Global warming

[Louis Proyect <lnp3@xxxxxxxxx>]

LRB | Vol. 27 No. 1 dated 6 January 2005 | Michael Byers

On Thinning Ice
Michael Byers

Impacts of a Warming Arctic: Arctic Climate Impact Assessment · Cambridge, 
139 pp, £19.99

The polar bears stare forlornly at Hudson Bay. It?s late November and they 
should be out on the sea ice hunting ring seals, but the ice hasn?t formed 
and the bears are starving. Ursus maritimus doesn?t hunt on land and 
normally fasts for months each summer. Now, however, the summers are 
growing longer across most of the Arctic, and the waters of Hudson Bay are 
ice-free for three weeks longer than they were thirty years ago. In a 
decade or two, polar bears won?t be found this far south; by the end of the 
century, they might exist only in zoos.

In the two hundred years since industrialisation ? a geological millisecond 
? we?ve increased the concentration of carbon dioxide in the Earth?s 
atmosphere by 35 per cent; a third of that has appeared in the last four 
decades. Carbon dioxide and other greenhouse gases, such as methane, trap 
heat that would otherwise radiate into space. As greenhouse gas levels 
rise, the lower atmosphere heats up and the climate changes, sometimes in 
unexpected ways.

The global average temperature has increased by about 0.6°C over the last 
two centuries. Most greenhouse gases remain in the atmosphere for decades, 
and have an ongoing, cumulative warming effect. In 2001, the UN 
Intergovernmental Panel on Climate Change, a group of 2500 scientists, 
predicted an additional increase during the 21st century of between 1.4 and 
5.8°C. In October, a body of nearly 300 scientists completed the Arctic 
Climate Impact Assessment, a report based not on worst-case scenarios but 
on observed changes to-date combined with projected temperature increases 
that are below the middle range of those anticipated by complex, 
increasingly accurate global climate models. Despite this methodological 
caution, the predictions made in the Assessment are terrifying. By the end 
of the century, annual average temperatures in the north will rise between 
3 and 5°C on land and up to 7°C over the Arctic Ocean, with winter 
temperatures increasing even more. Sea-ice cover will decline by 50 per 
cent, and could disappear entirely in summer.

full: http://www.lrb.co.uk/v27/n01/byer01_.html

--

www.marxmail.org