Substream - sub_gw_impact_arctic

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  2. 25-10-2003 eco nws - global warming - impact - arctic - U.S. satellite observations show a continuing retreat of the North Pole ice cap, as the Arctic warms. Scientists say the shrinking ice cover feeds global warming, but is also enhanced by it in a vicious cycle. Small changes can have a big impact on our lives. #One year ago#, the U.S. space agency NASA reported that the permanent Arctic ice layer covered less area than at any time since satellite measurements began. The agency found that Arctic temperatures were increasing about one degree Celsius a decade, with a corresponding ice cap loss of nine percent per decade. It warned that the ice could disappear in this century, if the trend continued. Now, the NASA researcher who published those findings, Josefino Comiso, said the trend is continuing. (voanews.com)

  3. 10-12-2003 eco nws - global warming - impact - arctic - ancient global warming - Measurements of ancient air bubbles trapped in Antarctic ice offered evidence that humans have been changing the global climate since thousands of years before the industrial revolution. Beginning 8,000 years ago, atmospheric levels of carbon dioxide began to rise as humans started clearing forests, planting crops and raising livestock, a scientist said Tuesday. Methane levels started increasing 3,000 years later. The combined increases of the two greenhouse gases implicated in global warming were slow but steady and staved off what should have been a period of significant natural cooling, said Bill Ruddiman, emeritus professor at the University of Virginia.

  4. 28-05-2004 eco nws - global warming - impact - arctic - arctic heating twice as fast as rest - Global warming is hitting the Arctic more than twice as fast as the rest of the planet, scientists reported this week. The Arctic is particularly sensitive because the ice normally reflects vast amounts of solar radiation. But when icecaps recede, much more sunlight is absorbed by the darker mass of ocean and land. All that additional heat melts even more ice in what becomes a feedback loop. Some parts of Alaska have heated up 10 times more than the global average, Robert Corell, a chairman of the Arctic Climate Impact Assessment, told Reuters. (wired)

  5. 24-09-2004 eco nws - global warming - impact - arctic - arctic glaciers accelerating - A number of massive glaciers in the West Antarctic are sliding into the ocean at an accelerating rate and raising sea levels, according to new data released Thursday. The new study, published Thursday in the journal Science, found that six glaciers flowing into the Amundsen Sea have quickened their march into the ocean over the past 15 years, and the pace has accelerated recently. The fastest of these, the Pine Island Glacier, is ripping along at a six-yards-a-day pace -- 25 percent faster than it was moving in the 1970s -- making it one of the fastest-moving glaciers on Earth. (wired)

  6. 31-10-2004 eco nws - global warming - impact - arctic - report - arctic assessment - The most comprehensive international assessment of Arctic climate change has concluded that Earth's upper latitudes are experiencing unprecedented increases in temperature, glacial melting and weather pattern changes, with most of those changes attributable to the human generation of greenhouse gases from automobiles, power plants and other sources. The 144-page report is the work of a coalition of eight nations that have Arctic territories -- including the United States, which has hosted and financed the coalition's secretariat at the University of Alaska. The findings, which reflect four years of study, confirm earlier evidence that the Arctic is warming far more quickly than the earth overall, with temperature increases in some northern regions exceeding by tenfold the average 1 degree Fahrenheit increase experienced on Earth in the past 100 years. (washingtonpost)

  7. 11-11-2004 eco nws - global warming - impact - arctic - 1m sea level rise in 2100 - Global warming is melting the Arctic ice faster than expected, and the world's oceans could rise by about a meter (3 feet) by 2100, swamping homes from Bangladesh to Florida, the head of a study said. Robert Corell, chairman of the eight-nation Arctic Climate Impact Assessment (ACIA), also told a news conference there were some hints of greater willingness by the United States, the world's top polluter, to take firmer action to slow climate change. Speaking at the start of a four-day scientific conference in Reykjavik, Corell said global warming was melting the Greenland ice sheet and Arctic glaciers from Alaska to Norway quicker than previously thought. (planet ark)

  8. 15-11-2004 eco nws - global warming - impact - arctic - arctic heating faster - Earth's climate has warmed by about 1 degree Fahrenheit since 1900. In the Arctic, where a number of processes amplify the warming effects of carbon dioxide, most regions have experienced a temperature rise of 4 to 7 degrees in the last 50 years. That warmth has reduced the amount of snow that falls every winter, melted away mountain glaciers and shrunk the Arctic Ocean's summer sea ice cover to its smallest extent in millennia, according to satellite measurements. Swaths of Alaskan permafrost are thawing into soggy bogs, and trees are moving northward at the expense of the tundra that rings the Arctic Ocean. (enn)

  9. 20-01-2005 eco nws - global warming - impact - arctic - arctic inflow of fresh water - The amount of fresh water entering the Arctic Ocean from the rivers that feed it is increasing, UK scientists report. Writing in the journal Geophysical Research Letters, they say the increase is caused in part by human activities and is an early sign of climate change. The rise in fresh water entering the Arctic Ocean could change the global distribution of water, the team says. It could also affect the balance of the climate system itself and even possibly alter the behaviour of the Gulf Stream. The team is from the Hadley Centre for Climate Prediction and Research, part of the UK Met Office. (bbc)

  10. 26-01-2005 eco nws - global warming - impact - arctic - ice covers vanishing all-over world - They'll disappear far beyond Bolivia['s CHACALTAYA GLACIER]. From Alaska in the north, to Montana's Glacier National Park, to the great ice fields of wild Patagonia at this continent's southern tip, the 'rivers of ice' that have marked landscapes from prehistory are liquefying, shrinking, retreating. In east Africa, the storied snows of Mount Kilimanjaro are vanishing. In the icebound Alps and Himalayas of Europe and Asia, the change has been stunning. From South America to south Asia, new glacial lakes threaten to overflow and drown villages below. (ap)

  11. 02-02-2005 eco nws - global warming - impact - arctic - arctic melting even faster - A team of UK researchers claims to have new evidence that global warming is melting the ice in Antarctica faster than had previously been thought. Scientists from the British Antarctic Survey (Bas) say the rise in sea levels around the world caused by the melting may have been under-estimated. It is thought that over 13,000 sq km of sea ice in the Antarctic Peninsula has been lost over the last 50 years. The findings were announced at the Climate Change Conference in Exeter. (bbc)

  12. 13-02-2005 eco nws - water - global warming - impact - arctic - The amount of fresh water entering the Arctic Ocean from the rivers that feed it is increasing, UK scientists report. Writing in the journal Geophysical Research Letters, they say the increase is caused in part by human activities and is an early sign of climate change. The rise in fresh water entering the Arctic Ocean could change the global distribution of water, the team says. It could also affect the balance of the climate system itself and even possibly alter the behaviour of the Gulf Stream. (bbc)

  13. 18-02-2005 eco nws - global warming - impact - arctic - A parcel of studies looking at the oceans and melting Arctic ice leave no room for doubt that it is getting warmer, people are to blame, and the weather is going to suffer, climate experts said on Thursday. New computer models that look at ocean temperatures instead of the atmosphere show the clearest signal yet that global warming is well underway, said Tim Barnett of the Scripps Institution of Oceanography. Speaking at an annual meeting of the American Association for the Advancement of Science, Barnett said climate models based on air temperatures are weak because most of the evidence for global warming is not even there. 'The real place to look is in the ocean,' Barnett told a news conference. (wired)

  14. 25-02-2005 eco nws - global warming - impact - arctic - other ice - melting outside arctic as well - Ice melting is not limited to the poles. According to glaciologist Lonnie Thompson of Ohio State University, all but 13 of the 2,000 glaciers in southeast Alaska are retreating. Montana�s Glacier National Park may have no glaciers left by 2030, and the ice cap on Tanzania�s Kilimanjaro may disappear completely by 2015. In South America, Andean glaciers have been melting three times faster in recent years than they were in the mid-twentieth century. Bolivia�s Chacaltaya, once home to the world�s highest ski slope, is estimated to be a mere 2 percent of its former size. It lost two-thirds of its mass in the 1990s alone and may disappear completely by 2010. Shrinking glaciers may mean a loss of power in Peru, where 70 percent of electricity comes from hydroelectric turbines powered by the annual runoff from glaciers. (earthhope)

  15. 21-04-2005 eco nws - global warming - impact - arctic - Antarctic glaciers show retreat - The glaciers of the Antarctic Peninsula are in rapid retreat. A detailed study reported in Science magazine shows nearly 90% of the ice bodies streaming down from the mountains to the ocean are losing mass. But the authors - a joint team from the British-Antarctic and US-Geological Surveys - say the big melt could have a number of complex causes. Although higher air temperatures are a factor, they say, the full picture may go beyond just simple global warming. (bbc)

  16. 21-04-2005 eco nws - global warming - impact - arctic - Climate Change Taking a Toll on Glaciers - Scientists have issued a fresh warning about the effect of climate change on Antarctica, saying that more than 200 coastal glaciers are in retreat because of higher temperatures. Of the 244 marine glaciers that drain inland ice on the Antarctic peninsula, a region previously identified as vulnerable to global warming, 87 percent have fallen back over the last half century, according to research by British experts. Using 2 000 aerial photos dating back to the late 1940s and 100 satellite pictures, experts from the British Antarctic Survey (BAS) compiled a record of glacier-ice shelves and tidewater glaciers along the peninsula - the tongue of land that juts 800km northwards out of continental Antarctica. 'Since then this pattern has reversed' Glacier-ice shelves are floating glaciers on the shoreline that are still connected to the land glaciers from which they flowed. Tidewater glaciers rest on rock and break off into the ocean when they reach the water's edge. Over the last half century, during which time regional temperatures have risen by around 2?C, these glacier fronts have reversed direction, the authors note in a study published on Friday in the US weekly journal Science. Until the mid-1950s, most of the glaciers advanced. For the next decade after that, they were roughly stable. Since then, though, most have been shrinking. In the past five years, the retreat has accelerated, and the pattern of retreat is widening. It started in the warmer northern tip of the peninsula and is heading progressively to the colder south as atmospheric temperatures rise. 'Fifty years ago, 62 percent of the glaciers that flowed down from the mountains to the sea we looked at were slowly growing in length, but since then this pattern has reversed,' said lead author Alison Cook. (earth hope)

  17. 20-05-2005 eco nws - global warming - impact - arctic - increased snow crows antarctic ice sheet - As Climate Shifts, Antarctic Ice Sheet Is Growing - As glaciers from Greenland to Kilimanjaro recede at record rates, the central icecap of Antarctica has been steadily growing for 11 years, partially offsetting the rise in seas from the melt waters of global warming, researchers said Thursday. The vast East Antarctic Ice Sheet � a 2-mile-thick wasteland larger than Australia, drier than the Sahara and as cold as a Martian spring � increased in mass every year from 1992 to 2003 because of additional annual snowfall, an analysis of satellite radar measurements showed. 'It is an effect that has been predicted as a likely result of climate change,' said David Vaughan, an independent expert on the ice sheets at the British Antarctic Survey in Cambridge, England. In a region known for the lowest temperatures recorded on Earth, it normally is too cold for snow to form across the 2.7 million square miles of the ice sheet. Any additional annual snowfall in East Antarctica, therefore, is almost certainly attributable to warmer temperatures, four experts on Antarctica said. (earth hope)

  18. 30-09-2005 eco nws - global warming - impact - arctic - Arctic ice 'disappearing quickly' - The area covered by sea ice in the Arctic has shrunk for a fourth consecutive year, according to new data released by US scientists. They say that this month sees the lowest extent of ice cover for more than a century. The Arctic climate varies naturally, but the researchers conclude that human-induced global warming is at least partially responsible. They warn the shrinkage could lead to even faster melting in coming years. 'September 2005 will set a new record minimum in the amount of Arctic sea ice cover,' said Mark Serreze, of the National Snow and Ice Data Center (NSIDC), Boulder, Colorado. (bbc)

  19. 08-12-2005 eco nws - global warming - impact - glaciers - arctic - arctic melting - Greenland glacier races to ocean - Scientists have been monitoring what they say may be the fastest moving glacier on the planet. Kangerdlugssuaq Glacier on the east coast of Greenland has been clocked using GPS equipment and satellites to be flowing at a rate of 14km per year. It is also losing mass extremely fast, with its front end retreating 5km back up its fjord this year alone. The glacier 'drains' about 4% of the ice sheet, dumping tens of cubic km of fresh water in the North Atlantic. This gives it significant influence not just on global sea level rise but on the system of ocean circulation which drives through the Arctic. 'We've seen a 5km retreat of the terminus, we've see an almost 300% acceleration in the flow speed and we've seen about a 100m thinning of the glacier - all occurring in the last one or so years,' said Dr Gordon Hamilton, of the Climate Change Institute at the University of Maine. 'These are very dramatic changes.' And they are not confined to Kangerdlugssuaq. He was speaking here at the American Geophysical Union Fall Meeting. Helheim Glacier, just to the south of Kangerdlugssuaq, is exhibiting similar changed behaviour. It is flowing only slightly slower at 12km per year - the equivalent of half a football field a day. Hamilton thinks a couple of factors may be triggering the quick melt. The observed recent increase in summer surface melting on the Greenland Ice Sheet is producing large quantities of liquid water which, if it percolates down to the base of the glacier, can lubricate its flow over rocks towards the ocean. And if that same warming is bringing higher-temperature sea waters into contact with the front of Kangerdlugssuaq and Helheim, this could explain their rapid retreat. If other large glaciers in the region are seen to go the same way, it could begin to 'pull the plug' on Greenland, said Dr Hamilton. 'The model predictions for sea level rise do not include the effects of rapid changes in ice dynamics,' he added. 'We're seeing now that this component might be extremely important. And what it suggests is that the predictions for both the rate and the timing for sea level rise in the next few decades will be largely underestimated.' (bbc)

  20. 09-03-2006 eco nws - global warming - impact - arctic - Polar ice sheets show net loss - There is a net loss of ice to the ocean from the Greenland and Antarctic ice sheets, a study has found. In one of the most comprehensive studies of its type, satellite data was used to plot changes in the height of the ice sheets between 1992 and 2002. Writing in the Journal of Glaciology, a US team says that 20 billion tonnes of water are added to oceans each year. Mass changes in the ice sheets match predictions from computer models of global climate change, they say. Dr H Jay Zwally, of the US space agency (Nasa) Goddard Flight Center in Maryland, and colleagues analysed radar altimeter data from two European remote-sensing satellites, ERS-1 and ERS-2, as well as Nasa's plane-based Airborne Topographic Mapper instrument. This seems to suggest that East Antarctica might not save our bacon after all Liz Morris, Scott Polar Research Institute The survey documents extensive thinning of the West Antarctic ice shelves, but a thickening in the East of the continent, though not by as much as some other studies have shown. It shows the interior of Greenland is gaining mass due to increased snowfall, but the edges are getting thinner. This mass gain is something which computer models of climate have predicted. Warmer air is able to carry more water; so as the atmosphere heats up, Greenland and Antarctica should experience greater snowfall. But rising temperatures could have the opposite effect at the edges of both landmasses, causing rates of melting to increase. A recent study led by Eric Rignot of Nasa's Jet Propulsion Laboratory showed the amount of ice dumped into the Atlantic Ocean by Greenland's glaciers has doubled in the last five years. (bbc)

  21. 14-09-2006 eco nws - global warming - impact - arctic - arctic ice - 'Drastic' shrinkage in Arctic ice - A Nasa satellite has documented startling changes in Arctic sea ice cover between 2004 and 2005. The extent of 'perennial' ice - thick ice which remains all year round - declined by 14%, losing an area the size of Pakistan or Turkey. The last few decades have seen summer ice shrink by about 0.7% per year. The drastic shrinkage may relate partly to unusual wind patterns found in 2005, though rising temperatures in the Arctic could also be a factor. The research is reported in the journal Geophysical Research Letters. The Arctic is warming about twice as fast as the global average; and recent studies have shown that the area of the Arctic covered by ice each summer, and the ice thickness, have been shrinking. September 2005 saw the lowest recorded area of ice cover since 1978, when satellite records became available. [...] When they compared figures for the 2004 and 2005 northern hemisphere winter solstices - 21 December - a huge change showed up. 'In previous years there is some variability, but it is much smaller and regional,' Dr Nghiem told the BBC News website. 'However the change we see between 2004 and 2005 is enormous.' The area of perennial sea ice lost was about 730,000 sq km, with a huge loss in the East Arctic (defined as north of Russia and Europe) and a small gain in the West Arctic, north of the Americas and the Atlantic Ocean. [...] If the pace of Arctic melting is quickening, the implications for the future are not reassuring. Ice reflects the Sun's energy back into space; open water absorbs it. So a planet with less ice warms faster, potentially turning the projected impacts of global warming into reality sooner than anticipated. (bbc)

  22. 12-12-2006 eco nws - global warming - impact - arctic - Arctic sea ice 'faces rapid melt' - The Arctic may be close to a tipping point that sees all-year-round ice disappear very rapidly in the next few decades, US scientists have warned. The latest data presented at the American Geophysical Union Fall Meeting suggests the ice is no longer showing a robust recovery from the summer melt. Last month, the sea that was frozen covered an area that was two million sq km less than the historical average. 'That's an area the size of Alaska,' said leading ice expert Mark Serreze. 'We're no longer recovering well in autumn anymore. The ice pack may now be starting to get preconditioned, perhaps to show very rapid losses in the near future,' the University of Colorado researcher added. The sea ice reached its minimum extent this year on 14 September, making 2006 the fourth lowest on record in 29 years of satellite record-keeping and just shy of the all time minimum of 2005. Dr Serreze's concern was underlined by new computer modelling which concludes that the Arctic may be free of all summer ice by as early as 2040. This is a positive feedback loop with dramatic implications for the entire Arctic region Marika Holland The new study, by a team of scientists from the National Center for Atmospheric Research (NCAR), the University of Washington, and McGill University, found that the ice system could be being weakened to such a degree by global warming that it soon accelerates its own decline. 'As the ice retreats, the ocean transports more heat to the Arctic and the open water absorbs more sunlight, further accelerating the rate of warming and leading to the loss of more ice,' explained Dr Marika Holland. 'This is a positive feedback loop with dramatic implications for the entire Arctic region.' Eventually, she said, the system would be 'kicked over the edge', probably not even by a dramatic event but by one year slightly warmer than normal. Very rapid retreat would then follow. Locally, this would have major consequences for wildlife in the region, not least polar bears which traverse ice-floes in search of food. Loss of summer ice would seriously compromise the lifestyles of the region's indigenous peoples, though it could also bring new trading opportunities as sea routes opened up. On a global scale, the Earth would lose a major reflective surface and so absorb more solar energy, potentially accelerating climatic change across the world. In one of the model's simulations, the September ice was seen to shrink from about 5.9 million sq km (2.3 million sq miles) to 1.9 million sq km (770,000 square miles) in just a 10-year period. By 2040, only a small amount of perennial sea ice remained along the north coasts of Greenland and Canada, while most of the Arctic basin was ice-free in September. 'We don't think that state has existed for hundreds of thousands of years; this is a dramatic change to the Arctic climate system,' Dr Holland told the BBC. Dr Serreze, who is not a modeller and deals with observational data, feels the tipping point could be very close. 'My gut feeling is that it might be around the year 2030 that we really see a rapid decline of that ice. Now could it occur sooner? It might well. Could it occur later? It might well. 'It depends on the aspects of natural variability in the system. We have to remember under greenhouse warming, natural variability has always been part of the picture and it always will be part of the picture.' The average sea ice extent for the entire month of September this year was 5.9 million sq km (2.3 million sq miles). Including 2006, the September rate of sea ice decline is now approximately -8.59% per decade, or 60,421 sq km (23,328 sq miles) per year. At that rate, without the acceleration seen in the new modelling, the Arctic Ocean would have no ice in September by the year 2060. (bbc)

  23. 29-12-2006 eco nws - global warming - impact - arctic - Huge Arctic ice break discovered - Scientists have discovered that an enormous ice shelf broke off an island in the Canadian Arctic last year, in what could be sign of global warming. It is said to be the largest break in 25 years, casting an ice floe with an area of 66 sq km (25 square miles). It occurred in August 2005 but was only recently detected on satellite images. The chunk of ice bigger than Manhattan could wreak havoc if it moves into oil drilling regions and shipping lanes next summer, scientists warned. For something that large to move that quickly is quite amazing Luke Copland, University of Ottawa 'The Arctic is all frozen up for the winter and it's stuck in the sea ice about 50km (30 miles) off the coast,' said Luke Copland, an assistant professor at the University of Ottawa. 'The risk is that next summer, as that sea ice melts, this large ice island can then move itself around off the coast and one potential path for it is to make its way westward toward the Beaufort Sea where there is lots of oil and gas exploration, oil rigs and shipping.' The ice break was initially undetected due to the remoteness of the northern coast of Ellesmere island, which is about 800km (500 miles) from the North Pole. Satellite images showed the 15km (9mile) crack, then the ice floating about 1km (0.6 miles) from the coast within about an hour, said Mr Copland, a specialist in glaciers and ice masses. 'You could stand at one edge and not see the other side, and for something that large to move that quickly is quite amazing,' he said. Mr Copland said a combination of low accumulations of sea ice around the edges of the ice mass, as well as the Arctic's warmest temperatures on record, contributed to the break. The region was 3C (5.4F) above average in the summer of 2005, he said. Ice shelves in Canada's far north have shrunk by as much as 90% since 1906. (bbc)

  24. 01-03-2007 eco nws - global warming - impact - arctic - Major two-year polar study begins - One of the world's biggest research programmes of the past 50 years has been launched in Paris. International Polar Year (IPY) is a $1.5bn (�763m) collaborative effort to study the north and south poles. Thousands of researchers will be carrying out more than 200 projects, with climate change top of the agenda. Some nations, including the UK and US, unveiled their IPY programmes earlier this week, but the Paris event sees the official start of the two-year study. This is the fourth IPY since 1882 but the first one in which the impact of man-made global warming will be clearly visible at both poles. Using ice breaking ships, satellites and submarines, an army of researchers from more than 60 countries will be studying the polar regions in unprecedented detail over the next two years. And climate change will be at the heart of many of the research projects. Scientists say rising temperatures are warming the polar regions faster than the rest of the planet. One of the key questions that scientists will hope the research effort will shed new light on is the potential rise in sea level caused by melting of ice sheets in Greenland and Antarctica. The southern polar ice sheet holds 90% of the world's fresh water. If it all melted, global sea levels would rise by 60m (197ft). There will also be projects to study the impacts of climate change on the millions of people who live in the Arctic and there will be efforts to study exotic marine life under the Antarctic ice. (bbc)

  25. 03-04-2007 eco nws - global warming - impact - arctic - NASA: Arctic Replenished Very Little Thick Sea Ice in 2005 - A new NASA study has found that in 2005 the Arctic replaced very little of the thick sea ice it normally loses and replenishes each year. Replenishment of this thick, perennial sea ice each year is essential to the maintenance and stability of the Arctic summer ice cover. The findings complement a NASA study released in fall 2006 that found a 14-percent drop in this perennial ice between 2004 and 2005. The lack of replenishment suggests that the decline may continue in the near future. Perennial ice coverage fluctuates seasonally for two reasons: summer melting and the transport of ice out of the Arctic. When perennial ice, which is three or more meters (10 or more feet) thick, is lost in these ways, new, thinner, first-year seasonal ice typically replaces it. Some of this seasonal ice melts in the following summer, and some is thick enough to survive and replenish the perennial ice cover. 'Recent studies indicate Arctic perennial ice is declining seven to 10 percent each decade,' explained Ron Kwok of NASA's Jet Propulsion Laboratory, Pasadena, Calif. 'Our study gives the first reliable estimates of how perennial ice replenishment varies each year at the end of summer. The amount of first-year ice that survives the summer directly influences how thick the ice cover will be at the start of the next melt season.' Using satellite data from NASA's QuikScat and other data, Kwok studied six annual cycles of Arctic perennial ice coverage from 2000 to 2006. The scatterometer instrument on QuikScat sends radar pulses to the surface of the ice and measures the echoed radar pulses bounced back to the satellite. These measurements allow scientists to differentiate the seasonal ice from the older, perennial ice. Kwok found that after the 2005 summer melt, only about four percent of the nearly 2.5 million square kilometers (965,000 square miles) of thin, seasonal ice that formed the previous winter survived the summer and replenished the perennial ice cover. That was the smallest replenishment seen in the study. As a result, perennial ice coverage in January 2006 was about 14 percent smaller than the previous January. Kwok examined how movement of ice out of the Arctic affected the replenishment of perennial sea ice in 2005. That year, the typically small amount of ice that moves out of the Arctic in summer was unusually high -- about seven percent of the perennial ice coverage area. Kwok said the high amount was due to unusual wind conditions at Fram Strait, an Arctic passage between Antarctic Bay in Greenland and Svalbard, Norway. Troughs of low atmospheric pressure in the Greenland and Barents/Norwegian Seas on both sides of Fram Strait created winds that pushed ice out of the Arctic at an increased rate. The effects of ice movement out of the Arctic depend on the season. When ice moves out of the Arctic in the summer, it leaves behind an ocean that does not refreeze. This, in turn, increases ocean heating and leads to additional thinning of the ice cover. These findings suggest that the greater the number of freezing temperature days during the prior season, the thicker the ice cover, and the better its chances of surviving the next summer's melt. 'The winters and summers before fall 2005 were unusually warm,' Kwok said. 'The low replenishment seen in 2005 is potentially a cumulative effect of these trends.' Kwok also examined the 2000-2006 temperature records within the context of longer-term temperature records dating back to 1958. He found a gradual warming trend in the first 30 years, which accelerated after the mid-1980s. 'The record doesn't show any hint of recovery from these trends,' he stated. 'If the correlations between replenishment area and numbers of freezing and melting temperature days hold long-term, its expected the perennial ice coverage will continue to decline.' Kwok points to a possible trigger for the declining perennial ice cover. In the early 1990s, variations in the North Atlantic Oscillation, a large-scale atmospheric seesaw that affects how air circulates over the Atlantic Ocean, were linked to a large increase in Arctic ice export. It appears the ice cover has not yet recovered from these variations. 'We're seeing a decreasing trend in perennial ice coverage,' he said. 'Our study suggests that, on average, the area of seasonal ice that survives the summer may no longer be large enough to sustain a stable perennial ice cover, especially in the face of accelerating climate warming and Arctic sea ice thinning.' (science blog)

  26. 30-04-2007 eco nws - global warming - impact - arctic - models - Ice Retreating Faster Than Computer Models Project - Arctic sea ice is melting at a significantly faster rate than projected by even the most advanced computer models, a new study concludes. The research, by scientists at the National Center for Atmospheric Research (NCAR) and the University of Colorado's National Snow and Ice Data Center (NSIDC), shows that the Arctic's ice cover is retreating more rapidly than estimated by any of the 18 computer models used by the Intergovernmental Panel on Climate Change (IPCC) in preparing its 2007 assessments. The study, 'Arctic Sea Ice Decline: Faster Than Forecast?' will appear tomorrow in the online edition of Geophysical Research Letters. It was led by Julienne Stroeve of the NSIDC and funded by the National Science Foundation, which is NCAR's principal sponsor, and by NASA. 'While the ice is disappearing faster than the computer models indicate, both observations and the models point in the same direction: the Arctic is losing ice at an increasingly rapid pace and the impact of greenhouse gases is growing,' says NCAR scientist Marika Holland, one of the study�s co-authors. The authors compared model simulations of past climate with observations by satellites and other instruments. They found that, on average, the models simulated a loss in September ice cover of 2.5 percent per decade from 1953 to 2006. The fastest rate of September retreat in any individual model was 5.4 percent per decade. (September marks the yearly minimum of sea ice in the Arctic.) But newly available data sets, blending early aircraft and ship reports with more recent satellite measurements that are considered more reliable than the earlier records, show that the September ice actually declined at a rate of about 7.8 percent per decade during the 1953-2006 period. 'This suggests that current model projections may in fact provide a conservative estimate of future Arctic change, and that the summer Arctic sea ice may disappear considerably earlier than IPCC projections,' says Stroeve. The study indicates that, because of the disparity between the computer models and actual observations, the shrinking of summertime ice is about 30 years ahead of the climate model projections. As a result, the Arctic could be seasonally free of sea ice earlier than the IPCC- projected timeframe of any time from 2050 to well beyond 2100. The authors speculate that the computer models may fail to capture the full impact of increased carbon dioxide and other greenhouse gases in the atmosphere. Whereas the models indicate that about half of the ice loss from 1979 to 2006 was due to increased greenhouse gases, and the other half due to natural variations in the climate system, the new study indicates that greenhouse gases may be playing a significantly greater role. There are a number of factors that may lead to the low rates of simulated sea ice loss. Several models overestimate the thickness of the present-day sea ice and the models may also fail to fully capture changes in atmospheric and oceanic circulation that transport heat to polar regions. Although the loss of ice for March is far less dramatic than the September loss, the models underestimate it by a wide margin as well. The study concludes that the actual rate of sea ice loss in March, which averaged about 1.8 percent per decade in the 1953 -2006 period, was three times larger than the mean from the computer models. March is typically the month when Arctic sea ice is at its most extensive. The Arctic is especially sensitive to climate change partly because regions of sea ice, which reflect sunlight back into space and provide a cooling impact, are disappearing. In contrast, darker areas of open water, which are expanding, absorb sunlight and increase temperatures. This feedback loop has played a role in the increasingly rapid loss of ice in recent years, which accelerated to 9.1 percent per decade from 1979 to 2006 according to satellite observations. (science blog)

  27. 26-03-2011 eco nws - global warming - impact - arctic - icebergs - biodiversity - animal life - Antarctic Icebergs Play a Previously Unknown Role in Global Carbon Cycle, Climate - ScienceDaily (Mar. 26, 2011) � In a finding that has global implications for climate research, scientists have discovered that when icebergs cool and dilute the seas through which they pass for days, they also raise chlorophyll levels in the water that may in turn increase carbon dioxide absorption in the Southern Ocean. An interdisciplinary research team supported by the National Science Foundation (NSF) highlighted the research this month in the journal Nature Geoscience. The research indicates that "iceberg transport and melting have a role in the distribution of phytoplankton in the Weddell Sea," which was previously unsuspected, said John J. Helly, director of the Laboratory for Environmental and Earth Sciences with the San Diego Supercomputer Center at the University of California, San Diego and Scripps Institution of Oceanography. Helly was the lead author of the paper, "Cooling, Dilution and Mixing of Ocean Water by Free-drifting Icebergs in the Weddell Sea," which was first published in the journal Deep-Sea Research Part II. The results indicate that icebergs are especially likely to influence phytoplankton dynamics in an area known as "Iceberg Alley," east of the Antarctic Peninsula, the portion of the continent that extends northwards toward Chile. The latest findings add a new dimension to previous research by the same team that altered the perception of icebergs as large, familiar, but passive, elements of the Antarctic seascape. The team previously showed that icebergs act, in effect, as ocean "oases" of nutrients for aquatic life and sea birds. The teams's research indicates that ordinary icebergs are likely to become more prevalent in the Southern Ocean, particularly as the Antarctic Peninsula continues a well-documented warming trend and ice shelves disintegrate. Research also shows that these ordinary icebergs are important features of not only marine ecosystems, but even of global carbon cycling. "These new findings amplify the team's previous discoveries about icebergs and confirm that icebergs contribute yet another, previously unsuspected, dimension of physical and biological complexity to polar ecosystems," said Roberta L. Marinelli, director of the NSF's Antarctic Organisms and Ecosystems Program. NSF manages the U.S. Antarctic Program, through which it coordinates all U.S. scientific research and related logistics on the southernmost continent and aboard ships in the Southern Ocean. The latest findings document a persistent change in physical and biological characteristics of surface waters after the transit of an iceberg, which has important effects on phytoplankton populations, clearly demonstrating "that icebergs influence oceanic surface waters and mixing to greater extents than previously realized," said Ronald S. Kaufmann, associate professor of marine science and environmental studies at the University of San Diego and one of the authors of the paper. The researchers studied the effects by sampling the area around a large iceberg more than 32 kilometers (20 miles) long; the same area was surveyed again ten days later, after the iceberg had drifted away. After ten days, the scientists observed increased concentrations of chlorophyll a and reduced concentrations of carbon dioxide, as compared to nearby areas without icebergs. These results are consistent with the growth of phytoplankton and the removal of carbon dioxide from the ocean. The new results demonstrate that icebergs provide a connection between the geophysical and biological domains that directly affects the carbon cycle in the Southern Ocean, Marinelli added. In 2007, the same team published findings in the journal Science that icebergs serve as "hotspots" for ocean life with thriving communities of seabirds above and a web of phytoplankton, krill and fish below. At that time, the researchers reported that icebergs hold trapped terrestrial material, which they release far out at sea as they melt, a process that produces a "halo effect" with significantly increased nutrients and krill out to a radius of more than three kilometers (two miles).

  28. 27-06-2011 eco nws - global warming - impact - arctic - glaciers - glacier melting - Ocean Currents Speed Melting of Antarctic Ice: A Major Glacier Is Undermined from Below - ScienceDaily (June 27, 2011) � Stronger ocean currents beneath West Antarctica's Pine Island Glacier Ice Shelf are eroding the ice from below, speeding the melting of the glacier as a whole, according to a new study in Nature Geoscience. A growing cavity beneath the ice shelf has allowed more warm water to melt the ice, the researchers say -- a process that feeds back into the ongoing rise in global sea levels. The glacier is currently sliding into the sea at a clip of four kilometers (2.5 miles) a year, while its ice shelf is melting at about 80 cubic kilometers a year -- 50 percent faster than it was in the early 1990s -- the paper estimates. "More warm water from the deep ocean is entering the cavity beneath the ice shelf, and it is warmest where the ice is thickest," said study's lead author, Stan Jacobs, an oceanographer at Columbia University's Lamont-Doherty Earth Observatory. In 2009, Jacobs and an international team of scientists sailed to the Amundsen Sea aboard the icebreaking ship Nathaniel B. Palmer to study the region's thinning ice shelves -- floating tongues of ice where landbound glaciers meet the sea. One goal was to study oceanic changes near the Pine Island Glacier Ice Shelf, which they had visited in an earlier expedition, in 1994. The researchers found that in 15 years, melting beneath the ice shelf had risen by about 50 percent. Although regional ocean temperatures had also warmed slightly, by 0.2 degrees C or so, that was not enough to account for the jump. The local geology offered one explanation. On the same cruise, a group led by Adrian Jenkins, a researcher at British Antarctic Survey and study co-author, sent a robot submarine beneath the ice shelf, revealing an underwater ridge. The researchers surmised that the ridge had once slowed the glacier like a giant retaining wall. When the receding glacier detached from the ridge, sometime before the 1970s, the warm deep water gained access to deeper parts of the glacier. Over time, the inner cavity grew, more warm deep water flowed in, more melt water flowed out, and the ice thinned. With less friction between the ice shelf and seafloor, the landbound glacier behind it accelerated its slide into the sea. Other glaciers in the Amundsen region have also thinned or widened, including Thwaites Glacier and the much larger Getz Ice Shelf. One day, near the southern edge of Pine Island Glacier Ice Shelf, the researchers directly observed the strength of the melting process as they watched frigid, seawater appear to boil on the surface like a kettle on the stove. To Jacobs, it suggested that deep water, buoyed by added fresh glacial melt, was rising to the surface in a process called upwelling. Jacobs had never witnessed upwelling first hand, but colleagues had described something similar in the fjords of Greenland, where summer runoff and melting glacier fronts can also drive buoyant plumes to the sea surface. In recent decades, researchers have found evidence that Antarctica is getting windier, and this may also help explain the changes in ocean circulation. Stronger circumpolar winds would tend to push sea ice and surface water north, says Jacobs. That in turn, would allow more warm water from the deep ocean to upwell onto the Amundsen Sea's continental shelf and into its ice shelf cavities. Pine Island Glacier, among other ice streams in Antarctica, is being closely watched for its potential to redraw coastlines worldwide. Global sea levels are currently rising at about 3 millimeters (.12 inches) a year. By one estimate, the total collapse of Pine Island Glacier and its tributaries could raise sea level by 24 centimeters (9 inches). The paper adds important and timely insights about oceanic changes in the region, says Eric Rignot, a professor at University of California at Irvine and a senior research scientist at NASA's Jet Propulsion Laboratory. "The main reason the glaciers are thinning in this region, we think, is the presence of warm waters," he said. "Warm waters did not get there because the ocean warmed up, but because of subtle changes in ocean circulation. Ocean circulation is key. This study reinforces this concept."

  29. 04-07-2011 eco nws - global warming - impact - arctic - ice sheets - ice sheet melting - Warming Ocean Layers Will Undermine Polar Ice Sheets, Climate Models Show - ScienceDaily (July 4, 2011) � Warming of the ocean's subsurface layers will melt underwater portions of the Greenland and Antarctic ice sheets faster than previously thought, according to new University of Arizona-led research. Such melting would increase the sea level more than already projected. The research, based on 19 state-of-the-art climate models, proposes a new mechanism by which global warming will accelerate the melting of the great ice sheets during this century and the next. The subsurface ocean layers surrounding the polar ice sheets will warm substantially as global warming progresses, the scientists found. In addition to being exposed to warming air, underwater portions of the polar ice sheets and glaciers will be bathed in warming seawater. The subsurface ocean along the Greenland coast could increase as much as 3.6 �F (2 �C) by 2100. "To my knowledge, this study is the first to quantify and compare future ocean warming around the Greenland and the Antarctic ice sheets using an ensemble of models," said lead author Jianjun Yin, a UA assistant professor of geosciences. Most previous research has focused on how increases in atmospheric temperatures would affect the ice sheets, he said. "Ocean warming is very important compared to atmospheric warming because water has a much larger heat capacity than air," Yin said. "If you put an ice cube in a warm room, it will melt in several hours. But if you put an ice cube in a cup of warm water, it will disappear in just minutes." Given a mid-level increase in greenhouse gases, the researchers found the ocean layer about 650 to 1,650 feet (200 to 500 meters) below the surface would warm, on average, about 1.8 �F (1 �C) by 2100. Along the Greenland coast, that layer would warm twice as much, but along Antarctica would warm less, only 0.9 �F (0.5 �C). "No one has noticed this discrepancy before -- that the subsurface oceans surrounding Greenland and Antarctica warm very differently," Yin said. Part of the warming in the North comes from the Gulf Stream carrying warm subtropical waters north. By contrast, the Antarctic Circumpolar Current blocks some of the subtropical warmth from entering the Antarctic's coastal waters. Even so, the Antarctic ice sheet will be bathed in warming waters, the team writes. Co-author Jonathan T. Overpeck said, "This does mean that both Greenland and Antarctica are probably going melt faster than the scientific community previously thought." Overpeck, a UA professor of geosciences and co-director of UA's Institute of the Environment, said, "This paper adds to the evidence that we could have sea level rise by the end of this century of around 1 meter and a good deal more in succeeding centuries." The paper by Yin, Overpeck and their colleagues, "Different Magnitudes of Projected Subsurface Ocean Warming Around Greenland and Antarctica," is scheduled for online publication in Nature Geoscience on July 3. Their co-authors are UA assistant professor of geosciences Joellen L. Russell; Stephen M. Griffies and Ronald J. Stouffer of the National Oceanographic Atmospheric Administration's Geophysical Fluid Dynamics Laboratory in Princeton, N.J.; and Aixue Hu of the National Center for Atmospheric Research in Boulder, Colo. Other researchers have recently measured surprisingly high subsurface ocean temperatures along coastal glaciers in Greenland, Yin said. In addition, scientists have reported the Greenland and Antarctica glaciers that empty into the sea are moving faster. Yin decided to figure out how much those subsurface currents would warm during this century and the next. Glaciers are rivers of ice. Like rivers of liquid water, glaciers move downhill. Some glaciers melt before reaching the ocean, and others, called tidewater glaciers, flow all the way to the sea. The face of a tidewater glacier visible from a boat is only part of it -- much of the glacier's leading edge is underwater in a deep fjord. Yin's research suggests Greenland's glaciers are being exposed to increasingly warm subsurface water that will melt the underwater portion of the glaciers. As a result, the tops of the glaciers will no longer have support and will topple into the sea, creating icebergs. In addition, as the undersides of the glaciers melt, that meltwater will speed the glaciers' movement into the sea by lubricating their undersides. Ultimately, those glaciers will melt back so far they no longer reach the sea, the team writes. In contrast, much more of the Antarctic ice sheet is based on land that is already below sea level. Therefore as the Antarctic ice sheet melts back, the leading edge of the ice sheet will continue to be underwater. As such warming and melting continues into the 22nd century and beyond, parts of the Antarctic ice sheet may disintegrate, the team writes. Yin's next step is examining climate models that can zero in even further on the regional effects of climate warming on the subsurface ocean and the ice sheets.

  30. 02-08-2011 eco nws - global warming - impact - arctic - glaciers - glacier melting - Ancient Glacial Melting Shows That Small Amount of Subsurface Warming Can Trigger Rapid Collapse of Ice Shelves - ScienceDaily (Aug. 2, 2011) � An analysis of prehistoric "Heinrich events" that happened many thousands of years ago, creating mass discharges of icebergs into the North Atlantic Ocean, make it clear that very small amounts of subsurface warming of water can trigger a rapid collapse of ice shelves. The findings, to be published this week in Proceedings of the National Academy of Sciences, provide historical evidence that warming of water by 3-4 degrees was enough to trigger these huge, episodic discharges of ice from the Laurentide Ice Sheet in what is now Canada. The results are important, researchers say, due to concerns that warmer water could cause a comparatively fast collapse of ice shelves in Antarctica or Greenland, increasing the flow of ice into the ocean and raising sea levels. One of the most vulnerable areas, the West Antarctic Ice Sheet, would raise global sea level by about 11 feet if it were all to melt. "We don't know whether or not water will warm enough to cause this type of phenomenon," said Shaun Marcott, a postdoctoral researcher at Oregon State University and lead author of the report. "But it would be a serious concern if it did, and this demonstrates that melting of this type has occurred before." If water were to warm by about 2 degrees under the ice shelves that are found along the edges of much of the West Antarctic Ice Sheet, Marcott said, it might greatly increase the rate of melting to more than 30 feet a year. This could cause many of the ice shelves to melt in less than a century, he said, and is probably the most likely mechanism that could create such rapid changes of the ice sheet. To find previous examples of such events, scientists reconstructed past ocean temperatures and used computer simulations to re-create what probably happened at various times during Heinrich events of the distant past. It had been known for some time that such events were associated with major climate changes, but less clear whether the events were a reaction to climate change or helped to cause them. "There is now better evidence that the climate was getting colder prior to the Heinrich events, causing surface ocean waters to cool but actually causing warmer water in the subsurface," Marcott said. "We tried to demonstrate how this warmer water, at depth, caused the base of the ice shelf to warm and collapse, triggering the Heinrich events." A present-day concern, Marcott said, is that ocean currents could shift and change direction even before overall ocean water had warmed a significant amount. If currents shifted and warmer water was directed toward ice shelves, more rapid melting might begin, he said.

  31. 04-08-2011 eco nws - global warming - system - impact - arctic - ice stability - Large Variations in Arctic Sea Ice: Polar Ice Much Less Stable Than Previously Thought, Study Finds - ScienceDaily (Aug. 4, 2011) � For the last 10,000 years, summer sea ice in the Arctic Ocean has been far from constant. For several thousand years, there was much less sea ice in The Arctic Ocean -- probably less than half of current amounts. This is indicated by new findings by the Danish National Research Foundation for Geogenetics at the University of Copenhagen. The results of the study will be published in the journal Science. Sea ice comes and goes without leaving a record. For this reason, our knowledge about its variations and extent was limited before we had satellite surveillance or observations from airplanes and ships. But now researchers at the Danish National Research Foundation for Geogenetics at the Natural History Museum of Denmark (University of Copenhagen) have developed a method by which it is possible to measure the variations in the ice several millennia back in time. The results are based on material gathered along the coast of northern Greenland, which scientists expect will be the final place summer ice will survive, if global temperatures continue to rise. This means that the results from northern Greenland also indicate what the conditions are like in the ocean. - Less ice than today - Team leader Svend Funder, and two other team members and co-authors of the Science article, Eske Willerslev and Kurt Kj�r, are all associated with the Danish Research Foundation at the University of Copenhagen. Regarding the research results, Funder says, "Our studies show that there have been large fluctuations in the amount of summer sea ice during the last 10,000 years. During the so-called Holocene Climate Optimum, from approximately 8000 to 5000 years ago, when the temperatures were somewhat warmer than today, there was significantly less sea ice in the Arctic Ocean, probably less than 50% of the summer 2007 coverage, which was absolutely lowest on record. Our studies also show that when the ice disappears in one area, it may accumulate in another. We have discovered this by comparing our results with observations from northern Canada. While the amount of sea ice decreased in northern Greenland, it increased in Canada. This is probably due to changes in the prevailing wind systems. This factor has not been sufficiently taken into account when forecasting the imminent disappearance of sea ice in the Arctic Ocean." - Driftwood unlocks mystery - In order to reach their surprising conclusions, Funder and the rest of the team organised several expeditions to Peary Land in northern Greenland. Named after American Polar explorer Robert E. Peary, the region is an inhospitable and rarely visited area, where summer blizzards are not uncommon. " Our key to the mystery of the extent of sea ice during earlier epochs lies in the driftwood we found along the coast. One might think that it had floated across sea, but such a journey takes several years, and driftwood would not be able to stay afloat for that long. The driftwood is from the outset embedded in sea ice, and reaches the north Greenland coast along with it. The amount of driftwood therefore indicates how much multiyear sea ice there was in the ocean back then. And this is precisely the type of ice that is in danger of disappearing today," Funder says. After the expeditions had been completed, the team needed to study the wood they had collected: wood types had to be determined and it had to be carbon-14 dated. The driftwood originated near the great rivers of present-day North America and Siberia. The wood types were almost entirely spruce, which is widespread in the Boreal forest of North America, and larch, which is dominates the Siberian taiga. The different wood types therefore are evidence of changing travel routes and altered current and wind conditions in the ocean. - Beach ridges and wave breaking - The team also examined the beach ridges along the coast. Today, perennial ice prevents any sort of beach from forming along the coasts of northern Greenland. But this had not always been the case. Behind the present shore long rows of beach ridges show that at one time waves could break onto the beach unhindered by sea ice. The beach ridges were mapped for 500 kilometres along the coast, and carbon-14 dating has shown that during the warm period from about 8000 until 4000 years ago, there was more open water and less coastal ice than today. - Point of no return - "Our studies show that there are great natural variations in the amount of Arctic sea ice. The bad news is that there is a clear connection between temperature and the amount of sea ice. And there is no doubt that continued global warming will lead to a reduction in the amount of summer sea ice in the Arctic Ocean. The good news is that even with a reduction to less than 50% of the current amount of sea ice the ice will not reach a point of no return: a level where the ice no longer can regenerate itself even if the climate was to return to cooler temperatures. Finally, our studies show that the changes to a large degree are caused by the effect that temperature has on the prevailing wind systems. This has not been sufficiently taken into account when forecasting the imminent disappearance of the ice, as often portrayed in the media," Funder says. - Research could also benefit polar bears - In addition to giving us a better understanding of what the climate in northern Greenland was like thousands of years ago, it could also reveal how polar bears fared in warmer climate. The team plans to use DNA in fossil polar bear bones to study polar bear population levels during the Holocene Climate Optimum.

  32. 18-08-2011 eco nws - global warming - impact - arctic - glaciers - glacier melting - Greenland Glacier Melting Faster Than Expected - ScienceDaily (Aug. 18, 2011) � A key glacier in Greenland is melting faster than previously expected, according to findings by a team of academics, including Dr Edward Hanna from University of Sheffield. Dr Hanna, from the University of Sheffield's Department of Geography, was part of a team of researchers that also included Dr Sebastian Mernild from the Los Alamos Laboratory, USA, and Professor Niels Tvis Knudsen from the University of Aarhus, Denmark. The team�s new findings present crucial insight into the effects of climate change. The researchers found that Greenland's longest-observed glacier, Mittivakkat Glacier, made two consecutive record losses in mass observations for 2010 and 2011. The observations indicate that the total 2011 mass budget loss was 2.45 metres, 0.29 metres higher than the previous observed record loss in 2010. The 2011 value was also significantly above the 16-year average observed loss of 0.97 metres per year. The 2011 observations further illustrate, even comparing the mass balance value against simulated glacier mass balance values back to 1898, that 2011 is a record-breaking glacier mass loss year. Mittivakkat Glacier has been surveyed for mass balance and glacier front fluctuations since 1995 and 1931 respectively. In 2011 the glacier terminus has retreated about 22 metres, 12 metres less than the observed record of 34 metres in 2010, and approximately 1,300 metres in total since the first photographic observations in 1931. These observations suggest that recent Mittivakkat Glacier mass losses, which have been driven largely by higher surface temperatures and low precipitation, are representative of the broader region, which includes many hundreds of local glaciers in Greenland. Observations of other glaciers in Greenland show terminus retreats comparable to that of Mittivakkat Glacier. These glaciers are similar to the Mittivakkat Glacier in size and elevation range. Local glacier observations in Greenland are rare, and the Mittivakkat Glacier is the only glacier in Greenland for which long-term observations of both the surface mass balance and glacier front fluctuations exist. Since 1995, the general trend for the Mittivakkat Glacier has been toward higher temperatures, less snowfall, and a more negative glacier mass balance, with record mass loss in 2011. In 14 of the last 16 years, the Mittivakkat Glacier had a negative surface mass balance. Principal Investigator on this summer's fieldwork, Dr Edward Hanna, commented: "Our fieldwork results are a key indication of the rapid changes now being seen in and around Greenland, which are evident not just on this glacier but also on many surrounding small glaciers. It's clear that this is now a very dynamic environment in terms of its response and mass wastage to ongoing climate change. "The retreat of these small glaciers also makes the nearby Greenland Ice Sheet more vulnerable to further summer warming which is likely to occur. There could also be an effect on North Atlantic Ocean circulation and weather patterns through melting so much extra ice. An extended glacier observation programme in east Greenland for the next few years is clearly needed to improve understanding of the links between climate change and response of the glaciers in this important region."

  33. 04-10-2011 eco nws - global warming - impact - arctic - arctic sea ice - record - almost record low - Arctic Sea Ice Continues Decline, Hits Second-Lowest Level - ScienceDaily (Oct. 4, 2011) � Last month the extent of sea ice covering the Arctic Ocean declined to the second-lowest extent on record. Satellite data from NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) at the University of Colorado in Boulder showed that the summertime sea ice cover narrowly avoided a new record low. The Arctic ice cap grows each winter as the sun sets for several months and shrinks each summer as the sun rises higher in the northern sky. Each year the Arctic sea ice reaches its annual minimum extent in September. It hit a record low in 2007. The near-record ice-melt followed higher-than-average summer temperatures, but without the unusual weather conditions that contributed to the extreme melt of 2007. "Atmospheric and oceanic conditions were not as conducive to ice loss this year, but the melt still neared 2007 levels," said NSIDC scientist Walt Meier. "This probably reflects loss of multiyear ice in the Beaufort and Chukchi seas as well as other factors that are making the ice more vulnerable." Joey Comiso, senior scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., said the continued low minimum sea ice levels fits into the large-scale decline pattern that scientists have watched unfold over the past three decades. "The sea ice is not only declining, the pace of the decline is becoming more drastic," Comiso said. "The older, thicker ice is declining faster than the rest, making for a more vulnerable perennial ice cover." While the sea ice extent did not dip below the 2007 record, the sea ice area as measured by the microwave radiometer on NASA's Aqua satellite did drop slightly lower than 2007 levels for about 10 days in early September, Comiso said. Sea ice "area" differs from extent in that it equals the actual surface area covered by ice, while extent includes any area where ice covers at least 15 percent of the ocean. Arctic sea ice extent on Sept. 9, the lowest point this year, was 4.33 million square kilometers (1.67 million square miles). Averaged over the month of September, ice extent was 4.61 million square kilometers (1.78 million square miles). This places 2011 as the second lowest ice extent both for the daily minimum extent and the monthly average. Ice extent was 2.43 million square kilometers (938,000 square miles) below the 1979 to 2000 average. This summer's low ice extent continued the downward trend seen over the last 30 years, which scientists attribute largely to warming temperatures caused by climate change. Data show that Arctic sea ice has been declining both in extent and thickness. Since 1979, September Arctic sea ice extent has declined by 12 percent per decade. "The oldest and thickest ice in the Arctic continues to decline, especially in the Beaufort Sea and the Canada Basin," NSIDC scientist Julienne Stroeve said. "This appears to be an important driver for the low sea ice conditions over the past few summers." Climate models have suggested that the Arctic could lose almost all of its summer ice cover by 2100, but in recent years, ice extent has declined faster than the models predicted. NASA monitors and studies changing sea ice conditions in both the Arctic and Antarctic with a variety of spaceborne and airborne research capabilities. This month NASA resumes Operation IceBridge, a multi-year series of flights over sea ice and ice sheets at both poles. This fall's campaign will be based out of Punta Arenas, Chile, and make flights over Antarctica. NASA also continues work toward launching ICESat-2 in 2016, which will continue its predecessor's crucial laser altimetry observations of ice cover from space.

  34. 06-10-2011 eco nws - global warming - impact - arctic - arctic sea ice - end of century - Why Climate Models Underestimated Arctic Sea Ice Retreat: No Arctic Sea Ice in Summer by End of Century? - ScienceDaily (Oct. 6, 2011) � In recent decades, Arctic sea ice has suffered a dramatic decline that exceeds climate model predictions. The unexpected rate of ice shrinkage has now been explained by researchers at CNRS, Universit� Joseph Fourier and Massachusetts Institute of Technology. They argue that climate models underestimate the rate of ice thinning, which is actually about four times faster than calculations. This model bias is due to the poor representation of the sea ice southward drift out of the Arctic basin through the Fram Strait. When this mechanism was taken into account to correct the discrepancy between simulations and observations, results from the new model suggested that there will be no Arctic sea ice in summer by the end of the century. This work was published in the Journal of Geophysical Research on 29 September 2011. The Arctic has been losing about 10% of its permanent ice layer every ten years since 1980. Melting of Arctic sea ice has also reached record heights: in mid-September 2007, at the point when sea ice reaches its annual minimum extent, perennial ice covered an area of 4.14 million km�(1). This record low level was nearly reached again in September 2011 (4.34 million km2). Climate simulations conducted for the IPCC(2) simulate the decline in Arctic sea ice resulting from global warming. They predict that summer ice will disappear altogether at the end of this century. However, when compared with 30 years of detailed satellite observations, these models appear optimistic. Arctic sea ice has thinned on average four times faster over the period 1979-2008 than in the climate simulations. True observations are therefore not correctly reproduced by these climate models, which were mainly calibrated using global variables, such as world average rather than "regional" temperature. An explanation for this difference has been put forward by a Franco-American team, involving in particular the Laboratoire de glaciologie et g�ophysique de l'environnement (CNRS / Universit� Joseph Fourier). It may be due to a misrepresentation of the mechanical behavior of pack ice and the drift of sea ice in the models. To demonstrate this, the researchers examined the mechanisms of sea ice drift with respect to their physical state (thickness and concentration), then analyzed the model predictions in combination with field data. In 2009, these same scientists demonstrated that there had been a significant acceleration of ice drift in recent decades. This can now be explained by ice thinning, which has accelerated. Sea ice has become thinner and more fragile. Because it breaks up more easily, its mobility is increased, as is its export from the Arctic Ocean through the Fram Strait between Greenland and the Svalbard archipelago, followed by its melting. This mechanism may be exacerbating the present decline in Arctic sea ice. The drift of sea ice is poorly described by the models, which do not take drift acceleration or southward evacuation of the ice into account. "Modeled" sea ice behaves as though it drifts freely, without any mechanical interaction between ice fragments, whatever the season, period or ice thickness. There is no link in the models between the thinning of the ice and the further acceleration of its drift. To close this gap between simulations and observations in terms of Arctic sea ice thinning rates and decline, the models should take into account an acceleration of ice export through the Fram Strait. This mechanism suggests that, well before the end of the century, the Arctic Ocean will be devoid of sea ice in late summer. The disappearance of Arctic sea ice will probably occur in the next few decades, with far-reaching consequences for ecosystems, sea routes and off shore exploitation of resources.