A. Introduction
This Summary sets out the key policy-relevant findings of the Fourth Assessment of Working Group II of the Intergovernmental Panel on Climate Change (IPCC).
The Assessment is of current scientific understanding of impacts of climate change on natural, managed and human systems, the capacity of these systems to adapt and their vulnerability. It builds upon past IPCC assessments and incorporates new knowledge gained since the Third Assessment.
Statements in this Summary are based on chapters in the Assessment and principal sources are given at the end of each paragraph.
B. Current knowledge about observed impacts of climate change on the natural and human environment
A full consideration of observed climate change is provided in the Working Group I Fourth Assessment. This part of the Working Group II Summary concerns the relationship between observed climate change and recent observed changes in the natural and human environment.
The statements presented here are based largely on data sets that cover the period since 1970. The number of studies of observed trends in the physical and biological environment and their relationship to regional climate changes has increased greatly since the Third Assessment in 2001. The quality of the data sets has also improved. There is, however, a notable lack of geographic balance in data and literature on observed changes, with marked scarcity in developing countries.
See full Report, in pdf format.
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