Arctic Ecology: Sea Ice
There use to be a time when knowing that polar bears lived at the north pole rather than the south pole made most people experts on Arctic ecology.
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You were reassured each year that the broken up ice pack reassembled because, of course, Santa and his reindeers (who do not as a rule enjoy surfing ice packs) completed another one of their legendary journeys.
Ice is still the predominant characteristic of arctic ecology today. However, the text accompanying the Arctic ice story has changed considerably over the past five decades.
Maps provided by the Arctic Climatology Project, a cooperative United States-Russian program, were among the first to illustrate an overall thinning pattern for the polar ice cap.
One set of maps which contrasts ice thickness at a 75 meter depth in the 1950s and in the 1980s shows ice pack density decreases in the potentially most dense ice packs off the coast of Norway and Russia. They also show overall density thinning throughout the entire Arctic Ocean.
Debate exists over the actual amount of sea-ice thinning to date, however, one scientific estimate, published in the journal, Geophysical Research Letters records an average 1.3 meter (~4 feet) thinning.
Why the thinning? Most scientists attribute the thinning to a weakening of the halocline layer of the Arctic Ocean, which basically is the bottom portion of the top layer of the three layers of water constituting the Arctic Ocean. The halocline layer, defined by its strong salinity, traditionally functioned as a road block, stopping the warmer Atlantic Ocean water (the Atlantic layer= 2nd level of Arctic Ocean) from mixing with and melting the top layer, the ice.
The National Snow and Ice Data Center recently published research showing historical low in Arctic sea ice, saying "September 2007 sea ice was 39 percent below the long-term average from 1979 to 2000".
© 2001-2007. Patricia A. Michaels.