Introduction:

The United States Global Change Research Program, in cooperation with the Department of State, request expert review of the Second Order Draft of the Working Group I Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) Climate Change 2013: The Physical Science Basis.

On behalf of the U.S. Department of State, the U.S. Global Change Research Program is coordinating the submission of comments by U.S. experts to inform development of an integrated set of U.S. Government comments on the report. Expert comments must be received via the internet-based application by Midnight, Eastern Daylight Time, 2 November 2012 to be considered for inclusion in the U.S. Government submission. An expert reviewer may also be asked to participate in the government review organized within his or her own country. In such a case, he/she should submit comments either as an individual or as part of the government review, but not both.

Because the report is still in draft form, distribution of the materials for review will be through a password-protected website. The chapters of the draft have undergone extensive revision based on comments received from many experts in the first round of review. IPCC practice is that drafts of IPCC reports are not published until they are final. In making the document available for review by U.S. experts, we are requiring reviewers to indicate that they understand and will respect this practice.

If you wish to review the draft document, please visit: URL. There you will find additional instructions about the review process and how to submit comments.

To receive a copy of the draft report for review, you will be asked to register with your first name, last name, institutional affiliation and email address. You will also be asked to accept a user agreement before submitting your request.

Background on the IPCC

The IPCC was established as an intergovernmental body under the auspices of the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988. In accordance with its mandate and as reaffirmed in various decisions by the Panel, the major activity of the IPCC is to prepare comprehensive and up-to-date assessments of policy-relevant scientific, technical, and socio-economic information for understanding the scientific basis of climate change, potential impacts, and options for mitigation and adaptation. The IPCC develops a comprehensive assessment spanning all the above topics approximately every six years. The First Assessment Report was completed in 1990, the Second Assessment Report in 1995, the Third Assessment Report in 2001, and the Fourth Assessment in 2007. Three working group volumes and a synthesis report comprise the Firth Assessment Report. Working Group I assesses the scientific aspects of the climate system and climate change; Working Group II assesses the vulnerability of socio-economic and natural systems to climate change, potential negative and positive consequences, and options for adapting to it; and Working Group III assesses options for limiting greenhouse gas emissions and otherwise mitigating climate change. Principles and procedures for the IPCC and its preparation of reports can be found at the following Web sites:

• http://www.ipcc.ch/organization/organization_review.shtml#.UEY0LqSe7x8 (pdf)
• http://ipcc.ch/organization/organization_procedures.shtml

Background on the Report

In October 2009, the IPCC approved the outline for the Working Group I contribution to the 5th Assessment Report. Authors were nominated in May of 2010 and selected in June of 2010. All IPCC reports go through two broad reviews: a ``first-order draft'' for experts, and a ``second-order draft'' for experts and governments. The Second Order Draft of the Working Group I contribution to the 5th Assessment Report will be available for review beginning on 5 October 2012.

Experts from the United States may choose one of two different methods to provide their comments on the Second Order Draft of the Working Group I contribution to the 5th Assessment Report. They may provide their comments directly to the IPCC or they may provide them through the U.S. Government and Expert Review coordinated by the United States Global Change Research Program. Beginning on 7 September, experts may register to review the draft report at either: https://www.ipcc-wg1.unibe.ch/ or http://globalchange.gov/. Whatever method an expert has chosen, the draft report will be made available to them on 5 October 2012. Comments are due to the IPCC Working Group I secretariat by 30 November. In order to accommodate the review process, comments to the U.S. Government review, comments through the United States Global Change Research Program are due by midnight 2 November 2012.

As part of the U.S. Government Review of the Second Order Draft of the Working Group I Contribution to the 5th Assessment Report, the U.S. Government is soliciting comments from experts in relevant fields of expertise. The United States Global Change Research Program will coordinate collection of U.S. expert comments and the review of the report by panels of Federal scientists and program managers in order to develop a consolidated U.S. Government submission. Expert comments received within the comment period will be considered for inclusion in the U.S. Government submission. Instructions for review and submission of comments are available at: URL. To be considered for inclusion in the U.S. Government collation, comments must be received by midnight November 2, 2012. Comments submitted for consideration as part of the U.S. Government Review should be reserved for that purpose, and not also sent to the IPCC Secretariat as a discrete set of expert comments.