The first and second drafts of the IPCC AR4 WG1 reports, together with the reviewer comments, can all be found here.
The timescales for the main report were:
- August 2005: First Order Draft (FOD) released.
- November 2005: Comments on FOD.
- March 2006: Second Order Draft (SOD) released.
- June 2006: Comments on SOD.
The timetable for the Summary for Policymakers (SPM) was rather different:
- April 2006: Draft
- August 2006: Comments by expert reviewers
- October 2006: Final Draft
- January 2007: Comments by Governments only.
Notice the tight time-frame between the final comments on the SPM and its release in February 2007. This may have been partly responsible for the erroneous table in the SPM.
The previous drafts and the reviewer comments were initially withheld by the IPCC. However, they were forced to do so by freedom of information requests in June 2007. See comments here. Looking through the comments and responses, it is easy to see why the IPCC was reluctant to publish the comments.
In the comments on the SPM, there were several objections (see pages 92, 93) to the misleading comments about sea level rise. These comments were all rejected. Several objections to the IPCC's vague statement about "Widespread increases in heavy precipitation events" were also ignored (pages 110,111). There were numerous objections (pages 113-118) to the table SPM1 (which became table SPM2 in the final version) saying that some of the claims about increased likelihood of certain events were speculative or unjustified. These were all rejected.
A very detailed study of the reviewer comments and the IPCC response by John McLean can be found here.
See also this Climate Audit discussion on how reviewer comments on a technical statistical issue were handled.
IPCC Reviewer Madhav Khandekar wrote in a US Senate Report "To my dismay, IPCC authors ignored all my comments and suggestions for major changes in the FOD (First order Draft) and sent me the SOD (second order draft) with essentially the same text as the FOD". He has written a paper containing a list of examples of how the IPCC has exaggerated the adverse impact of warming. "While reviewing the IPCC WGII chapter as an external reviewer, I felt time and time again that there were areas where the chapter authors highlighted adverse impact of GW (Global Warming) on human societies, while downplaying possible beneficial impacts. The IPCC authors referred to several publications which projected adverse impacts while ignoring many excellent studies which have questioned these impacts." He discusses many examples including claims of increased flooding, 'rapid' shrinking of glaciers, 'increased catastrophes', claims of increase in disease, and sea level rise. However, since these deal with IPCC WGII, they will not be discussed in detail here.
The task of assigning reviewers, and ensuring that reviewer comments were adequately considered, is undertaken by the IPCC 'Review Editors'; there is a different review editor for each chapter. For all but one chapter, the review editor signed an identical form letter stating "I can confirm that all substantive expert and government review
comments have been afforded appropriate consideration by the writing
team in accordance with IPCC procedures." In one case (chapter 6, Paleoclimate) the review editor wrote "There will inevitably remain some disagreement on how they have dealt
with the reconstructions of the last 1000 years, and there is further
work to do here in the future, but in my judgement, the authors have
made a reasonable assessment of the evidence they have to hand." See Climate Audit discussion.