The WWF said observations on ice coverage and thickness pointed toward a record low for the second year in a row, continuing a "catastrophic" trend that could threaten polar wildlife and accelerate global warming.
"If you take reduced ice thickness into account, there is probably less ice overall in the Arctic this year than in any other year since monitoring began," said Martin Sommerkorn, senior climate adviser of the WWF's Arctic program.
"This is also the first year that the Northwest Passage over the top of North America, and the Northeast Passage over the top of Russia, are both free of ice," he said.
The U.S. National Snow and Ice Data Center said earlier this month that Arctic sea ice coverage was the second lowest on record, and could break last year's low mark before the season is over. Satellite measurements began in 1979.
Last month, a scientist at Trent University in Ontario, Canada, reported that a chunk of ice shelf nearly the size of Manhattan broke away from Ellesmere Island in Canada's northern Arctic, another dramatic indication of how warmer temperatures are changing the polar frontier.
"There are already signs that species such as polar bears are experiencing negative effects as climate change erodes the ice platform on which they rely," Sommerkorn said. "These changes are also affecting the peoples of the Arctic whose traditional livelihoods depend on healthy ecosystems."
Arctic ice melts in summer and refreezes in winter. But over the years, more of the ice is lost to the sea with less of it recovered in winter. While ice reflects the sun's heat, the open ocean absorbs more heat and the melting accelerates warming in other parts of the world.
"As that ice goes, Arctic waters absorb more heat, adding to global warming," Sommerkorn said. "This is not just an Arctic problem, it is a global problem, and it demands a global response."
The group said governments must accelerate climate talks to ensure that a new deal to replace the Kyoto treaty on greenhouse gas emissions can be agreed on at a U.N. summit in Copenhagen, Denmark, in December 2009.