Richard Siegmund Lindzen (born 1940) is an atmospheric physicist and a professor of meteorology at MIT renowned for his research in dynamic meteorology, especially atmospheric waves. He is a member of the National Academy of Sciences and held positions at the University of Chicago, Harvard University, and MIT. He was a lead author of Chapter 7 [1] of the IPCC Third Annual Report. He frequently speaks out against the IPCC position that significant global warming is caused by humans (see anthropogenic global warming).

Table of contents
1 National Academy of Sciences panel
2 Wall Street Journal 2001
3 IPCC Policymakers Summary criticism
4 Letter to his town mayor, 2003
5 Links

National Academy of Sciences panel

Lindzen served on an 11-member panel [1] organized by the National Academy of Sciences. The panel's report, titled Climate Change Science: An Analysis of Some Key Questions[1], has been widely cited as evidence that leading scientists believe in global warming.

Indeed, the first paragraph of the report summary states,

"Greenhouse gases are accumulated in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise. Temperatures are, in fact, rising. The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes is also a reflection of natural variability."[1]

Wall Street Journal 2001

Subsequently, however, Lindzen wrote an article for the Wall Street Journal [1] (June 11, 2001), which insisted that "there is no consensus, unanimous or otherwise, about long-term climate trends or what causes them" and "we are not in a position to confidently attribute past climate change to carbon dioxide or to forecast what the climate will be in the future."

Indeed, he pointed out

"As usual, far too much public attention was paid to the hastily prepared summary rather than to the body of the report. The summary began with a zinger -- that greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise, etc., before following with the necessary qualifications. For example, the full text noted that 20 years was too short a period for estimating long-term trends, but the summary forgot to mention this."

IPCC Policymakers Summary criticism

Lindzen worked on IPCC Working Group 1, Chapter 7, which is the section which considers the physical processes that are active in real world climate. Lindzen stated in May 2001 [1] that the IPCC summary does not support the full document: see IPCC. Lindzen further criticized the IPCC for alterations to the Policymakers Summary of its 2001 global warming report, saying:

The draft of the Policymakers Summary was significantly modified at Shanghai. The IPCC, in response to the fact that the Policymakers Summary was not prepared by participating scientists, claimed that the draft of the Summary was prepared by a (selected) subset of the 14 coordinating lead authors. However, the final version of the summary differed significantly from the draft. For example the draft concluded the following concerning attribution:

From the body of evidence since IPCC (1996), we conclude that there has been a discernible human influence on global climate. Studies are beginning to separate the contributions to observed climate change attributable to individual external influences, both anthropogenic and natural. This work suggests that anthropogenic greenhouse gases are a substantial contributor to the observed warming, especially over the past 30 years. However, the accuracy of these estimates continues to be limited by uncertainties in estimates of internal variability, natural and anthropogenic forcing, and the climate response to external forcing.

The version that emerged from Shanghai concludes instead:

In the light of new evidence and taking into account the remaining uncertainties, most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations. [1]

Editorial note: The "30 years" period begins at 1970, near the start of the warming trend. The IPCC Shanghai version's "50 years" period of "observed warming" begins in the midst of the 1945-1975 cooling period before the warming trend[1].

However, the NAS panel on which Lindzen served (see above) said [1]:

"The committee finds that the full IPCC Working Group I (WGI) report is an admirable summary of research activities in climate science, and the full report is adequately summarized in the Technical Summary. The full WGI report and its Technical Summary are not specifically directed at policy. The Summary for Policymakers reflects less emphasis on communicating the basis for uncertainty and a stronger emphasis on areas of major concern associated with human-induced climate change. This change in emphasis appears to be the result of a summary process in which scientists work with policy makers on the document. Written responses from U.S. coordinating and lead scientific authors to the committee indicate, however, that (a) no changes were made without the consent of the convening lead authors (this group represents a fraction of the lead and contributing authors) and (b) most changes that did occur lacked significant impact."

Letter to his town mayor, 2003

In September 2003 Lindzen wrote an open letter to his town mayor [1], putting his opinions on global warming. He says "...the temperature rise seen so far is much less (by a factor of 2-3) than models predict...". This statement is, however, false: see climate model.