February 2, 2007
The IPCC Fourth Assessment “Summary for Policymakers” Working Group I report represents the IPCC’s strongest statement to date on climate change. The report calls the evidence of climate warming “unequivocal.” This report expresses more confidence than past reports that most of the observed warming is due to human influences (“very likely”-- that is, greater than 90% confidence). The report finds that rates of both observed warming and sea level rise have accelerated over the past century, and discusses other important changes being observed, including more intense precipitation in some regions, prolonged droughts in others, and intensification of hurricanes in some tropical regions.
The assessment is based on extensive published, peer-reviewed scientific literature. Today’s report is the first of three major studies that comprise the Fourth Assessment with input from more than 1,200 authors and 2,500 scientific expert reviewers from more than 130 countries. Subsequent reports will look at the impacts of climate change and options for reducing emissions.
According to Vicki Arroyo, Director of Policy Analysis, "The scientists have spoken. The message for policymakers is clear: we need to act now to both reduce emissions of greenhouse gases and adapt to the climate changes we are already experiencing."