The clock has run out on climate, says Jim Hansen.
Ask one of the bureaucrats attending U.N. climate negotiations in Durban, South Africa, this week to define dangerous climate change, and there’s a good chance the answer will be “2 degrees Celsius.”
It’s a loosely defined target, part bureaucratic and part scientific — a best guess put forth by some scientists and many governments that believe warming beyond that point could greatly increase the chance of catastrophic changes in the world’s climate.
But according to NASA climate scientist James Hansen, it’s just plain wrong.
Hansen, in San Francisco for the annual meeting of the American Geophysical Union, says his study of the past climate stretching back 65 million years demonstrates that focusing on limiting warming to 2 degrees C above the pre-industrial level is “a prescription for long-term disaster.”
That’s because the new work by Hansen and his colleagues shows the Earth’s climate is more sensitive to greenhouse gas emissions than scientists had believed, the scientist told reporters yesterday.
“What the paleoclimate record tells us is that the dangerous level of global warming is less than what we thought a few years ago,” Hansen said. “The target that has been talked about in international negotations, 2 degrees Celsius for global warming, is actually a prescription for long-term disaster. We can’t say exactly what long-term means but we are beginning to see signs of slow feedbacks beginning to come into play already.”
Those signs include accelerating ice loss from ice sheets in Greenland and Antarctica and the release of methane hydrates from thawing permafrost in some areas of the seafloor.
“If we are looking to maintain the climate humanity has known,” Hansen said, “we are basically out of time.” [Emphasis added]
Here’s your ‘out of time’ flashback: