*NEWS*GREENHOUSE GASES @ HISTORIC HIGH

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*NEWS*GREENHOUSE GASES @ HISTORIC HIGH

 user 2005-11-25 at 10:21:00 am Views: 76
  • #13226

    Greenhouse gases at historic high
     CO2 ‘highest for 650,000 years’
    Current
    levels of the greenhouse gases carbon dioxide and methane in the
    atmosphere are higher now than at any time in the last 650,000 years.
    That is the conclusion of new European studies looking at ice taken from 3km below the surface of Antarctica.
    The scientists say their research shows present day warming to be exceptional.
    Other
    research, also published in the journal Science, suggests that sea
    levels may be rising twice as fast now as in previous centuries.
    Treasure dome
    The evidence on atmospheric concentrations comes from an Antarctic region called Dome Concordia (Dome C).
    Over
    a five year period commencing in 1999, scientists working with the
    European Project for Ice Coring in Antarctica (Epica) have drilled
    3,270m into the Dome C ice, which equates to drilling nearly 900,000
    years back in time.
    Gas bubbles trapped as the ice formed yield
    important evidence of the mixture of gases present in the atmosphere at
    that time, and of temperature.
    “One of the most important things is
    we can put current levels of carbon dioxide and methane into a
    long-term context,” said project leader Thomas Stocker from the
    University of Bern, Switzerland.
    “We find that CO2 is about 30%
    higher than at any time, and methane 130% higher than at any time; and
    the rates of increase are absolutely exceptional: for CO2, 200 times
    faster than at any time in the last 650,000 years.”
    Stable relationship
    Last
    year, the Epica team released its first data. The latest two papers
    analyse gas composition and temperature dating back 650,000 years.
    This extends the picture drawn by another Antarctic ice core taken near Lake Vostok which looked 440,000 years into the past.
    The
    extra data is crucial because around 420,000 years there appears to
    have been a significant shift in the Earth’s long-term climate patterns.
    Before
    and after this date, the planet went through 100,000 year cycles of
    alternating cold glacial and warm interglacial periods.
    But around
    the 420,000 year mark, the precise pattern changed, with the contrast
    between warm and cold conditions becoming much more marked.
    The Dome C core gives data from six cycles of glaciation and warming; two from before this change, four from after.
    “We found a very tight relationship between CO2 and temperature even before 420,000 years,” said Professor Stocker.
    “The
    fact that the relationship holds across the transition between climatic
    regimes is a very strong indication of the important role of CO2 in
    climate regulation.”
    Epica scientists will now try to extend their analysis further back in time.
    Water rise
    Another
    study reported in the same journal claims that for the last 150 years,
    sea levels have been rising twice as fast as in previous centuries.
    Using
    data from tidal gauges and reviewing findings from many previous
    studies, US researchers have constructed a new sea level record
    covering the last 100 million years.
    They calculate the present rate of rise at 2mm per year.
    “The
    main thing that’s changed since the 19th Century and the beginning of
    modern observation has been the widespread increase in fossil fuel use
    and more greenhouse gases,” said Kenneth Miller from Rutgers University.
    The
    Intergovernmental Panel on Climate Change, the body which collates
    scientific evidence for policymakers, concludes that sea level rose by
    1-2cm during the last century, and will rise by anything up to 88cm by
    the end of this century.