Log in | Subscribe | RSS feed

What’s New

IPCC adopts major assessment of climate change science

6 February 2007

Most of the observed increase in globally averaged temperatures is very likely due to the observed increase in anthropogenic greenhouse gas concentrations, concludes the UN’s Intergovernmental Panel on Climate Change (IPCC) in his newest assessment of climate change science. The IPCC is nearing the completion of its “Climate Change 2007”, also known as the Fourth Assessment Report (AR4). The major conclusions of the first volume of the report, Climate Change 2007: The Physical Science Basis, have been released as the “Summary for Policymakers” document.

The “very likely” designation is an advance from the previous, 2001 report, which concluded that global warming was “likely” caused by increasing greenhouse gas concentrations. The IPCC report uses the term very likely to indicate the assessed likelihood, using expert judgement, of an outcome of over 90%, while the term likely denotes the likelihood of 66%.

Climate Change 2007: The Physical Science Basis, assesses the current scientific knowledge of the natural and human drivers of climate change, observed changes in climate, the ability of science to attribute changes to different causes, and projections for future climate change. The report was produced by some 600 authors from 40 countries, with the participation of over 620 expert reviewers and a large number of government reviewers from 113 countries.

Selected findings of the report include:

The report analyzed six emission scenarios. The predicted warming by the end of the 21st century is 1.8°C (a range from 1.1 to 2.9) for the most optimistic scenario, and 4.0°C (2.4 - 6.4) for the most pessimistic one. The corresponding ranges of rise in sea levels are 0.18-0.38 m and 0.26-0.59 m, respectively.

For the 20th century, the average temperature increase is estimated to be 0.74°C (0.56 - 0.92), and the sea level rise 0.17 m (0.12 - 0.22).

When completed later this year, the Climate Change 2007 report will include three main volumes:

and a short 30-page synthesis report.

Source: IPCC