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The Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change "Climate Change 2007 - The Physical Science Basis" was launched on 2 February 2007 in Paris. The report includes information on changes in greenhouse gases and aerosols in the atmosphere and the extent to which they affect climate. It provides details of recent changes in air, land and ocean temperatures, rainfall, glaciers and ice sheets and considers a large amount of new satellite and other data that have not been assessed previously. A paleoclimatic perspective considers the Earth's past cold and warm periods and the understanding of climate processes that can be gained from these. New information on feedbacks arising from the interaction of climate change with the biosphere and geochemistry is also considered. The most recent climate models were evaluated in detail, as is their use to explain observed climate change in terms of different driving factors. Projections of future climate change using climate models are considered broadly and cover near term climate change, the degree to which this is 'committed' due to past increases in greenhouse gases, and a range of potential longer term climate changes. Patterns of future climate change are considered both globally and regionally.


The report is available in print and electronic formats. The printed publication, along with the companion CD-ROM, may be purchased from Cambridge University Press. The Summary for Policymakers (SPM), Technical Summary (TS), individual Chapters, and other materials of the Working Group I report are available in pdf format. Supplementary Material is provided in a mixture of pdf and online formats. The FAQs are available in online and pdf formats



Front Matter

Summary for Policymakers

Technical Summary

Frequently Asked Questions html pdf (extracted from chapters below)


Chapter 1 Historical Overview of Climate Change Science

Chapter 2 Changes in Atmospheric Constituents and in Radiative Forcing

Chapter 3 Observations: Surface and Atmospheric Climate Change

     Supplementary Material: Appendix 3.B. Techniques, Error Estimation and Measurement Systems (including references)

Chapter 4 Observations: Changes in Snow, Ice and Frozen Ground

Chapter 5 Observations: Oceanic Climate Change and Sea Level

Chapter 6 Palaeoclimate

     Supplementary Material: Appendix 6.A. Glossary for Terms Specific to Chapter 6

Chapter 7 Couplings Between Changes in the Climate System and Biogeochemistry

Chapter 8 Climate Models and their Evaluation

     Supplementary Material: Appendix 8.A. Supplementary Figures and Tables

Chapter 9 Understanding and Attributing Climate Change

     Supplementary Material: Appendices & References

Chapter 10 Global Climate Projections

     Supplementary Material: Supplementary Details, Tables & Figures

      Figures Showing Individual Model Results for Different Climate Variables

Chapter 11 Regional Climate Projections

     Supplementary Material: Appendix 11. Tables, Figures, References

Annexes: (1)Glossary, (2)Authors, (3)Reviewers, (4)Acronyms




Uncertainty Guidance Note for the Fourth Assessment Report


Errata for the Working Group I Fourth Assessment Report (Updated 15/06/2012)


Online archive of the WGI AR4 Drafts, Review Comments and Author Responses