As promised to Ron Cram, I am creating this post to discuss Allegre’s skeptic turn and the reasons for it.
Here is an excerpt from the NP article:
Fifteen years ago, Dr. Allegre was among the 1500 prominent scientists who signed “World Scientists’ Warning to Humanity,” a highly publicized letter stressing that global warming’s “potential risks are very great” and demanding a new caring ethic that recognizes the globe’s fragility in order to stave off “spirals of environmental decline, poverty, and unrest, leading to social, economic and environmental collapse.”
So we have a bona fide AGW supporter who signed the letter regarding the threat of global warming. Here is his current stance:
Calling the arguments of those who see catastrophe in climate change “simplistic and obscuring the true dangers,” Dr. Allegre especially despairs at “the greenhouse-gas fanatics whose proclamations consist in denouncing man’s role on the climate without doing anything about it except organizing conferences and preparing protocols that become dead letters.” The world would be better off, Dr. Allegre believes, if these “denouncers” became less political and more practical, by proposing practical solutions to head off the dangers they see, such as developing technologies to sequester C02. His dream, he says, is to see “ecology become the engine of economic development and not an artificial obstacle that creates fear.”
Much is made of his socialist politics and his credentials as a scientist.
“…he is an exalted member of France’s political establishment, a friend of former Socialist president Lionel Jospin, and, from 1997 to 2000, his minister of education, research and technology, charged with improving the quality of government research through closer co-operation with France’s educational institutions. For another, Dr. Allegre has the highest environmental credentials. The author of early environmental books, he fought successful battles to protect the ozone layer from CFCs and public health from lead pollution. His break with scientific dogma over global warming came at a personal cost: Colleagues in both the governmental and environmental spheres were aghast that he could publicly question the science behind climate change.”
Clearly, this is an appeal to authority, but that’s OK since the previous article I linked to did the same when referring to a former skeptic who turned AGW supporter.
So what evidence turned him to a skeptic?
Increasing ice in Antarctica, and the fact that the retreat of Kilimanjaro’s snow was due to natural causes, not global warming.
Of course, my immediate response is that I’ve read the increase in ice in the center of Antarctica is explained by the increase in the moisture content of the air due to warming oceans… As to the snows of Kilimanjaro — well, what about other glacier retreats that aren’t the result of natural variations?
In the end, I’m left with this question: How does one sum up all the evidence, pro and con? Is it a simple matter of maths? 15 glacier retreats vs 4 increasing ice masses vs 4 errors in various databases vs 2000 scientists signing a petition vs 500?
What is the acid test? Is it Hansen’s reference to tempest in tea pot domes? Lights being out? “Mike’s Nature Trick”? “Hide the decline”? SSTs? Satellite data? Ocean temperature anomalies? Ice core CO2 data?
What does it for you?