From Science:
The U.N.-sponsored Intergovernmental Panel on Climate Change (IPCC) report released today in Brussels has a familiar ring. As the climate disasters headlined recently–intense hurricanes, drought in the American West, Arctic thawing–become commonplace in a greenhouse world, plants, animals, and people will suffer. That has been the presumption, but the latest report from the IPCC projecting greenhouse impacts calculates mounting costs that will fall the heaviest on the world’s poor.
February’s IPCC report on the physical science of climate firmly links most of the recent warming of the world to human activity. Scientists authoring the second report had a tougher challenge: figuring out the likely consequences. To do that, they considered 29,000 datasets from 75 studies. Of those data series, 89% showed changes–receding glaciers or earlier blooming, for example–consistent with a response to warming. Because those responses usually occurred where the warming has been greatest, the scientists concluded that it’s “very unlikely” the changes were due to natural variability of climate or of the system involved. “For the first time, we concluded anthropogenic warming has had an influence on many physical and biological systems,” says Cynthia Rosenzweig of NASA’s Goddard Institute for Space Studies in New York City, a coordinating lead author on the report.
More here.