Following in the footsteps of a long line of Bush’s nominees, Michael Griffin, director of NASA, embarrassed himself with his inability to acknowledge that human-caused agents might have anything to do with climate change and global warming on NPR on Thursday. (Check out this ABC news story for reaction to his verbal gaffe.)

Despite the ignorance displayed by the director, NASA along with the Columbia University Earth Institute announced on Wednesday “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.

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. Lead author James Hansen, NASA Goddard Institute for Space Studies, New York, concludes: “If global emissions of carbon dioxide continue to rise at the rate of the past decade, 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.”

<!-more-> The article goes on to describe in a little more detail some of the study covered and its conclusions:

Based on climate model studies and the history of the Earth the authors conclude that additional global warming of about 1ºC (1.8ºF) or more, above global temperature in 2000, is likely to be dangerous. In turn, the temperature limit has implications for atmospheric carbon dioxide (CO2), which has already increased from the pre-industrial level of 280 parts per million (ppm) to 383 ppm today and is rising by about 2 ppm per year. According to study co-author Makiko Sato of Columbia’s Earth Institute, “the temperature limit implies that CO2 exceeding 450 ppm is almost surely dangerous, and the ceiling may be even lower.”

The study also shows that the reduction of non-carbon dioxide forcings such as methane and black soot can offset some CO2 increase, but only to a limited extent. Hansen notes that “we probably need a full court press on both CO2 emission rates and non-CO2 forcings, to avoid tipping points and save Arctic sea ice and the West Antarctic ice sheet.”

Why is saving the Arctic sea ice and the West Antarctic ice sheet critical?

Well, here’s a crib sheet on Climate Change produced by Seed Magazine that I think does a great job of summarizing critical points in the various factors which feed into the climate change equation in a simple graphic style. Yes, sometimes a picture is worth a 1000 words.

Click for larger image

You can see there that the ice sheets are critical for reflecting light (and heat) back into space.

Maybe someone should send this graphic to Mr. Griffin. Looks like it might be straightforward enough.

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  Sidenote: For those who appreciate a brush up on their various science classes, Seed has put together some good crib sheets on other topics as well. Check them out.