From: baalke@zagami.jpl.nasa.gov   
      
   Elvia H. Thompson   
   Headquarters, WashingtonOctober 23, 2003   
   (Phone: 202/358-1696)   
      
   Krishna Ramanujan   
   Goddard Space Flight Center, Greenbelt, Md.   
   (Phone: 607/273-2561)   
      
   RELEASE: 03-340   
      
   RECENT WARMING OF ARCTIC MAY AFFECT WORLDWIDE CLIMATE   
      
        Recently observed change in Arctic temperatures and sea   
   ice cover may be a harbinger of global climate changes to   
   come, according to a recent NASA study. Satellite data -- the   
   unique view from space -- are allowing researchers to more   
   clearly see Arctic changes and develop an improved   
   understanding of the possible effect on climate worldwide.   
      
   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.   
      
   The result has direct connections to NASA-funded studies   
   conducted last year that found perennial, or year-round, sea   
   ice in the Arctic is declining at a rate of nine percent per   
   decade and that in 2002 summer sea ice was at record low   
   levels. Early results indicate this persisted in 2003.   
      
   Researchers have suspected loss of Arctic sea ice may be   
   caused by changing atmospheric pressure patterns over the   
   Arctic that move sea ice around, and by warming Arctic   
   temperatures that result from greenhouse gas buildup in the   
   atmosphere.   
      
   Warming trends like those found in these studies could   
   greatly affect ocean processes, which, in turn, impact Arctic   
   and global climate, said Michael Steele, senior oceanographer   
   at the University of Washington, Seattle. Liquid water   
   absorbs the Sun's energy rather than reflecting it into the   
   atmosphere the way ice does. As the oceans warm and ice   
   thins, more solar energy is absorbed by the water, creating   
   positive feedbacks that lead to further melting. Such   
   dynamics can change the temperature of ocean layers, impact   
   ocean circulation and salinity, change marine habitats, and   
   widen shipping lanes, Steele said.   
      
   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.   
      
   If the high latitudes warm, and sea ice extent declines,   
   thawing Arctic soils may release significant amounts of   
   carbon dioxide and methane now trapped in permafrost, and   
   slightly warmer ocean water could release frozen natural   
   gases in the sea floor, all of which act as greenhouse gases   
   in the atmosphere, said David Rind, a senior researcher at   
   NASA's Goddard Institute of Space Studies, New York. "These   
   feedbacks are complex and we are working to understand them,"   
   he added.   
      
   The surface temperature records covering from 1981 to 2001   
   were obtained through thermal infrared data from National   
   Oceanic and Atmospheric Administration satellites. The   
   studies were funded by NASA's Earth Science Enterprise, which   
   is dedicated to understanding the Earth as an integrated   
   system and applying Earth System Science to improve   
   prediction of climate, weather and natural hazards using the   
   unique vantage point of space.   
      
   For more information and images on the Internet, visit:   
   http://www.gsfc.nasa.gov/topstory/2003/1023esuice.html   
   and   
   http://www.earth.nasa.gov   
   -end-   
      
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