Hansen: paleoclimate record indicates”strong amplifying feedbacks” to additional GHG

“We don’t have a substantial cushion between today’s climate and dangerous warming,” Hansen said. “Earth is poised to experience strong amplifying feedbacks in response to moderate additional global warming. – James Hansen

This is definitely not good: the latest bulletin from NASA’s Goddard Institute for Space Studies offers evidence that earth’s climate sensitivity is actually higher than we thought. I.e., more sensitive to increasing atmospheric GHG levels. As best I can tell Dr. Hansen discussed this research at the AGU Fall Meeting 2011. I’m reading the 8 Dec, 2011 NASA Paleoclimate Record Points Toward Potential Rapid Climate Changes:

(…) In recent research, Hansen and co-author Makiko Sato, also of Goddard Institute for Space Studies, compared the climate of today, the Holocene, with previous similar “interglacial” epochs – periods when polar ice caps existed but the world was not dominated by glaciers. In studying cores drilled from both ice sheets and deep ocean sediments, Hansen found that global mean temperatures during the Eemian period, which began about 130,000 years ago and lasted about 15,000 years, were less than 1 degree Celsius warmer than today. If temperatures were to rise 2 degrees Celsius over pre-industrial times, global mean temperature would far exceed that of the Eemian, when sea level was four to six meters higher than today, Hansen said.

“The paleoclimate record reveals a more sensitive climate than thought, even as of a few years ago. Limiting human-caused warming to 2 degrees is not sufficient,” Hansen said. “It would be a prescription for disaster.”

Hansen focused much of his new work on how the polar regions and in particular the ice sheets of Antarctica and Greenland will react to a warming world.

Two degrees Celsius of warming would make Earth much warmer than during the Eemian, and would move Earth closer to Pliocene-like conditions, when sea level was in the range of 25 meters higher than today, Hansen said. In using Earth’s climate history to learn more about the level of sensitivity that governs our planet’s response to warming today, Hansen said the paleoclimate record suggests that every degree Celsius of global temperature rise will ultimately equate to 20 meters of sea level rise. However, that sea level increase due to ice sheet loss would be expected to occur over centuries, and large uncertainties remain in predicting how that ice loss would unfold.

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It is very definitely time to get serious about a rapid global deployment of nuclear reactors. We need to average the equivalent of at least one 1GWe power plant every day through 2060 — a challenge that becomes more difficult every year we delay launching the effort.

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