A weekly UPI series examining the potential human impact on global climate change.
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SEATTLE, Feb. 16 (UPI) -- The Arctic region has experienced a decrease in its ice extent of 3 percent per decade and a 42 percent decrease in ice thickness over the past several decades, according to scientists who study climate-related changes in the region.
These are only two of the dramatic, apparently climate-induced changes to the Arctic that also figure to affect the entire northern hemisphere. There also have been changes in surface temperatures, wind speeds and biology in the Arctic over a relatively short period -- changes that researchers said are unprecedented over at least the past 100 years.
Scientists studying the area have called this suite of impacts Unaami, after a Siberian Yup'ik word that means "tomorrow."
Speaking at the American Association for the Advancement of Science annual meeting, Jamie Morrison, a scientist with the Polar Science Center at the University of Washington, said researchers have detected a pattern called the Arctic Oscillation. It is an Arctic ocean circulation analogous to -- but weaker than -- the El Niño-Southern Oscillation or the Pacific Decadal Oscillation, two important climate influences in the Pacific.
After remaining relatively stable with high atmospheric pressure between 1979 and 1987, the Arctic Oscillation, or AO, weakened in the 1988-96 period, Morrison said. The transpolar drift of ice has shifted axes to a counterclockwise motion, producing a more cyclonic pattern. Arctic ocean salinity has increased 2 parts per thousand and the water temperature being brought up from deeper in the Atlantic has warmed by an average of about 1 degree Celsius.
All these changes portend implications for global climate, Morrison said. The circulation is spreading the ice further apart, which creates more open water in the Beaufort Sea. The result is a decrease in the ice albedo, or solar heat reflectivity, and permits more warming.
"In 2002," he said, "we saw the minimum ice extent we're ever encountered. There was open water in areas that are usually covered by ice north of Canada."
Over the past 64 years, he continued, the six largest Eurasian rivers have increased their freshwater flows into the Arctic by 7 percent. Permafrost temperatures also began to rise in the early 1990s.
"These are large changes, occurring not just in the ice and the ocean, but in lands animals and fish," said James Overland, with the U.S. National Oceanic and Atmospheric Administration in Seattle. "Since the 1980s, there have been changes in all parts of the Arctic across all different elements."
Tundra areas in the Arctic, Overland continued, "that were mostly mosses have changed so that the covered area has shrunk. They have been replaced by plants usually found farther south. In northwest Canada, eastern Siberia and northern Alaska, there has been about a 15 percent replacement of tundra by lower latitude plants."
Overland said there has been a large amount of spring warming in the Arctic since the 1980s across virtually the whole extent of the land. Weather stations are showing a 4 degree C temperature increase in monthly averages. In contrast, global climate warming is often measured in tenths of a degrees Celsius.
"There are major changes over the last 30 years in all parts of the Arctic," he said. Compared the past 100 years, "the Arctic changes are unique."
Arctic warming does not appear to be driving climate change at lower latitudes, he added, but rather the reverse -- it is linked to changes in the subtropics and influenced by them.
George Hunt, a biologist with the University of California, Irvine, has been studying algae blooms in the Bering Sea, which apparently resulted in the deaths of as many as 2 million short-tailed shearwaters -- a relative of the albatross -- or about 10 percent of the population. Some cold water fish are declining in the area, and being replaced by fish usually seen in warmer water. Biologists have spotted subtropical birds as far north as Barrow, Alaska.
"There is a suggestion that the Bering Sea is going from an Arctic-type place to a sub-Arctic one," Hunt noted.
Climate changes also have been noticed by the natives of the Arctic, who can be very astute commentators on the changes they face, according to Smithsonian Institution anthropologist Igor Krupnik.
He quoted Caleb Pungowiyi of Kotzebue, Alaska, who said: "Things are not coming back to normal year after year after year ... That scares us."
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Dan Whipple covers the environment for UPI Science News. E-mail [email protected]
