Sea ice in the Arctic has failed to re-form for the second consecutive winter, raising fears that global warming may have tipped the polar regions in to irreversible climate change far sooner than predicted.
Satellite measurements of the area of the Arctic covered by sea ice show that for every month this winter, the ice failed to return even to its long-term average rate of decline. It is the second consecutive winter that the sea ice has not managed to re-form enough to compensate for the unprecedented melting seen during the past few summers.
Scientists are now convinced that Arctic sea ice is showing signs of both a winter and a summer decline that could indicate a major acceleration in its long-term rate of disappearance. The greatest fear is that an environmental "positive feedback" has kicked in, where global warming melts ice which in itself causes the seas to warm still further as more sunlight is absorbed by a dark ocean rather than being reflected by white ice.
Stuart Staniford at The Oil Drum has an excellent post on this news as well as a link to a very interesting site, The Cryosphere Today which is a site focused on the ice coverage of the Northern and Southern Hemispheres. As usual (for articles at The Oil Drum) the comments are excellent and it's evident that many folks are greatly concerned with the effects of positive feedback as well as thinning ice. I think we are now realizing that we greatly underestimated the rapidity of climate change... in truth I think we'll soon see that the reality is the worst case scenario.
Also today the BBC is reporting that there is a Sharp rise in recorded levels of CO2
US climate scientists have recorded a significant rise in the concentration of carbon dioxide in the atmosphere, pushing it to a new record level.
BBC News has learned the latest data shows CO2 levels now stand at 381 parts per million (ppm) - 100ppm above the pre-industrial average.
The research indicates that 2005 saw one of the largest increases on record - a rise of 2.6ppm.
The figures are seen as a benchmark for climate scientists around the globe.
The US National Oceanic and Atmospheric Administration (Noaa) has been analysing samples of air taken from all over the world, including America's Rocky Mountains.
The chief carbon dioxide analyst for Noaa says the latest data confirms a worrying trend that recent years have, on average, recorded double the rate of increase from just 30 years ago.
"We don't see any sign of a decrease; in fact, we're seeing the opposite, the rate of increase is accelerating," Dr Pieter Tans told the BBC.
More coverage via Reuters: Global warming gases at highest levels ever: UN
GENEVA (Reuters) - Greenhouse gases blamed for global warming and climate change have reached their highest ever levels in the atmosphere, the World Meteorological Organization (WMO) said on Tuesday.
A bulletin from the United Nations agency said the gases -- the main warming culprit carbon dioxide (CO2), methane and nitrous oxide -- "all reached new highs in 2004."
Other recent coverage of the melting ice sheets
On March 3 the Washington Post reported on new findings that were published in the journal Science: Antarctic Ice Sheet Is Melting Rapidly. From the article:
The Antarctic ice sheet is losing as much as 36 cubic miles of ice a year in a trend that scientists link to global warming, according to a new paper that provides the first evidence that the sheet's total mass is shrinking significantly.
It is one of a slew of scientific papers in recent weeks that have sought to gauge the impact of climate change on the world's oceans and lakes. Just last month two researchers reported that Greenland's glaciers are melting into the sea twice as fast as previously believed, and a separate paper in Science today predicts that by the end of this century lakes and streams on one-fourth of the African continent could be drying up because of higher temperatures.
The new Antarctic measurements, using data from two NASA satellites called the Gravity Recovery and Climate Experiment (GRACE), found that the amount of water pouring annually from the ice sheet into the ocean -- equivalent to the amount of water the United States uses in three months -- is causing global sea level to rise by 0.4 millimeters a year. The continent holds 90 percent of the world's ice, and the disappearance of even its smaller West Antarctic ice sheet could raise worldwide sea levels by an estimated 20 feet.
"The ice sheet is losing mass at a significant rate," said Isabella Velicogna, the study's lead author and a research scientist at Colorado University at Boulder's Cooperative Institute for Research in Environmental Sciences. "It's a good indicator of how the climate is changing. It tells us we have to pay attention."
The Independent Online also covered that story:
More evidence has emerged indicating the Antarctic ice sheet is melting so fast it is contributing to a rise in global sea levels.
The first satellite study of the continent's ice inventory has revealed that Antarctica is releasing around 35 cubic miles of water into the sea each year.
This is equivalent to an increase in global sea level of about 0.4mm a year. This would account for between 20 and 50 per cent of the average rise seen each year for the past century.
The findings suggest that the Intergovernmental Panel on Climate Change, which in its 2001 assessment assumed that Antarctica was not contributing to sea level rise, will have to review its position.
"This is the first study to indicate the total mass balance of the Antarctic ice sheet is in significant decline," said Isabella Velicogna of the University of Colorado at Boulder.
"The overall balance of the Antarctic ice is dependent on regional changes in the interior and those in the coastal areas. The changes we are seeing are probably a good indicator of the changing climatic conditions there," she said.
The study, published in the journal Science, results from a new way of investigating Antarctica's ice sheet by measuring changes in the gravitational pull of the continent - which corresponds to the total mass of its ice sheet - on a pair of orbiting satellites.
Until now satellites have concentrated on making accurate measurements of changes to the height of the ice sheet, or by taking images of the surface area of the ice shelves and floating sea ice fringing the continent's coast.
Scientists involved in the latest gravity recovery and climate experiment (Grace) used two satellites, launched in 2002, to measure small perturbations in gravity and hence variations in the total mass of the ice sheet.
The satellites orbit the poles at a distance of 137 miles from one another. A change in gravity due to a change in thickness of the ice sheet below is detected by small changes in the distance between the satellites. Scientists said that they can detect changes in distance between the Grace satellites equivalent to one fiftieth of the diameter of a human hair.
Here's the Los Angeles Times coverage of the story:
Study finds continent is shrinking faster than it can grow. Experts say changes to the global water cycle could hasten the pace of sea-level rise.
The ice sheets of Antarctica — the world's largest reservoir of fresh water — are shrinking faster than new snow can fall, scientists reported Thursday in the first comprehensive satellite survey of the entire continent.
Researchers at the University of Colorado determined that between 2002 and 2005 Antarctica lost ice at a rate of 36 cubic miles a year, rather than growing from heavier snowfalls as had been predicted. That amount of ice is equivalent to about 30 times the fresh water used by Los Angeles every year.
"It is the first time we can say that if you look at the entire ice sheet, it is losing mass," said geophysicist Isabella Velicogna, whose findings were published online Thursday by the journal Science.
This month, an independent research team at the Jet Propulsion Laboratory in La Cañada Flintridge reported that the Arctic glaciers of Greenland were melting twice as fast as five years ago, adding an extra 38 cubic miles of fresh water to the Atlantic Ocean every year.
Taken together, the findings suggest that a century of steady increases in global temperatures is altering the seasonal balance of the world's water cycle, in which new snow and ice neatly offset thaw and rainfall runoff every year to maintain the current level of the seas.
If so, experts say, increasing global temperatures — the 10 warmest years on record all occurred after 1990 — may be hastening the demise of the polar icecaps and estimates of the pace of sea-level rise could be too low.