Unprecedented 5 degree heating of part of Arctic Ocean due to global warming

December 13th, 2007 - 4:32 pm ICT by admin  

Washington, Dec 13 (ANI): A new research has indicated that sea surface temperatures in one section of the Arctic Ocean have risen up to 5 degree Celsius above average, due to the effects of global warming.

A major reason for this increase in temperature in the particular area of the Arctic Ocean is the record-breaking amounts of ice-free water, which has deprived the Arctic of more of its natural sunscreen than ever in recent summers.

Such superwarming of surface waters can affect how thick ice grows back in the winter, as well as its ability to withstand melting the next summer, said Michael Steele, an oceanographer with the University of Washington’s Applied Physics Laboratory.

The extra ocean warming also might be contributing to some changes on land, such as previously unseen plant growth in the coastal Arctic tundra, if heat coming off the ocean during freeze-up is making its way over land, adds Steele.

According to the research, warming is particularly pronounced since 1995, and especially since 2000. The spot where waters were 5 Celsius above average was in the region just north of the Chakchi Sea. The historical average temperature there is -1 C.

But this year, water in that area warmed to 4 C, for a 5-degree change from the average.

That general area, the part of the ocean north of Alaska and Eastern Siberia that includes the Bering Strait and Chukchi Sea, experienced the greatest summer warming.

Temperatures for that region were generally 3.5 C warmer than historical averages and 1.5 C warmer than the historical maximum.

Such widespread warming in those areas and elsewhere in the Arctic is probably the result of having increasing amounts of open water in the summer that readily absorb the sun’s rays, said Steele.

The warming also may be partly caused by increasing amounts of warmer water coming from the Pacific Ocean, something scientists have noted in recent years.

The Arctic was primed for more open water since the early 1990s as the sea-ice cover has thinned, due to a warming atmosphere and more frequent strong winds sweeping ice out of the Arctic Ocean via Fram Strait into the Atlantic Ocean where the ice melts.

Now the situation could be self-perpetuating, said Steele.

For example, he calculates that having more heat in surface waters in recent years means 23 to 30 inches less ice will grow in the winter than formed in 1965. Since sea ice typically grows about 80 inches in a winter, that is a significant fraction of ice that’s going missing, he says.

Then too, higher sea surface temperatures can delay the start of freeze-up because the extra heat must be discharged from the upper ocean before ice can form.

“The effect on net winter growth would probably be negligible for a delay of several weeks, but could be substantial for delays of several months,” said the authors. (ANI)

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