Posted by Big Gav
Alternet looks at the peril of accelerating global warming.
The news of melting Siberian permafrost means, in all likelihood, that global warming is accelerating much faster than climatologists had predicted. The finding from Siberia comes amidst evidence, presented at Tony Blair's special climate change conference last February, that the West Antarctic Ice Sheet could be in danger of disintegrating -- another warming-induced event once thought to be decades or centuries away.
Meanwhile, according to a September 29, 2005 report in the Guardian, scientists at the University of Colorado, Boulder's National Snow and Ice Data Center have measured a drastic shrinking of ice floes in the Arctic Ocean. Arctic waters are now expected to be ice-free well before the end of this century.
How many more milestones will there be? The prospects of a worst case scenario, with a temperature increase approaching or exceeding 5.8 degrees Celsius, are increasing dramatically, with all the attending disasters that would entail -- inundated coastlines, extreme storms and drought, disease pandemics, collapsing agriculture, massive environmental refugee flows.
And how far will it go? Climate forecasts have long noted that every increase in global temperature heightens the odds of runaway global warming, beyond any human control. Continued overheating could unlock more methane from Arctic regions beyond Siberia. It could cripple the vital ability of plants and oceans to absorb CO2 from the atmosphere, turning them into gushing sources of new CO2 that accelerate the superheating even further. The ice caps that help cool the Earth by reflecting sunlight into space could vanish. In the end, the relentless rise in temperature could induce a cataclysmic venting of billions of tons of methane from the oceans.
A paper by British scientists Michael J. Benton and Richard J. Twitchett, published in the July 2003 issue of Trends in Ecology & Evolution, shows how this could happen. 251 million years ago, at the end of the Permian era, a release of carbon dioxide from volcanic eruptions apparently heated the Earth's atmosphere by about 6 degrees Celsius.
This initial increase in temperature triggered, in turn, a massive release of methane from Arctic tundra and the oceans. Research by Jeffrey Kiehl and others at the National Center for Atmospheric Research at University of Colorado, Boulder, tells us what happened next. According to their paper in the September 2005 issue of the journal Geology, the Earth's annual mean surface temperature rose by an additional 10 to 30 degrees Celsius.
The result of this runaway global warming was the greatest mass extinction since life emerged from the sea -- 95 percent of all species in existence died. That from an initial temperature rise only 0.2 degrees Celsius more than what the IPCC says could occur by the end of this century. We now know that human industry is causing in our lifetimes the same kind of methane release that triggered the Permian extinction.