Global warming increases the rate of "ocean acidification" and is damaging some of the most important living organisms in the sea's food web, U.S. scientists have warned.(Xinhua/AFP File Photo)
LOS ANGELES, July 4 (Xinhua) -- Global warming
increases the rate of "ocean acidification" and is damaging some of the most
important living organisms in the sea's food web, U.S. scientists have warned.
The world's oceans now absorb millions of tons of the
global warming gas each year, and thus help to slow the pace of climate change,
but the benefit is far outweighed by extreme and damaging changes in the water's
chemistry due to global warming, according to two studies published in the
journal Science available here on Friday.
"While the changes are alarming, it's nearly
impossible to predict how this unprecedented acidification will affect entire
ecosystems," said Ken Caldeira, an atmospheric scientist with the Carnegie
Institute's Department of Global Ecology at Stanford.
Caldeira and his colleagues raised the issue in the
July issue of Science.
Only two weeks ago in the same journal, Richard
Feely, a chemical oceanographer in Seattle with the National Oceanic and
Atmospheric Administration (NOAA), reported that the world's oceans have become
at least 30 percent more acidic since the Industrial Age began more than 200
Feely's study warned that if greenhouse gas emissions
continue uncontrolled, the world's oceans in this century will become 150
percent more acidic than they are today.
Feely's report showed that ocean waters welling up
from the depths along the Pacific Coast from Canada to Mexico are threatening a
wide variety of marine organisms as carbon dioxide, the major greenhouse gas,
saturates the water and increases its corrosive acidity.
Each spring along the West Coast, winds from the
northwest blow strongly across the sea surface toward the shore and generate
strong upwelling currents, Feely explained. The upwelling, in turn, brings water
saturated with carbon dioxide from the deep bottom toward the surface.
Then, as the gas mixes with seawater, it becomes
carbonic acid, and when that acidity of the water becomes strong enough, it can
dissolve the calcium carbonate shells of many of the sea's most important
The acid can endanger all kinds of marine animals,
from the shells of microscopic plankton to the beaks of giant squid.
Scientists have already reported the severe damage
that acidity in seawater is causing to corals -- both the shallow coral reefs of
the tropics and the lesser-known deepwater corals of the northern oceans that
also require calcium carbonate to build their bony skeletal homes.
But mussels, oysters, crabs, urchins, squid, and the
kind of microscopic carbonate-shelled plankton that form the diet of creatures
ranging in size from krill to whales are also organisms that can fall prey to
increases in the ocean's acidity, according to Feely's study.