full of such people. We had political support, the ear of government, big budgets. We felt fairly important and useful (I did anyway). It was great. We were working to save the planet!

Better data shows that from 1940 to 1975 the earth cooled while atmospheric carbon increased. That 35 year non-correlation might eventually be explained by global dimming, only discovered in about 2003.

The temporal resolution of the ice core data improved. By 2004 we knew that in past warming events, the temperature increases generally started about 800 years before the rises in atmospheric carbon. Causality does not run in the direction I had assumed in 1999 — it runs the opposite way!

There is now a credible alternative suspect. In October 2006 Henrik Svensmark showed experimentally that cosmic rays cause cloud formation. Clouds have a net cooling effect, but for the last three decades there have been fewer clouds than normal because the sun's magnetic field, which shields us from cosmic rays, has been stronger than usual. So the earth heated up. It's too early to judge what fractionThere is now no observational evidence that global warming is caused by carbon emissions. You would think that in over 20 years of intense investigation we would have found something. For example, greenhouse warming due to carbon emissions should warm the upper atmosphere faster than the lower atmosphere — but until 2006 the data showed the opposite, and thus that the greenhouse effect was not occurring! In 2006 better data allowed that the effect might be occurring, except in the tropics. of global warming is caused by cosmic rays.

None of the new evidence actually says that carbon emissions are definitely not the cause of global warming, there are lots of good science jobs potentially at stake, and if the scientific message wavers then it might be difficult to later recapture the attention of the political system. What has happened is that most research efforts since 1990 have assumed that carbon emissions were the cause, and the alternatives get much less research or political attention.