NASA study shows Antarctica’s Larsen B ice shelf nearing its final act

NASA: A new NASA study finds the last remaining section of Antarctica's Larsen B Ice Shelf, which partially collapsed in 2002, is quickly weakening and likely to disintegrate completely before the end of the decade.

A team led by Ala Khazendar of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, found the remnant of the Larsen B Ice Shelf is flowing faster, becoming increasingly fragmented and developing large cracks. Two of its tributary glaciers also are flowing faster and thinning rapidly.

"These are warning signs that the remnant is disintegrating," Khazendar said. "Although it’s fascinating scientifically to have a front-row seat to watch the ice shelf becoming unstable and breaking up, it’s bad news for our planet. This ice shelf has existed for at least 10,000 years, and soon it will be gone."

Ice shelves are the gatekeepers for glaciers flowing from Antarctica toward the ocean. Without them, glacial ice enters the ocean faster and accelerates the pace of global sea level rise. This study, the first to look comprehensively at the health of the Larsen B remnant and the glaciers that flow into it, has been published online in the journal Earth and Planetary Science Letters.

...NASA research has found that the last section of Antarctica's Larsen B Ice Shelf is likely to disintegrate before the end of the decade. Khazendar noted his estimate of the remnant's remaining life span was based on the likely scenario th
at a huge, widening rift that has formed near the ice shelf's grounding line will eventually crack all the way across. The free-floating remnant will shatter into hundreds of icebergs that will drift away, and the glaciers will rev up for their unhindered move to the sea.

Located on the coast of the Antarctic Peninsula, the Larsen B remnant is about 625 square miles (1,600 square kilometers) in area and about 1,640 feet (500 meters) thick at its thickest point. Its three major tributary glaciers are fed by their own tributaries farther inland. "What is really surprising about Larsen B is how quickly the changes are taking place," Khazendar said. "Change has been relentless." ...

The polar research ship Nathaniel B. Palmer in Barilari Bay, Antarctic Peninsula being a part of the U.S. Antarctic Program (USAP). The icebreaker was on a two-month science expedition to the Larsen B. Embayment, which was occupied for 10,000 years until 2002 by an ice shelf, 23 January 2010.

Antarctic ice shelves are melting dramatically

Karl Mathiesen in the Guardian (UK): The ice around the edge of Antarctica is melting faster than previously thought, potentially unlocking metres of sea-level rise in the long-term, researchers have warned. A team of US scientists looked at 18 years’ worth of satellite data and found the floating ice shelves that skirt the continent are losing 310km3 of ice every year. One shelf lost 18% of its thickness during the period.

The loss of ice shelves does not contribute much directly to sea level rise. But they act like a cork in a bottle at the point where glaciers meet the sea – jamming the flow of ice from the massive ice sheets of east and west Antarctica.

Professor Andrew Shepherd, director of the Centre for Polar Observation and Modelling at the University of Leeds, said the rates of ice loss were unsustainable and could cause a major collapse. This is already occurring at the massive Pine Island glacier, where ice loss has doubled in speed over the last 20 years as its blocking ice shelf has melted.

“This is a real concern, because such high rates of thinning cannot be sustained for much longer, and because in the places where Antarctic ice shelves have already collapsed this has triggered rapid increases in the rate of ice loss from glaciers above ground, causing global sea levels to rise,” he said.

The new research, published in the journal Science on Thursday, discovered for the first time that ice shelf melt is accelerating.

Dr Paul Holland, a climate scientist at the British Antarctic Survey (BAS), said the loss of the shelves would speed the complete collapse of the west Antarctic ice sheet, which would eventually cause up to 3.5m of sea level rise. But he said it was highly unlikely this would occur this century. He said the “worst case scenario” for 2100 was that ice sheets would contribute an additional 70cm to the sea level rise caused by the warming of the ocean....

Via NASA, a satellite image of Schokalsky Bay, Antarctica

Iceland rises as its glaciers melt from climate change

Mari N. Jensen at the University of Arizona College of Science: The Earth’s crust under Iceland is rebounding as global warming melts the island’s great ice caps, a University of Arizona-led team reports in an upcoming issue of Geophysical Research Letters.

The paper is the first to show the current fast uplift of the Icelandic crust is a result of accelerated melting of the island’s glaciers and coincides with the onset of warming that began about 30 years ago, the scientists said.

Some sites in south-central Iceland are moving upward as much as 1.4 inches per year — a speed that surprised the researchers. "Our research makes the connection between recent accelerated uplift and the accelerated melting of the Icelandic ice caps," said first author Kathleen Compton, a UA geosciences doctoral candidate.

Geologists have long known that as glaciers melt and become lighter, the Earth rebounds as the weight of the ice decreases. Whether the current rebound geologists detect is related to past deglaciation or modern ice loss has been an open question until now, said co-author Richard Bennett, a UA associate professor of geosciences. "Iceland is the first place we can say accelerated uplift means accelerated ice mass loss," Bennett said.

To figure out how fast the crust was moving upward, the team used a network of 62 global positioning satellite receivers fastened to rocks throughout Iceland. By tracking the position of the GPS receivers year after year, the scientists "watch" the rocks move and can calculate how far they have traveled — a technique called geodesy.

The new work shows that, at least for Iceland, the land’s current accelerating uplift is directly related to the thinning of glaciers and to global warming. "What we’re observing is a climatically induced change in the Earth’s surface," Bennett said....

The geyser called Strokkur erupts in Iceland, shot by Andreas Tille, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Greenland Ice: The warmer it gets the faster it melts

Space Daily via SPX: Melting of glacial ice will probably raise sea level around the globe, but how fast this melting will happen is uncertain. In the case of the Greenland Ice Sheet, the more temperatures increase, the faster the ice will melt, according to computer model experiments by Penn State geoscientists.

"Although lots of people have thought about sea level rise from the ice sheets, we don't really know how fast that will happen," said Patrick Applegate, research associate, Penn State's Earth and Environmental Systems Institute.

If all the ice in the Greenland Ice Sheet melts, global sea level would rise by about 24 feet. In the last 100 years, sea level in the New York City area has only increased by about one foot. However, storm surges from hurricanes stack on top of this long-term increase, so sea level rise will allow future hurricanes to flood places where people are not ready for or used to flooding. A vivid example occurred during Hurricane Sandy when parts of the New York City subway tunnel system flooded.

Greenland might be especially vulnerable to melting because that area of the Earth sees about 50 percent more warming than the global average. Arctic sea ice, when it exists, reflects the sun's energy back through the atmosphere, but when the sea ice melts and there is open water, the water absorbs the sun's energy and reradiates it back into the air as heat.

Arctic sea ice coverage has decreased over the last few decades, and that decrease will probably continue in the future, leading to accelerated temperature rise over Greenland. Floating ice does not add to sea level, but the Greenland Ice Sheet rests on bedrock that is above sea level.

Feedbacks in the climate system cause accelerated temperature rise over the Arctic. Other feedbacks in the Greenland Ice Sheet that contribute to melting include height-melting feedback. A warm year in Greenland causes more melt around the edges of the ice sheet, lowering the surface. The atmosphere is warmer at lower altitudes, so the now lower surface experiences even more melting. This process can lead to accelerated ice melt and sea level rise....

A glacier seen from offshore near Amassalik, Greenland, shot by Christine Zenino Christine Zenino ,Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Changing Antarctic waters could trigger steep rise in sea levels

A press release from the ARC Centre for Excellence for Climate Science (Australia): Current changes in the ocean around Antarctica are disturbingly close to conditions 14,000 years ago that new research shows may have led to the rapid melting of Antarctic ice and an abrupt 3-4 metre rise in global sea level.

The research published in Nature Communications found that in the past, when ocean temperatures around Antarctica became more layered - with a warm layer of water below a cold surface layer -  ice sheets and glaciers melted much faster than when the cool and warm layers mixed more easily. This defined layering of temperatures is exactly what is happening now around the Antarctic.

“The reason for the layering is that global warming in parts of Antarctica is causing land-based ice to melt, adding massive amounts of freshwater to the ocean surface,” said ARC Centre of Excellence for Climate System Science researcher Prof Matthew England an author of the paper.

“At the same time as the surface is cooling, the deeper ocean is warming, which has already accelerated the decline of glaciers on Pine Island and Totten. It appears global warming is replicating conditions that, in the past, triggered significant shifts in the stability of the Antarctic ice sheet.”

The modelling shows the last time this occurred, 14,000 years ago, the Antarctic alone contributed 3-4 metres to global sea levels in just a few centuries. “Our model simulations provide a new mechanism that reconciles geological evidence of past global sea level rise,” said researcher UNSW ARC Future Fellow Dr Chris Fogwill.

“The results demonstrate that while Antarctic ice sheets are remote, they may play a far bigger role in driving past and importantly future sea level rise than we previously suspected.” The accelerating melting of land ice into the sea makes the surface of the ocean around Antarctica colder, less salty and more easily frozen, leading to extensive sea ice in some areas. It is one of the reasons ascribed to the increasing trend in sea ice around Antarctica....

A backlit iceberg off the Antarctic coast, shot by Jason Auch, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Study tracks global sea-levels over the last five ice ages

A press release from the University of Southampton: Land-ice decay at the end of the last five ice-ages caused global sea-levels to rise at rates of up to 5.5 metres per century, according to a new study. An international team of researchers developed a 500,000-year record of sea-level variability, to provide the first account of how quickly sea-level changed during the last five ice-age cycles.

The results, published in the latest issue of Nature Communications, also found that more than 100 smaller events of sea-level rise took place in between the five major events.

Dr Katharine Grant, from the Australian National University (ANU), Canberra, who led the study, says: “The really fast rates of sea-level rise typically seem to have happened at the end of periods with exceptionally large ice sheets, when there was two or more times more ice on the Earth than today.

“Time periods with less than twice the modern global ice volume show almost no indications of sea-level rise faster than about 2 metres per century. Those with close to the modern amount of ice on Earth, show rates of up to 1 to 1.5 metres per century.”

Co-author Professor Eelco Rohling, of both the University of Southampton and ANU, explains that the study also sheds light on the timescales of change. He says: “For the first time, we have data from a sufficiently large set of events to systematically study the timescale over which ice-sheet responses developed from initial change to maximum retreat.”

“This happened within 400 years for 68 per cent of all 120 cases considered, and within 1100 years for 95 per cent. In other words, once triggered, ice-sheet reduction (and therefore sea-level rise) kept accelerating relentlessly over periods of many centuries.”

Professor Rohling speculates that there may be an important lesson for our future: “Man-made warming spans 150 years already and studies have documented clear increases in mass-loss from the Antarctic and Greenland ice sheets. Once under way, this response may be irreversible for many centuries to come.”

NASA image of an iceberg calving from the Petermann Glacier in Greenland, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license 

Record decline of ice sheets: For the first time scientists map elevation changes of Greenland and Antarctic glaciers

A press release from the Alfred Wegener Institute: Researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), have for the first time extensively mapped Greenland’s and Antarctica’s ice sheets with the help of the ESA satellite CryoSat-2 and have thus been able to prove that the ice crusts of both regions momentarily decline at an unprecedented rate. In total the ice sheets are losing around 500 cubic kilometres of ice per year. This ice mass corresponds to a layer that is about 600 metres thick and would stretch out over the entire metropolitan area of Hamburg, Germany's second largest city. The maps and results of this study are published today in The Cryosphere, an open access journal of the European Geoscience
s Union (EGU).

“The new elevation maps are snapshots of the current state of the ice sheets. The elevations are very accurate, to just a few metres in height, and cover close to 16 million km2 of the area of the ice sheets. This is 500,000 square kilometres more than any previous elevation model from altimetry”, says lead-author Dr. Veit Helm, glaciologist at the Alfred Wegener Institute in Bremerhaven.

For the new digital maps, the AWI scientists had evaluated all data by the CryoSat-2 altimeter SIRAL. Satellite altimeter measure the height of an ice sheet by sending radar or laser pulses in the direction of the earth. These signals are then reflected by the surface of the glaciers or the surrounding waters and are subsequently retrieved by the satellite. This way the scientists were able to precisely determine the elevation of single glaciers and to develop detailed maps.

...The team derived the elevation change maps using over 200 million SIRAL data points for Antarctica and around 14.3 million data points for Greenland. The results reveal that Greenland alone is reducing in volume by about 375 cubic kilometres per year. “When we compare the current data with those from the ICESat satellite from the year 2009, the volume loss in Greenland has doubled since then. The loss of the West Antarctic Ice Sheet has in the same time span increased by a factor of 3. Combined the two ice sheets are thinning at a rate of 500 cubic kilometres per year. That is the highest speed observed since altimetry satellite records began about 20 years ago,” says AWI glaciologist Prof. Dr. Angelika Humbert, another of the study’s authors.

The areas where the researchers detected the largest elevation changes were Jakobshavn Isbrae (Jakobshavn Glacier) in West Greenland and Pine Island Glacier in West Antarctica. Since February 2014 scientists know that the Jakobshavn Isbrae is moving ice into the ocean at a record rate of up to 46 meters a day. The Pine Island Glacier hit the headlines in July 2013. Back then AWI scientists reported that a table iceberg as large as the area of Hamburg had broken off the tip of its ice shelf. (Link to the AWI press release from the 9th July 2013)

But whereas both the West Antarctic Ice Sheet and the Antarctic Peninsula, on the far west of the continent, are rapidly losing volume, East Antarctica is gaining volume – though at a moderate rate that doesn’t compensate the losses on the other side of the continent....

The border of an Antarctic glacier, photo from the Alfred Wegener Institute

Minor variations in ice sheet size can trigger abrupt climate change

AlphaGalileo via Cardiff University: Small fluctuations in the sizes of ice sheets during the last ice age were enough to trigger abrupt climate change, scientists have found. The team, which included Cardiff University researchers, compared simulated model data with that retrieved from ice cores and marine sediments in a bid to find out why temperature jumps of up to ten degrees took place in far northern latitudes within just a few decades during the ice age.

...The research confirms that thicker ice sheets increased ocean circulation and transferred more heat to the north due to a redirection of the prevailing winds. As the north warmed, glaciers retreated, the winds returned to normal conditions, and the north became cooler once again, completing the cycle

Conor Purcell from Cardiff University’s School of Earth and Ocean Sciences, said: “Using the simulations performed with our climate model, we were able to demonstrate that the climate system can respond to small changes with abrupt climate swings. Our study suggests that at medium sea levels, powerful forces, such as the dramatic acceleration of polar ice cap melting, are not necessary to create abrupt climate shifts and temperature changes.”

At present, the extent of Arctic sea ice is far less than during the last glacial period. The Laurentide Ice Sheet, the major driving force for ocean circulation during the glacials, has also disappeared. Climate changes following the pattern of the last ice age are therefore not anticipated under today’s conditions.

Professor Gerrit Lohmann, leader of the Paleoclimate Dynamics group at the AWI said: “In terms of the Earth’s history, we are currently in one of the climate system’s more stable phases. The preconditions which gave rise to rapid temperature changes during the last ice age do not exist today, but sudden climate changes cannot be excluded in future.”

The Greenland Ice Sheet, shot by Christine Zenino, Wikimedia Commons via Flickr,  under the Creative Commons Attribution 2.0 Generic license

Has Antarctic sea ice expansion been overestimated?

A press release from the European Geosciences Union: New research suggests that Antarctic sea ice may not be expanding as fast as previously thought. A team of scientists say much of the increase measured for Southern Hemisphere sea ice could be due to a processing error in the satellite data. The findings are published today in The Cryosphere, a journal of the European Geosciences Union (EGU).

Arctic sea ice is retreating at a dramatic rate. In contrast, satellite observations suggest that sea ice cover in the Antarctic is expanding – albeit at a moderate rate – and that sea ice extent has reached record highs in recent years. What’s causing Southern Hemisphere sea ice cover to increase in a warming world has puzzled scientists since the trend was first spotted. Now, a team of researchers has suggested that much of the measured expansion may be due to an error, not previously documented, in the way satellite data was processed.

“This implies that the Antarctic sea ice trends reported in the IPCC’s AR4 and AR5 [the 2007 and 2013 assessment reports from the Intergovernmental Panel on Climate Change] can’t both be correct: our findings show that the data used in one of the reports contains a significant error. But we have not yet been able to identify which one contains the error,” says lead-author Ian Eisenman of the Scripps Institution of Oceanography at University of California San Diego in the US.

...In the study published in The Cryosphere, Eisenman and collaborators compare two datasets for sea ice measurements. The most recent one, the source of AR5 conclusions, was generated using a version of Bootstrap updated in 2007, while the other, used in AR4 research, is the result of an older version of the algorithm.

The researchers found a difference between the two datasets related to a transition in satellite sensors in December 1991, and the way the data collected by the two instruments was calibrated. “It appears that one of the records did this calibration incorrectly, introducing a step-like change in December 1991 that was big enough to have a large influence on the long-term trend,” explains Eisenman.

“You’d think it would be easy to see which record has this spurious jump in December 1991, but there’s so much natural variability in the record – so much ‘noise’ from one month to the next – that it’s not readily apparent which record contains the jump. When we subtract one record from the other, though, we remove most of this noise, and the step-like change in December 1991 becomes very clear.”

With the exception of the longer time period covered by the most recent dataset, the two records were thought to be nearly identical. But, by comparing the datasets and calculating Antarctic sea ice extent for each of them, the team found that there was a stark difference between the two records, with the current one giving larger rates of sea ice expansion than the old one in any given period. If the error is in the current dataset, the results could contribute to an unexpected resolution for the Antarctic sea ice cover enigma.

An iceberg off the Antarctic coast, shot by Christopher Michel - 091203_iceberg_6964, Wikimedia Commons via Flickr, under the Creative Commons 2.0 license 

Hidden Greenland canyons mean more sea level rise

NASA: Scientists at NASA and the University of California, Irvine (UCI), have found that canyons under Greenland's ocean-feeding glaciers are deeper and longer than previously thought, increasing the amount of Greenland's estimated contribution to future sea level rise.

"The glaciers of Greenland are likely to retreat faster and farther inland than anticipated, and for much longer, according to this very different topography we have discovered,” said Mathieu Morlighem, a UCI associate project scientist who is lead author of the new research paper. The results were published Sunday in the journal Nature Geoscience.

Ice loss from Greenland has accelerated during the last few decades. However, older ice sheet models predicted the speedup would be temporary because the glaciers would soon melt back onto higher ground and stabilize. The models projected that Greenland's contribution to global sea level rise would therefore be limited.

Morlighem's new topography shows southern Greenland's ragged, crumbling coastline is scored by more than 100 canyons beneath glaciers that empty into the ocean. Many canyons are well below sea level as far as 60 miles (100 kilometers) inland. Higher ground, where glaciers could stabilize, is much farther from the coastline than previously thought. The finding calls into question the idea that the recent accelerated ice loss will be short lived.

..."We have been able to make a quantum leap in our knowledge of bed topography beneath ice sheets in the last decade, thanks to the advent of missions like NASA's Operation IceBridge in combination with satellite data on the speed these ice sheets are flowing," said coauthor Eric Rignot of UCI and NASA's Jet Propulsion Laboratory (JPL), Pasadena, California.

The same research team reported new findings on glacial melt in West Antarctica last week. "Together the papers illustrate clearly the globe’s ice sheets will contribute far more to sea level rise than current projections show,” said Rignot...

Kejser Franz Josef Fjord near Stensjö Bjerg, Greenland Nationalpark. Shot by Erik Christensen, Wikimedia Commons, under Creative Commons 3.0 license

East Antarctica more at risk than thought to long-term thaw

Reuters: Part of East Antarctica is more vulnerable than expected to a thaw that could trigger an unstoppable slide of ice into the ocean and raise world sea levels for thousands of years, a study showed on Sunday. The Wilkes Basin in East Antarctica, stretching more than 1,000 km (600 miles) inland, has enough ice
to raise sea levels by 3 to 4 meters (10-13 feet) if it were to melt as an effect of global warming, the report said.

The Wilkes is vulnerable because it is held in place by a small rim of ice, resting on bedrock below sea level by the coast of the frozen continent. That "ice plug" might melt away in coming centuries if ocean waters warm up.

"East Antarctica's Wilkes Basin is like a bottle on a slant. Once uncorked, it empties out," Matthias Mengel of the Potsdam Institute for Climate Impact Research, lead author of the study in the journal Nature Climate Change, said in a statement.

Co-author Anders Levermann, also at Potsdam in Germany, told Reuters the main finding was that the ice flow would be irreversible, if set in motion. He said there was still time to limit warming to levels to keep the ice plug in place.

...Worries about rising seas that could swamp low-lying areas from Shanghai to Florida focus most on ice in Greenland and West Antarctica, as well as far smaller amounts of ice in mountain ranges from the Himalayas to the Andes...

Sea ice and icebergs in East Antarctica, NASA image

Study projects big thaw for Antarctic sea ice

David Malmquist at William & Mary's Virginia Institute of Marine Science: Antarctica’s Ross Sea is one of the few polar regions where summer sea-ice coverage has increased during the last few decades, bucking a global trend of drastic declines in summer sea ice across the Arctic Ocean and in two adjacent embayments of the Southern Ocean around Antarctica.

Now, a modeling study led by Professor Walker Smith of the Virginia Institute of Marine Science suggests that the Ross Sea’s recent observed increase in summer sea-ice cover is likely short-lived, with the area projected to lose more than half its summer sea ice by 2050 and more than three quarters by 2100.

These changes, says Smith, will significantly impact marine life in what is one of the world’s most productive and unspoiled marine ecosystems, where rich blooms of phytoplankton feed krill, fish, and higher predators such as whales, penguins, and seals.

...Smith says “The Ross Sea is critically important in regulating the production of Antarctica’s sea ice overall and is biologically very productive, which makes changes in its physical environment of global concern. Our study predicts that it will soon reverse its present trend and experience major drops in ice cover in summer, which, along with decreased mixing of the vertical column, will extend the season of phytoplankton growth. These changes will substantially alter the area’s pristine food web.”

Researchers attribute the observed increase in summertime sea ice in the Ross Sea—where the number of days with ice cover has grown by more two months over the past three decades—to a complex interplay of factors, including changes in wind speed, precipitation, salinity, ocean currents, and air and water temperature....

NASA image of ice in the Ross Sea, Antarctica

Climate change puts Arctic winters on thin ice

A press release from the University of Waterloo (Canada): Arctic lakes have been freezing up later in the year and thawing earlier, creating an ice season about 24 days shorter than it was in 1950, a University of Waterloo study has found.

The research, sponsored by the European Space Agency (ESA), also reveals that climate change has dramatically affected the thickness of lake ice at the coldest point in the season: In 2011, Arctic lake ice was up to 38 centimetres thinner than it was in 1950.

“We’ve found that the thickness of the ice has decreased tremendously in response to climate warming in the region,” said lead author Cristina Surdu, a PhD student in Waterloo’s Department of Geography and Environmental Management. “When we saw the actual numbers we were shocked at how dramatic the change has been. It’s basically more than a foot of ice by the end of winter, so it’s very significant.”

The study of more than 400 lakes of the North Slope of Alaska, is the first time researchers have been able to document the magnitude of lake-ice changes in the region over such a long period of time, says author Claude Duguay, a University of Waterloo professor and member of the Interdisciplinary Centre on Climate Change.

The research team used satellite radar imagery from ESA to determine that 62 per cent of the lakes in the region froze to the bottom in 1992. By 2011, only 26 per cent of lakes froze down to the bed, or bottom of the lake. Overall, there was a 22 per cent reduction in what the researchers call “grounded ice” from 1992 to 2011.

Researchers were able to tell the difference between a fully frozen lake and one that had not completely frozen to the bottom, because satellite radar signals behave very differently, depending on presence or absence of water underneath the ice....

Ekutna Lake in Alaska, shot by Frank K., Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

After bad year, insurers face potential ice-storm hit

Tim Kiladze in the Globe and Mail (Toronto): Canadian insurers are grappling with the prospect of financial damage from yet another severe storm, capping off a brutal year that raised serious questions about how the industry will deal with the costs of climate change.

After suffering a $3-billion hit from natural disasters such as the summer floods in Alberta and the Greater Toronto Area, property and casualty insurers are now racking up claims from the ice storm that hit Ontario, Quebec and Atlantic Canada. It is still too early to determine the costs, but insurers are bracing for a bruising.

 “The ice storm that hit Central Canada this weekend has caused significant physical damage and emotional trauma for many households, and will likely be a significant insured event for the industry,” André-Philippe Hardy, a financial services analyst at RBC Dominion Securities, wrote in a note to clients. Insurer RSA Canada said the storm was “one of the worst we’ve seen in Toronto in quite some time.”

Insurers aren’t the only ones on the hook – they share the burden with reinsurance companies that take on a portion of the risk – but the latest storm reopens a deep wound. The property insurance industry is coming to grips with evidence that severe weather events are becoming more frequent. That has potentially significant implications for consumers and businesses, who may be forced to pay higher premiums as insurers try to recover from the losses.

“As severe weather events become more extreme and frequent, we will continue to pursue our efforts to ensure that the protection we offer reflects our country’s new climate reality and that governments, consumers, businesses and all stakeholders pursue their efforts to better adapt to climate change,” Charles Brindamour, chief executive officer of insurer Intact Financial Corp., said in November after the company reported its first underwriting loss in a decade....

Generic NOAA image of ice storm damage

Greenland ice stores liquid water year-round

University of Utah News Center: Researchers at the University of Utah have discovered a new aquifer in the Greenland Ice Sheet that holds liquid water all year long in the otherwise perpetually frozen winter landscape. The aquifer is extensive, covering 27,000 square miles.

The reservoir is known as a “perennial firn aquifer” because water persists within the firn – layers of snow and ice that don’t melt for at least one season. Researchers believe it figures significantly in understanding the contribution of snowmelt and ice melt to rising sea levels. The study was published online Sunday, Dec. 22, in the journal Nature Geoscience.

“Of the current sea level rise, the Greenland Ice Sheet is the largest contributor – and it is melting at record levels,” says Rick Forster, lead author and professor of geography at the University of Utah. “So understanding the aquifer’s capacity to store water from year to year is important because it fills a major gap in the overall equation of meltwater runoff and sea levels.”

Forster’s team has been doing research in southeast Greenland since 2010 to measure snowfall accumulation and how it varies from year to year. The area they study covers 14 percent of southeast Greenland yet receives 32 percent of the entire ice sheet’s snowfall, but there has been little data gathered.

In 2010, the team drilled core samples in three locations on the ice for analysis. Team members returned in 2011 to approximately the same area, but at lower elevation. Of the four core samples taken then, two came to the surface with liquid water pouring off the drill while the air temperatures were minus 4 degrees Fahrenheit. The water was found at about 33 feet below the surface at the first hole and at 82 feet in the second hole.

“This discovery was a surprise,” Forster says. “Although water discharge from streams in winter had been previously reported, and snow temperature data implied small amounts of water, no one had yet reported observing water in the firn that had persisted through the winter.”...

Drill rig used to extract firn cores from within the Greenland firn aquifer. One of the snowmobiles used in the 300 km traverse of the ice sheet to reach the drill site. Pictured, Clément Miège (co-author and PhD student University of Utah), and Terry Gacke (Ice Drilling Design and Operations). Photo Credit: Evan Burgess

Glacier melt helps sea level forecasts

A press release from the University of Edinburgh: Studies of the Greenland ice sheet, including during a record warm summer, are helping scientists better understand how summer conditions affect its flow. This is important for predicting the future contribution made by melting glaciers to sea level rise.

Ice flows slowly from the centre of the Greenland Ice Sheet towards its margins, where it eventually melts or calves into the ocean as icebergs. Knowing how fast this movement occurs is essential for predicting the contribution of the ice sheet to sea level rise.

In summer, ice from the surface of a glacier melts and drains to the bed of the ice sheet, initially raising water pressure at the base and enabling the glacier to slide more quickly. It can, at times, move more than twice as fast in summer compared with winter, they found.

In 2012, an exceptionally warm summer caused the Greenland Ice Sheet to undergo unprecedented rates of melting. However, researchers have found that fast summer ice flow caused by significant melting is cancelled out by slower motion the following winter.

Scientists found that this is because large drainage channels, formed beneath the ice by the meltwater, helped to lower the water pressure, ultimately reducing the sliding speed. The discovery suggests that movement in the parts of the ice sheet that terminate on land are insensitive to surface melt rates.

It improves scientists’ understanding of how the ice sheet behaves and curbs error in estimating its contribution to sea level rise in a warming world. Scientists led by the University of Edinburgh gathered detailed GPS ice flow data and ice surface melt rates along a 115 km transect in west Greenland. They compared ice motion from an average melt year, 2009, with the exceptionally warm year of 2012....

A Greenland glacier, west of Tasiliaq, shot by Ville Miettinen, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Volcano discovered smoldering under a kilometer of ice in West Antarctica

Washington University in St. Louis Newsroom: It wasn’t what they were looking for — but that only made the discovery all the more exciting. In January 2010, a team of scientists had set up two crossing lines of seismographs across Marie Byrd Land in West Antarctica....

...There were big questions to be asked and answered. The goal, said Doug Wiens, PhD, was essentially to weigh the ice sheet to help reconstruct Antarctica’s climate history. (Wiens is a professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis and one of the project’s principal investigators.) But to do this accurately, the scientists had to know how the earth’s mantle would respond to an ice burden, and that depended on whether it was hot and fluid or cool and viscous. The seismic data would allow them to map the mantle’s properties.

In the meantime, automated-event-detection software was put to work to comb the data for anything unusual. When it found two bursts of seismic events between January 2010 and March 2011, Wiens’ PhD student Amanda Lough looked more closely to see what was rattling the continent’s bones.... Uncertain at first, the more Lough and her colleagues looked, the more convinced they became that a new volcano was forming a kilometer beneath the ice.

...A colleague suggested that the event waveforms looked like Deep Long Period earthquakes, or DPLs, which occur in volcanic areas, have the same frequency characteristics and are as deep. “Everything matches up,” Lough said.

...Will the new volcano erupt?  “Definitely,” Lough said. “In fact, because the radar shows a mountain beneath the ice, I think it has erupted in the past, before the rumblings we recorded.”

... On the other hand, a subglacial eruption and the accompanying heat flow will melt a lot of ice. “The volcano will create millions of gallons of water beneath the ice — many lakes full,” Wiens said.  This water will rush beneath the ice toward the sea and feed into the hydrological catchment of the MacAyeal Ice Stream, one of several major ice streams draining ice from Marie Byrd Land into the Ross Ice Shelf. By lubricating the bedrock, it will speed the flow of the overlying ice, perhaps increasing the rate of ice-mass loss in West Antarctica....

Melt water from the new volcano will drain into the MacAyeal Ice Stream, labeled above as ice stream E, its original designation. This radar image of West Antarctica (see box on the inset at bottom right for location) has been color-coded to indicate the speed at which the ice is moving. Red marks the fast-moving centers of the ice streams and black lines outline each stream’s catchment area. By greasing the skids with water, the new volcano might increase the rate of ice loss from the MacAyeal Ice Stream. From the Earth Observatory/NASA

'Tiger stripes' underneath Antarctic glaciers slow the flow

Catherine Zandonella in News at Princeton: Narrow stripes of dirt and rock beneath massive Antarctic glaciers create friction zones that slow the flow of ice toward the sea, researchers at Princeton University and the British Antarctic Survey have found. Understanding how these high-friction regions form and subside could help researchers understand how the flow of these glaciers responds to a warming climate.

Just as no-slip strips on flooring prevent people from slipping on a wet floor, these ribs or "tiger stripes" — named in reference to Princeton's tiger mascot — provide friction that hinders the glaciers from slipping along the underlying bed of rock and sediment, the researchers report online in the journal Science.

Researchers at Princeton University and the British Antarctic Survey used mathematical modeling and data from satellites and ground-penetrating radar to infer the existence of stripes or ribs (in red) indicating areas of high friction between the glacier and the underlying bedrock. These high-friction ribs slow the movement of ice toward the sea. The image on the left is the Pine Island Glacier and the image on the right is the Thwaites Glacier, both in West Antarctica. (Image courtesy of Olga Sergienko, Program in Atmospheric and Oceanic Sciences)

The researchers discovered these tiger stripes, which occur in large, slippery regions under the glaciers, using mathematical modeling based on data from the National Snow and Ice Data Center and the British Antarctic Survey. The work was conducted by Olga Sergienko, an associate research scientist in Princeton's Program in Atmospheric and Oceanic Sciences, and Richard Hindmarsh, a scientist at the British Antarctic Survey.

...Studying the bottom of these glaciers is next to impossible due to the inability to see through the ice, which is over a mile-and-a-half thick. Instead, the researchers used satellite measurements of the ice velocity and ground-penetrating radar collected from airplane flyovers to detect bedrock and surface topography, as well as field observations. Using the data, Sergienko created a mathematical model that calculated what happens inside the glacier as it flows along the bedrock. The model predicted the formation of the tiger stripes or ribs, which Hindmarsh had theorized some years earlier...

Researchers at Princeton University and the British Antarctic Survey used mathematical modeling and data from satellites and ground-penetrating radar to infer the existence of stripes or ribs (in red) indicating areas of high friction between the glacier and the underlying bedrock. These high-friction ribs slow the movement of ice toward the sea. The image on the left is the Pine Island Glacier and the image on the right is the Thwaites Glacier, both in West Antarctica. (Image courtesy of Olga Sergienko, Program in Atmospheric and Oceanic Sciences)

NASA begins airborne campaign to map Greenland ice sheet summer melt

Space Daily via SPX: For the first time, a NASA airborne campaign will measure changes in the height of the Greenland Ice Sheet and surrounding Arctic sea ice produced by a single season of summer melt. NASA's C-130 research aircraft flew from the Wallops Flight Facility in Wallops Island, Va., to Greenland Wednesday where they will conduct survey flights to collect data that will improve our understanding of seasonal melt and provide baseline measurements for future satellite missions. Flights are scheduled to continue through Nov. 16.

The land and sea ice data gathered during this campaign will give researchers a more comprehensive view of seasonal changes and provide context for measurements that will be gathered during NASA's ICESat-2 mission, which is scheduled for launch in 2016.

"The more ground we cover the more comparison points we'll have for ICESat-2," said Bryan Blair of Goddard Space Flight Center in Greenbelt, Md., principal investigator for the Land, Vegetation and Ice Sensor, or LVIS.

Warm summer temperatures lead to a decline in ice sheet elevation that often can be significant in low-lying areas along the Greenland coast. In past years, the Jakobshavn Glacier, located in the lower elevations of western Greenland, has experienced declines of nearly 100 feet in elevation over a single summer. Higher elevations farther inland see less dramatic changes, usually only a few inches, caused by pockets of air in the snowpack that shrink as temperatures warm.

"Surface melt is more than half of the story for Greenland's mass loss," said Ben Smith, senior physicist at the University of Washington's Advanced Physics Laboratory, Seattle, and member of the science team that selected flight lines for this campaign. The rest of Greenland's mass loss comes from ice flowing downhill into the ocean, often breaking off to form icebergs, and from melting at the base of the ice sheet....

Tasilaq, Greenland, shot by Christine Zenino, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Giant channels discovered beneath Antarctic ice shelf

A press release from the University of Exeter:  Scientists have discovered huge ice channels beneath a floating ice shelf in Antarctica. At 250 metres high, the channels are almost as tall as the Eiffel tower and stretch hundreds of kilometres along the ice shelf.  The channels are likely to influence the stability of the ice shelf and their discovery will help researchers understand how the ice will respond to changing environmental conditions.

Researchers from the University of Exeter, Newcastle University, the University of Bristol, the University of Edinburgh, the British Antarctic Survey and the University of York, used satellite images and airborne radar measurements to reveal the channels under the ice shelf. The channels can be seen on the surface of the ice shelf, as well as underneath, because the ice floats at a different height depending on its thickness.

The researchers also predicted the path of meltwater flowing under the part of the ice in contact with the land – known as the ice sheet. They discovered that the predicted flow paths lined up with the channels under the ice shelf at the point where the ice starts to float.

The match-up indicates that the water flow beneath the grounded ice sheet is responsible for the formation of the channels beneath the floating ice shelf. When the meltwater flowing under the ice sheet enters the ocean beneath the ice shelf, it causes a plume of ocean water to form, which then melts out the vast channels under the ice shelf. Previously, it was thought that water flowed in a thin layer beneath the ice sheet, but the evidence from this study suggests it flows in a more focussed manner much like rivers of water. The way in which water flows beneath the ice sheet strongly influences the speed of ice flow, however, the implications for the future of the ice sheet are yet to be determined.

Dr Anne Le Brocq from the University of Exeter said: “If we are to understand the behaviour of the ice sheet, and its contribution to changes in sea level, we need to fully understand the role of water at the base of the ice sheet. The information gained from these newly discovered channels will enable us to understand more fully how the water system works and how the ice sheet will behave in the future.”...

The Brunt Ice Shelf, shot by NASA's Operation Ice Bridge