Arctic resists warming

Arctic resists warming
New patterns suggest region returning to 1970s conditions

RESEARCHERS: New patterns of cooling ocean currents, winds suggest region is struggling to keep its balance.

An international team of scientists reported Thursday that rising temperatures are steadily transforming the Arctic -- warming millions of square miles of permafrost, promoting lush greenery on previously arid tundras and steadily shrinking the annual sea ice.

Yet the researchers also found new patterns of cooling ocean currents and prevailing winds that suggested the Arctic, long considered a bellwether of global warming, may be reverting in some ways to more normal conditions not seen since the 1970s.

Taken together, these findings may be evidence, the researchers said, of the region struggling to keep its balance, as rising temperatures slowly overturn the long-established order of seasonal variations.

"This is a region that is fighting back," said lead author Jacqueline Richter-Menge, a civil engineer at the Cold Regions Research and Engineering Laboratory in Hanover, N.H. "There are things that showed signs of going back to norms, trying to right themselves under very dire circumstances."

For a year, 20 researchers in seven countries reviewed the condition of the atmosphere, ocean, sea ice and land at the top of the world. They summarized their findings in the "State of The Arctic," a report released Thursday by the National Oceanic & Atmospheric Administration.

On average, global temperatures have been steadily warming for decades -- 2005 was the warmest year since record-keeping began in 1880 -- but the polar region appears to be warming twice as fast as the rest of the world. Local weather variations at Earth's upper latitudes create a seesaw of annual hot spots and cold sinks above the Arctic Circle that, combined with incomplete data records, can easily disguise longer regional climate trends.

By pulling together data from many countries and scientific sources, the researchers sought to determine more conclusively how the climate throughout the Arctic behaved from 2000 through winter 2006.

"Arctic temperatures were above their average -- at least 1 degree centigrade above average over the entire Arctic over the entire year. This is a unique situation," said co-author James Overland at NOAA's Pacific Marine Environmental Laboratory in Seattle.

The study reports an increase in northward movement of warmer water through the Bering Strait in 2001 to 2004. This may have contributed to a continuing reduction of sea ice.

Last year, the Arctic sea ice set record lows every month except May, the researchers reported, continuing a trend that started in 2000. The permanent ice cap has been thinning as well. Summer melting began earlier every year of the study and was more extensive.

Glaciers everywhere receded. For the past five years, rivers flowing into the Arctic Ocean have been 3 percent to 9 percent higher than average with fresh melt water, stream gauges showed. That, in turn, has made the seawater less salty, affecting ocean currents.

Permafrost throughout the Alaska Arctic steadily warmed, records documented. Last year, soil temperatures in the interior of Alaska were among the warmest of the past 70 years, the researchers reported.

In response, vegetation in the tundras increased by 10 percent over the past 20 years, satellite measurements showed.

Shrubs rooted more readily above the Arctic Circle in Alaska and Siberia. The new ground cover provided shelter for some creatures while making it harder for others, such as reindeer and caribou herds, to move through their grazing grounds.

The study was designed to assess the overall impact of climate change in the Arctic and will be updated annually. It was compiled by researchers from the United States, Canada France, Germany, Poland, Norway, Sweden and Russia, she said.

In addition, 2007 has been designated the International Year of the Arctic, with intense scientific study of the region planned.

There have been many changes over the Arctic land areas, said Vladimir E. Romanovsky, a professor at the geophysical institute of the University of Alaska. These include changes in vegetation, river discharge into the Arctic Ocean, glaciers and permafrost.

The tundra is becoming greener with the growth of more shrubs, he said. This development is causing problems in some areas as herds of reindeer migrate.

At the same time, there is some decrease in the greening of the northern forest areas, probably due to drought. The glaciers are continuing to shrink and river discharge into the Arctic Ocean is rising, Romanovsky said.