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Global warming of Atlantic could hit fish -study

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  • Mike Neuman
    Global warming of Atlantic could hit fish -study 30 Mar 2005 18:00:01 GMT Source: Reuters By Jeremy Lovell LONDON, March 30 (Reuters) - The potential shutdown
    Message 1 of 1 , Mar 31, 2005
      Global warming of Atlantic could hit fish -study
      30 Mar 2005 18:00:01 GMT

      Source: Reuters

      By Jeremy Lovell

      LONDON, March 30 (Reuters) - The potential shutdown due to climate
      warming of the key Atlantic Conveyor current that warms northern
      Europe could have a major impact on fish stocks in the region, a
      scientist said on Wednesday.

      Oceanographers have predicted that the current that drags warm water
      from the south to the north could weaken or even come to a halt as
      global warming melts the Arctic polar icecap and dilutes the ocean's

      "A disruption of the Atlantic meridional overturning (AMO)
      circulation leads to a collapse of the North Atlantic plankton stocks
      to less than half their initial biomass," said Andreas Schmittner of
      Oregon State University.

      Writing in the science journal Nature, Schmittner said the steep drop
      in the plankton population was due to it becoming separated from deep
      water nutrient layers as the ocean current failed.

      To date much work has been done on the potential disruption of the
      Atlantic Conveyor as the climate warms by an estimated two degrees
      centigrade this century due to man-made greenhouse gases such as
      carbon dioxide.

      However, relatively little research has been published on the
      possible effect on the seaborne food chain which provides sustenance
      for millions of people.

      "A massive decline of plankton stocks could have catastrophic effects
      on fisheries and human food supply in the affected regions,"
      Schmittner wrote.

      "Hence, emission pathways that lead to fast and large increases of
      future CO2 including the risk of a collapse or substantial reduction
      of the AMO should be avoided through early measures for emission
      reductions," he added.

      He said there was evidence that the current had switched on and off
      during the ice ages, and his modelling work indicated that ocean
      productivity could drop by 20 percent as plankton vanished.

      "These model results ... suggest that global ocean productivity is
      sensitive to changes in the Atlantic meridional overturning
      circulation," he said.

      It is not confined to the northern Atlantic but has implications
      across the Indian, Pacific, Arabian and southern Atlantic Oceans, he

      Although the effect was most noticeable in the north Atlantic where
      even a partial weakening in the life-giving current caused a
      substantial drop in productivity, it also registered globally.

      "The results ... have important implications for the assessment of
      future greenhouse gas emission scenarios," Schmittner said.
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