IPCC Fourth Assessment Report

Climate Change 2007, the Fourth Assessment Report (AR4) of the United Nations Intergovernmental Panel on Climate Change (IPCC), is the fourth in a series of reports intended to assess scientific, technical and socio-economic information concerning climate change, its potential effects, and options for adaptation and mitigation. The report is the largest and most detailed summary of the climate change situation ever undertaken, involving thousands of authors from dozens of countries, and states in its summary,

• "Warming of the climate system is unequivocal."
• "Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations."

Climate Change 2007: Report Overview

The Fourth Assessment Report (Climate Change 2007) was released in four distinct sections:

• Working Group I Report (WGI): .
• Working Group II Report (WGII): .
• Working Group III Report (WGIII): (final version).
• The Synthesis Report (SYR): (pre-copy edit version).

For each section, the IPCC will release the main report and a summary version, known as the Summary for Policymakers. Full reports and summaries of Working Groups I-III have been released, plus a summary of the Synthesis Report.

Working Group I (WGI): The Physical Science Basis

The Working Group I Summary for Policymakers (SPM) was published on...
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