A new assessment concludes that the Earth has been getting warmer over the past 50 years and the past decade was the warmest on record -- but doesn't try to make the link between climate change and what might be causing it.
The State of the Climate 2009 report, published Wednesday as a special supplement to the Bulletin of the American Meteorological Society, was compiled by 300 scientists from 48 countries and drew on measures of 10 crucial climate indicators.
Seven of the indicators were rising, including air temperature over land, sea-surface temperature, sea level, ocean heat and humidity. Three indicators were declining, including Arctic sea ice, glaciers and spring snow cover in the Northern Hemisphere.
"Each indicator is changing as we'd expect in a warming world," said Peter Thorne, senior researcher at the Cooperative Institute for Climate and Satellites, a research consortium based in College Park, Md., who was involved in compiling the report.
The report's conclusions broadly match those of the Intergovernmental Panel on Climate Change, a United Nations body, which published its last set of findings in 2007. The IPCC report contained several errors, which further stoked the debate about the existence, causes and effects of global warming.
The new report incorporates data from the past few years that weren't included in the last IPCC assessment. While the IPCC report concluded that evidence for human-caused global warming was "unequivocal" and was linked to emissions of greenhouse gases, the latest report didn't seek to address the issue.
The report "doesn't try to make the link" between climate change and what might be causing it, said Tom Karl, an official at the National Oceanic and Atmospheric Administration involved in the new assessment.