"MIT’s Richard Lindzen is one of the world’s leading climate scientists. He is also a climate 'skeptic,' rejecting claims that anthropogenic emissions of greenhouse gases are likely to create a climate catastrophe. Above all others, he is the climate skeptic environmental activists most fear, as he has unimpeachable credentials. As a prominent climate scientist who believes global warming could cause an environmental catastrophe confided to me, Dr. Lindzen’s views are not easily dismissed, even if his views are somewhat outside the 'mainstream' of climate science. (Of course, we may have to reconsider what constitutes 'mainstream' climate science after the leak of e-mails and other documents from the University of East Anglia’s Climate Research Unit.)"
http://volokh.com/2009/12/01/mits-lindzen-on-climategate/