Wednesday, May 30, 2007

Global Warming Tipping Point Only Ten Years Away?

Mention global warming recently, and the attention rightfully turns to Al Gore, who has been hitting the airwaves promoting his new book, The Assault on Reason. One of the topics highlighted in Gore's book is the attempt to subvert science for political purposes. And one man who knows this only too well is NASA scientist James Hansen.

Like Gore, Dr. Hansen has been a tireless advocate on the environmental front. He first testified before Congress to raise awareness of the issue back in the 1980's. As one might expect, Hansen has also been a vocal and determined critic of the Bush administration's policies, or lack thereof, regarding global warming.

In the University of Iowa speech, Hansen recounted how NASA Administrator Sean O'Keefe told him in a 2003 meeting that he shouldn't talk "about dangerous anthropogenic interference" -- humans' influence on the atmosphere -- "because we do not know enough or have enough evidence for what would constitute dangerous anthropogenic interference."

But Hansen said that scientists know enough to conclude we have reached this danger point and that their efforts to get the word out are being blocked by the administration. "In my more than three decades in government, I have never seen anything approaching the degree to which information flow from scientists to the public has been screened and controlled as it has now," Hansen said. He added that although the administration wants to wait 10 years to evaluate climate change, "delay of another decade, I argue, is a colossal risk."

Hansen's concern is predicated on the concept of a "tipping point," the point at which the earth's biofeedback mechanisms kick in and warming becomes a runaway process.

As the tipping points pass, "there is an acceleration, potentially uncontrollable, of emissions of vast natural stores of greenhouse gas," according to Hansen.....

The melting ice caps are one example of a biofeedback loop. As warmer temperatures cause the ice to melt...
The disappearance of that bright sea ice and snow is uncovering more and more dark water and bare ground — creating another dangerous feedback loop.

These feedbacks all produce more heat, thus all reinforcing each other, leading to evermore thawing — and thus releases of natural greenhouse gases (including CO2 and methane) in a viciously accelerating circlering more and more dark water and bare ground — creating another dangerous feedback loop.

Given this scenario, some economic advisors are suggesting that the best course of action may be adaptation rather than prevention. Hansen disagrees.

According to the Intergovernmental Panel on Climate Change, scenarios modeled by scientists predict CO2 emissions rise to anywhere from a low of 450 ppm (parts per million) to as high as 650 ppm.

Hansen told ABC News today he believes the upper limit for avoiding dangerous climate change "could well be much lower" than 450 ppm.

In the NASA announcement, Hansen said, "'business as usual' emissions would be a guarantee of global and regional disaster."

Earth's CO2 concentration is currently 383 ppm, up from 280 ppm at the start of the industrial age.

Studies released earlier this month report human-made emissions now spiraling upward at an accelerating rate much faster than scientists expected only a few years ago.

But not to worry - after dilly dallying around for six years, President Bush has finally decided the government should take action - after he leaves office.

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