McMurdo Dry Valleys
January 17, 2002
The photo above is of a U.S. Antarctic Program field camp at Lake Hoare in the McMurdo Dry Valleys, with the Canada Glacier in the background. The Dry Valleys - a perpetually snow-free, mountainous area adjacent to McMurdo Sound - are the largest ice-free area in Antarctica, a desert region that encompasses perennially ice-covered lakes, ephemeral streams, arid soils, exposed bedrock and alpine glaciers. All indigenous life there is microscopic.
A 14-year continuous weather station record from the shore of Lake Hoare reveals that seasonally averaged surface air temperature has decreased by 0.7 degrees Celsius per decade. The temperature decrease is most pronounced in summer and autumn. While the Antarctic Peninsula is warming, Antarctica overall has cooled measurably during the last 35 years - despite a global average increase in air temperature of 0.06 degrees Celsius during the 20th century - making it unique among the Earth's continental landmasses. The findings are puzzling because many climate models indicate that the Polar regions should serve as bellwethers for any global warming trend, responding first and most rapidly to an increase in temperatures. An ice sheet many kilometers thick in places perpetually covers almost all of Antarctica. Temperature anomalies also exist in Greenland, the largest ice sheet in the Northern Hemisphere, with cooling in the interior concurrent with warming at the coast. The cooling trend could adversely affect the unique ecosystems in the region.
Photo credit: Peter West/National Science Foundation