Average changes in ice thickness in centimeters per year from 2003 to 2010, as measured by NASA’s Grace satellites, in each of the world’s ice caps and glacier systems outside of Greenland and Antarctica. Blue represents ice mass loss, while red represents ice mass gain. NASA/JPL-Caltech/University of Colorado
By JOANNA M. FOSTER February 8, 2012, 3:42 pm
Melting glaciers and ice caps are perhaps the most striking illustrations of the effects of global climate change. Surprisingly, however, there is relatively little data on just how fast the ice is disappearing.
Now, a new paper [ http://www.nature.com/nature/journal/vaop/ncurrent/full/nature10847.html ] from researchers at the University of Colorado, Boulder offers the most up-to-date and comprehensive numbers on glacier and ice cap melt worldwide. The research, published in the journal Nature [ http://www.nature.com/nature/index.html ], calculates that from 2003 to 2010, the world’s glaciers and ice caps lost about 150 billion tons of ice each year. This ice loss was responsible for an average rise of four-tenths of a millimeter in sea level every year over the eight-study period.
The new numbers come from measurements made by the two Gravity Recovery and Climate Experiment satellites, or Grace [ http://science.nasa.gov/missions/grace/ ], a joint project of NASA and German scientists. The tandem satellites, which are usually 137 miles apart, are sensitive to regional changes in the Earth’s mass and gravitational pull caused by the distribution of water and ice on the planet.
When the lead satellite flies over an area of increased mass, it will sense the increase in gravity and pull slightly away [ http://www.csr.utexas.edu/grace/publications/flyer/GRACEflyer0612a.pdf ] from the trailing satellite. Researchers can detect changes of just one micron changes between the two satellites, giving them new insights into the dynamics of the Earth’s aquifers and glaciers.
While the loss from glaciers and ice caps certainly isn’t trifling, over the same time period, Antarctica and Greenland and their peripheral glaciers and ice caps lost about 385 billion tons of ice annually.
John Wahr [ http://cires.colorado.edu/people/wahr/ ], a professor of physics who helped lead the study, said the results provided an important baseline, although he cautioned that there were so many variables at play that the next eight years could look very different than the past eight years.
“Eight years of data is great, but it’s still hard to see any kind of trend or to say whether ice loss is accelerating,” Dr. Wahr said. “All I can say is that we have a better sense of the current state of the cryosphere,” or frozen regions of the planet.
Eric Rignot [ http://www.faculty.uci.edu/profile.cfm?faculty_id=5467 ], a professor of earth systems science at the University of California, Irvine who was not involved in the study, said the research was noteworthy because it was the first time that researchers were able to use the same technique to gather measurements of all of the world’s glaciers and ice caps.
“All the studies done in the past were based on just a few data points from the few accessible glaciers in the world where you can do ground-based analysis,” he said. “We were using data from 120 glaciers to extrapolate for about 160,000 different sites.”
Scientists are hopeful that the Grace satellites, which were launched in 2002 on what was expected to be a mission of just three years, will keep orbiting for at least a few more years and that funding can be assured for a follow-up mission to be launched at the end of 2016.
“I hope these kinds of studies provide the incentive to ensure that there is no gap in the Grace coverage of the Earth,” Dr. Rignot said.
While the contribution of melting glaciers and ice caps to sea-level rise may be dwarfed by the potentially catastrophic melt of Greenland and Antarctica, their loss will affect the water supplies of billions of people worldwide.
This image shows a scanning electron micrograph of very small (about 0.2 micron) and numerous bacterial cells found inhabiting icy brine channels in Antarctica's Lake Vida, which lies in the Victoria Valley, one of the northernmost of the Antarctic dry valleys. CREDIT: Christian H. Fritsen, DRI Research Professor, and Clinton Davis DRI graduate student [ http://www.ouramazingplanet.com/3809-ancient-antarctic-microbes-found.html ]
Diverse microbial life may use different strategies to survive in Lake Vida's freezing and hostile Antarctic waters. Bernd Wagner, University of Cologne, Germany
Lake Vida's cold brine has yielded a bounty of microbes.
Quirin Schiermeier 26 November 2012
It is permanently covered by a massive cap of ice up to 27 metres thick, is six times saltier than normal sea water, and at -13 °C is one of the coldest aquatic environments on Earth — yet Lake Vida in Antarctica teems with life.
Scientists drilling into the lake have found abundant and diverse bacteria. “Lake Vida is not a nice place to make a living in,” says Peter Doran, an Earth scientist from the University of Illinois at Chicago and a member of the team that has been exploring the lake — the largest of a number of small bodies of water in the McMurdo Dry Valleys Antarctic desert. “It is quite remarkable that something wants to live in that cold, dark and salty environment at all.”
Doran and his colleagues have drilled into Lake Vida twice: once in 2005 and again in 2010. The remarkable array of microbial life that they found is described today in Proceedings of the National Academy of Sciences [ http://www.pnas.org/content/early/2012/11/21/1208607109 ].
Water samples from both trips yielded around one-tenth of the abundance of cells usually found in freshwater lakes in moderate climate zones. Some of the cells measured up to 1 micrometre in diameter — about normal for microbes — but the samples contained many more particles that were around 0.2 micrometres in diameter.
Neither cell type represents a previously unknown life form, says Alison Murray, a microbial environmentalist at the Desert Research Institute in Reno, Nevada, and a co-author of the paper. Genetic analysis suggests that most of the cells — both those of standard size and the microcells — are related to known types of bacterium. However, one abundant bacterium of normal size seems to have no close relatives among cultivated bacteria, and so may represent a new phylum.
Exotic energy sources
The team has not yet worked out how the bacteria produce energy. They might emulate many known bacteria by living solely on dissolved organic carbon; or they might use more exotic forms of energy, as do some other microbes living in extreme environments. For example, bacteria in deep gold mines are known to survive on molecular hydrogen produced by chemical reactions in the rocks.
“For sure, there is a lot of energy in the brine,” says Murray. “Carbon may be the primary energy source, but hydrogen may be vital to sustain the lake’s microbial life in the long-term.”
The ice cap over the lake grows upwards as melt water from surrounding glaciers flows over the ice and refreezes. Isotope analysis of organic carbon particles in the ice suggests that the lake has been sealed for around 2,800 years, so any carbon in the brine must have been there for at least that long and there probably isn't very much of it — suggesting that the microbes may be using something else to produce energy.
Because they are isolated and there are no predators in the lake, says Murray, the cells might have switched to a biologically reduced ‘survival mode’ — without cell division and reproduction — that allows them to endure stress and harsh environments for a long time.
Under other ice
Lake Vida is an exceptional environment: because it is ice-sealed, it is likely to be very different in terms of geochemistry and biology from Antarctica's numerous subglacial rivers and lakes, which have been under several-kilometre-thick parent ice for millions of years. But efforts are under way to sample three subglacial lakes in various parts of the frozen continent.
Over the next two months, British, US and Russian teams plan to drill into and probe lakes Ellsworth, Whillans and Vostok. These waters may yield clues as to what conditions are needed to support life on Earth and other planets, the teams hope (see 'Hunt for life under Antarctic ice heats up').
Although Lake Vida has not been isolated for nearly as long as the subglacial lakes, the discovery of diverse microbial life below its ice is significant in its own right, says Martin Siegert, a glaciologist at the University of Bristol, UK, who is leading the British Antarctic Survey’s expedition to Lake Ellsworth.
“It is another extreme place where life is found and it provides evidence of a different set of boundary conditions in which life can exist,” he says. “Lake Vida’s extreme saltiness, too, marks a likely difference — although in truth we'll only know that for sure next month.”
.. a real story of man against weather, hope it is the one i saw awhile ago today ..
South Pole Superstructure 2:00pm - 3:00pm
Classified: G Genre: Documentary
Temperatures hover around -50 degrees on this massive construction site. Steel tools shatter, extension cords snap like twigs, hydraulic fluid turns to ice and human flesh freezes within seconds. With only 110 days left in this massive eight-year project, time is short and the elements unpredictable. .. http://au.tv.yahoo.com/tv-guide/73/0/0/13/
.. guarantee it's well worth a relaxed watch .. lol, that's one which ticks on at just the right speed ..
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