Antarctic ice sheet built ‘bottom-up’

By Jonathan Amos, Science correspondent, BBC News. Original article here

Radar image (AGAP)

Radar reveals the ghostly shapes of the Gamburtsevs and the giant freeze-on “beehive” structure above

Scientists have seen once again just how dynamic a place the underside of the Antarctic ice sheet can be.Survey data collected from the middle of the White Continent shows liquid water is being frozen on to the bottom of the sheet in huge quantities.In places, this deeply buried add-on layer is hundreds of metres thick and represents about half of the entire ice column, researchers say.The discovery is reported online in the journal Science.

Project leaders confess to being astonished by the findings.”It’s jaw-dropping, I have to say,” said Professor Robin Bell from Columbia University’s Lamont-Doherty Earth Observatory.”The first time I showed the data to colleagues, there was an audible gasp,” she told BBC News.The new data will add to the understanding of how the ice sheet expands and moves, which in turn will inform researchers as they try to grasp how Antarctica might change in a warmer world.

Twin Otter (M.Studinger)
Twin Otter planes criss-crossed the Antarctic interior with their instruments

The observations come from a major expedition to survey the Gamburtsev mountain range in the polar summer of 2008-2009.Although similar to the European Alps in scale, the Gamburtsevs are hidden under kilometres of ice deep in the Antarctic interior.

“We’ll have to choose a drill site very carefully; we can’t just throw a dart in a board”
Tom Jordan, British Antarctic Survey

An expeditionary team used instrumented planes to gather a wealth of new information about the peaks and their ice shroud. Equipment included radar to see through the ice, showing its many layers, right down to the rock bed. The survey data also gives new insights into how liquid water funnels through the mountains’ valleys.

It is well known that ice sheets grow from the top down, as snow settles on the surface and is compacted over thousands of years. But the new findings illustrate clearly how the sheet can also grow from the bottom up by accumulating layers of liquid water.

Sub-glacial water can be maintained in a liquid state at the bottom of the sheet, either by the intense pressure of the overlying ice or by being in contact with the warmth of the bedrock. But if the water is forced up valley sides to locations of lower pressure, or into ponds in places away from retained heat in rocks, then it will rapidly turn to ice – and can stick to the bottom of the sheet above.

The survey data reveals that this add-on ice makes up 24% of the ice sheet base around Dome A, a 4.2km-high plateau of ice that represents the greatest elevation on the continent. And in some other places, this refreeze phenomenon accounts for slightly more than half of the total ice thickness.

That means in these locations, ice is being created faster on the bottom of the sheet than it is being accumulated through snow deposition on the top.

New dimensions
Liquid water at the base of the sheet has long been recognised to be a “lubricant” for movement, but the latest data adds a whole new dimension to our understanding, said Professor Bell.

“We’ve known there’s been melting under ice sheets from a long time – since the 1960s,” she explained.

“Then it was demonstrated this water could move, it could slosh around; but I think we still had this idea that it just spilled into the ocean.

“Well, now we can show these hydrologic systems are modifying the fundamental stratigraphy of the ice sheet.”

ANTARCTIC GAMBURTSEV PROJECT (AGAP)

Map of Antarctica's Gamburtsev mountains
  • Two camps (N & S) were established deep in the Antarctic interior around the plateau region known as Dome A
  • Aircraft used radar to detect ice thickness and layering, and mapped the shape of the deeply buried bedrock
  • The planes also conducted gravity and magnetic surveys to glean more information about the mountains’ structure
  • By listening to seismic waves passing through the range, scientists could probe rock properties deep in the Earth
  • The Gamburtsev range is totally hidden by ice. In some places that ice covering is more than 4,000m thick
  • A key quest was to find a location to drill ancient ice – ice made from snow that has accumulated over a million years
  • The oldest ice drilled so far comes from a location known as Dome C. It records climate conditions 800,000 years into the past

The discovery also has implications for the search for ancient ice.

Scientists are looking for a location to drill accumulated snow layers, because bubbles trapped in the layers retain information about the climate at the time of precipitation.

Currently, the oldest ice core climate record in the Antarctic extends back about 800,000 years.

Potentially, a core drilled from around Dome A could find ice that was laid down more than a million years ago.

The latest data could have a positive or a negative bearing on that search, said Dr Tom Jordan from the British Antarctic Survey.

“The new process we’re observing suggests old ice could be pushed up towards the surface, which could make this very old ice that would give you a very long climate record much more accessible,” he told BBC News.

“So instead of having to drill a three-kilometre core, the record might have been pushed to within a kilometre of the surface.

“That’s the good news; but it’s balanced against the recognition that in these places where we’ve found these structures, we may also be getting significant melting, deformation and destruction of ice sheet records.

“We’ll have to choose a drill site very carefully; we can’t just throw a dart in a board.”

The Gamburtsev survey was a flagship expedition for International Polar Year (IPY), comprising scientists, engineers, pilots and support staff from the US, the UK, Germany, Australia, China and Japan.

The team established two field camps from which to mount the airborne campaign.

As well as the ice-penetrating radar, other instruments measured the local gravitational and magnetic fields.

Some 120,000km were flown in total, the equivalent of three trips around the globe.

More than 20% of the East Antarctic Ice Sheet was explored.

Jonathan.Amos-INTERNET@bbc.co.uk

Changes in Consistency of Snow Causes Problems for Reindeer Herders in Scandinavia


Tuesday, 23 November 2010 10:56 Written by Jonni Skoglund, Sámiradio
Original article here

The consistency of snow has changed over the last twenty years. Observations at the Abisko Scientific Research Station in northern Sweden show that today’s snow contains more ice than before. This has created problems for reindeer owners, among others.

Alf Johansen, reindeer herder in Finnmark in north Norway is forced to feed his reindeer more often now to survive the winter. He points to two leading causes: stronger winds that create hard-packed snowdrifts which destroy the grazing land and mild periods in winter.

“Periods of mild temperatures combined with frost create ice. We know what that means. The reindeer will not graze,” Johansen says.

The consistency of snow has been measured at the Abisko Scientific Research Station since the 1960s. Researchers at Uppsala University have analysed the material and the results show that the amount of ice in the snow has increased from five to ten per cent.

“There are more layers of ice in the snow and we see in particular that the ice on the ground surface has increased considerably,” remarks Cecilia Johansson, meteorologist at Uppsala University.

The Uppsala scientists believe that this is because the average annual temperature has increased. “Winter temperatures are rising and this enables ice layers to form in the snow,” explains Cecilia Johansson.

For reindeer herder Alf Johansen this is disastrous. “Ice forms on the ground in periods with a milder temperature and this causes the reindeer to stop grazing.”

Arctic sea ice thinnest in thousands of years

The Economic Times, WASHINGTON: Arctic sea ice is at its record low in the recent geologic history, a major international study has claimed. The first comprehensive history of Arctic ice, carried out by a team of scientists from five countries, found that the recent retreat is the worst in thousands of years.

“The ice loss that we see today — the ice loss that started in the early 20th Century and sped up during the last 30 years — appears to be unmatched over at least the last few thousand years,” said Leonid Polyak, a research scientist at Byrd Polar Research Center at Ohio State University. Polyak is lead author of the research paper which will be published in the upcoming issue of Quarternary Science Reviews.

The sea ice that normally covers huge swaths of the Arctic Ocean has been retreating and thinning over the last few decades, due to the amplified warming at the North Pole, which is a consequence of the buildup of greenhouse gases in Earth’s atmosphere.
The most dramatic sea-ice melt in recent years came in 2007, when sea-ice extent (or the area of ocean covered by the ice) dropped to its lowest level since 1979, when satellite measurements began.

For decades, scientists have strived to collect sediment cores from the difficult-to-access Arctic Ocean floor, to discover what the Arctic was like in the past. Their most recent goal: to bring a long-term perspective to the ice loss we see today.

Now, the team led by Ohio State University has re-examined the data from past and ongoing studies — nearly 300 in all — and combined them to form a big-picture view of the pole’s climate history stretching back millions of years, the university said.

Satellites can provide detailed measures of how much ice is covering the pole right now, but sediment cores are like fossils of the ocean’s history, said Polyak.

To review and combine the data from hundreds of studies, he and his cohorts had to combine information on many different proxies as well as modern observations.

Their conclusion: the current extent of Arctic ice is at its lowest point for at least the last few thousand years. During the summer of 2011, they hope to draw cores from beneath the Chukchi Sea, just north of the Bering Strait between Alaska and Siberia, which can provide a detailed history of interaction between oceanic currents and ice.

Original article here

Hillary Clinton spreads Arctic chill

Rebukes Canada for leaving 3 countries off summit invitation list at time when ‘we need all hands on deck’; ice return seen as blip.
Gary Park
For Petroleum News

Hillary Clinton eating ice cream

Arctic sea ice has returned to average 1979-2000 levels for the first time in a decade after years of alarming shrinkage, according to the National Snow and Ice Data Center in Boulder, Colo.
The expansion at a time of year when ice is normally melting was accompanied by a severe chill emanating from U.S. Secretary of State Hillary Clinton when she left a summit of Arctic coastal countries in Gatineau, Quebec.
She delivered what was characterized as a “smack-down” to Canada for not extending summit invitations to all of those with “legitimate interests in the region.”
And she hammered home the rebuke by shunning a news conference that ended the one-day meeting of foreign ministers from the U.S., Canada, Russia, Norway and Denmark.
In Clinton’s view, Sweden, Finland and Iceland — all members of the eight-nation Arctic Council along with Inuit indigenous groups — and the region’s indigenous peoples should have participated in the discussions.
“I hope the Arctic will always showcase our ability to work together, not create new divisions,” she said. “We need to have all hands on deck because there is a huge amount to do and not much time to do it.
“What happens in the Arctic will have broad consequences of the earth and its climate. The melting of sea ice, glaciers and permafrost will affect people and ecosystems around the world,” Clinton said.
“Understanding how these changes fit together is a task that demands international cooperation.”

Shoreline state solidarity

Canadian Foreign Minister Lawrence Cannon said the summit was intended to build solidarity among the five shoreline states and underscore their “unique” position as chief guardian’s of the region’s environment.
The tensions among the Group of Five were evident prior to the summit when Norway’s Foreign Minister Jonas Gahr Store, who said Russia is “not yet a stable, reliable, predictable state,” while stressing Norway’s desire to build a trusting, cooperative relationship with Russia on Arctic issues.
He said it was “unhelpful” that Russian President Dmitry Medvedev recently declared it “absolutely inadmissible” for other countries to try to “limit Russia’s access” to northern resources.
Medvedev’s remarks were interpreted as a poke at European Union efforts to become a bigger player in setting environmental regulations in Arctic waters as melting sea ice opened the way to increased northern shipping and petroleum exploration.
Store said that, unlike Canada’s “well-managed” Arctic territorial disputes with Denmark and the United States, Norway was trying to resolve a boundary dispute in a potentially oil-rich portion of the Barents Sea with Russia, when that country was still grappling with its transition from a totalitarian state to a democratic nation.
He mused that some experts say Russia is “lost in transition.”
But, like Clinton, Store acknowledged it was “not a good thing” to exclude Sweden, Finland and Iceland from the talks, although he argued the five participants have a special geographic status.

Protestors oppose drilling
Protesters from various organizations, including Greenpeace, urged participants in the summit to avoid a scramble to launch offshore drilling, arguing Arctic mineral resources should remain untouched.
Michael Byers, a professor of politics at the University of British Columbia, said the “three worst emitters of carbon dioxide on the planet — the United States, Canada and Russia — are around the table talking about a region of the world that is at the epicenter of climate change impact.”
The summit reached no significant agreements, with participants confining themselves to discussing “issues that relate to the continental mapping that fall under the United Nations Convention Law of the Seas.”
That extended to talk about creating mandatory shipping regulations, settling maritime boundaries, establishing search and rescue protocols and negotiating territorial disputes in the Beaufort Sea and Barents Sea.
Meanwhile, the Colorado snow and ice data center, which publishes monthly sea-ice updates, does not view the sea ice comeback as “the end of global warming,” said spokesman Mark Serreze.
He said a few weeks of cold weather in one part of the Arctic had distorted the overall numbers.
Serreze said “all of the action is in the Bering Sea … (causing) a late spurt in ice growth,” while the rest of the Arctic Ocean is experiencing “very warm” temperatures.
He also cautioned that satellite data used to develop the center’s information offers no information on ice thickness, suggesting most of the recent Bering Sea ice is likely very thin and won’t last.

Original article here

Submerged Antarctic Lakes Within Reach

Three teams are drilling at separate locations

By Tudor Vieru, Science Editor March 24th, 2010, 08:04 GMT
Original article here

Millions of years ago, as Antarctica was covered by plains and mountains, not ice, lakes adorned its surface, as they do on all other continents. As the weather cooled, and ice began to form, the majority of these lakes solidified, and became a part of the thick ice sheet currently covering the Southern Continent. But a small part of these lakes endured. They were covered by a cap of ice, on which miles of other ice deposited itself. Now, researchers are drilling to get to them, for several different reasons, Nature News reports.

The most important is life. With millions of years gone since the microorganisms in these underground lakes had any contact with the outside world, biologists hypothesize that they changed considerably. Finding out how life can evolve within such tightly-closed ecosystems is of tremendous importance for space exploration, among others. If bacteria, microbes and viruses can endure in the freezing, oxygen-free conditions of submerged lakes, then it shouldn’t be too far-fetched to believe that the same can happen in the covered ocean of Enceladus, or in the liquid hydrocarbon lakes of Titan.

Using advanced observations methods, geologists and other experts were able to observe the contours of these lakes even through the miles of ice covering them, and have set up experiments to get to them. Three nations are currently engaged in this type of efforts. At a joint meeting they held last week, researchers from the United Kingdom, the United States, and the Russian Federations, described the progress they registered in their drills this far. They also exposed their plans on how to handle this delicate task. All experts involved underlined the fact that breaching the surface of these lakes would need to be conducted in an environment as sterile as an operating room.

Any small contaminants from the outside world could change the ecosystem in a matter of minutes, and so this needs to be avoided at all costs. Still the curiosity to explore the world’s last unknown ecosystem is very great. Experts say that these subglacial lakes will be reached next year, as the technology needed to avoid contamination will be produced, delivered to Antarctica, installed, and then operated. Though three groups are working on this type of exploration, there are at least 150 underground lakes under the ices, all of them identified as having various ages and sizes. They will most likely constitute a target for future investigations.

Teams set for first taste of Antarctic lakes
Samples could reveal unique life forms from beneath the ice.

Quirin Schiermeier

The pitch-black lakes hidden beneath Antarctica’s ice sheet will finally start to release their secrets next year. At a meeting last week, scientists from Russia, the United Kingdom and the United States described their plans to explore the planet’s last uncharted ecosystems by drilling into three very different examples of these subglacial lakes.

Over the past 40 years, radar imagery has revealed around 150 freshwater lakes of various sizes and ages beneath the massive Antarctic ice sheet. Some have been isolated from the outside world for millions of years, raising the possibility that they hold unique life forms. The dark, nutrient-deprived environment of the lakes could resemble conditions on Jupiter’s moon Europa, which is assumed to hold a large ocean beneath its frozen surface.

Scientists have longed to draw samples from the lakes, but technical problems and environmental concerns have slowed their progress. Now, the Russian team expects to reach its quarry, Lake Vostok, by February 2011. The Americans and British will follow several years later with forays into lakes with different hydrological and geological characteristics (see graphic).

“Over the next few years we’ll be able to explore a continental-scale ecosystem that has never before been sampled,” says Robin Bell, a senior researcher at Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York. “This is a madly exciting endeavour.”

Lake Vostok is the best known and largest of the subglacial lakes, measuring roughly the size of Lake Ontario. Buried beneath almost 4,000 metres of ice in eastern Antarctica, the lake is thought to be 35 million years old and could host ancient microbial life.

Russian drillers had planned to penetrate the lake in the 2008–09 Antarctic field season, but their drill got stuck 80 metres above the lake surface. All technical problems have been resolved during the past field season, says Valery Lukin, director of the Russian Antarctic programme, who spoke at the meeting, held by the American Geophysical Union in Baltimore, Maryland.

Some researchers worry that a Russian success could come at the cost of biological and chemical contamination of the pristine waters. “Let’s hope they don’t spoil the lake,” says Robert Bindschadler, a glaciologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Lukin says that his country’s team has come up with plans to safeguard Lake Vostok. The team will cut through the ice using a heated drill, with non-toxic silicone oil serving as the lubricating fluid. It will also explore the lake in stages; at first it will only suck up a water sample before allowing the bottom of the hole to refreeze. Plans for lowering instruments into the lake to explore the bottom sediment will be postponed until an extra environmental assessment has been completed.

The Antarctic Treaty’s committee for environmental protection is expected to approve the Russian plans in October, although there is no official requirement for the team to wait until then. “The Russians are trying very hard to do it right, and that means a lot,” says Bell.

At the meeting, US and British researchers described their longer-term plans for exploring subglacial lakes on the opposite side of the pole. Lake Ellsworth, a relatively small lake in western Antarctica, is the target for researchers from the British Antarctic Survey. And over the next two field seasons, US researchers will conduct radar surveys from the surface to study Lake Whillans near Antarctica’s Ross Ice Shelf, says Ross Powell, a geologist at Northern Illinois University in DeKalb. The US$20-million Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project, which Powell oversees, plans to drill into the lake during the 2012–13 field season.

Lake Whillans has a subsurface connection with the ocean beneath the ice shelf, making it more dynamic than isolated lakes such as Vostok. “We know that the lake surface is constantly falling and rising, and we assume the lake is occasionally draining and refilling completely,” says Powell.

The ebb and flow of lakes such as Whillans are thought to influence
the movement of the overlying ice sheet. The WISSARD team will study
processes at the interface of ice and water that affect the movement.

With so many drilling projects, “it’s like going fishing in the
Everglades, in the Rocky Mountains and in Northern Canada”, says Bell.
“The catch will be very different and we’re going to learn a lot.”

Interactive map of the Antarctic: browse and download recent satellite images


British Antarctic Survey

As the Antarctic field season continues with the usual mix of exciting research programmes new enhancements to the online satellite image system that improves ship safety and efficiency are launched.
The Polar View sea ice service, coordinated by the British Antarctic Survey, has greatly improved the service for the 2009/2010 Antarctic season. A combination of easier access through the new website and a significant increase in the number of images available means more real time sea ice information. The range of users of this service continues to expand, encompassing everything from science vessels to tour ships to those coordinating rescue efforts.

The new website (www.polarview.aq) now provides an interactive map displaying the latest imagery and sea ice information. Simple tools allow users to zoom into their area of interest and see recent cloud free satellite imagery from the European Space Agency. In combination with other information provided by partners in Denmark and Germany, anyone can access an up to date picture of current sea ice conditions, even on ships with limited internet access.

Thanks to the frequent satellite images being acquired for the European MyOcean project, users of the Polar View service benefit from refreshed sea ice information at least every three days. Keep an eye on the website for updates about new services in the pipeline. As well as easier access to sea ice drift information and iceberg locations, the Norwegian Meteorological Institute will shortly begin delivery of interpreted ice charts. All of which make for a more comprehensive sea ice service.

http://www.antarctica.ac.uk/by British Antarctic Survey   5:26 AM Wed 10 Feb 2010 GMT

Original article here