Canadian Press:
A groundbreaking study that traces Arctic temperatures further back than ever before... provides real-world evidence to back mathematical climate models that suggest greenhouse gases are behind global warming.
'There are no other forcing factors at work other than the greenhouse gas composition of the atmosphere that could explain the dramatic warming that took place,' said Darrell Kaufman, the paper's lead author...
Kaufman and nearly three dozen scientists used data from tree rings, lake sediments and glacial ice deposits from 23 sites around the circumpolar world to track average summer temperatures for every decade of the last two millennia -- 1,600 years longer than had ever been done before...
The measurements showed that from Year 1 to about 1900, summer Arctic temperatures were slowly decreasing by about 0.2 every 1,000 years... But things began to change at the 20th century's outset... Four of the Arctic's five warmest decades occurred after 1950. Warmest of all was 1999-2008, with average temperatures about 1.4C higher than they would have been if the cooling trend had continued.
The study says the constancy of other major variables about that time -- no large volcanic eruptions, for example -- suggests there could only be one culprit for the warming Arctic: carbon dioxide emissions that began increasing rapidly during the Industrial Revolution.
AP: The Arctic is experiencing its warmest temperatures in 2,000 years, even though it should be cooling because of changes in the Earth's orbit that cause the region to get less direct sunlight... 'If it hadn't been for the increase in human-produced greenhouse gases, summer temperatures in the Arctic should have cooled gradually over the last century,' said Bette Otto-Bleisner, a National Center for Atmospheric Research scientist and co-author of a study of Arctic temperatures...
It is the latest in a drumbeat of reports on warming conditions in the Arctic, including:
-- Alaskan waters are turning acidic from absorbing greenhouse gases faster than tropical waters...
-- Sea ice in the Arctic is more than just shrinking in area; it is thinning dramatically. The volume of older crucial sea ice in the Arctic has shrunk by 57 per cent from the winer of 2004 to 2008.
-- Shrinking glaciers, coastal erosion and the march north of destructive forest beetles formerly held in check by cold winters...
'Greenhouse gases from human activities are overwhelming the Arctic's natural climate systems,' commented NCAR scientist David Schneider, a co-author of the study... As the Arctic warms there is less snow and ice to reflect solar energy back into space and the newly exposed dark soil and dark ocean surfaces absorb solar energy and warm further, accelerating the warming process.
Canadian Press: 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... 'We thought by 2050, multi-year (sea) ice would be cut in half, said [Craig] Stewart from Ottawa. 'Well, it happened in 2007.'
But the biggest worry is the so-called methane hydrates -- 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...
'The carbon in that methane is the equivalent of all the coal, oil and gas combined worldwide.' said Stewart. 'If that methane gets released, that will become the single greatest driver of climate change anywhere in the world.'...
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...
Major weather patterns such as the North Atlantic Oscillation, which affect both storms and precipitation throughout Asia, Europe and North America, are strongly influenced by what happens in the Arctic... '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 the key to our existing climate.'
