Earth’s Climate Approaches Dangerous Tipping Point

New York (June 1, 2007)- A stern warning that global warming is nearing an irreversible tipping point was issued today by the climate scientist who the Bush administration has tried to muzzle. James Hansen, director of NASA’s Goddard Institute for Space Studies in New York, today published a study showing that greenhouse gases emitted by human activities have brought the Earth’s climate close to critical tipping points, with potentially dangerous consequences for the planet.


“If global emissions of carbon dioxide continue to rise at the rate of the past decade,” said Dr. Hansen, “this research shows that there will be disastrous effects, including increasingly rapid sea level rise, increased frequency of droughts and floods, and increased stress on wildlife and plants due to rapidly shifting climate zones.”
Physicist James Hansen heads the NASA’s Institute for Space Studies, a division of Goddard Space Flight Center in Greenbelt, Maryland (photo courtesty of NASA). Dr. Hansen has said in the past that a global tipping point will be reached by 2016 if levels of greenhouse gases like methane and carbon dioxide are not reduced. This study finds that global warming of 0.6 degrees Celcius 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.
In May another team of NASA and university scientists found the first evidence that extensive areas of snow melted in west Antarctica in January 2005 in response to warm temperatures. (Photo courtesy NASA) 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.
The researchers used data on earlier warm periods in Earth’s history to estimate climate impacts as a function of global temperature, climate models to simulate global warming, and satellite data to verify ongoing changes. The research appears in the current issue of “Atmospheric Chemistry and Physics.”
Antarctic ice is melting (Photo courtesy British Antarctic Survey). In January 2006, Dr. Hansen said that officials at NASA headquarters had ordered the public affairs staff to review his coming lectures, papers, postings on the Goddard website and requests for interviews from journalists. Dr. Hansen said he would decline to adhere to the restrictions. NASA officials said its scientists were free to discuss science but not policy issues.
In March 2007, Hansen told the House of Representatives Committee on Oversight and Government Reform, “The effect of the filtering of climate change science during the current administration has been to make the reality of climate change less certain than the facts indicate, and to reduce concern about the relation of climate change to human-made greenhouse gas emissions.”
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