- Global warming is being accelerated by a massive drop
in the tiny organisms that absorb CO2 in the North Atlantic, NASA satellites
have revealed.
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- The latest results are highly significant and could help
explain some of the decline in fish stocks and weather changes.
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- They are based on a 20-year snapshot of the ocean which
has seen phytoplankton levels drop by 14 per cent in the North Atlantic
and 30 per cent in the North Pacific.
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- Phytoplankton serve as food to other species so any reduction
in their level ultimately affects the numbers of fish in the sea. Phytoplankton
also currently account for half the transfer of CO2 from the atmosphere
back into the biosphere by photosynthesis - a process in which plants absorb
CO2 from the air for growth. Since CO2 acts as a heat-trapping gas in the
atmosphere, phytoplanton helps reduce the rate it accumulates and may mitigate
global warming.
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- Scientists from NASA and the National Oceanic and Atmospheric
Administration (NOAA) say warmer ocean temperatures and low winds may be
depriving the tiny ocean plants of nutrients.
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- Images from NASAÕs Nimbus 7 satellite taken between
1979 and 1986 were compared to those taken by the OrbView 2 satellite from
1997 to 2000. The images were also supplemented with information from ocean
buoys and research vessels.
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- The results showed that phytoplankton levels have declined
substantially since the 1980s.
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- However, at the same time phytoplankton levels in open
water areas near the equator have increased significantly - by more than
50 per cent - but since most phytoplankton is concentrated in the north
there was an overall decrease globally.
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- The authors of the study, Watson Gregg of NASAÕs
Goddard Space Flight Centre and Margarita Conkright of NOAAÕs National
Oceanographic Data Centre, also discovered what appears to be an association
between more recent regional climate changes - higher sea surface temperatures
and reductions in surface winds - and areas where phytoplankton levels
have dropped.
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- A warmer ocean surface layer reduces mixing with cooler,
deeper nutrient-rich waters. A reduction in winds can also limit the availability
of nutrients being stirred up to generate more phytoplankton. However,
the scientists still do not know if the loss of phytoplankton, which thrive
on sunlight and nutrients, is a long-term trend or a climate cycle.
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- Since the whole ocean food chain depends on phytoplankton,
a significant change could indicate a shift in our climate.
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- One of the worldÕs leading marine scientists,
Dr Martin Angel, said the findings were "very important".
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- Dr Angel, UK co-ordinator of the International Year of
the Ocean, said he was now convinced global warming was happening and man
was a major cause.
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- Dr Angel, who believes deep sea fishing should be banned
in at least a third of oceans, said the decline in phytoplankton had massive
implications not just for the climate but also for the whole ecosystem,
including fishing.
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- http://www.thescotsman.co.uk/international.cfm?id=946502002
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- ___
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- Additional story:
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- http://www.msnbc.com/news/794063.asp?pne=msntv
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