The regular reader of Science and Nature is treated to an almost weekly load of data, virtually all of it showing results at the very upper end of the ranges predicted by climate models, or beyond them altogether. Compared with the original models of a few years ago, ice is melting faster; forest soils are giving up more carbon as they warm; storms are increasing much more quickly in number and size; and droughts are becoming worse.

Arctic sea ice is melting fast, the tundra of Siberia, permafrost has begun to melt rapidly,whilst the melting of the southern icecaps is happening a lot faster than was expected. I watched a report on Lateline last night about the melting of the Antartica icecap.

Pine island Antartica. Dec 2000, aster

The process we are now seeing is the breaking up of the ice shelves, the melting of the glaciers behind them, water flowing into the oceans and rising sea levels. And as the ice sheet discharges more icebergs into the ocean and loses mass, its surface sinks to a lower level where the temperature is warmer, causing it to melt faster.

We need to think in terms of the earth as a self-regulating system become significantly hotter. We need to reverse the flow of carbon into the atmosphere before we cross a threshold and create a "different planet." In this article in the New York Times Jim Hansen talks in terms of two scenarios:

In the business-as-usual scenario, annual emissions of CO2 continue to increase at the current rate for at least fifty years, as do non-CO2 warming agents including methane, ozone, and black soot. In the alternative scenario, CO2 emissions level off this decade, slowly decline for a few decades, and by mid-century decrease rapidly, aided by new technologies.The business-as-usual scenario yields an increase of about five degrees Fahrenheit of global warming during this century, while the alternative scenario yields an increase of less than two degrees Fahrenheit during the same period...The business-as-usual scenario, with five degrees Fahrenheit global warming and ten degrees Fahrenheit at the ice sheets, certainly would cause the disintegration of ice sheets. The only question is when the collapse of these sheets would begin.

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