BEIJING, Dec. 7 (Xinhuanet) -- New satellite data
show the vital base of the ocean food chain -- hytoplankton --decreases when the
world's seas warm up and that has scientists worried about how much food marine
life as oceans become warmer because of global warming.
The data show a significant link between warmer
water -- either from the El Nino weather phenomenon or global
warming -- and reduced production of phytoplankton, according to a study in
Thursday's journal Nature.
Phytoplankton are the microscopic plant life that
zooplankton and other marine animals eat, essentially the grain crop of the
Study lead author Michael Behrenfeld, a biological
oceanographer at Oregon State University, said Wednesday the recent dplunge in
phytoplankton production in much of the world's oceans is a "sneak peak of how
ocean biology" will respond later in the century with global warming.
A satellite commissioned by NASA recorded water
temperature and phytoplankton production from 1997 to 2006. It revealed that for
most of the world's oceans when increased the other decreased and vice versa,
As water temperatures rose from 1999 to 2004,
the crop of phytoplankton dropped significantly, about 200 million tons a year.
On average about 50 billion tons of phytoplankton are produced yearly,
"Everything else up the food web is going to be
impacted," said oceanographer Scott Doney of the Woods Hole Oceanographic
Institute, who was not involved in the study. "What's worrisome is that small
changes that happen in the bottom of the food web can have dramatic changes to
certain species at higher spots on the food chain."
This is yet another recent scientific study with
real-time data showing the much predicted harmful effects of global warming are
not just coming, but in some cases are already here and can be tallied
scientifically, researchers said.
When the satellite first started taking measurements
in 1997 water temperatures were at their warmest because of El Nino, a
warming of part of the Pacific Ocean that affects climate worldwide.
After that year, the ocean significantly cooled until
1999 and the phytoplankton crop soared by 2 billion tons during those two years.
"The results are showing this very tight coupling
between production and climate," Behrenfeld said.
Phytoplankton, which turn sunlight into food, need
nutrients such as nitrogen, phosphates and iron from colder water below,
Behrenfeld said. With warmer surface water, it is harder for the phytoplankton
to get those nutrients.
Another worry is with reduced phytoplankton, the
world's oceans will absorb less carbon dioxide and
increase Earth's primary global warming gas, said NASA ocean biology
project manager Paula Bontempi. That's because phytoplankton take carbon dioxide
out of the atmosphere in making food.