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May 09, 2006
| James Hansen: A Point Of No Return Is Looming | Economy Environment |
James Hansen, perhaps the country's most senior climate scientist, has posted a talk he gave in February at the New School (link via Energy Bulletin). In a nutshell: time is quickly running out. We're about to pass a global warming point of no return. Summary:
The Earth's temperature, with rapid global warming over the past 30 years, is now passing through the peak level of the Holocene, a period of relatively stable climate that has existed for more than 10,000 years. Further warming of more than 1ºC will make the Earth warmer than it has been in a million years."Business-as-Usual" scenarios, with fossil fuel CO2 emissions continuing to increase ~2%/year as in the past decade, yield additional warming of 2-3°C this century and imply changes that constitute practically a different planet. Multiple lines of evidence indicate that the Earth's climate is nearing, but has not passed, a point of no return beyond which it will be impossible to avoid climate change with far ranging undesirable consequences.
The changes include not only loss of the Arctic as we know it, with all that implies for wildlife and indigenous peoples, but losses on a much vaster scale due to worldwide rising seas. Sea level will increase slowly at first, as losses at the fringes of Greenland and Antarctica due to accelerating ice streams are partly balanced by increased snowfall and ice sheet thickening in the ice sheet interiors. But as Greenland and West Antarctic ice is softened and lubricated by melt-water, and as buttressing ice shelves disappear due to a warming ocean, the balance will tip to rapid ice loss, bringing multiple positive feedbacks into play and causing cataclysmic ice sheet disintegration.
The Earth's history suggests that with warming of 2-3°C the new equilibrium sea level will include not only most of the ice from Greenland and West Antarctica, but a portion of East Antarctica, raising sea level of the order of 25 meters (80 feet). Contrary to lethargic ice sheet models, real world data suggest substantial ice sheet and sea level change in centuries, not millennia. The century time scale offers little consolation to coastal dwellers, because they will be faced with irregular incursions associated with storms and with continually rebuilding above a transient water level.
The grim "Business-as-Usual" climate change is avoided in an Alternative Scenario in which growth of greenhouse gas emissions is slowed in the first quarter of this century, primarily via concerted improvements in energy efficiency and a parallel reduction of non-CO2 climate forcings, and then reduced via advanced energy technologies that yield a cleaner atmosphere as well as a stable climate.
The required actions make practical sense and have other benefits, but they will not happen without strong policy leadership and international cooperation. Action must be prompt, otherwise CO2-producing infrastructure that may be built within a decade will make it impractical to keep further global warming under 1°C.
There is little merit in casting blame for inaction, unless it helps point toward a solution. It seems to me that special interests have been a roadblock wielding undue influence over policymakers. The special interests seek to maintain short-term profits with little regard to either the long-term impact on the planet that will be inherited by our children and grandchildren or the long-term economic well-being of our country. The public, if well-informed, has the ability to override the influence of special interests, and the public has shown that they feel a stewardship toward the Earth and all of its inhabitants. Scientists can play a useful role. [Emphasis added]
Something I just don't get: the many people, here in the US, especially, who continue to cling to the idea that the private sector is the source of all things good, while public institutions are the parasitic source of nothing but waste, inefficiency, and error. But the atmosphere (and the oceans and wildlife and the commons in all its other forms) shows up on no private sector balance sheet, so the market Titanic speeds full steam ahead toward the iceberg.
Corporations — international corporations, especially, since they owe allegiance to nobody and nowhere — are single-minded machines programmed to pursue one goal: maximum profits. Their focus is short term, and they are by their nature incapable of self-restraint. If governments were to impose regulations that caused all corporations to restrain themselves equally, they might welcome it (it beats suicide), but in the meantime the logic of the market bars them from any form of self-restraint not also being practiced by their competitors. And so, with a cliff looming dead ahead, when you might expect them to be stepping on the brakes, they instead have got the pedal to the floor. Wheeeee!
Posted by Jonathan at May 9, 2006 08:21 PM
