|
Thread Rating:
- 8 Votes - 3.75 Average
- 1
- 2
- 3
- 4
- 5
|
Large methane reservoirs suggested beneath Antarctic ice sheet
|
•REC 14877 User ID: 14877 04-05-2012 02:59 PM
Posts: 20,356
|
Large methane reservoirs suggested beneath Antarctic ice sheet
Latest Update: Large methane reservoirs suggested beneath Antarctic ice sheet
http://phys.org/news/2012-08-large-metha...rctic.html
Antarctic Peninsula is warming up rapidly
http://www.msnbc.msn.com/id/48755351/ns/...DVEEKDNnlZ
Thousands of earthquakes occurring in rapid succession under an Antarctic glacier
http://news.discovery.com/earth/antarcti...20820.html
Scientists discover new unstable region the size of New Jersey under Antarctica Ice Sheet
A vast ice shelf in the Antarctic peninsula, a hotspot for global warming, has shrunk by 85 per cent in 17 years, the European Space Agency (ESA) says.
Images taken by its Envisat satellite show that the so-called Larsen B ice shelf decreased from 11,512 square kilometres in 1995 to only 1670 sq km today.
Larsen B is one of three ice shelves that run from north to south along the eastern side of the peninsula, the tongue of land that projects towards South America.
From 1995 to 2002, Larsen B experienced several calving events in which parts of the shelf broke away. It had a major break-up in 2002 when half of the remainder disintegrated.
Larsen A broke up in January 1995.
"Larsen C so far has been stable in area, but satellite observations have shown thinning and an increasing duration of melt events in summer," the agency said.
The northern Antarctic peninsula has been subject to atmospheric warming about 2.5C over the past 50 years, a figure that is several times greater than the global average.
Ice shelves are not the same as ice sheets, the vast blankets of frozen water that cover Antarctica.
If these melted, even partially, they would drive up sea levels, threatening small island states and coastal cities.
But the scientific evidence is that the ice sheets so far are stable.
"These observations are very relevant for measuring the future behaviour of the much larger ice masses of West Antarctica if warming spreads further south," ESA quoted Helmut Rott, a professor at the University of Innsbruck in Austria, as saying.
http://www.news.com.au/breaking-news/vas...z1rAcZhuKl
|
|
|
(This post was last modified: 08-29-2012 07:09 PM by •REC.)
|
|
tethys Registered User User ID: 59284 04-05-2012 03:13 PM
Posts: 6,371
|
RE: Vast ice shelf in Antarctic has shrunk by 85% since 1995
|
|
|
(This post was last modified: 04-05-2012 03:13 PM by tethys.)
|
|
•REC 14877 User ID: 14877 04-05-2012 03:28 PM
Posts: 20,356
|
RE: Vast ice shelf in Antarctic has shrunk by 85% since 1995
Larsen A and Larsen B iceshelves marked in red.
|
|
|
|
tethys Registered User User ID: 59284 04-05-2012 05:37 PM
Posts: 6,371
|
RE: Vast ice shelf in Antarctic has shrunk by 85% since 1995
http://www.hamilton.edu/expeditions/antarctica-2012
2012 Expedition to Antarctica
Prior to the LARISSA project during his 2004 expedition, Domack and his team discovered an underwater volcano in the Antarctic Sound. In 2005, he returned to study the causes of the collapse of the Larsen B ice shelf. This had been the original focus in 2004 when thick ice prevented access to the area. Using an underwater video sled to map the seafloor landscape during the 2005 trip, the team discovered a cold-vent chemotrophic ecosystem.
http://en.wikipedia.org/wiki/Cold_seep
Cold seeps occur over fissures on the seafloor caused by tectonic activity. Oil and methane "seep" out of those fissures, get diffused by sediment, and emerge over an area several hundred meters wide.
The area is volcanic and known to have large earthquakes -
http://earthquake.usgs.gov/earthquakes/r...hp#details
Taking all these factors into consideration it is more probable that the collapse of the ice shelves are due to volcanic activity also very large earthquakes which generate tsunamis are known to break off ice bergs.
http://www.nasa.gov/topics/earth/feature...bergs.html
Tohoku Tsunami Created Icebergs In Antarctica
|
|
|
(This post was last modified: 04-05-2012 05:41 PM by tethys.)
|
|
•REC 14877 User ID: 14877 04-27-2012 11:53 AM
Posts: 20,356
|
RE: Vast ice shelf in Antarctic has shrunk by 85% since 1995
Antarctic ice melting from below, reveals satellite
Underwater volcanism is also sublimating portions of the Antarctica ice mass from underneath. In 2004, a research team led by Eugene Domack, aboard the research vessel Lawrence M. Gould, made a remarkable discovery of a massive underwater volcano off the coast of Antarctica using a deep water submersible vehicle equipped with a cadre of sensors and video cameras. The volcano was 2300 feet (700 meters) tall. The British team findings confirmed the volcano was still active and was contributing to the melting of the ice sheet from beneath the Antarctica land mass.
http://theextinctionprotocol.wordpress.c...satellite/
http://www.youtube.com/watch?v=08sDlxhNE...el&list=UL
|
|
|
(This post was last modified: 08-22-2012 11:22 PM by •REC.)
|
|
•REC 14877 User ID: 14877 05-09-2012 08:16 PM
Posts: 20,356
|
RE: Vast ice shelf in Antarctic has shrunk by 85% since 1995
New Antarctic ice shelf threatened by warming
Scientists are predicting the disappearance of another vast ice shelf in Antarctica by the end of the century that will accelerate rising sea levels.
The Filchner-Ronne Ice Shelf fringing the Weddell Sea on the eastern side of Antarctica has so far not seen ice loss from global warming and much of the observation of melting has focused on the western side of the continent around the Amundsen Sea. But new research from the Alfred Wegener Institute for Polar and Marine Research in Germany says the 450,000-sq-km ice shelf is under threat.
"According to our calculations, this protective barrier will disintegrate by the end of this century," said Dr Harmut Hellmer, lead author of the study, published in the journal Nature this week.
The huge ice shelves that float on the seas fringing Antarctica provide a buffer against warming waters eating away at the base of the much larger glaciers behind them that sit on the land.
"Ice shelves are like corks in the bottles for the ice streams behind them," said Hellmer. "They reduce the ice flow.
"If, however, the ice shelves melt from below, they become so thin that the dragging surfaces become smaller and the ice behind them starts to move."
Hellmer and his team predict the melting of the Filchner-Ronne shelf could add up to 4.4 mm per year to rising global sea levels.
According to the latest estimates based on remote sensing data, global sea levels rose 1.5 mm a year between 2003 and 2010 due to melting glaciers and ice shelves, the scientists say. This is on top of an estimated 1.7 mm annual rise due to the expansion of the oceans as the water warms.
Full-
http://www.reuters.com/article/2012/05/0...1E20120509
|
|
|
|
akhenaten Registered User User ID: 78766 05-09-2012 08:30 PM
Posts: 1,265
|
RE: Vast ice shelf in Antarctic has shrunk by 85% since 1995
Ohhhh.I can't believe that I beat Lensman into this thread. LOL
GL comments in t-minus 3....2... 
5* REC....nice read!
User ID: 157962- to "an unlearned man"
"I would guess you have a book case which contains greater than zero but less than two books. "
In a time of universal deceit - telling the truth is a revolutionary act.
George Orwell
|
|
|
(This post was last modified: 05-09-2012 08:30 PM by akhenaten.)
|
|
Thucydides lop guest User ID: 91955 05-09-2012 08:34 PM
|
RE: Vast ice shelf in Antarctic has shrunk by 85% since 1995
Volcanism YES, AGW NO...
|
|
|
|
tethys Registered User User ID: 59284 05-09-2012 08:40 PM
Posts: 6,371
|
RE: Vast ice shelf in Antarctic has shrunk by 85% since 1995
http://en.wikipedia.org/wiki/Pine_Island_Glacier
In January 2008 the British Antarctic Survey (BAS) scientists, Hugh Corr and David Vaughan, reported that 2,200 years ago a volcano erupted under the Antarctic ice sheet. This was the biggest Antarctic eruption in the last 10,000 years. The volcano is situated in the Hudson Mountains, close to Pine Island Glacier.
|
|
|
|
LoP Guest lop guest User ID: 95501 05-09-2012 08:44 PM
|
RE: Vast ice shelf in Antarctic has shrunk by 85% since 1995
|
|
|
|
•REC 14877 User ID: 14877 05-10-2012 09:56 PM
Posts: 20,356
|
RE: Antarctic - Scientists discover new unstable region under Antarctica Ice Sheet
Scientists discover new unstable region the size of New Jersey under Antarctica Ice Sheet
Using ice-penetrating radar instruments flown on aircraft, a team of scientists from the U.S. and U.K. have uncovered a previously unknown sub-glacial basin nearly the size of New Jersey beneath the West Antarctic Ice Sheet (WAIS) near the Weddell Sea.
The location, shape and texture of the mile-deep basin suggest that this region of the ice sheet is at a greater risk of collapse than previously thought.
Team members at The University of Texas at Austin compared data about the newly discovered basin to data they previously collected from other parts of the WAIS that also appear highly vulnerable, including Pine Island Glacier and Thwaites Glacier.
Although the amount of ice stored in the new basin is less than the ice stored in previously studied areas, it might be closer to a tipping point. “If we were to invent a set of conditions conducive to retreat of the West Antarctic Ice Sheet, this would be it,” said Don Blankenship, senior research scientist at The University of Texas at Austin’s Institute for Geophysics and co-author on the new paper.
“With its smooth bed that slopes steeply toward the interior, we could find no other region in West Antarctica more poised for change than this newly discovered basin at the head of the Filchner-Ronne Ice Shelf. The only saving grace is that losing the ice over this new basin would only raise sea level by a small percentage of the several meters that would result if the entire West Antarctic Ice Sheet destabilized.”
“This is a significant discovery in a region of Antarctica that at present we know little about,” said Professor Martin Siegert of the University of Edinburgh, who led the project. “The area is on the brink of change, but it is impossible to predict what the impact of this change might be without further work enabling better understanding of how the West Antarctic Ice Sheet behaves.”
The seaward edge of the newly discovered basin lies just inland of the ice sheet’s grounding line, where streams of ice flowing toward the sea begin to float. Two features of the basin, which is entirely below sea level, are particularly worrisome to scientists: First, like a cereal bowl, its edges slope down steeply. If the grounding line begins to retreat upstream, seawater will replace it and more ice will begin to float.
The study’s authors predict that this positive feedback mechanism would sustain retreat of the ice sheet until eventually all of the ice filling the basin goes afloat. Second, the bed of the basin on which the ice rests is smooth. There are few big bumps, or “pinning points,” to hold back sliding ice. The newly discovered basin covers 20,000 square kilometers (7,700 square miles), nearly the size of New Jersey, and is well below sea level, nearly 2 kilometers (about 1.2 miles) deep in places.
http://www.utexas.edu/news/2012/05/10/ice_sheet/
|
|
|
|
•REC 14877 User ID: 14877 07-25-2012 07:50 PM
Posts: 20,356
|
RE: Antarctic rift 'speeding ice melt'
Antarctic rift 'speeding ice melt'
A rift in the Antarctic rock as deep as the Grand Canyon is increasing ice melt from the continent, researchers say.
A UK team found the Ferrigno rift using ice-penetrating radar, and showed it to be about 1.5km (1 mile) deep.
Antarctica is home to a geological rift system where new crust is being formed, meaning the eastern and western halves of the continent are slowly separating.
The team writes in Nature journal that the canyon is bringing more warm sea water to the ice sheet, hastening melt.
Continued-
http://www.bbc.co.uk/news/science-environment-18959399
|
|
|
|
•REC 14877 User ID: 14877 08-22-2012 10:50 PM
Posts: 20,356
|
RE: Antarctic rift 'speeding ice melt'
Thousands of earthquakes occurring in rapid succession under an Antarctic glacier
• About 20,000 seismic events under David Glacier were stronger and lasted longer than the shaking typically seen with glaciers.
• The earthquakes occurred at regular intervals about 25 minutes apart.
Thousands of earthquakes occurring in rapid succession in less than a year under an Antarctic glacier may have been linked to ocean tides, new research suggests.
Scientists investigated seismic activity under David Glacier, a large glacier in East Antarctica about 270 square miles (700 square kilometers) in size.
To learn more about the foundations and behavior of this glacier, the researchers analyzed seismic data gathered from there over a nine-month period between 2002 and 2003 by the Transantarctic Mountains Seismic Experiment array of 42 seismometers. They identified about 20,000 seismic events during this period that were stronger and lasted longer than the shaking typically seen with glaciers.
"The fact these events exist is fairly surprising," researcher Lucas Zoet, a glaciologist at Pennsylvania State University, told OurAmazingPlanet. "This type of seismic behavior had not been observed before in Antarctic outlet glaciers, so one main challenge was just to categorize it initially."
Cont-
http://news.discovery.com/earth/antarcti...20820.html
|
|
|
|
•REC 14877 User ID: 14877 08-22-2012 10:51 PM
Posts: 20,356
|
RE: Antarctic rift 'speeding ice melt'
Antarctic Peninsula is warming up rapidly
Modern rate is bringing temperatures close to those that followed end of last ice age
The Antarctic Peninsula, which juts out about 1,000 miles (1,610 kilometers) from the western flank of the frozen continent, is one of the fastest warming places on Earth.
In the past 50 years, the air temperature has increased by about 3.6 degrees Fahrenheit (2 degrees Celsius). While this rate of warming is highly unusual, it is not unprecedented, indicates a new study.
The rapid, modern warming is bringing the peninsula's temperatures close to the warmth that followed the end of the last ice age, lead researcher Richard Mulvaney, a paleoclimatologist with the British Antarctic Survey, told LiveScience.
"We are now approaching the temperatures last seen 12,000 years ago," he wrote in an email.
To look back at millennia of temperature history for the peninsula, a research team extracted a 1,200-foot (364-meter) ice core from the summit of an island mountain near the northern tip of the peninsula.
Chemical clues in the sections of ice enabled researchers to reconstruct a record of temperature changes going back about 15,000 years, to a time when the last ice age was coming to an end.
Cont-
http://www.msnbc.msn.com/id/48755351/ns/...DVEEKDNnlZ
|
|
|
(This post was last modified: 08-22-2012 10:55 PM by •REC.)
|
|
tethys Registered User User ID: 59284 08-22-2012 11:10 PM
Posts: 6,371
|
RE: Antarctic Peninsula is warming up rapidly
|
|
|
|
|