A new report says Arctic climate change is happening faster than anyone anticipated and may soon be forcing more rapid warming on the rest of the planet.
"It is a tipping point," said Craig Stewart of the World Wildlife Fund, which was to release the report Wednesday in London.
The report is an attempt to update the work of scientists involved in the 2007 Intergovernmental Panel on Climate Change as world leaders prepare to gather in Copenhagen in December to discuss how to deal with the problem. The conclusion of many of those same top researchers is that changes are occurring much more quickly - especially in the Arctic - than was believed even two years ago.
"We thought by 2050, multi-year [sea]ice would be cut in half," said Mr. Stewart from Ottawa. "Well, it happened in 2007."
But the biggest worry is the "methane hydrates" - a strange, slushy form of methane frozen in ice molecules that exists in vast volumes in permafrost and continental shelves around the circumpolar globe. Cold and high pressure have so far kept that methane - a greenhouse gas 25 times more potent than carbon dioxide - out of the atmosphere.
Underground methane, however, has recently been observed bubbling up in Arctic Russia.
"There is so much methane under the permafrost and under ocean floor sediments that the carbon in that methane is the equivalent of all the coal, oil and gas combined worldwide," Mr. Stewart said.
"If that methane gets released, that will become the single greatest driver of climate change anywhere in the world."
Sea levels are also being increasingly affected by Arctic climate change.
In 2007, scientists were unsure if the Greenland ice cap was diminishing and thought Antarctic ice might actually be increasing in volume.
They now know Greenland is losing enough ice every year to supply 280 cities the size of Los Angeles with water, and the rate is increasing. Antarctica loses almost as much.
That has led researchers to sextuple their estimates of sea level rise, to 1.2 metres by 2100. About one-quarter of the earth's population lives in low-lying coastal regions.
The North also has the power to change weather patterns around the globe. Major weather patterns such as the North Atlantic Ocillation, which affect both storms and precipitation throughout Asia, Europe and North American, are strongly influenced by what happens in the Arctic.
"Evidence for responses of atmospheric circulation to declining sea ice extent is just beginning to emerge," the report says.
Sea water once covered by ice becomes warmed by the sun, changing ocean currents that begin in the Arctic. Those currents are also affected by meltwater flooding into the oceans, altering its salinity.
Ocean currents - major climate determinants in coastal regions - have yet to show significant climate-change impacts, but scientists are growing more concerned about the possibility.
"The Arctic does have a huge influence on global circulation patterns," said Stewart. "The ability for the Arctic to essentially serve as a refrigerator for the planet is key to our existing climate."
Stewart said it's sometimes tough to get people to connect the dots between a collapsing ice shelf at the other end of the planet and their morning weather forecast. But the Arctic's influence on the south is both real and only imperfectly understood, he says.
"It's not all about warming, it's all about change - weather change. It will make life more unpredictable and more expensive."
Stewart said the report, peer-reviewed and written by some of the world's top climate resaerchers, is intended to inform the debate leading up to the Copenhagen meeting. Members of the world's 20 leading economies meet later this month to try to hammer out financial commitments to deal with climate change.
"The meetings begin now," said Stewart. "We want to make sure the latest information is in their hands."