A number of leading climate scientists have found that their opinions are incompatible with the conclusions of the IPCC. They have found it impossible to reconcile their scientific work with the IPCC, and so have resigned from the IPCC. Other IPCC authors find that when they express any criticism of the IPCC, they are not selected to write for the next report.
Landsea has worked on hurricanes for over 20 years and has over publications in the field. He took part in the second and third IPCC reports. He resigned from the IPCC in January 2005 over the issue of exaggerated claims of the influence of global warming on hurricanes, discussed previously. In his resignation letter, he stated "I am withdrawing because I have come to view the part of the IPCC to which my expertise is relevant as having become politicized. In addition, when I have raised my concerns to the IPCC leadership, their response was simply to dismiss my concerns." He added "All previous and current research in the area of hurricane variability has shown no reliable, long-term trend up in the frequency or intensity of tropical cyclones, either in the Atlantic or any other basin....It is beyond me why my colleagues would utilize the media to push an unsupported agenda that recent hurricane activity has been due to global warming." and concluded: "I personally cannot in good faith continue to contribute to a process that I view as both being motivated by pre-conceived agendas and being scientifically unsound."
Reiter is an expert in tropical diseases such as malaria. He was a contributing author to the WGII report of the TAR (2001) (chapter 9, dealing with impacts on human health). He found it impossible to work with lead authors who were not experts in the field, who were insisting on a link between climate change and diseases such as malaria, so he resigned from the IPCC process. He was interviewed for the Channel 4 programme, The Great Global Warming Swindle. He gave evidence to a US Senate Committee, launching a scathing attack on the IPCC: A galling aspect of the debate is that this spurious ‘science’ is endorsed in the public forum by influential panels of “experts.” I refer particularly to the Intergovernmental Panel on Climate Change (IPCC). Every five years, this UN-based organization publishes a ‘consensus of the world’s top scientists’ on all aspects of climate change. Quite apart from the dubious process by which these scientists are selected, such consensus is the stuff of politics, not of science. In a report to the House of Lords he wrote: "In my opinion, the IPCC has done a disservice to society by relying on "experts" who have little or no knowledge of the subject, and allowing them to make authoritative pronouncements that are not based on sound science. In truth, the principal determinants of transmission of malaria and many other mosquito-borne diseases are politics, economics and human activities."
Lindzen, Professor of Meteorology at MIT, has over 200 publications in meteorology and climate. He was a lead author on Chapter 7 of the IPCC TAR, published in 2001. Subsequently, in May 2001, he was critical of the Summary for Policymakers, which he said "misrepresents what scientists say" and "Exaggerates scientific accuracy and certainty". He also said that the IPCC encourages misuse of the Summary, and that the Summary does not reflect the full document, and that the final version was modified from the draft in a way to exaggerate man-made warming (all of these comments refer to the 2001 TAR, but as we have seen on these pages, are equally applicable to the 2007 AR4). Lindzen played no part in the writing of AR4.
Everett is an expert in fisheries and the oceans. He worked for the IPCC until 2000. In a statement to the US House of Representatives in 2007 he called for "a reality check" and said that "Warming is not a big deal and is not a bad thing". He has written a web site climatechangefacts.info that is highly critical of the IPCC.
Segalstad is a geologist and former IPCC expert reviewer. He also has a web site highly critical of the IPCC and climate alarmism.
Roger Pielke is an atmospheric scientist with over 300 publications. He was invited to write as a coauthor for the second IPCC report (1995), but his comments were ignored, so he resigned from "this clearly biased assessment process" and was not invited to take part in the 3rd or 4th reports. See his resignation letter. See also his comments for the IAC Review.