WASHINGTON, Dec. 16 — Record high air temperatures over land areas and decreasing sea ice extent and Greenland ice sheet mass are threatening survival of walruses and forcing a northward movement of some fish species in the Arctic zone, a new U.S. government-sponsored report said Tuesday.
The average Arctic land surface air temperature for the past year, between October 2014 and September 2015, was 2.3 degrees Fahrenheit (1.3 degrees Celsius) above average, the warmest in the observational record which began in 1900, according to the Arctic Report Card 2015, an annual peer-reviewed report released by the U. S. National Oceanic and Atmospheric Administration (NOAA).
"The Arctic is warming twice as fast as other parts of the planet, which has ramifications for global security, climate, commerce, and trade," NOAA chief scientist Rick Spinrad said in a statement. "This year's report shows the importance of international collaboration on sustained, long-term observing programs that provide insights to inform decisions by citizens, policymakers, and industry."
The report found Arctic sea ice reached its annual maximum extent on Feb. 25, 15 days earlier than average and "the lowest extent recorded since records began in 1979." The minimum sea ice extent, which occurred in September 2015, was 29 percent less than the average for 1981-2010 and the fourth lowest value in the satellite record.
First year ice, it said, now dominated the winter ice cover, comprising about 70 percent of the March 2015 ice pack, compared to about half that in the 1980s when older, thicker ice was more prevalent. "The thinner, younger ice is more vulnerable to melting in the summer," the report said.
While Arctic-wide terrestrial snow cover extent in April was above average, June snow cover in both the North American and Eurasian parts of the Arctic was the second lowest in the satellite record that began in 1967. On average, Arctic-wide June snow extent has declined 18 percent per decade since 1979.
This year, over half of the surface of the Greenland ice sheet melted, representing its first significant melting since 2012. In total, "22 of 45 of the widest and fastest flowing glaciers terminating in the ocean had retreated, but the advance of nine relatively wide glaciers resulted in a low annual net loss of 6.4 square miles (16.5 square kilometers)," said the report.
Melting and retreat of sea ice during spring has led to an increase in sunlight reaching the upper layers of the ocean, promoting photosynthesis and stimulating the growth of algae, tiny marine plants which form the base of the food chain.
"Widespread and exceptional phytoplankton blooms were observed in 2015 in Arctic seas along the edge of the continental shelf, including waters to the southwest and east of Greenland, in the Bering Sea between Alaska and Russia, and in the Barents, Kara and Laptev seas north of Russia," the report wrote.
Guest essays included in this year's report showed that the decline in sea ice is dramatically changing the habitat for walruses — large marine mammals that traditionally use sea ice for mating, giving birth to young, finding food and shelter from storms and predators.
"In recent years, large numbers of walrus have been forced to haul out on land in northwest Alaska," it said. "This behavior, documented through aerial surveys, has created problems such as overcrowding which has led to stampedes that have killed calves, and difficulty finding food."
Scientists from Norway and Russia who drew on annual ecosystem surveys from the Barents Sea from 2004 to 2013 also found "a northward movement of subarctic fish species such as cod, beaked redfish and long rough dab, into Arctic waters."
"These predators may pose potential problems for smaller Arctic fish that must now face these new warmer-water predators," the report noted.
The report included some 70 authors from 11 countries and was guided by an editorial team from the Office of Naval Research, the U.S. Army Corps of Engineers' Cold Regions Research and Engineering Laboratory, and the NOAA. (PNA/Xinhua)