Archive for the ‘Antarctica’ Category

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One of the big environmental stories of 2012 was the record melting of sea ice in the Arctic, which reached its smallest extent this summer since satellite data began being kept in the late 1970s. But it’s not the Arctic alone that’s reacting to manmade climate change by transforming into a large puddle. On the other end of the Earth, the continent of Antarctica contains enough ice to swamp just about every coastal city on the planet were it all to melt. The Arctic is transforming before our eyes, but it’s changes in Antarctica that could make Waterworld into a documentary.

That day is still in the distant future—in fact, sea ice in Antarctica has actually increased in recent years, as more powerful northward winds refreeze ice on the continent. But as a new study published in Nature Geoscience shows, temperatures are on the increase in the massive West Antarctica Ice Sheet (WAIS)—and so is melting.

Using data from Byrd Station, a scientific outpost in West Antarctica, researchers from Ohio State University and other institutions have report that average annual temperatures in the region have risen by 2.4 C (4.3 F) since 1958. That’s nearly twice as much warming as had been previously estimated, and the data shows for the first time an increase in warming trends during the summer. The timing of the temperature increase is particularly alarming because while temperatures in Antarctica remain well below freezing for nearly the entire year, the Antarctic summer is when any melting is likely to occur—just as it does in the Arctic.

As lead author David Bromwich put it in a statement:

Our record suggests that continued summer warming in West Antarctica could upset the surface mass balance of the ice sheet, so that the region could make an even bigger contribution to sea level rise than it already does.

Even without generating significant mass loss directly, surface melting on the WAIS could contribute to sea level indirectly, by weakening the West Antarctic ice shelves that restrain the region’s natural ice flow into the ocean.

Today melting from the WAIS adds only a few millimeters to the ongoing global sea level rise. But there is potential for much, much more—if all the ice in the 10 million sq. mile WAIS were to melt, it would be enough to add 3.05 m (10 ft.) to sea levels. To put that in perspective, all the warming the world has experienced since the Industrial Revolution has cause sea levels to rise by a few inches. That’s scary, world-changing stuff.

http://science.time.com/2012/12/24/antarctica-its-getting-hot-at-the-bottom-of-the-planet/?hpt=hp_t3

Thanks to Ray Gaudette for bringing this to the attention of the It’s Interesting community.

 

Ancient microbes have been discovered in bitter-cold brine beneath 60 feet of Antarctic ice, in permanent darkness and subzero temperatures of Antarctica’s Lake Vida, located in the northernmost of the McMurdo Dry Valleys of East Antarctica.

In the current issue of the Proceedings of the National Academy of Sciences, Nathaniel Ostrom, Michigan State University zoologist, has co-authored “Microbial Life at -13ºC in the Brine of an Ice-Sealed Antarctic Lake.” Ostrom was part of a team that discovered an ancient thriving colony, which is estimated to have been isolated for more than 2,800 years living in a brine of more than 20 percent salinity that has high concentrations of ammonia, nitrogen, sulfur and supersaturated nitrous oxide—the highest ever measured in a natural aquatic environment.”It’s an extreme environment – the thickest lake ice on the planet, and the coldest, most stable cryo-environment on Earth,” Ostrom said. “The discovery of this ecosystem gives us insight into other isolated, frozen environments on Earth, but it also gives us a potential model for life on other icy planets that harbor saline deposits and subsurface oceans, such as Jupiter’s moon Europa.”Members of the 2010 Lake Vida expedition team, Dr. Peter Doran (professor, University of Illinois, Chicago), Dr. Chris Fritsen (research professor, Desert Research Institute, Reno, Nev.) and Jay Kyne (an ice driller) use a sidewinder drill inside a secure, sterile tent on the lake’s surface to collect an ice core and brine existing in a voluminous network of channels 16 meters and more below the lake surface. 

On the Earth’s surface, water fuels life. Plants use photosynthesis to derive energy. In contrast, at thermal vents at the ocean bottom, out of reach of the sun’s rays, chemical energy released by hydrothermal processes supports life. Life in Lake Vida lacks sunlight and oxygen. Its high concentrations of hydrogen gas, nitrate, nitrite and nitrous oxide likely provide the chemical energy used to support this novel and isolated microbial ecosystem. The high concentrations of hydrogen and nitrous oxide gases are likely derived from chemical reactions with the surrounding iron-rich rocks.

Consequently, it is likely that the chemical reactions between the anoxic brine and rock provide a source of energy to fuel microbial metabolism. These processes provide new insights into how life may have developed on Earth and function on other planetary bodies, Ostrom said. The research team comprised scientists from the Desert Research Institute (Reno, Nev.), the University of Illinois-Chicago, NASA, the University of Colorado, the Jet Propulsion Laboratory, Montana State University, the University of Georgia, the University of Tasmania and Indiana University.

For more information: “Microbial life at −13 °C in the brine of an ice-sealed Antarctic lake,” by Alison E. Murray et al. PNAS, 2012. http://www.pnas.org/content/early/2012/11/21/1208607109.abstract Journal reference: Proceedings of the National Academy of Sciences.

http://www.dailygalaxy.com/my_weblog/2012/11/ancient-microbial-life-found-thriving-in-permanent-darkness-60-feet-beneath-antarctica-ice.html

 

The Northern Hemisphere’s largest expanses of ice have thawed faster and more extensively this year than scientists have previously recorded. And the summer isn’t over.

Studies suggest that more of the massive Greenland ice cap has melted than at any time since satellite monitoring began 33 years ago, while the Arctic sea’s ice is shrinking to its smallest size in modern times.

“This year’s melting season is a Goliath,” said geophysicist Marco Tedesco, director of the Cryospheric Processes Laboratory at City University of New York. “The ice is being lost at a very strong pace.”

Scientists monitor the annual thaw closely because changes in the ice of the far North can raise sea levels and affect weather throughout the hemisphere by altering wind currents, heat distribution and precipitation.

Shrinkage of the Arctic sea ice since 2006, for instance, helped lead to seasons of severe snow across Europe, China and North America, researchers at Columbia University, the Georgia Institute of Technology and the Chinese Academy of Sciences reported earlier this year.

As the seasonal ice abates more each year, new polar shipping lanes also open up, as do opportunities for mineral exploration. By some estimates, as much as 25% of the world’s oil and natural-gas reserves are under the Arctic seafloor. Russia, Denmark, Norway and Canada are vying to control these assets.

The giant ice cap at the top of the world partly melts every summer and refreezes every winter. In recent years, the thaw has become progressively more extensive, NASA and European satellite observations suggest. At the same, the refreeze has been smaller—adding up to long-term shrinkage in the ice cover.

This year’s unusual summer thaw was spurred partly by natural variations in weather, but also reflected rising levels of heat-trapping carbon dioxide and methane in the air, amplified by carbon soot from widespread wildfires and the burning of fuels, said scientists at Stanford University and the National Snow and Ice Data Center.

Carried north across the Arctic by winds, soot not only darkens snow and ice, making it absorb more heat from sunlight, but also interferes with the formation of clouds that might otherwise providing cooling shade.

“They all cause enhanced warming in the Arctic,” said Stanford University atmospheric scientist Mark Jacobson, who advocates for renewable energy. “Soot can double the warming.”

In many ways, the Arctic ice pack and Greenland ice cap are mirror opposites. The ice pack is a vast layer of frozen salt water, a few yards thick at most, floating atop an open sea, like ice cubes in a highball. Changes in the size of the Arctic ice can alter weather patterns globally, though the melting doesn’t raise sea levels since the ice displaces the same amount of ocean water when frozen as when liquid.

The Greenland ice sheet is a land-based formation of frozen fresh water up to two miles thick. The water runoff from Greenland ice dilutes the salinity of ocean water, changing its density and altering currents. The runoff that doesn’t refreeze adds to rising ocean levels.

Despite their differences, their fates are linked. “There is little doubt that in terms of warming, things are coming together in the Arctic,” said glaciologist Paul Mayewski, director of the Climate Change Institute at the University of Maine. “Without a doubt, warming in the Arctic is very, very strong,”

In fact, more melting occurred across the Greenland ice cap—the world’s second-largest ice sheet after Antarctica—in June and July than in any year since at least 1979, when satellite monitoring of the island’s ice began, Dr. Tedesco and his colleagues reported earlier this month. The Greenland thaw began in May, a month earlier than usual.

On average, about half of the surface of Greenland’s ice sheet naturally melts during the summer, and then mostly refreezes with the approach of winter. This year, nearly the entire ice cover, from its thin, low-lying coastal edges to its two-mile-thick center, experienced some melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists.

“This summer, we have seen melting at the very highest elevations of the Greenland ice sheet, which we have not seen before in the satellite record,” said climatologist Thomas Mote of the University of Georgia, who studies snow cover. Researchers expect much of it to refreeze.

By Wednesday, the Arctic sea ice had shrunk to 1.54 million square miles, about 70,000 square miles smaller than the previous modern low set in September 2007, according to the satellite readings compiled by NASA and the National Snow and Ice Data Center in Boulder, Colo. By that measure, the six lowest Arctic sea ice levels on record all occurred in the past six years.

Even when the Arctic ice refreezes, the new ice is often thinner, making it more vulnerable to storms and seasonal temperature variations, said climate scientist Julienne Stroeve at the Snow and Ice Data Center.

About a week remains in the melt season. Researchers won’t know the full extent of this year’s melting until the end of September.

http://online.wsj.com/article/SB10000872396390444772804577621470127844642.html?mod=googlenews_wsj#articleTabs%3Darticle