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New Melting Moment

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  • mtneuman@juno.com
    New Melting Moment Washington (AFP) Aug 04, 2005 The collapse of a huge ice shelf in Antarctica in 2002 has no precedent in the past 11,000 years, according to
    Message 1 of 1 , Aug 8, 2005
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      New Melting Moment

      Washington (AFP) Aug 04, 2005 The collapse of a huge ice shelf in
      Antarctica in 2002 has no precedent in the past 11,000 years, according
      to a study that points the finger at global warming.

      Measuring some 3,250 sq km in area and 220m thick, the Larsen B iceshelf
      broke away from the eastern Antarctic Peninsula in 2002, eventually
      disintegrating into giant icebergs.

      By chance, a US-led team of geologists had gathered a rich harvest of
      data around the iceshelf just before the spectacular collapse, including
      six cores that had been drilled into marine sediment.

      The cores contain the remains of plankton and algae imbedded in layers of
      minerals, and their radiocarbon and oxygen isotopes provide clues about
      ice cover and climate change over the millennia.

      The researchers, reporting in Nature, the British science weekly, say
      that since the end of the last Ice Age, some 11,000 years ago, the
      iceshelf had been intact but had slowly thinned, by several dozen metres.

      Its coup de grace came from a recent but decades-long rise in air
      temperature, they say.

      "The modern collapse of the LIS-B [Larsen B iceshelf] is a unique event
      within the Holocene," they write.

      "The LIS-B eventually thinned to the point where it succumbed to the
      prolonged period of regional warming now affecting the entire Antarctic
      Peninsula region."

      The Holocene is the period of relatively balmy weather that followed the
      last Ice Age.

      The research is the latest in a series of studies to sound the alarm
      about the effects of climate change in Antarctica, where the bulk of the
      world's freshwater is locked up.

      The Antarctic Peninsula, which juts northwards out of West Antarctica, is
      considered a warming hot-spot.

      Over the past half century, temperatures in the peninsula have risen by
      around two degrees Celsius.

      In recent years, the peninsula has lost ice shelves totalling more than
      12,500 sq km, equivalent to four times the area of Luxembourg.

      Of the 244 glaciers that drain inland ice and feed these shelves, 87 per
      cent have fallen back since the mid-1950s, according to a British study
      published in April.

      Global warming, also called the greenhouse effect, is caused by carbon
      gases mostly discharged by burning oil, gas and coal, that trap the Sun's
      heat.

      But Earth's climate also goes through natural oscillations of warming and
      cooling, resulting in Ice Ages and the milder interglacial periods in
      between.

      The new study does not say that global warming caused by human activity
      was responsible for the Larsen B's demise.

      However, it refers to a steep rise in the temperatures over the past
      several decades, a phenomenon that climatologists concur was unleashed by
      fossil fuels.

      http://www.terradaily.com/news/antarctic-05o.html
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