LiveScience.com Yahoo News 8 Feb 11;
Arctic sea ice was at its lowest extent ever recorded in January this year, according to a new report by the U.S. National Snow and Ice Data Center (NSIDC).
This winter has been cold and snowy in North America, but farther north, temperatures have been unusually warm. Data collected by NASA's Aqua satellite shows that ice was low in Canada's Hudson Bay, Hudson Strait and the Davis Strait between Canada and Greenland. Normally these areas are frozen over by late November, the NSIDC reported. This winter, they didn't free until mid-January 2011. The Labrador Sea was similarly ice-free.
Arctic ice in January covered 5.23 million square miles (13.55 million square kilometers), 19,300 square miles (50,000 square km) less than the previous record in 2006. Arctic ice monitoring began in 1979. This January's ice cover was also 490,000 square miles (1.27 million square km) below the 1979 to 2000 average.
In October, NSIDC reported an unusual late-season decline in Arctic sea ice.
There are two possible explanations for the extended thaw, NSIDC reported. The Arctic Oscillation, a seesaw pattern of atmospheric pressure differences, was in negative mode in December 2010 and January 2011. When the Arctic Oscillation is negative, it brings cold and snow to Europe and North America but allows warmer air to creep into the Arctic. (A positive oscillation traps cold air up north.)
Another factor, NSIDC explained, could be that areas of open ocean were still releasing heat into the atmosphere. Bright white ice reflects solar heat back into space, but dark ocean waters (or those without ice cover) absorb the energy, warming and reinforcing the ice-melting process.
The National Oceanic and Atmospheric Administration (NOAA) has forecast that the Arctic Oscillation should return to positive mode in February 2011. According to NSIDC, Arctic winter sea ice has declined by approximately 3.3 percent per decade since 1979.
Loss of Arctic Ice Imperils Polar Bear Births
LiveScience.com Yahoo News 8 Feb 11;
Loss of Arctic sea ice is linked to a decrease in polar bear birth rates in Canada's Hudson Bay, according to new research. If the trend continues, the polar bears in the region could be facing a population crisis.
In fact, if climate change continues unabated, the researchers say, polar bear populations across the entire Arctic will be in serious trouble.
Polar bears rely on sea ice during their hunting season, using the solid floes to reach waters rich with seals - polar bears' main food source.
Researchers at the University of Alberta in Canada examined sea ice data from the 1990s on, and found that as temperatures increased and sea ice levels dropped, so did the number of newborn polar bear cubs.
Polar bear mothers retreat to a maternity den during pregnancy, never once emerging for food. An early spring ice breakup reduces the hunting season, and pregnant females aren't able to amass enough body fat to support them through their 8-month fast, when they must stay hidden in their dens to gestate their young and give birth.
Using mathematical modeling to estimate the impact of a shortened hunting season, the research team found that if ice in the Hudson Bay disappears one month earlier than in the 1990s, between 40 and 73 percent of pregnant female polar bears will not give birth to a surviving cub.
If the ice is gone a full two months earlier, between 55 and 100 percent of pregnant bears will not reproduce.
According to the most recent estimates, Hudson Bay is home to about 900 polar bears, down from 1,200 bears in the past decade.
Since the region's bear population is the world's most southerly, they are the first to be affected by global warming trends.
However, the researchers say that if temperatures across the Arctic continue to rise, much of the global population of polar bears will be at risk.
The research is detailed today (Feb. 8) in the journal Nature Communications.
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This article was provided by OurAmazingPlanet, a sister site to LiveScience.
