NASA - Generalized Arctic Warming Continues, Sea Ice Extent At Record Low

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"The Arctic warming study, appearing in the November 1 issue of the American Meteorological Society’s Journal of Climate, shows that compared to the 1980s, most of the Arctic warmed significantly over the last decade, with the biggest temperature increases occurring over North America.

“The new study is unique in that, previously, similar studies made use of data from very few points scattered in various parts of the Arctic region,” said the study’s author, Dr. Josefino C. Comiso, senior research scientist at NASA’s Goddard Space Flight Center, Greenbelt, Md. “These results show the large spatial variability in the trends that only satellite data can provide.” Comiso used surface temperatures taken from satellites between 1981 and 2001 in his study.

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In related NASA-funded research that observes perennial sea-ice trends, Mark C. Serreze, a scientist at the University of Colorado, Boulder, found that in 2002 the extent of Arctic summer sea ice reached the lowest level in the satellite record, suggesting this is part of a trend. “It appears that the summer 2003 -- if it does not set a new record -- will be very close to the levels of last year,” Serreze said. “In other words, we have not seen a recovery; we really see we are reinforcing that general downward trend.” A paper on this topic is forthcoming. According to Comiso’s study, when compared to longer term ground-based surface temperature data, the rate of warming in the Arctic over the last 20 years is eight times the rate of warming over the last 100 years.

Comiso’s study also finds temperature trends vary by region and season. While warming is prevalent over most of the Arctic, some areas, such as Greenland, appear to be cooling. Springtimes arrived earlier and were warmer, and warmer autumns lasted longer, the study found. Most importantly, temperatures increased on average by 1.22 degrees Celsius per decade over sea ice during Arctic summer. The summer warming and lengthened melt season appears to be affecting the volume and extent of permanent sea ice. Annual trends, which were not quite as strong, ranged from a warming of 1.06 degrees Celsius over North America to a cooling of .09 degrees Celsius in Greenland."

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NASA Earth Observatory

The polar ice cap is melting at an alarming rate due to global warming, according to Nasa scientists, with satellite images showing the ice cap has been shrinking by 10 percent per decade over the past quarter century.

"It is happening now. We cannot afford to wait a long period of time for technological solutions," said David Rind of Nasa's Goddard Institute for Space Studies in New York. "Change is in the air -- literally," he told a press conference
here on Thursday.

By means of a special satellite launched last year to measure the thickness of the polar ice cap, Nasa has confirmed that part of the Arctic Ocean that remains frozen all year round shrank at a rate of 10% per decade since 1980, Nasa researcher Josefino Comiso said.

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