posted 08-26-2002 08:53 PM               

Fried chicken!
http://www.thescotsman.co.uk/international.cfm?id=946502002

Plunging plankton levels may be disastrous

JAMES REYNOLDS

GLOBAL warming is being accelerated by a massive drop in the tiny organisms that absorb CO2 in the North Atlantic, NASA satellites have revealed.

The latest results are highly significant and could help explain some of the decline in fish stocks and weather changes.

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.

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.

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.

Images from NASA’s 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.

The results showed that phytoplankton levels have declined substantially since the 1980s.

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.

The authors of the study, Watson Gregg of NASA’s Goddard Space Flight Centre and Margarita Conkright of NOAA’s 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.

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.

Since the whole ocean food chain depends on phytoplankton, a significant change could indicate a shift in our climate.

One of the world’s leading marine scientists, Dr Martin Angel, said the findings were "very important".

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.