May 30, 2007
RESEARCH FINDS THAT EARTH'S CLIMATE IS APPROACHING 'DANGEROUS' POINT
NASA and Columbia University Earth Institute research finds that human-made greenhouse gases have brought the Earth’s climate close to critical tipping points, with potentially dangerous consequences for the planet.From a combination of climate models, satellite data, and paleoclimate records the scientists conclude that the West Antarctic ice sheet, Arctic ice cover, and regions providing fresh water sources and species habitat are under threat from continued global warming. The research appears in the current issue of Atmospheric Chemistry and Physics.
Tipping points can occur during climate change when the climate reaches a state such that strong amplifying feedbacks are activated by only moderate additional warming. This study finds that global warming of 0.6ºC in the past 30 years has been driven mainly by increasing greenhouse gases, and only moderate additional climate forcing is likely to set in motion disintegration of the West Antarctic ice sheet and Arctic sea ice. Amplifying feedbacks include increased absorption of sunlight as melting exposes darker surfaces and speedup of iceberg discharge as the warming ocean melts ice shelves that otherwise inhibit ice flow.