Carbon dioxide poisoning the oceans -- Study suggests rising acidity in seawater could be irreversible
David Perlman, SF Chronicle, September 25, 2003
Long-term emissions of carbon dioxide by the world's automobiles, power plants and industries could sharply increase the acidity of the oceans and devastate much of their marine life, scientists at Lawrence Livermore National Laboratory warn.
In a study based on computer models and limited experiments, the Livermore researchers contend that if emissions are not curbed, the acidity of the seas will increase more rapidly over the next 1,000 years than it has over the past 300 million years, and efforts to stave off the damage are unlikely to succeed.
Carbon dioxide emissions are already known as the biggest offenders in global warming, but the new findings by the scientists at one of the Department of Energy's major laboratories point to a wholly different problem -- the increasing acidity of the world's oceans -- that has received scarcely any public attention.
Ken Caldeira, a Livermore climatologist and ocean chemist, and Michael Wickett, a colleague who specializes in computer modeling, are publishing the results of their study today in the journal Nature.
Burning fossil fuels like coal, oil and natural gas are the major culprits in emitting carbon dioxide to the atmosphere. The oceans absorb much of the carbon dioxide, but the chemical reaction with seawater also increases the water's acidity. At current rates, carbon dioxide is entering the atmosphere 50 times more rapidly than it does from natural sources, according to Caldeira, and thus the oceans are rapidly becoming more acidic too.
One computer model that Caldeira and Wickett developed calculated the increase in ocean acidity that would occur over the next 1,000 years if industrial carbon dioxide emissions continued at their present rate. The scientists then used another model based on geological and historical records to estimate the natural rate of past increases in ocean acidity.
The result: It must have taken at least 300 million years for the world's oceans to reach today's natural levels of acidity.
Acid in seawater is particularly harmful to all the marine organisms that contain calcium carbonate in their bodies or in their shells. Particularly endangered would be coral reefs, many types of calcium-containing plankton, and all the shelled marine animals.
In experiments based on the effects of acidic seawater on marine organisms near coastal power plants, Caldeira said that repairing the damage would be unlikely. It might be possible to remediate some of the damage by spreading crushed limestone in a few threatened areas such as Australia's Great Barrier Reef, he said, but reducing acidity in all the world's oceans would probably be impossible.