Comment On “An Open Letter from Scientists in the United States on the Intergovernmental Panel on Climate Change and Errors Contained in the Fourth Assessment Report: Climate Change 2007”

The March 23 2010 issue of the AGU publication EOS has an article by Kaitlin Chell titled “Scientists’ Letter Supports Climate Change Panel“.  This article is headlined in a section title “About AGU” and the story also includes the link to the AGU position statement on climate change [http://www.agu.org/sci_pol/positions].

The Letter that is reported on by the AGU is titled

An Open Letter from Scientists in the United States on the Intergovernmental Panel on Climate Change and Errors Contained in the Fourth Assessment Report: Climate Change 2007

and is written to support the IPCC process (although it makes recommendations to improve the process).

The Letter starts with

“Many in the popular press and other media, as well as some in the halls of Congress, are seizing on a few errors that have been found in the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) in an attempt to discredit the entire report. None of the handful of mis-statements (out of hundreds and hundreds of unchallenged statements) remotely undermines the conclusion that “warming of the climate system is unequivocal” and that most of the observed increase in global average temperatures since the mid-twentieth century is very likely due to observed increase in anthropogenic greenhouse gas concentrations. Despite its excellent performance for accurately reporting the state-of-the-science, we certainly acknowledge that the IPCC should become more forthcoming in openly acknowledging errors in a timely fashion, and continuing to improve its assessment procedures to further lower the already very low rate of error.”

The list of signatories documents those who support this Letter and its content including the statement

“that most of the observed increase in global average temperatures since the mid-twentieth century is very likely due to observed increase in anthropogenic greenhouse gas concentrations.”

The above statement, of course, is hypothesis 2b in our paper

Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell,  W. Rossow,  J. Schaake, J. Smith, S. Sorooshian,  and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union.

Hypothesis 2b reads

“Although the natural causes of climate variations and changes are undoubtedly important, the human influences are significant and are dominated by the emissions into the atmosphere of greenhouse gases, the most important of which is CO2. The adverse impact of these gases on regional and global climate constitutes the primary climate issue for the coming decades.”

However, in the Pielke et al 2009 EOS paper we present evidence to show that this IPCC conclusion (hypothesis 2b) can be rejected.

The hypothesis that remains robust is hypothesis 2a which reads

“Although the natural causes of climate variations and changes are undoubtedly important, the human influences are significant and involve a diverse range of first-order climate forcings, including, but not limited to, the human input of carbon dioxide (CO2). Most, if not all, of these human infl uences on regional and global climate will continue to be of concern during the coming decades.”

The list of signatories have identified themselves as advocates of the IPCC view and certainly should not be part of any  formal independent assessment to determine the quality of the science in the 2007 IPCC reports.

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