New map reveals giant fjords beneath East Antarctic ice sheet-10

New map reveals giant fjords beneath East Antarctic ice sheet

This new topographic map of a portion of the East Antarctic Ice Sheet revealed several giant fjords carved by the advancing and reatreating ice sheet between 34 and 14 million years ago.

 Scientists from the U.S., U.K. and Australia have used ice-penetrating radar to create the first high- resolution topographic map of one of the last uncharted regions of Earth, the Aurora Subglacial Basin, an immense ice-buried lowland in East Antarctica larger than Texas.

 The map reveals some of the largest fjords or ice cut channels on Earth, providing important insights into the history of ice in Antarctica. The data will also help computer modelers improve their simulations of the past and future Antarctic ice sheet and its potential impact on global sea level.

"We knew almost nothing about what was going on, or could go on, under this part of the ice sheet and now we've opened it up and made it real," said Duncan Young, research scientist at The University of Texas at Austin's Institute for Geophysics and lead author on the study, which appears in this week's journal Nature.

"We chose to focus on the Aurora Subglacial Basin because it may represent the weak underbelly of the East Antarctic Ice Sheet, the largest remaining body of ice and potential source of sea-level rise on Earth," said Donald Blankenship, principal investigator for the ICECAP project, a multinational collaboration using airborne geophysical instruments to study the ice sheet.

Because the basin lies kilometers below sea level, seawater could penetrate beneath the ice, causing portions of the ice sheet to collapse and float off to sea. Indeed, this work shows that the ice sheet has been significantly smaller in the past.

Previous work based on ocean sediments and computer models indicates the East Antarctic Ice Sheet grew and shrank widely and frequently, from about 34 to 14 million years ago, causing sea level to fluctuate by 200 feet . Since then, it has been comparatively stable, causing sea-level fluctuations of less that 50 feet. The new map reveals vast channels cut through mountain ranges by ancient glaciers that mark the edge of the ice sheet at different times in the past, sometimes hundreds of kilometers from its current edge. 

New topographic map of the bedrock below a portion of the East Antarctic Ice Sheet, including the Aurora Subglacial Basin which lies more than a kilometer below sea level in some places.

"We're seeing what the ice sheet looked like at a time when Earth was much warmer than today," said Young. "Back then it was very dynamic, with significant surface melting. Recently, the ice sheet has been better behaved."

However, recent lowering of major glaciers near the edge detected by satellites has raised concerns about this sector of Antarctica.

Young said past configurations of the ice sheet give a sense of how it might look in the future, although he doesn't foresee it shrinking as dramatically in the next 100 years. Still, even a small change in this massive ice sheet could have a significant effect on sea level. Scientists at The University of Texas at Austin's Institute for Computational Engineering and Sciences, and at Australia's Antarctic Climate and Ecosystems CRC are developing models that will use the new map to forecast how the ice sheet will evolve in the future and how it might affect sea level.

This research is part of ICECAP (Investigating the Cryospheric Evolution of the Central Antarctic Plate), a joint project of The University of Texas at Austin's Jackson School of Geosciences, the University of Edinburgh and the Australian Antarctic Division. For three field seasons, the team flew an upgraded World War II-era DC-3 aircraft with a suite of geophysical instruments to study the ice and underlying rock in East Antarctica.

Provided by University of Texas at Austin.

 

 

Is Antarctica melting?-9

Is Antarctica melting?

 By Erik Conway
Historian, NASA/Jet Propulsion Laboratory

There has been lots of talk lately about Antarctica and whether or not the continent’s giant ice sheet is melting. One new paper¹, which states there has been less surface melting recently than in past years, has been cited as “proof” that there’s no global warming. Other evidence that the amount of sea ice around Antarctica seems to be increasing slightly^2-4 is being used in the same way. But both of these data points are misleading. Gravity data collected from space using NASA’s Grace satellite show that Antarctica has been losing more than a hundred cubic kilometers (24 cubic miles) of ice each year since 2002. The latest data reveals that Antarctica is losing ice at an accelerating rate, too. How is it possible for surface melting to decrease, but for the continent to lose mass anyway? The answer boils down to the fact that ice can flow without melting.

 

Two-thirds of Antarctica is a high, cold desert. Known as East Antarctica, this section has an average altitude of about 2 kilometers (1.2 miles), higher than the American Colorado Plateau. There is a continent about the size of Australia underneath all this ice; the ice sheet sitting on top averages at a little over 2 kilometers (1.2 miles) thick. If all of this ice melted, it would raise global sea level by about 60 meters (197 feet). But little, if any, surface warming is occurring over East Antarctica. Radar- and laser-based satellite data show a little mass loss at the edges of East Antarctica, which is being partly offset by accumulation of snow in the interior, although a very recent result from the NASA/German Aerospace Center’s Gravity Recovery and Climate Experiment (Grace) suggests that since 2006 there has been more ice loss from East Antarctica than previously thought⁵. Overall, not much is going on in East Antarctica — yet.

A frozen Hawaii

West Antarctica is very different. Instead of a single continent, it is a series of islands covered by ice — think of it as a frozen Hawaii, with penguins. Because it’s a group of islands, much of the West Antarctic Ice Sheet (WAIS, in jargon) is actually sitting on the floor of the Southern Ocean, not on dry land. Parts of it are more than 1.7 kilometers (1 mile) below sea level. Pine Island is the largest of these islands and the largest ice stream in West Antarctica is called Pine Island Glacier. The WAIS, if it melted completely, would raise sea level by 5 to 7 meters (16 to 23 feet). And the Pine Island Glacier would contribute about 10 percent of that.

Since the early 1990s, European and Canadian satellites have been collecting radar data from West Antarctica. These radar data can reveal ice motion and, by the late 1990s, there was enough data for scientists to measure the annual motion of the Pine Island Glacier. Using radar information collected between 1992 and 1996, oceanographer Eric Rignot, based at NASA’s Jet Propulsion Laboratory, found that the Pine Island Glacier’s “grounding line” — the line between the glacier’s floating section and the part of the glacier that rests on the sea floor — had retreated rapidly towards the land. That meant that the glacier was losing mass. He attributed the retreat to the warming waters around West Antarctica⁶. But with only a few years of data, he couldn’t say whether the retreat was a temporary, natural anomaly or a longer-term trend from global warming.

Rignot’s paper surprised many people. JPL scientist Ron Kwok saw it as demonstrating that “the old idea that glaciers move really slowly isn’t true any more.” One result was that a lot more people started to use the radar data to examine much more of Antarctica. A major review published in 2009 found that Rignot’s Pine Island Glacier finding hadn’t been a fluke⁷: a large majority of the marine glaciers of the Antarctic Peninsula were retreating, and their retreat was speeding up. Last summer, a British group revisited the Pine Island Glacier finding and found that its rate of retreat had quadrupled between 1995 and 2006⁸.

How the ice shelf crumbles
The retreat of West Antarctica’s glaciers is being accelerated by ice shelf collapse. Ice shelves are the part of a glacier that extends past the grounding line towards the ocean; they are the most vulnerable to warming seas. A longstanding theory in glaciology is that these ice shelves tend to buttress (support the end wall of) glaciers, with their mass slowing the ice movement towards the sea. This was confirmed by the spectacular collapse of the Rhode Island-sized Larsen B shelf along the eastern edge of the Antarctic Peninsula in 2002. The disintegration, which was caught on camera by NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) imaging instruments on board its Terra and Aqua satellites, was dramatic: it took just three weeks to crumble a 12,000-year old ice shelf. Over the next few years, satellite radar data showed that some of the ice streams flowing behind Larsen B had accelerated significantly, while others, still supported by smaller ice shelves, had not⁹. This dynamic process of ice flowing downhill to the sea is what enables Antarctica to continue losing mass even as surface melting declines.

Michael Schodlok, a JPL scientist who models the way ice shelves and the ocean interact, says melting of the underside of the shelf is a pre-requisite to these collapses. Thinning of the ice shelf reduces its buttressing effect on the glacier behind it, allowing glacier flow to speed up. The thinner shelf is also more likely to crack. In the summer, meltwater ponds on the surface can drain into the cracks. Since liquid water is denser than solid ice, enough meltwater on the surface can open the cracks up deeper down into the ice, leading to disintegration of the shelf. The oceans surrounding Antarctica have been warming¹⁰, so Schodlok doesn’t doubt that the ice shelves are being undermined by warmer water being brought up from the depths. But he admits that it hasn’t been proven rigorously, because satellites can’t measure underneath the ice.

Glaciologist Robert Bindschadler of NASA’s Goddard Space Flight Center intends to show just that. He’s leading an expedition scheduled to start in 2011 to drill through the Pine Island Glacier and place an automated buoy into the water below it. According to Bindschadler, Pine Island Glacier “is the place to go because that is where the changes are the largest. If we want to understand how the ocean is impacting the ice sheet, go to where it’s hitting the ice sheet with a sledgehammer, not with a little tack hammer.”

Meanwhile, measurements from the Grace satellites confirm that Antarctica is losing mass (Figure 1)¹¹. Isabella Velicogna of JPL and the University of California, Irvine, uses Grace data to weigh the Antarctic ice sheet from space. Her work shows that the ice sheet is not only losing mass, but it is losing mass at an accelerating rate. “The important message is that it is not a linear trend. A linear trend means you have the same mass loss every year. The fact that it’s above linear, this is the important idea, that ice loss is increasing with time,” she says. And she points out that it isn’t just the Grace data that show accelerating loss; the radar data does, too. “It isn’t just one type of measurement. It’s a series of independent measurements that are giving the same results, which makes it more robust.”

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Lasers From Space Show Thinning Of Greenland And Antarctic Ice Sheets-8

New comprehensive maps of Greenland and Antarctica show extent of glacier thinning. (Credit: ICESat, NASA)

The most comprehensive picture of the rapidly thinning glaciers along the coastline of both the Antarctic and Greenland ice sheets has been created using satellite lasers. The findings are an important step forward in the quest to make more accurate predictions for future sea level rise.

Reporting this week in the journal Nature, researchers from British Antarctic Survey and the University of Bristol describe how analysis of millions of NASA satellite measurements* from both of these vast ice sheets shows that the most profound ice loss is a result of glaciers speeding up where they flow into the sea.

The authors conclude that this 'dynamic thinning' of glaciers now reaches all latitudes in Greenland, has intensified on key Antarctic coastlines, is penetrating far into the ice sheets' interior and is spreading as ice shelves thin by ocean-driven melt. Ice shelf collapse has triggered particularly strong thinning that has endured for decades.

Lead author Dr Hamish Pritchard from British Antarctic Survey (BAS) says, "We were surprised to see such a strong pattern of thinning glaciers across such large areas of coastline – it's widespread and in some cases thinning extends hundreds of kilometres inland. We think that warm ocean currents reaching the coast and melting the glacier front is the most likely cause of faster glacier flow. This kind of ice loss is so poorly understood that it remains the most unpredictable part of future sea level rise."

The scientists compared the rates of change in elevation of both fast-flowing and slow-flowing ice. In Greenland for example they studied 111 fast-moving glaciers and found 81 thinning at rates twice that of slow-flowing ice at the same altitude.They found that ice loss from many glaciers in both Antarctica and Greenland is greater than the rate of snowfall further inland.

In Antarctica some of the fastest thinning glaciers are in West Antarctica (Amundsen Sea Embayment) where Pine Island Glacier and neighbouring Smith and Thwaites Glacier are thinning by up to 9 metres per year.

New Research on Antarctica's Melting Pine Island Glacier-7

ScienceDaily (June 21, 2010) — New results from an investigation into Antarctica's potential contribution to sea level rise are reported by scientists from the British Antarctic Survey (BAS), Lamont-Doherty Earth Observatory (LDEO) and the National Oceanography Centre in the journal Nature Geoscience.

Thinning ice in West Antarctica is currently contributing nearly 10 per cent of global sea level rise and scientists have identified Pine Island Glacier (PIG) as a major source. As part of a series of investigations to better understand the impact of melting ice on sea level an exciting new discovery has been made. Using Autosub (an autonomous underwater vehicle) to dive deep and travel far beneath the pine Island Glacier's floating ice shelf, scientists captured ocean and sea-floor measurements, which revealed a 300m high ridge (mountain) on the sea floor.

Pine Island Glacier was once grounded on (sitting on top of) this underwater ridge, which slowed its flow into the sea. However, in recent decades it has thinned and disconnected from the ridge, allowing the glacier to move ice more rapidly from the land into the sea. This also permitted deep warm ocean water to flow over the ridge and into a widening cavity that now extends to an area of 1000 km² under the ice shelf. The warm water, trapped under the ice, is causing the bottom of the ice shelf to melt, resulting in continuous thinning and acceleration of the glacier.

Lead author Dr Adrian Jenkins of British Antarctic Survey said, "The discovery of the ridge has raised new questions about whether the current loss of ice from Pine Island Glacier is caused by recent climate change or is a continuation of a longer-term process that began when the glacier disconnected from the ridge.

"We do not know what kick-started the initial retreat from the ridge, but we do know that it started some time prior to 1970. Since detailed observations of Pine Island Glacier only began in the 1990s, we now need to use other techniques such as ice core analysis and computer modelling to look much further into the glacier's history in order to understand if what we see now is part of a long term trend of ice sheet contraction. This work is vital for evaluating the risk of potential wide-spread collapse of West Antarctic glaciers."

Co-author Stan Jacobs adds: "Since our first measurements in the Amundsen Sea, estimates of Antarctica's recent contributions to sea level rise have changed from near-zero to significant and increasing. Now finding that the PIG's grounding line has recently retreated more than 30 km from a shallow ridge into deeper water, where it is pursued by a warming ocean, only adds to our concern that this region is indeed the 'weak underbelly' of the West Antarctic Ice Sheet. Increased melting of continental ice also appears to be the primary cause of persistent ocean freshening and other impacts, both locally and downstream in the Ross Sea."

Record melt from Greenland icesheet in 2010 -6

Greenland's icesheet, feared as a major driver of rising sea levels, shed a record amount of melted snow and ice in 2010, scientists reported, a day after the UN said last year was the warmest on record.

Greenland's icesheet, feared as a major driver of rising sea levels, shed a record amount of melted snow and ice in 2010, scientists reported Friday, a day after the UN said last year was the warmest on record.

The 2010 runoff was more than twice the average annual loss in Greenland over the previous three decades, surpassing a record set in 2007, said the study, published in the US-based journal Environmental Research Letters.

Ice melt has now topped this benchmark every year since 1996, according to the paper, derived from long-term satellite and observational data.

Were it to melt entirely, Greenland's icesheet would drive up ocean levels by some seven metres (23 feet), drowning coastal cities around the world.

No credible projections today include a doomsday scenario for the coming centuries. But recent research, including the new study, suggest that Greenland will contribute more to rising seas than predicted only a few years ago.

Based on computer models, Tedesco estimated that runoff in 2010 was 530 gigatonnes, or billions of tonnes, compared to an average of 274 gigatonnes for the period 1958-2009, and 285 gigatonnes for 1979-2009.

"The process is far from being linear, and it is not possible to simply draw a line" into the future, said lead researcher Marco Tedesco, who heads the Cryosphere Processes Laboratory at the City College of New York.

But over the last 30 years "there has been an increase in runoff," he said in an email exchange.

Researchers have thrown up different figures for how much, and how fast, Greenland is shedding its icy mantle, which is up to three kilometres (1.7 miles) thick in places.

They concur, though, that climate change is largely to blame: temperatures in the Arctic region have risen at two to three times the global average over the last 40 years.

In Greenland, summer temperatures in 2010 were 3.0 degrees Celsius (5.4 degrees Fahrenheit) above average.

"The capital, Nuuk, had the warmest spring and summer since records began in 1873," Tedesco noted.

Globally, the year was also the warmest ever recorded, as was the decade it brought to a close, the UN's World Meteorological Organisation (WMO) said on Thursday.

The new study focused on surface melt, runoff and the number of days when bare ice, free of snow, is exposed to the Sun's radiative force.

In 2010, "melting in some areas stretched up to 50 days longer than average," Tedesco said.

The study also showed that land area where melting has been observed has been increasing at a rate of about 17,000 square kilometers (6,500 square miles) per year.

Not only do melting snow and ice flow directly into the sea, they also form torrential under-ice streams that lubricate the passage of glaciers toward the ocean.

In assessing the icesheet's total mass loss, melt is only part of the picture, Tedesco said.

"Our calculations do not account for losses due to calving" -- the splitting of large chunks of glacier ice into the sea -- "and ice dynamics, which are as big if not bigger than those due to surface melting," he said.

Nor did they factor in cyclical contributions to the icesheet from snowfall, he said.

Current estimates of the Greenland icesheets net mass loss vary between 130 and 250 gigatonnes per year.

Antarctica is the world's biggest source of land ice after Greenland, but -- with the exception of West Antarctica -- is considered more resistant to any doomsday collapse.

By century's end, Greenland could contribute as much as 50 centimetres (20 inches) to average worldwide sea levels, many experts agree today.

This would double the predictions for overall sea-level rise in the UN climate panel's landmark 2007 report, which factored in glacial runoff and the thermal expansion of the sea, but not the loss of mass from Greenland.

A one-metre (3.25 feet) increase in the global watermark would devastate many island nations, and wreak havoc in heavily-populated delta regions across the planet.

                                                            Greenland iceberg melt.

Melting Himalayan glaciers threaten 1.3 billion Asians-5

The Himalayan glaciers are receding at a rate of 20 metres every year, at this speed they may disappear altogether by 2035, according to a United Nations report.

More than a billion people in Asia depend on Himalayan glaciers for water, but experts say they are melting at an alarming rate, threatening to bring drought to large swathes of the continent.

Glaciers in the Himalayas, a 2,400-kilometre (1,500-mile) range that sweeps through Pakistan, India, China, Nepal and Bhutan, provide headwaters for Asia's nine largest rivers, lifelines for the 1.3 billion people who live downstream.

But temperatures in the region have increased by between 0.15 and 0.6 degrees Celsius (0.27 and 1.08 degrees Fahrenheit) each decade for the last 30 years, dramatically accelerating the rate at which glaciers are shrinking.

As world leaders gather in Copenhagen this month for a crucial climate change summit, campaigners warn that some Himalayan glaciers could disappear altogether within a few decades.

"Scientists predict that most glaciers will be gone in 40 years as a result of climate change," said Prashant Singh, leader of environmental group WWF's Climate for Life campaign.

"The deal reached at Copenhagen will have huge ramifications for the lives of hundreds of millions of people living in the Himalayan drainage systems who are already highly vulnerable due to widespread poverty."

The Intergovernmental Panel on Climate Change (IPCC), a UN body regarded as the world's top authority on climate change, has warned Himalayan glaciers could "disappear altogether by 2035" and experts say the effects of global warming are already being felt in the region.

In Nepal and Bhutan, the receding glaciers have formed vast lakes that threaten to burst, devastating villages downstream.

Nepalese mountaineer and environmental campaigner Dawa Steven Sherpa said he first became interested in climate change after a close call when part of the Khumbu icefall above Everest base camp collapsed during an expedition in 2007.

Sherpa, who has scaled Everest three times, was walking on the glacier minutes before the collapse, and said his near miss alerted him to the dramatic toll that global warming is already taking on the Himalayas.

"Every time I go to the mountains the older Sherpas tell me this is the warmest year yet," Sherpa, who will take part in a special "summiteers' summit" in Copenhagen, told AFP.

"Initially it struck me how much more dangerous mountaineering would become. But then I realised it was much bigger than that. Entire villages could be wiped out if one of the glacial lakes burst."

In China, studies have shown that the rapid melting of the glaciers will result in an increase in flooding in the short term, state news agency Xinhua has reported.

In the longer term, it said, the continued retreat of glaciers would lead to a gradual decrease in river flows, severely affecting large parts of western China.

Experts say the resulting water shortages could hit the economic development of China and India, with potentially dire consequences for development in two of the world's most populated countries.

Even in low-lying Bangladesh, prone to severe floods, the IPCC has said rivers could run dry by the end of the century.

But research on the impact of global warming on the rugged and inaccessible Himalayas remains sparse, with the IPCC describing the region as a "blank spot" due to a lack of scientific data.

Even the experts disagree on the issue, with some arguing that some of the Himalayan glaciers are actually advancing.

India's Environment Minister Jairam Ramesh recently came under fire for denying that climate change was causing Himalayan glaciers to melt, citing research by the Indian geologist Vijay Kumar Raina.

The Nepal-based International Centre for Integrated Mountain Development (ICIMOD) has studied the Himalayan region for more than three decades and warns of an "urgent need" for more research on the impact of climate change.

"There are so many uncertainties surrounding where, how and to what extent the Himalayan region will be affected by climate change," ICIMOD climate change expert Arun Shrestha told AFP.

"But most experts accept that temperatures are changing, and this is happening more rapidly at altitude."

ICIMOD has warned that the current trends in glacial melt suggest flows in major Asian rivers including the Ganges, Indus and Yellow Rivers will be "substantially reduced" in the coming decades.

"The situation may appear to be normal in the region for several decades to come, and even with increased amounts of water available to satisfy dry season demands," it said in a recent report on the Himalayas.

"However, when the shortage arrives, it may happen abruptly, with water systems going from plenty to scarce in perhaps a few decades or less."

Shrestha added: "When the glaciers get hotter, you get more water, but there comes a point when the water will run out.

"It's like a bank balance, if you're not putting money in, you can't take it out."

Glaciers of the Himalayan Mountains are melting faster than anywhere else. Parts of surrounding ecology are not growing, and the River Ganges which flows from the Himalayan snow and ice currently provides water for hundreds of millions of people.

Swiss Glaciers Melting Rapidly-4

                                              Today                                   Rhone glacier 1850 

BRUSSELS, Jan. 19, 2007 (IPS) - Receding Alpine glaciers are appearing a sure telltale of global warming. In Switzerland, 84 out of 85 glaciers under observation became shorter in 2006.

The hot summers and the lack of precipitation in recent years will accelerate the melting process even more, scientists say.

Glaciers are large masses of snow, ice and rock debris that accumulate in great quantities and begin to flow downwards under pressure of their own weight. They are formed when yearly snowfall in a region far exceeds the amount of snow and ice that melts in a given summer, like in the Swiss Alps.

The results published by the Swiss Academy of Sciences confirm the measurements of previous campaigns, which clearly showed that Swiss glaciers are shrinking. Approximately three-quarters of the observed shrinkage in 2006 is between one and 30 metres.

On top of the list this year was the small Suretta glacier in the canton of Graübunden, which lost 725 metres of its length. This is due to the fact that since last year the ice tongue has been broken up in separate patches that melt more rapidly.

The 24-km long Aletsch glacier in the canton of Wallis, Europe's biggest glacier and part of the United Nations Educational, Scientific and Cultural Organisation (UNESCO) World Heritage, receded 114 metres.

"The Aletsch has been receding steadily over the past 150 years," Swiss glaciologist Andreas Bauder of the Zürich-based Federal Institute of Technology (ETH) told IPS. "The smaller glaciers have shrunk and then grown again, but in the last 20 years they are all getting smaller."

The measurements clearly show the sensitivity of Alpine ice masses to global warming, though with a certain delay depending on their length. "A big glacier like the Aletsch gives you the long-term picture and will remain unaffected by a series of hot summers. A smaller glacier will react more quickly to climate changes, which makes them more vulnerable," Bauder said.

Two variables enter into the glacier equation: temperature and precipitation. "Typically you would expect rising temperatures to lead to more precipitation, because warmer air can contain more water," Bauder said. "We do measure a bit more rain and snowfall, but apparently not enough to compensate for the rising temperatures."

To get an immediate feedback on the weather pattern of the last year, the survey teams also measured the "mass balance". The measurement reflects the balance between the fresh snow the glacier receives from the surrounding area and the ice that melts away in a given year, and thus gives an idea of the state of health of a glacier.

The three glaciers under examination show a negative mass balance for several years in a row, which leads to expectation of a further recession. Last year was particularly bad because of little snowfall in the winter of 2005/2006. The Basodino glacier on the southern slopes of the Alps lost even more of its mass than after the extremely hot summer of 2003.

In Switzerland, glaciers play an important role as water reservoirs for hydro-power production (generating half of all electricity). They are a vital source of water, and without them summer water levels in Europe would drop substantially. Moreover, they are frequently associated with natural hazards endangering humans and infrastructure.

Steep glaciers are prone to ice avalanches, like the one from the Gutz Glacier in Grindelwald in 1996, which affected road infrastructure and injured tourists.

Glacier retreat can lead to the formation of lakes, typically in the recently de-glaciated area in front of a glacier. Such lakes are often dammed by large moraines consisting of loose glacial sediments. The potential instability of moraine dams makes the lakes prone to water outbursts, with potentially devastating effects on the steep yet densely populated Alpine valleys.

Scientists of the Laboratory of Hydraulics, Hydrology and Glacioloy of the ETH Zürich have compiled a list of 82 glaciers which in the past have inflicted damage on persons or property. Fifty-one of these are expected to cause new damage within the next 10 to 20 years.

The lower Grindelwald glacier already made the headlines in 2006. On Jul. 13 500,000 cubic metre of rock crashed down because it was no longer supported sideways by glacier ice, which had receded. The rockslide had been announced in advance, which allowed spectators on the terrace of a mountain hut on the opposite slope to watch the spectacle having coffee and cake.

Research using satellite images by the University of Zürich indicates that Switzerland's glaciers lost 18 percent of their surface between 1985 and 2000, at a rate seven times faster than between 1850 and 1973.

Small glaciers contributed disproportionately to the total loss of glacier area: they represent 18 percent of total glacier area but 44 percent of the losses incurred. By 2025, scientists expect a glacier area loss of 30 percent. (END/IPS/EU/EN/KP/MC/SS/07) 

Not so long ago, when summer skiing was all the rage, lift companies made tidy profits all year round. These days, due to global warming and melting glaciers, there are only two resorts left in Switzerland where out of season skiing is still possible. (SF, swissinfo.ch 27.08.2009)

Cities in peril as Andean glaciers melt-3

"Glacier in Patagonia, Argentina 1928. Glacier in Patagonia, Argentina 2004.

Ice sheets expected to last centuries could disappear in 25 years, threatening water supplies.

Andean glaciers are melting so fast that some are expected to disappear within 15-25 years, denying major cities water supplies and putting populations and food supplies at risk in Colombia, Peru, Chile, Venezuela, Ecuador, Argentina and Bolivia.
The Chacaltaya glacier in Bolivia, the source of fresh water for the cities of La Paz and El Alto, is expected to completely melt within 15 years if present trends continue. Mount Huascarán, Peru's most famous mountain, has lost 1,280 hectares (3,163 acres) of ice, around 40% of the area it covered only 30 years ago. The O'Higgins glacier in Chile has shrunk by nine miles in 100 years and Argentina's Upsala glacier is losing 14 metres (46ft) a year.
Although a few glaciers in southern Patagonia are increasing in size, almost all near the tropics are in rapid retreat. Some glaciers in Colombia are now less than 20% of the mass recorded in 1850 and Ecuador could lose half its most important glaciers within 20 years.
The rate of glacier retreat has shocked scientists, says a report on the effects of global warming in Latin America by 20 UK-based environment and development groups who have drawn on national scientific assessments. Their study says climate change is accelerating the deglaciation phenomenon.
"The speeding up of the ... process is a catastrophic danger," says Carmen Felipe, president of Peru's water management institute. In the short term, the president says, it could cause overflows of reservoirs and trigger mudslides, and in the longer term cut water supplies.
According to the Colombian institute of hydrology, back in 1983 the five major glaciers in El Cocuy national park were expected to last at least 300 years, but measurements taken last year suggest that they may all disappear within 25 years. Meanwhile, the ice sheet on the Ecuadorean volcano Cotopaxi and its glacier has shrunk by 30% since 1976.
"The [drastic melt] forces people to farm at higher altitudes to grow their crops, adding to deforestation, which in turn undermines water sources and leads to soil erosion and putting the survival of Andean cultures at risk," says the report by the Working Group on Climate Change and Development, which includes the International Institute for Environment and Development, Christian Aid, Cafod, WWF, Greenpeace and Progressio.
Their report, Up in Smoke, says snow and rainfall patterns in South America and the Caribbean are becoming less predictable and more extreme. "East of the Andes, rainfall has been increasing since about 1970, accompanied by more destructive, sudden deluges. Meanwhile, the last two hurricane seasons in the Caribbean rim have caused $12bn (£6.3bn) damage to countries other than the US. Tropical storms are expected to become more destructive as climate change intensifies. Climate change models predict more rainfall in eastern South America and less in central and southern Chile with a likelihood of greater and opposite extremes. The 2005 drought in the Amazon basin was probably the worst since records began."
Rises in sea level are expected to be especially severe in the region over the next 50 years, with 60 of Latin America's 77 largest cities located on the coast. The first hurricanes have recently hit south of the equator line in Brazil. "The net effect ... is to reduce the capacity of natural ecosystems to act as buffers against extreme weather."
"What we are seeing are many more negative and cumulative impacts. The larger the rate of [climate] change, the more the adverse effects predominate. Climate change is set to turn an already rough ride into an impossible one," says the report, which adds that the impact of climate change is "hugely" magnified by existing environmental abuse.
It proposes that Latin American governments do not repeat the mistakes made by past and present North American and European governments. Several countries in the region are proposing a new generation of mega dams which would displace thousands more people and destroy vast areas of the Brazilian Amazon. The new importance of soya, both as a food and biofuel crop, could also devastate the environment, leading to a battle for land between companies.
Large-scale coal, oil, and copper mining not only threaten fragile environments, says the report, but in some cases can physically endanger remaining glaciers and greatly increase climate changing emissions. "The Pascua Lama project on the borders of Chile and Argentina intends to move three glaciers that cover gold, silver and copper deposits. The glaciers sustain the mountain and valley ecosystems and there are fears that toxic wastes used in the mining will contaminate land and water," says the report.
Yesterday, the groups called on rich countries to urgently reduce greenhouse gas emissions and proposed that Latin America and the Caribbean governments be helped to reduce their vulnerability to extreme weather.
"The only option we have, apart from demanding that developed countries take responsibility for the damages that climate change is causing, is to try to neutralise the adverse impacts that are [already] upon us. It is time to rethink the model of international aid," said Juan Maldonado, former Colombian environment minister and president of the UN convention on biological diversity.
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"With each new flood, drought or hurricane in Latin America, precious gains in poverty reduction are lost. Extreme weather is set to cause massive loss of life in developing countries throughout the region. The international community must invest more in helping poor communities cope with the effect of climate change," said Paul Cook, head of policy for Tearfund.
The world's many thousands of glaciers have been stable or in slow retreat for more than 100 years but since around 1980 they have mostly been retreating drastically. The fastest decline is in the Himalayas, the Arctic, the Alps, the Rockies and the tropics. Most glaciologists believe this natural phenomenon is being accelerated by global warming. The effects of glacier melt are expected to be severe. Hundreds of millions of people in Asia and Latin America are dependent on glacier water. A reduction in runoff will affect the ability to irrigate crops and will reduce summer stream flows to keep dams and reservoirs replenished. In Norway, the Alps, and the Pacific north-west, glacier runoff is important for hydropower. If all the ice on the polar icecaps were to melt, the oceans would rise an estimated 70 metres (230ft). But even a small melt will affect coastal life.

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Glaciers And Ice Caps To Dominate Sea Level Rise This Century, Says New Study

ScienceDaily (July 20, 2007) — Ice loss from glaciers and ice caps is expected to cause more global sea rise during this century than the massive Greenland and Antarctic ice sheets, according to a new University of Colorado at Boulder study.

The researchers concluded that glaciers and ice caps are currently contributing about 60 percent of the world's ice to the oceans and the rate has been markedly accelerating in the past decade, said Emeritus Professor Mark Meier of CU-Boulder's Institute of Arctic and Alpine Research, lead study author. The contribution is presently about 100 cubic miles of ice annually -- a volume nearly equal to the water in Lake Erie -- and is rising by about three cubic miles per year.

In contrast, the CU-Boulder team estimated Greenland is now contributing about 28 percent of the total global sea rise from ice loss and Antarctica is contributing about 12 percent. Greenland is not expected to catch up to glaciers and ice caps in terms of sea level rise contributions until the end of the century, according to the study.

A paper on the subject appears in the July 19 issue of Science Express, the online edition of Science magazine. Co-authors include CU-Boulder INSTAAR researchers Mark Dyurgerov, Ursula Rick, Shad O'Neel, Tad Pfeffer, Robert Anderson and Suzanne Anderson, as well as Russian Academy of Sciences scientist Andrey Glazovsky.

"One reason for this study is the widely held view that the Greenland and Antarctic ice sheets will be the principal causes of sea-level rise," said Meier, former INSTAAR director and professor in geological sciences. "But we show that it is the glaciers and ice caps, not the two large ice sheets, that will be the big players in sea rise for at least the next few generations."

The accelerating contribution of glaciers and ice caps is due in part to rapid changes in the flow of tidewater glaciers that discharge icebergs directly into the ocean, said the study. Many tidewater glaciers are undergoing rapid thinning, stretching and retreat, which causes them to speed up and deliver increased amounts of ice into the world's oceans, said CU-Boulder geology Professor Robert Anderson, study co-author.

Water controls how rapidly glaciers slide along their beds, said Anderson. When a glacier with its "toe in the water" thins, a larger fraction of its weight is supported by water and it slides faster and calves more ice into the ocean at the glacier terminus.

"While this is a dynamic, complex process and does not seem to be a direct result of climate warming, it is likely that climate acts as a trigger to set off this dramatic response," said Anderson, also an INSTAAR researcher.

Alaska's Columbia Glacier, which is now discharging about 2 cubic miles of ice annually into Price William sound, is a good example, according Anderson. The Columbia Glacier, which has thinned up to 1,300 feet in places, has shrunk by about 9 miles since 1980 and is expected to shrink by another 9 miles in the next two decades.

The team estimated accelerating melt of glaciers and ice caps could add from 4 inches to 9.5 inches of additional sea level rise globally by 2100. This does not include the expansion of warming ocean water, which could potentially double those numbers. A one-foot sea-level rise typically causes a shoreline retreat of 100 feet or more, and about 100 million people now live within about three feet of sea level.

"At the very least, our projections indicate that future sea-level rise may be larger than anticipated, and that the component due to glaciers and ice caps will continue to be substantial," wrote the researchers in Science Express.

The team summarized satellite, aircraft and ground-based data from glaciers, ice caps, the Greenland ice sheet, the West Antarctic ice sheet and the East Antarctic ice sheet to calculate present and future rates of ice loss for the study. 

Meier estimated there are several hundred thousand small glaciers and small, pancake-shaped ice caps in polar and temperate regions. They range from modest, high mountain glaciers to huge glaciers like the Bering Glacier in Alaska, which measures about 5,000 square miles in area and is nearly one-half mile thick in places.

The researchers used a mathematical "scaling" process to estimate more remote glacier volumes, thicknesses and trends by factoring in data like altitude, climate and geography. They used data gathered from around the world, including cold regions in Russia, Europe, China, Central Asia, Canada and South America.

While warming temperatures will likely cause many small high mountain glaciers in North America Europe to disappear by the end of the century, large ice fields and ice caps will continue to produce large amounts of melt water, Meier said. The scientists also believe many "cold" polar glaciers and ice caps will soon warm up enough to begin melting and contributing to sea rise.

The retreat of the Greenland and Antarctic ice sheets also is giving birth to new, smaller glaciers that are prime candidates for study by scientists. "It is incorrect to assume that the small glaciers will simply go away next century -- they will continue to play a key role in the sea level story," said Anderson.

Anderson also said that although the volume of ice locked up in Greenland is equal to roughly 23 feet in sea rise, only a small fraction is likely to be "pulled out" during the next century, most of it through outlet glaciers.

Many smaller "benchmark" glaciers around the world that have been under study for decades are expected to disappear by the end of the century, said Anderson. "We need to start gathering benchmark information on some of the larger glaciers that are unlikely to disappear, so that we can have a long-term record of their behavior."

Anderson said outlet glaciers in Greenland behave much like tidewater glaciers in Canada and Alaska, making them very relevant for long-term study. "Since the world is becoming increasingly aware that sea-level rise is a very real problem, we need to acknowledge the role of all of the ice masses and understand the physical mechanisms by which they deliver water to the sea."

The study was funded primarily by the National Science Foundation and NASA.

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Mountain Glacier Melt to Contribute 12 Centimeters to World Sea-Level Increases by 2100.

ScienceDaily (Jan. 11, 2011) — Melt off from small mountain glaciers and ice caps will contribute about 12 centimetres to world sea-level increases by 2100, according to UBC research published this week in Nature Geoscience.

The largest contributors to projected global sea-level increases are glaciers in Arctic Canada, Alaska and landmass bound glaciers in the Antarctic. Glaciers in the European Alps, New Zealand, the Caucasus, Western Canada and the Western United Sates--though small absolute contributors to global sea-level increases--are projected to lose more than 50 per cent of their current ice volume.

The study modelled volume loss and melt off from 120,000 mountain glaciers and ice caps, and is one of the first to provide detailed projections by region. Currently, melt from smaller mountain glaciers and ice caps is responsible for a disproportionally large portion of sea level increases, even though they contain less than one per cent of all water on Earth bound in glacier ice.

"There is a lot of focus on the large ice sheets but very few global scale studies quantifying how much melt to expect from these smaller glaciers that make up about 40 percent of the entire sea-level rise that we observe right now," says Valentina Radic, a postdoctoral researcher with the Department of Earth and Ocean Sciences and lead author of the study.

Increases in sea levels caused by the melting of the Greenland and Antarctic ice sheets, and the thermal expansion of water, are excluded from the results.

Radic and colleague Regine Hock at the University of Alaska, Fairbanks, modelled future glacier melt based on temperature and precipitation projections from 10 global climate models used by the Intergovernmental Panel on Climate Change.

"While the overall sea level increase projections in our study are on par with IPCC studies, our results are more detailed and regionally resolved," says Radic. "This allows us to get a better picture of projected regional ice volume change and potential impacts on local water supplies, and changes in glacier size distribution."

Global projections of sea level rises from mountain glacier and ice cap melt from the IPCC range between seven and 17 centimetres by the end of 2100. Radic's projections are only slightly higher, in the range of seven to 18 centimetres.

Radic's projections don't include glacier calving--the production of icebergs. Calving of tide-water glaciers may account for 30 per cent to 40 per cent of their total mass loss.

"Incorporating calving into the models of glacier mass changes on regional and global scale is still a challenge and a major task for future work," says Radic.

However, the new projections include detailed projection of melt off from small glaciers surrounding the Greenland and Antarctic ice sheets, which have so far been excluded from, or only estimated in, global assessments.