Wednesday, September 23, 2009

I have read that the ice sheets of Antartica are melting at an alarming rate even faster then the scientists had knowledge of.

The most detailed satellite information available shows that ice sheets in Greenland and western Antarctica are shrinking faster than scientists thought and in some places are already in runaway melt mode, a new study found.

"Dynamic thinning of Greenland and Antarctic ice-sheet ocean margins is more sensitive, pervasive, enduring and important than previously realized," researchers wrote in the paper published online Wednesday in the peer-reviewed journal Nature.

Using 50 million laser readings from a NASA satellite, scientists for the first time calculated changes in the height of the vulnerable but massive ice sheets and found them especially worse at their edges. That's where warmer water eats away from below. In some parts of Antarctica, ice sheets have been losing 30 feet a year in thickness since 2003, according to the study.

Sunday, February 15, 2009

മേല്റ്റ് Down

Polar Ice Cap
Scientists and engineers at the University of Kansas are applying their expertise to develop and utilize innovative radar and robotic rovers to measure ice thickness and determine bedrock conditions below the ice sheets in Greenland and Antarctica. They are doing this through the auspices of a grant from the National Science Foundation (NSF) and NASA. This grant has been named PRISM (Polar Radar for Ice Sheet Measurements).

The Reason
The data collected and the technology developed will enable researchers to do three things: a) determine the presence or absence of a film of water between the ice and the bedrock; b) measure ice thickness and c) map internal layers in both shallow and deep ice. The measurement of water at the bedrock level (basal water) is important because basal water lubricates the ice/bedrock interface and makes it easier for the ice to flow toward the ocean. Data on near-surface internal ice layers will be used to estimate the average, recent accumulation rate, while the deeper layers provide a history of past snow accumulation and flow rates. This combination of data will help earth scientists determine more unambiguously how quickly the polar ice sheets are melting and to make more accurate predictions of the effects of this melting on sea level rise. Scientists have postulated that excess water is being released from polar ice sheets due to long-term, global climate change; but there are insufficient data to confirm these theories. Understanding the interactions between the ice sheets, oceans, and atmosphere is essential to quantifying the role of ice sheets in sea level rise. This, in turn, allows earth scientists to more accurately predict the probability of significant sea level rise. A significant sea level rise would have a devastating impact on world population, agriculture, and ecosystems since nearly 60% of the world's population lives in coastal regions which would become flooded.

The Plan
PRISM scientists plan to use synthetic aperture radar carried on ground level rovers to map the polar ice sheets and the bedrock. Ground-level radar of this type will provide a 2-D picture and more details than have previously been available from satellite imagery and airborne SAR radar. This radar will be able to operate in either monostatic or bistatic mode in order to produce the detail needed by glaciologists. Much of this project will focus on developing new technologies needed to carry out the project. These new technologies include development of an "intelligent" and "collaborative" radar system; that is, one that can look at the data it is generating in real-time, determine if these data indicate that an area should be studied in more detail and then send that information to another radar system which is taking similar measurements only a few kilometers away. PRISM engineers also need to design and build a semiautonomous ground rover capable of: a) withstanding the rigors of the polar environment, b) towing the radar safely and accurately, c) providing power for the radar systems and data analysis systems as well as the rover, and d) keeping track of the exact position of the radar units at all times. PRISM scientists will also be developing a wireless communication system that operates in harsh polar environments to allow the rover and radars to communicate with one another as well as transmit near-real-time data back to other researchers and educators in distant locations.

Additional Aspects
This project also has a strong public outreach and educational program designed for educators and students through alliances with staff from Haskell Indian Nations University and ALTEC (Advanced Learning Technologies). The K-12 outreach will provide educators and students with quick access to educational resources related to: a) polar regions and their inhabitants; b) global weather and climatic change; c) radar; and d) robotics. There will also be near-real-time broadcasts of data from the field. Haskell students and faculty will work with the project by analyzing the data provided by PRISM field teams and transforming the data into maps more easily understood by the general public.

"A great area of snow, ice, and occasional rock which goes on forever with little else besides the wearying wind!

What we call the Antarctic continent is a circular pancake of ice more than 2000 miles across, centred directly over the South Pole and mainly resting on rock. The continental ice sheet as it is called is built up by falling snow, only a very little, about 4 inches a year in the centre but hardly any of it ever melts. Much more seems to fall near the coasts but an unknown amount is also wind-blown drift. Water vapour drifts in from the north very high up as ice crystals which shimmer in the sun and form strange green and pink "mother of pearl" clouds. Even on the calmest and sunniest of days ice crystals glitter as they softly fall, but occasionally it snows quite hard if a patch of wet air drifts in from over the sea. As compacted ice, it slowly flows outwards a few inches or feet a year until it reached the warmer sea at about latitude 75ºS where it melts.

Up on the Ice Cap at 10,000 ft. 15 knot SW wind, T about -10F, a little drift, quite good surface, fast travelling. Xmas Day, 1957.

In the middle, the ice cap is up to about 12,000ft thick, and it mainly rests on rock which may be above or below present sea level. Near the Russian Station of Vostok, deep under thousands of feet of ice, in a valley there is a large freshwater lake, where the geothermal heat-flow from below must be greater than the heat-loss through the ice-blanket above it.

Rock can only be seen around the edges or in the Victoria Mountains, a great chain of icy peaks up to 15,000 ft high that extend for 2000 miles across the continent for Cape Adare to Queen Maud Land, virtually cutting the continent in half. Even higher mountains pierce the ice cap in the Pacific ocean sector.

The Royal Society Range (part of the Victoria chain) as seen from McMurdo Sound. Mt Lister is 13,000ft.

The Ross Sea Dependency

This is a wedged shaped sector between longitude 160E and 140W. It includes the Ross Sea and McMurdo Sound where the sea extends further south than at any other point. Most of the early exploration of the Antarctic by Sir James Clarke Ross and by Borshgrevink, Scott, Shackleton, Scott again, Amundsen, Byrd, Hillary and Fuchs took place here. It is also the site of two major bases, and an airfield on a floating ice runway. The Ross Sea has the mountains on the western side, has most of the scenery, almost all of the ice-free land and a goodly portion of the whales, seals, penguins. Apart from Graham Land, also called the Antarctic Peninsula over on the other side, the rest of Antarctica is pretty boring, OK if you like flying over a thousand miles of glaring ice with perhaps a green crevasse showing up once an hour, but nothing what you would call stirring. Below are some of the more interesting features found in the Ross Dependency. It was originally claimed by Britain, but they rather lost interest in it and New Zealand inherited it, hence our presence.

Greenland in parts has some similarities but apart from that our Antarctic sector is like no place on Earth. If you stand on the South Pole, all directions no matter which way you look, are north and there few place on Earth where you can do THAT. From 4 to 6 months of the year there is no sun and for two weeks of each month there is no moon, only star light. However if you go outside in winter you may be lucky and have some extra light from the aurora which flashes red and green patches and beams of light about in the sky. It is caused by charged particles from the sun, attracted into the ionoshere and swept tpwards the magnetic pole which lies over near Adelie Land.

In McMurdo Sound there is only one tide a day for two weeks of each month, in the summer if the sun is to the south you know it is midnight. The volcano Mt Erebus mainly steams away quietly but may send up a few puffs and bangs. Forty years ago there was a geyser on the north slopes which blew out a fifty foot high jet of boiling water every half hour but it seems to have quietened down. Some volcanoes stand up 10-13,000 feet, others are almost buried in ice.

Out in the Sound, you may see a few whales diving, while seals lie on the ice edge sunbathing, a few Adelie penguins may walk over and look you up and down, ice flows moved by the tide grind softly and make a "Shhhh" noise but otherwise it is pretty quiet. I once heard a "boom" as an avalanche fell, and apart from the odd howl or bark from a husky, it was the only sound heard in four months. Away from the bases you may go pretty much where your feet can take you, no one has ever charged us for camping and no one sent bills. The climate varies from "Unbearable", (above 32º Fahrenheit); "Warm", (down to zero) to "Cool", (zero to -40ºF below). Fifty below is getting too cool altogether but it only occurs in winter. At -70º, they tell me your words freeze into ice and they may break when they hit the ground but I have never seen it actually happen.

There is a ski-tow, and holes in the ice for scuba-diving, though you need a pretty good dry-suit. There are no mosquitoes, snakes, bears or black flies and no one has been eaten by a sea-leopard for a long time. There is no salt on the roads, it never rains, there are no trees to block the view and grass never needs mowing. Altogether an OK place.

Do Scientists really know what causes Global Warming?

Wait, now pollution is preventing global warming? That’s the conclusion of a recent study in the journal Geophysical Research Letters, which says rising temperatures seen in Europe over the last few years result as much from the reduction of air pollution as from the creation of it. The research, which looked at the effects of aerosols on climate, confirms an older concept known as global dimming, and complicates our understanding of how mankind affects the climate.

According to the study, temperatures in Europe have risen over the past 28 years far faster than could be explained by the greenhouse effect alone. After looking at the aerosol concentrations in the atmosphere in six spots, the authors of the paper realized the temperature rise was assisted by more sunlight penetrating the newly pollution free skies. It seems that the stricter pollution standards, adopted in part to slow global warming, may have sped it up.

The idea that pollution may be reflecting some of the sun’s energy is not new. The term global dimming is decades old, and some believed that the reduction in pollution was the cause global warming. But now, with the link between greenhouse gas pollution and global warming firmly established, papers like this one highlight how complex the situation is, and how solutions like simply cutting air pollution may have a range of unintended and counterintuitive consequences