Phytoplankton vanishing at a rate that alarms scientists
Were it not for reassurances from the Bush administration that global warming
is (a) not happening and (b) would not be of any significance even if it were,
this report would be worrisome. From a story by David Perlman in the San Francisco Chronicle ....
"Plant life covering the surface of the world's oceans, a vital resource that
helps absorb the worst of the "greenhouse gases" involved in global warming,
is disappearing at a dangerous rate, scientists have discovered.
Satellites and seagoing ships have confirmed the diminishing productivity
of the microscopic plants, which oceanographers say is most striking in the
waters of the North Pacific -- ranging as far up as the high Arctic.
Whether the lost productivity of the plants, called phytoplankton, is
directly due to increased ocean temperatures that have been recorded
for at least the past 20 years remains part of an extremely complex puzzle,
says Watson W. Gregg, a NASA biologist at the Goddard Space Flight Center
in Greenbelt, Md., but it surely offers a fresh clue to the controversy over
According to Gregg, the greatest loss of phytoplankton has occurred
where ocean temperatures have risen most significantly between the
early 1980s and the late 1990s. In the North Atlantic summertime, sea
surface temperatures rose about 1.3 degrees Fahrenheit during that
period, Gregg said, while in the North Pacific the ocean's surface temperatures
rose about 7/10ths of a degree.
While the link between ocean temperatures and the productivity of
plankton is striking, other factors can also affect the health of the plants.
They need iron as nourishment, for example, and much of it reaches them
in powerful winds that sweep iron-containing dust across the oceans from
continental deserts. When those winds diminish or fail, plankton can suffer.
There have been small but measurable decreases in the amount of iron
deposited over the oceans in recent years, according to Gregg and his colleagues.
PRODUCTIVITY OFF 6% GLOBALLY
The significant decline in plankton productivity has a direct effect on the
world's carbon cycle, Gregg said. Normally, he noted, the ocean plants
take up about half of all the carbon dioxide in the world's environment
because they use the carbon, along with sunlight, for growth, and release
oxygen into the atmosphere in a process known as photosynthesis.
Primary production of plankton in the North Pacific decreased by more
than 9 percent during the past 20 years, and by nearly 7 percent in the
North Atlantic, Gregg and his colleagues determined from their satellite
observations and shipboard surveys. Combining all the major ocean basins
of the world, Gregg and his colleagues found the decline in plankton
productivity more than 6 percent."