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The Rajon Blog » Blog Archive » Antarctic shelves still melting and faster than expected

Antarctic shelves still melting and faster than expected

Global warming is a fact and whether we like it or not the ice mass is being affected and will affect the global sea levels.

All of the major ice shelves have been affected and as these are being affected both from under as well as above especially the sea ice ones then trouble can only be ahead. The ozone hole over the antarctic is also bigger than before so all these conditions add together to form a not very bright future for the area with regards to the ice pack.

18 Responses to “Antarctic shelves still melting and faster than expected”

  1. moryah4 Says:


    Last Updated: 12:01am GMT 26/03/2008

    An ice shelf of 5,000 square miles in western Antarctica has started to collapse, scientists said.
    The disintegration of the Wilkins ice sheet, the largest on the Antarctic Peninsula to be threatened, is more evidence of rapid climate change on the continent, they claimed.
    The British Antarctic Survey said the ice shelf was “hanging by a thread”.
    Satellite images from the US National Snow and Ice Data Centre showed an iceberg measuring 25.5 miles by 1.5 miles - the size of the Isle of Man - broke off last month.
    A large section of the sheet, a broad plate of permanent floating ice around 1,000 miles south of South America, is now held together by a four-mile strip of ice.
    The collapse of the shelf had been predicted, but is happening more quickly than expected, scientists said. It is thought the warming of the atmosphere, which has been happening several times faster on the Antarctic Peninsula than the global average, has melted more surface ice, which is weakening the shelf.
    Prof David Vaughan, of the BAS, said: “I didn’t expect to see things happen this quickly. The ice shelf is hanging by a thread.”

    Although the summer melting period in Antarctica is coming to an end, making it unlikely there will be further collapse before next year, Prof Vaughan said a major storm in the coming days could accelerate the disintegration.
    He added: “Climate warming has pushed the limit of viability for ice shelves further south - setting some of them that used to be stable on a course of retreat. The Wilkins breakout won’t have any effect on sea level because it is floating already but it is another indication of the impact of that climate change.”

  2. moryah4 Says:


    By Andrew Darby,
    (Melbourne Age) Hobart
    October 6, 2008

    THE latest alarming ice shelf collapse in the Antarctic has been caused by a warming Southern Ocean melting the shelf from below.

    The climate-change-induced break-up of the Wilkins Ice Shelf began last February, and has become the only documented collapse to run through the depths of winter.

    At least 1350 square kilometres of ice shelf on the western side of the Antarctic Peninsula has broken off so far, and more is expected to go, say US and European scientists.
    An ice bridge buttressing a large part of the Wilkins against an island off the peninsula is likely to fail soon, taking another 500 square kilometres. The collapse may not halt until the shelf, once 13,680 square kilometres, is at least halved, said Ted Scambos of the US National Snow and Ice Data Centre in Colorado.
    Much of the loss of seven great ice shelves on the vulnerable Antarctic Peninsula has been blamed on surface melting.
    With the area having experienced the world’s greatest regional temperature rise — 2.5 degrees in 50 years — scientists have seen summer melt ponds form on top of ice shelves, before the water falls hundreds of metres through the ice, splitting it apart.
    Dr Scambos said a different culprit had been found in the case of the Wilkins.
    “This is the first time that it’s been observed in a way that’s so clearly attributable to basal melt,” he said.
    The conclusion was reinforced by a team led by the University of Bonn’s Matthias Braun.
    “We show that drainage of melt ponds into crevasses was of no relevance for the break-up at Wilkins,” Dr Braun concluded in the journal Cryosphere.
    He said the ice was over-stressed by buoyancy forces pressing on it from below, breaking open rifts in the shelf.
    Changes in wind patterns further north have meant that, at vulnerable places such as the Wilkins, warmer water is being pushed more vigorously beneath the ice front.
    “The water below the Wilkins was two, three or four degrees above the melting point of sea water,” Dr Scambos said.

  3. moryah4 Says:


    October 6, 2008

    Geo-scientists from the Oregon State University recently analyzed West Antarctic ice core samples taken in the 1960’s and ocean deposits going back 20,000 to 100,000 years ago and found some interesting results, according to Environmental Research letters.

    The ice samples were carefully crushed, releasing gases from bubbles that were frozen within the ice cores. The gas samples were then tested to measure the levels of carbon dioxide (CO2) in each one.

    The geo-scientists then compared the CO2 levels from the samples with climate data from Greenland and Antarctica that reflected the approximate temperatures when the gases were trapped. The samples were also compared with ocean sediments, according to ScienceDaily.

    “The most interesting findings are firstly that atmospheric carbon dioxide is strongly correlated with Antarctic temperature and secondly that it begins to increase a few thousand years prior to large abrupt warming events in Greenland,” researchers Jinho Ahn and Edward Brook told environmentalresearchweb. “We also see some links between increases in carbon dioxide and changes in ocean circulation that might release carbon dioxide from the deep ocean.”

  4. moryah4 Says:

    Patrick Henry:

    The first thing you learn in freshman geology is that warmer seawater can hold less CO2. Thus rising temperatures lead to more CO2 in the atmosphere.


  5. moryah4 Says:

    Kipp Alpert:
    PaulM: A rise in CO2 in our atmosphere means a rise in temperatures.CO2 is a greenhouse gas. It causes Global Warming, not the opposite. Patrick got it right. The warmer the water is, the less CO2 is absorbed. The heat comes back via water vapor and makes the oceans warmer. This is called a positive feed-back loop. On land, and in this article they are looking for the sequence of events, but not the timeline. In 150 years, the earth has become warmer because the CO2 in the atmosphere reacts to heat and the heat cannot escape. So what comes first,the CO2. A thermodynamic anomaly. Please read the IPCC report.It’s good for you! The reason that the Arctic is warming faster is the much larger amount of land in the northern hemisphere. Also The Antarctic Circumpolar Current (ACC) is an ocean current that flows from west to east around Antarctica. This is a dominant circulation pattern around the Antarctic. It keeps the colder water in and doesn’t take in the warmer water of the Southern Ocean. The SO kicks off the El Nino,
    which is the largest oscillation in the world. That comes from the southern ocean to the Pacific, and then the Atlantic and Indian Ocean. There are… many oscillations and circulation patterns..


  6. moryah4 Says:

    Devastation of warmer temperatures encoaches further north in Southern Hemisphere.


    Greg Roberts and Sean Parnell | October 14, 2008

    GLOBAL warming has been blamed for dramatic declines in seabird populations on the Great Barrier Reef and surrounding waters.
    Tens of thousands of seabirds are failing to breed because warmer water from more frequent and intense El Nino events means there is insufficient food to raise their young, according to research compiled by the Great Barrier Reef Marine Park Authority.
    Warm water near the surface forces fish, plankton and other prey into deeper water, where it cannot be reached by seabirds.
    The research forms the basis of a report commissioned by the marine park authority and the Queensland Environment Protection Agency to address the impact of climate change on seabirds, and obtained by The Australian under freedom of information laws. “Recent analyses at key sites have revealed significant declines in populations of some of the most common seabird species, which raises concerns regarding the threatening processes acting on these populations,” says the report, prepared by C&R Consulting.
    The report, Seabirds and Shorebirds in the Great Barrier Reef World Heritage Area in a Changing Climate, says the reef is home to between 1.3 and 1.7million seabirds and half the world’s population of several species.
    The results of research by Bradley Congdon and five other seabird experts working for the marine park authority have been published in another report, Climate Change and the Great Barrier Reef: A Vulnerability Assessment.
    The authors concluded that recent climate fluctuations were having significant detrimental impacts on seabird populations.
    The two reports paint a grim picture of the predicament for seabirds. In the Coral Sea, populations of great and least frigatebirds declined by 6-7 per cent annually between 1992 and 2004.
    Despite a return to more favourable conditions since the severe El Nino event of 1997-98, populations have not recovered.
    On Raine Island, in the northern barrier reef, populations of at least 10 of the 14 breeding seabird species have been falling. Numbers of common noddies have fallen by 96 per cent, sooty terns by 84 per cent, bridled terns by 69 per cent, and red-footed boobies by 68 per cent.
    The park authority’s vulnerability assessment report says there is no evidence of significant human interference or habitat loss on Raine Island, indicating “depletion of marine food stocks linked to changing climate” as the cause.
    On the Swain Reefs, in the southern reef, the number of brown booby nests has dropped from 350 in 1975 to less than 30 since 2000.
    “The declining trend was consistent throughout the region and was not simply a consequence of inter-seasonal migration between islands,” the report says.
    On Heron Island, the black noddy population had been rising since early last century, but the number of active nests fell from about 70,000 to 30,000 between 1996 and 2000, with mass mortality of adults and chicks in the El Nino year of 1998.
    In 2002, another year of abnormally high sea surface temperatures, almost none of the huge numbers of wedge-tailed shearwaters that normally nest annually on Heron Island succeeded in raising young.
    Off Heron in 2003, a 1C increase in sea surface temperature reduced feeding frequency by shearwaters from one night in two to one night in five.
    In 2006, a similar rise in water temperature resulted in the number of daily meals fed to the chicks of black noddies falling from three to one-half.
    Negative impacts on seabird populations were recorded in all parts of the barrier reef, in virtually all species, and in nearly all components of reproductive biology. Timing of breeding, year-to-year recruitment, number of breeding pairs, annual hatching, chick growth and adult survival were all affected.,25197,24492395-11949,00.html

  7. moryah4 Says:

    Finally some Australian academics are waking up to the fact that..hmm..if the sea levels are rising and the continent of Australia is mainly at sea-level or below..oh Bugger!


    Ben Doherty
    (October 17, 2008)

    MORE than 700,000 Australian homes are vulnerable to rising sea levels, with up to $150 billion worth of homes, property and infrastructure at risk of seawater inundation, a parliamentary inquiry has heard.

    Almost all Australians will be affected by rising sea levels, according to the Federal Government’s Department of Climate Change.

    “Eighty per cent of the Australian population lives in the coastal zone, and approximately 711,000 addresses are within three kilometres of the coast and less than six metres above sea level,” the department said in a submission.

    The Intergovernmental Panel on Climate Change predicts sea levels could rise between 0.18 metres and 0.59 metres over the next 100 years.

    But even a small rise will dramatically change Australia’s coastline, the department warns. “It is estimated that erodible coasts will recede one metre for every one centimetre rise in sea level. Storm surges will exacerbate coastal erosion.”

    Other experts believe sea levels could jump even more dramatically, rising several metres over the next century, inundating thousands of homes and threatening infrastructure.
    (Zarlen speaks of casual estimates of between 15 metres (initially) but 50 metres is not out of the question. Oh and forget 100 years ,50 years or even 20 years we ain’t got that long. Doc Sherwood keeps reiterating we have gone off the map when it comes to previous scientists models and projections.Just the same as the ‘Titanic’ was anticipated to be about to enjoy a long and illustrious career so Australians expect to enjoy their sunny lazy liefestyle indefinitely with little or no responsibility.
    Even the Maoris of New Zealand right next door to Australia prophesize the attempted arrival of many refugees on their shores,where they are required to stand their with guns to protect.
    Consider Australia’s recent disturbing background in accommodating refugees one has to wonder where we are going to park our 20,434,176 people.)

    The director of the Fenner School of Environment and Society at the Australian National University, Professor Will Steffen, told the inquiry, which is investigating the effects of climate change on coastal settlements, there was enormous uncertainty among the scientific community about the rate of sea-level rise, and that “the science … has progressed significantly since the publication of the IPCC [report] last year”.

    “The observed rate of sea-level rise is tracking at or near the upper limits of the envelope of IPCC projections. With no further changes in the rate of sea-level rise, this would suggest that sea levels in 2100 would be 0.75 metres to 1 metre above the 2000 levels.”

    But there is further uncertainty over the loss of polar ice sheets, particularly Greenland, which is now melting rapidly.

    “The concern is that a threshold may soon be passed beyond which we’ll be committed to losing most or all of the Greenland ice sheet,” said Professor Steffen. “This would lead to 6 metres of sea level rise (with enormous implications for Australia), although the time frame required to lose this amount of ice is highly uncertain, ranging from a century to a millennium or more.”

    Meanwhile, Insurance Australia Group has said billions of dollars in property, homes, businesses and public infrastructure are vulnerable to sea inundation. “Preliminary estimates of the value of property in Australia exposed to this risk range from $50 billion to $150 billion. The figure depends upon the extent of sea-level rise assumed and the effectiveness or otherwise of potential mitigation measures,” chief risk officer and group actuary Tony Coleman told the inquiry.

    And coastal property owners who have insurance for buildings may still be millions of dollars out of pocket if their land is swamped or swept away.

    “In coastal locations, land value can form a significant component of a property’s overall value,” Mr Coleman said. “Whereas the value of coastal buildings may be protected to some extent by insurance, the land value of properties is not insured at all. Accordingly, where land is inundated or eroded by rising sea levels, coastal landowners and lenders in the banking and finance sector face significant losses.”

  8. moryah4 Says:


    By Roger Highfield, Science Editor
    Last Updated: 10:01pm GMT 11/02/2008

    The prospect that the King penguin will go extinct as a result of climate warming is rising inexorably, scientists say today.
    Second only to Emperor penguins in size, King Penguins - distinguished by their ear patches of bright golden-orange feathers - thrive on the islands at the northern reaches of Antarctica, with a total population of over two million breeding pairs.
    Because King penguins sit on the food chain in their region, they are sensitive indicators of alterations to the marine ecosystem and feel the effects of climate change more keenly as a result - in this case, the warming is reducing their food supply.
    Global warming is happening much more quickly in some parts of the frozen continent, particularly the north-west area known as the Antarctic Peninsula, where in the last 50 years temperatures have risen by about 2.5ºC - as much as five times the world average
    .But for these penguins, which do not live near the peninsula, the effects are caused by a warming of sub polar sea surface temperatures.
    A decade ago, Yvon Le Maho of the CNRS Institut Pluridisciplinaire Hubert Curien, Strasbourg, and an engineer began a study of the breeding and survival of penguins on Possession Island in the Crozet Archipelago in the southern Indian Ocean that continued over the course of nine years, marking the birds with electronic tags under the skin as the penguins migrated.
    With Céline Le Bohec and colleagues, Dr Le Maho shows today in the Proceedings of the National Academy of Sciences that high sea surface temperatures in the penguins wintering range, where two thirds of the world’s population of this species reside, diminished the amount of available marine prey, which decreased the survival of adult King penguins since they
    Read more here…

  9. moryah4 Says:

    (Quote Dr Jon/Zarlen,2008) :

    ” One day Australia will stand as an example to rest of the world to do with the environment …The Australian people will either show an example to the rest of the world of how to get control of global warming and become a leader in the world and innovative researcher of alternative power sources such as solar technologies,wind power,etc. OR alternatively the Australian people will lose their entire continent,it becoming submerged by rising sea levels.In event of the latter occuring which seems the more likely at this point in time,this will happen sooner than scientists realize as so far all scientific models have been exceded and scientists are now running blind or in denial.It is the latter who will scream when the first thing goes wrong ( the sh** hits the fan so to speak) but by then it will be too late.
    Global warming is a fact and whether we like it or not the ice mass is being affected and will affect the global sea levels.
    All of the major ice shelves have been affected and as these are being affected both from under as well as above especially the sea ice ones then trouble can only be ahead. The ozone hole over the antarctic is also bigger than before so all these conditions add together to form a not very bright future for the area with regards to the ice pack.
    Global warming is starting to kick in and unless drastic measures are taken it will happen faster than anticipated due to the exponential curve ratio in relation to heating verses melting ratios.
    MUCH OF THE WEST ANTARCTIC ICE SHEET, unlike all the other big ice sheets in the world, lies on top of land that is below sea level, filling a large valley in Antarctica. And that makes it extraordinarily vulnerable to global warming, says Reed Scherer, a geologist at Uppsala University in Sweden. A warmer ocean would melt the vast floating islands of ice at the margins of the ice sheet, which might set in motion an inexorable rise in global sea levels.
    If floating ice along the continental ice sheet’s edges were to melt, says Scherer, rivers of ice flowing from Antarctica’s interior would have unchecked access to the sea, increasing the amount of water entering the ocean. If the ice sheet were to melt completely–a process that could take as little as 500 years according to some models–global sea levels could rise by as much as 20 feet, inundating islands and coastal areas worldwide.
    If the current calculation for these glaciers to melt completely will increase the ocean levels by 20 feet and at current rates will happen within 100 (not the 500 years some scientist project) then expect it even faster as we have seen these type of calculations before and it ended up being much faster.
    Ratios are variable when it comes to exponential melt.
    For instance 1 degree equals say 1 year so if it then addes to say a 2 degree variation then that 2 degree increase by 1 degree becomes a 3 degree variations which supplies a 1.5 degree increase and so it goes. The 3 degrees becomes 4.5 degrees and so forth.
    Current rates are speculative at best! As ratios change according to the curve.
    There are any number of factors that have to be taken into account pollution increases in output from countries where they say they will reduce by 20% but the curve ratio is 35% so in actuality there is a further increase of 5% above the current level estimate in the 10 year period, you have to understand that increases are taking place due to the consistent use of fossil fuels and the burning of coal and fuel oil and emissions of other gases. Carbon trading only moves the problem about it does not stop it!
    As the Methane is released due to melting of tundra etc we also see a further increase as well as releases of further carbon storage areas so the pattern keeps getting worse all it takes is for folks to run the numbers.
    So unless serious thought and construction of sea defences is started asap it will happen faster than current predictions portray and cities will go under with no time for contruction of defences. Some urgent forward thinking is required.
    Now do you think Australia will put any thought to this (i.e. sea defence) i.e. building dykes or lochs as they have done in London(which like Australia is mainly situated at sea level or below) ? Knowing Australia’s lackadaisical society I somehow do not think so.If they do they will do it at the last minute when it is alll too late,losing their whole continent due to scale of ‘too little effort’.”

    If major civilizations like Atlantis and Lemuria can disappear without a trace both possessing larger populations than Australia,don’t think a whole continent and its occupants cannot disappear within a very short time span again providing a huge lesson for mankind.And regarding Australia’s applling recored on refugees to its shores in the past.A famous incident where the samll pacific nation of Tuvola sent delegates to ask could they shift their entire tiny population to Australia’s massive continent in event of global sea rise inundation and they were soundly told by the previous Prime Minister and his Liberal party a flat, “NO!”.
    so where would you place 20 odd million refugees on the planet.
    Maori elders have a prophecy in New zealand of their people, in some future time defending thier shores from hordes of boat people (refugees)from the east.
    The east? Why that’s Australia!

    Coal is mined in every state of Australia as well as the Northern Territory. It is used to generate electricity and is exported. 75% of the coal mined in Australia is exported, mostly to eastern Asia. In 2000/01, 258.5 million tonnes of coal was mined, and 193.6 million tonnes exported. Coal also provides about 85% of Australia’s electricity production.[1]

    “Coal mining in Australia has become more controversial because of the strong link between burning coal, including exported coal, and climate change, global warming and sea level rise and the effects of global warming on Australia.[2].
    Coal is responsible for 42.1% of Australia’s greenhouse gas emissions, not counting export coal, based on 2004 GHG inventory. [2] (Australia has 564.7 Mt CO2e. Of that, Energy was responsible for 387.2 Mt CO2e. Of that, Stationary Energy was responsible for 279.9 Mt CO2e. Approximately 85% of stationary energy is produced by burning coal. Coal is therefore responsible for approx 237.9 Mt CO2e or 42.1% of Australia’s total GHG emissions. There needs to be minor adjustments for the amounts of major hydro electric, gas, wind and solar power to arrive at a more exact amount and proportion, which is likely to be higher because major hydro produces negligible emissions.)
    Australia is the world’s largest exporter of black coal, a position it has held since 1984
    Australia has more than 42 billion tonnes of economically recoverable reserves of black coal throughout Australia. The production for export markets is currently based on deposits in Queensland and New South Wales
    Australia is the fourth largest coal producer in the world
    Australia produced 258.5 million tonnes of coal in 2000/01, of which nearly 230 million tonnes was saleable coal
    Coal is Australia’s largest export commodity
    Australia exports 75% of its coal production, making the country the largest coal exporter in the world - a position Australia has held since 1986
    Exports of 193.6 million tonnes in 2000/01 were worth $10.8 billion or 10% of Australia’s merchandise trade
    Coal provides about 85% of Australia’s electricity generation requirements
    The coal industry employs 18,840 workers directly and many more indirectly
    Productivity has increased by 15% annually since 1996/97
    Australia has about 77 billion tonnes of coal resources
    The Asian market accounts for 80% of Australian coal exports with the top three markets being Japan (47%), Korea (12%) and Taiwan (9%)
    In the metallurgical coal market, Australia is competitive in exporting coal to the Asian region and Europe.
    In the thermal coal market, Australia is competitive in exporting coal to the Asian region, with its main competitors being China and Indonesia. Australia is less competitive in exporting coal to the European market due to shipping distances, and as such the main competition is from South Africa, Colombia, USA, and the Russian Federation. ”

  10. moryah4 Says:

    In some of the last lectures Dr Jon (Sherwood)’s prediction about the rising sea levels caused by the aggragate exponential ice melt ,and we are talking decades or less was ,”How would a hundred foot rise (30 metre) rise sound ?”

  11. moryah4 Says:

    (From 2007 but worth noting)


    by Vene

    The impact of global warming on the vast Southern Ocean around Antarctica is starting to pose a threat to ocean currents that distribute heat around the world, Australian scientists say, citing new deep-water data.

    Melting ice-sheets and glaciers in Antarctica are releasing fresh water, interfering with the formation of dense “bottom water”, which sinks 4-5 kilometres to the ocean floor and helps drive the world’s ocean circulation system.

    A slowdown in the system known as “overturning circulation” would affect the way the ocean, which absorbs 85 percent of atmospheric heat, carries heat around the globe.

    “If the water gets fresh enough … then it won’t matter how much ice we form, we won’t be able to make this water cold and salty enough to sink,” said Steve Rintoul, a senior scientist at the Australian government-funded CSIRO Marine Science.

    “Changes would be felt … around the globe,” said Rintoul, who recently led a multinational team of scientists on an expedition to sample deep-basin water south of Western Australia to the Antarctic.

    Water dense enough to sink to the ocean floor is formed in polar regions by surface water freezing, which concentrates salt in very cold water beneath the ice. The dense water then sinks.

    Only a few places around Antarctica and in the northern Atlantic create water dense enough to sink to the ocean floor, making Antarctic “bottom water” crucial to global ocean currents.

    But the freshening of Antarctic deep water was a sign that the “overturning circulation” system in the world’s oceans might be slowing down, Rintoul said, and similar trends are occurring in the North Atlantic.

    For the so-called Atlantic Conveyor, the surface warm water current meets the Greenland ice sheet then cools and sinks, heading south again and driving the conveyor belt process.

    But researchers fear increased melting of the Greenland ice sheet risks disrupting the conveyor. If it stops, temperatures in northern Europe would plunge.

    Rintoul, who has led teams tracking water density around the Antarctic through decades of readings, said his findings add to concerns about a “strangling” of the Southern Ocean by greenhouse gases and global warming.

    Australian scientists warned last month that waters surrounding Antarctica were also becoming more acidic as they absorbed more carbon dioxide produced by nations burning fossil fuels.

    Acidification of the ocean is affecting the ability of plankton — microscopic marine plants, animals and bacteria — to absorb carbon dioxide, reducing the ocean’s ability to sink greenhouse gases to the bottom of the sea.

    Rintoul said that global warming was also changing wind patterns in the Antarctic region, drawing them south away from the Australian mainland and causing declining rainfall in western and possibly eastern coastal areas.

    This was contributing to drought in Australia, one of the world’s top agricultural producers, he said.

    (Source: Reuters News Service )

  12. moryah4 Says:

    (A report from several years ago-How bad is it now?)


    The vast loop of winds that drives climate and ocean behavior across the tropical Pacific has weakened by 3.5% since the mid-1800s, and it may weaken another 10% by 2100, according to a study led by University Corporation for Atmospheric Research (UCAR) scientist Gabriel Vecchi. The study indicates that the only plausible explanation for the slowdown is human-induced climate change. The findings appear in the May 4 issue of Nature.
    The Walker circulation, which spans almost half the circumference of Earth, pushes the Pacific Ocean’s trade winds from east to west, generates massive rains near Indonesia, and nourishes marine life across the equatorial Pacific and off the South American coast. Changes in the circulation, which varies in tandem with El Niño and La Niña events, can have far-reaching effects.

    “The Walker circulation is fundamental to climate across the globe,” says Vecchi.

    In their paper, “Weakening of Tropical Pacific Atmospheric Circulation Due to Anthropogenic Forcing,” the authors used observations as well as state-of-the-art computer climate model simulations to verify the slowdown and determine whether the cause is human-induced climate change. The work was performed at NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL), where Vecchi is stationed through the UCAR Visiting Scientist Programs. His coauthors include Brian Soden (University of Miami) and the GFDL team of Andrew Wittenberg, Isaac Held, Ants Leetmaa, and Matthew Harrison.

    The Walker circulation takes the shape of a loop with rising air in the western tropical Pacific, sinking air in the eastern tropical Pacific, west-to-east winds a few miles high, and east-to-west trade winds at the surface. The trade winds also steer ocean currents. Any drop in winds produces an even larger reduction in wind-forced ocean flow–roughly twice as much in percentage terms for both the observed and projected changes, says Vecchi.

    “This could have important effects on ocean ecosystems,” Vecchi says. “The ocean currents driven by the trade winds supply vital nutrients to the near-surface ocean ecosystems across the equatorial Pacific, which is a major fishing region.”

    Several theoretical studies have shown that an increase in greenhouse gases should produce a weakening of the Walker circulation. As temperatures rise and more water evaporates from the ocean, water vapor in the lower atmosphere increases rapidly. But physical processes prevent precipitation from increasing as quickly as water vapor. Since the amount of water vapor brought to the upper atmosphere must remain in balance with precipitation, the rate at which moist air is brought from the lower to the upper atmosphere slows down to compensate. This leads to a slowing of the atmospheric circulation.

    Based on observations since the mid-1800s, the paper reports a 3.5% slowdown in the Walker circulation, which corresponds closely to the number predicted by theory. To establish whether human-induced climate change is at work, Vecchi and colleagues analyzed 11 simulations using the latest version of the GFDL climate model spanning the period 1861 to 2000. Some of the simulations included the observed increase in greenhouse gases; others included just the natural climate-altering factors of volcanic eruptions and solar variations. Only the simulations that included an increase in greenhouse gases showed the Walker circulation slowing, and they did so at a rate consistent with the observations.

    Based on the theoretical considerations, and extrapolating from their 1861-2000 analysis as well as from other simulations for the 21st century, the authors conclude that by 2100 the Walker circulation could slow by an additional 10%. This means the steering of ocean flow by trade winds could decrease by close to 20%.

  13. moryah4 Says:


    04 Dec 2008:

    Recent satellite photographs show that the Wilkins Ice Shelf in Antarctica, which began to rapidly break apart earlier this year, is being split by numerous new cracks and appears to be on the verge of a new phase of disintegration. With the southern summer approaching in Antarctica, new satellite images from the European Space Agency show that fissures dozens of miles long developed in the ice shelf in late November. Large slabs of ice from the shelf’s earlier breakup in February are at upper right in the photo. Once the size of the state of Connecticut, the Wilkins Ice Shelf has lost much if its Shelfmass and now the only thing holding it in place is a narrow ice bridge, 1.6 miles wide, between Latady and Charcot islands. That bridge could easily shatter in the next three months.
    The Wilkins Ice shelf is located on the western Antarctic Peninsula, which is one of the fastest-warming places on earth. The Wilkins shelf is nearly 200 miles closer to the pole than the Larsen B Ice Shelf, which completely disintegrated in 2002.

  14. moryah4 Says:


    (By Paul Eastern - The Dominion Post | Wednesday, 21 January 2009)

    Scientists fear a giant Antarctic ice shelf threatened by global warming will help spark a rise in sea levels if it collapses.

    The Wilkins Ice Shelf is being held together by a rapidly shrinking strip of ice, now just 500 metres wide at its narrowest point. Experts say it could break up at any time.

    Ice shelves are floating extensions of ice sheets, formed as a sheet hits the coast and spreads on top of the sea. As the ice hits an island or bay it becomes trapped. The Wilkins Ice Shelf spans 13,680 square kilometres 22 times the size of Lake Taupo.

    Tim Naish, of Victoria University’s Antarctic Research Centre, said its collapse would not directly add to rising sea levels. He compared it to an ice cube in a glass of water when the cube melts, the water level does not rise, because the ice cube has already displaced the water.

    But the ice sheet and glaciers now trapped by the Wilkins Ice Shelf could add new water to the sea if released. “It’s the cork in the bottle.”

    When the Larsen B ice shelf broke up in 2003, nearby glaciers started moving eight times faster.

    Professor Naish said the Wilkins Ice Shelf was being affected from above and below by global warming.

    On top, pools of melted water were seeping into cracks, freezing and pushing them apart. Below, the warming ocean was eating away at the ice.

    “…we are starting to see things happen so quickly that it’s a struggle for science to keep up.”
    Victoria University climate change professor Martin Manning, who was on the panel, said this was because of a lack of published research on the subject.

  15. moryah4 Says:


    (Deborah Smith, Science Editor)
    January 22, 2009

    MORE of Antarctica is heating up than scientists had thought.

    A large part of West Antarctica, not just the peninsula area, has warmed during the past 50 years, a study shows.

    The issue of climate change on the frozen continent has been controversial because East Antarctica has been cooling and temperature records are sparse.

    Eric Steig, of the University of Washington, said his research showed that, overall, warming had outweighed cooling.

    “The thing you hear all the time is that Antarctica is cooling. But it’s more complex than that,” Professor Steig said. “Antarctica isn’t warming at the same rate everywhere and, while some areas have been cooling for a long time, the evidence shows the continent as a whole is getting warmer.”

    Warming in West Antarctica exceeded 0.1 degrees a decade during the past 50 years, similar to the rest of the world, the study, published in the journal Nature, said.

    “Significant warming extends well beyond the Antarctic Peninsula to cover most of West Antarctica, an area of warming much larger than previously reported,” Professor Steig said.

    The research was based on 50 years of temperature measurements from weather stations, 25 years of satellite observations and a statistical analysis of the link between the two sets of data.

    Professor Barry Brook, of the University of Adelaide, said the finding was alarming because it suggested the ice sheet in West Antarctica was at greater risk of melting.

    Along with the Greenland ice sheet, a complete melt of both sheets would raise sea levels by 14 metres.

    “Even losing a fraction of both would cause a few metres this century, with disastrous consequences,” Professor Brook said. “I worry, with the observed polar warming over the last few decades and more in the pipeline due to lags in the climate system, that their large-scale melt is now a fait accompli.”

    Professor Steig said that the hole in the ozone had contributed to the cooling of East Antarctica but that it could close up by the middle of the century.

    “If that happens, all of Antarctica could begin warming on a par with the rest of the world.”

    Another study, also published in Nature, has found that the seasons are starting about a 1.7 days earlier on average around the globe than during the first half of the century.

    AAP reports: “[It's] bad news if you live near the Australian coast,” Professor Brook said.

    “In some areas where you’ve currently got housing, you’d probably have to abandon those areas.”

    He said the sea would penetrate up to one kilometre inland in flat areas such as South Australia’s lower lakes.
    Large areas which don’t see flooding now would get flooded by king tides.
    House prices for coastal areas would probably drop, Professor Brook said.

    (Wish Zarlen’s prediction was this harmless)


  16. moryah4 Says:


    An ice bridge linking a shelf of ice the size of Jamaica to two islands in Antarctica has snapped.

    Scientists say the collapse could mean the Wilkins Ice Shelf is on the brink of breaking away, and provides further evidence of rapid change in the region.

    Sited on the western side of the Antarctic Peninsula, the Wilkins shelf has been retreating since the 1990s.

    Researchers regarded the ice bridge as an important barrier, holding the remnant shelf structure in place.

    Its removal will allow ice to move more freely between Charcot and Latady islands, into the open ocean.

    European Space Agency satellite pictures had indicated last week that cracks were starting to appear in the bridge. Newly created icebergs were seen to be floating in the sea on the western side of the peninsula, which juts up from the continent towards South America’s southern tip.

    Professor David Vaughan is a glaciologist with the British Antarctic Survey who planted a GPS tracker on the ice bridge in January to monitor its movement.

    He said the breaking of the bridge had been expected for some weeks and much of the ice shelf behind was likely to follow.

    “We know that [the Wilkins Ice Shelf] has been completely or very stable since the 1930s and then it started to retreat in the late 1990s. But we suspect that it’s been stable for a very much longer period than that,” he told BBC News.

    “The fact that it’s retreating and now has lost connection with one of its islands is really a strong indication that the warming on the Antarctic is having an effect on yet another ice shelf.”

    While the break-up will have no direct impact on sea level because the ice is floating, it heightens concerns over the impact of climate change on this part of Antarctica.

    Over the past 50 years, the peninsula has been one of the fastest warming places on the planet.

    Many of its ice shelves have retreated in that time and six of them have collapsed completely (Prince Gustav Channel, Larsen Inlet, Larsen A, Larsen B, Wordie, Muller and the Jones Ice Shelf).

    Separate research shows that when ice shelves are removed, the glaciers and landed ice behind them start to move towards the ocean more rapidly. It is this ice which can raise sea levels, but by how much is a matter of ongoing scientific debate.

    Such acceleration effects were not included by the UN’s Intergovernmental Panel on Climate Change (IPCC) when it made its latest projections on likely future sea level rise. Its 2007 assessment said ice dynamics were poorly understood.

    Story from BBC NEWS:

    Published: 2009/04/05 07:13:59 GMT

  17. moryah4 Says:

    Ice Bridge Holding Antarctic Wilkins
    Ice Shelf Cracked Apart Today.

    (April 4, 2009 )

    “It’s amazing how the ice has ruptured. Two days ago it was intact.”
    - David Vaughan, Glaciologist, British Antarctic Survey

    The Wilkins Ice Shelf is breaking away from the Antarctic Peninsula
    as the ice bridge (blue lines) that connects it to Charcot Island (upper left)
    is cracking apart. The Advanced Synthetic Aperture Radar (ASAR) image (at the below link)
    was acquired on April 2, 2009, by ESA’s Envisat satellite confirm that
    rifts are quickly expanding along the ice bridge. See ESA.

    Today, a European Space Agency (ESA) satellite showed that a 25-mile-long (40 kilometers) strip of ice holding the Wilkins Ice Shelf in place snapped at its narrowest point of about 1,640 feet (500 meters) wide off the Antarctic Peninsula. Huge, flat-topped icebergs were knocked into the sea. The loss of the ice bridge can allow ocean currents to wash away more of the Wilkins, exposing Antarctic ice on land to more melting that raises sea levels more rapidly.

  18. moryah4 Says:

    (April 2008)

    by Catherine Brahic

    A warmer world could be a more explosive one. Global warming is having a much more profound effect than just melting ice caps - it is melting magma too.

    Vatnajökull is the largest ice cap in Iceland, and is disappearing at a rate of 5 cubic kilometres per year.

    Carolina Pagli of the University of Leeds, UK, and Freysteinn Sigmundsson of the University of Iceland have calculated the effects of the melting on the crust and magma underneath.

    They say that, as the ice disappears, it relieves the pressure exerted on the rocks deep under the ice sheet, increasing the rate at which it melts into magma. An average of 1.4 cubic kilometres has been produced every century since 1890, a 10% increase on the background rate.

    Frequent eruptions
    In Iceland there are several active volcanoes under the ice. The last big eruption was in 1996 at Gjàlp, and before then in 1938 - a gap of 58 years. But Pagli and Sigmundsson say that the extra magma produced as the ice cap melts could supply enough magma for similar eruptions to take place every 30 years on average.

    Predicting the eruptions precisely will be tricky, though, as the rate of magma migration to the surface is unknown.

    The situation in Iceland does not necessarily mean magma will be melting faster around the world. Vatnajökull sits atop a boundary between plates in the Earth’s crust, and it is this configuration that is allowing the release in pressure to have such a great effect deep in the mantle.

    But the thinning ice has another effect on volcanoes which will be more widespread.

    As the amount of weight on the crust changes, geological stresses inside the crust will also change, increasing the likelihood of eruptions. “Under the ice’s weight, the crust bends and as you melt the ice the crust will bounce up again,” explains Bill McGuire of University College London in the UK, who was not involved in the study.

    Unexpected activity
    Pagli say places likely to be at increased risk of eruption due to ice-melt include Antarctica’s Mount Erebus, the Aleutian Islands and other Alaskan volcanoes.

    The shifting stress might even cause eruptions in unexpected places.

    “We think that during the Gjàlp eruption, magma reached the surface at an unusual location, mid-way between two volcanoes, because of these stress changes,” says Pagli.

    McGuire thinks the Vatnajökull study is based on “perfectly reasonable” physics. However, he says that climate change presents an even more explosive threat. “It’s not just unloading the crust that triggers volcanic activity but loading as well.”

    He and his team are looking into the effects that rising sea-levels - also a consequence of melting ice caps - will have on volcanoes. “We are going to see a massive increase in volcanic activity globally,” he told New Scientist. “If we look back at previous warm periods, that is what happened.”

    Journal reference: Geophysical Research Letters (in press)

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