Sunday, September 18, 2011

Northwest Passage open as sea ice falls to lowest cover ever recorded

Arctic sea ice cover fell to its lowest level on record, report researchers from the University of Bremen.

Analyzing data from NASA's Aqua satellite, Georg Heygster and colleagues found that Arctic sea ice fell to a record low of 4.24 million square kilometers on September 8, about 27,000 square kilometers than the previous record set roughly four years ago.

Heygster said this year's mark is "most probably" the lowest Arctic sea ice extent "since the last climate optimum about 8,000 years ago." He added that the record could be extended if sea ice continues to melt in coming weeks. Sea ice is no longer melting from the surface; instead if it melting from underneath due to warmer water below.

The U.S. National Snow and Ice Data Center (NSIDC), which tracks sea ice using a different methology, is expected to release an update on sea ice extent later this month. Its last update showed sea ice coverage at 4.3 million square kilometers.

Melting of sea ice opened the Northwest Passage to navigation again this summer. The ice retreat has set off a scramble between Canada, Russia, the U.S., Denmark, Sweden and Norway which are all seeking to claim rights to the Arctic's rich mineral and gas deposits.

Sea ice hits its nadir in September before rebounding during the long Arctic winter. The loss of sea ice in the Arctic, which imperils a number of key species, has been widely linked to climate change resulting global greenhouse gas emissions.

"The sea ice retreat can no more be explained with the natural variability from one year to the next," said a statement from the University of Bremen. "Climate models show rather, that the reduction is related to the man-made global warming." more