The American Physical Society, an organization representing nearly 50,000 physicists, has reversed its stance on climate change and is now proclaiming that many of its members disbelieve in human-induced global warming. The APS is also sponsoring public debate on the validity of global warming science. The leadership of the society had previously called the evidence for global warming "incontrovertible."

In a posting to the APS forum, editor Jeffrey Marque explains,"There is a considerable presence within the scientific community of people who do not agree with the IPCC conclusion that anthropogenic CO2 emissions are very probably likely to be primarily responsible for global warming that has occurred since the Industrial Revolution."

The APS is opening its debate with the publication of a paper by Lord Monckton of Brenchley, which concludes that climate sensitivity — the rate of temperature change a given amount of greenhouse gas will cause — has been grossly overstated by IPCC modeling. A low sensitivity implies additional atmospheric CO2 will have little effect on global climate.

Larry Gould, Professor of Physics at the University of Hartford and Chairman of the New England Section of the APS, called Monckton's paper an "expose of the IPCC that details numerous exaggerations and "extensive errors"

In an email to DailyTech, Monckton says, "I was dismayed to discover that the IPCC's 2001 and 2007 reports did not devote chapters to the central 'climate sensitivity' question, and did not explain in proper, systematic detail the methods by which they evaluated it. When I began to investigate, it seemed that the IPCC was deliberately concealing and obscuring its method."

According to Monckton, there is substantial support for his results, "in the peer-reviewed literature, most articles on climate sensitivity conclude, as I have done, that climate sensitivity must be harmlessly low."

Monckton, who was the science advisor to Britain's Thatcher administration, says natural variability is the cause of most of the Earth's recent warming. "In the past 70 years the Sun was more active than at almost any other time in the past 11,400 years ... Mars, Jupiter, Neptune’s largest moon, and Pluto warmed at the same time as Earth."

But since 1999 new evidence has seriously weakened the case that carbon emissions are the main cause of global warming, and by 2007 the evidence was pretty conclusive that carbon played only a minor role and was not the main cause of the recent global warming. As Lord Keynes famously said, "When the facts change, I change my mind. What do you do, sir?"

2. There is no evidence to support the idea that carbon emissions cause significant global warming. None. There is plenty of evidence that global warming has occurred, and theory suggests that carbon emissions should raise temperatures (though by how much is hotly disputed) but there are no observations by anyone that implicate carbon emissions as a significant cause of the recent global warming.