Working Group I Contribution to the IPCC Fifth Assessment Report (AR5), Climate Change 2013: The Physical Science Basis

The IPCC's Fifth Assessment Report (AR5) is being released in four parts between September 2013 and November 2014. The first of three working group reports is "Climate Change 2013: The Physical Science Basis, the contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.

There are three parts:
Summary for Policymakers, Technical Summary, and the full report: Final Draft Underlying Scientific Technical Assessment. Publication of the final version of the Report is foreseen in January 2014.

This comprehensive assessment of the physical aspects of climate change puts a focus on those elements that are relevant to understand past, document current, and project future climate change. The assessment builds on the IPCC Fourth Assessment Report (AR4) and the recent Special Report on Managing the Risk of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX)2 and is presented in 14 Chapters and 6 Annexes.

The Technical Summary serves as a starting point for those readers who seek the full information on more specific topics covered by this assessment. This purpose is facilitated by including pointers to the chapters and sections where the full assessment can be found. Policy-relevant topics, which cut across many chapters and involve many interlinked processes in the climate system, are presented as Thematic Focus Elements, allowing rapid access of this information. The chapters cover direct and proxy observations of changes in all components of the climate system, they assess the current knowledge of various processes within, and interactions among, climate system components, which determine the sensitivity and response of the system to changes in forcing, and they quantify the link between the changes in atmospheric constituents, and hence radiative forcing3, and the consequent detection and attribution of climate change. Projections of changes in all climate system components are based on model simulations forced by a new set of scenarios. The report also provides a comprehensive assessment of past and future sea level change in a dedicated chapter. Regional climate change information is presented in the form of an Atlas of Global and Regional Climate Projections (Annex I). This is complemented by Annex II: Climate System Scenario Tables and Annex III: Glossary.

See also this data visualization from the NASA Center for Climate Simulation and NASA's Scientific Visualization Studio at Goddard Space Flight Center, Greenbelt, Md., showing how climate models used in the new report from the IPCC estimate possible temperature and precipitation pattern changes throughout the 21st century.