"We are acidifying our oceans," says Dr. Mark Green, an environmental science professor who spoke to a national workshop on ocean acidification at Scripps Institution of Oceanography in California last month. The scientific community has become interested in Green's research on the effects of lowered pH on juvenile clams and other small marine organisms with calcium carbonate shells. Publications by Green in both 2003 and 2004 were the first to show that small organisms with calcium carbonate shells are prone to dissolving and die-off when exposed to just slightly lower oceanic pH - levels that we are now starting to see as carbon dioxide (CO2) in the ocean increases.
Although the scientific community has known about global warming for several decades, it was not until 2005 that anyone realized how its root cause affected our oceans. It turns out that as humans add roughly 7 billion tons of CO2 to the atmosphere each year by burning fossil fuels and harvesting the rainforest, one-third of that dissolves into the oceans, where it creates carbonic acid.
Ocean acidification will have a devastating effect on shell fisheries, according to Green. His research shows that nearly 100 percent of the larval clam community dies within several days of exposure to pH levels already seen now in some regions of the oceans, and that will be seen nearly everywhere by 2100. If none of the larval clams are able to survive, it will only be a matter of years before entire adult clam communities disappear, says Green.
The lowered pH will also dissolve several small phytoplankton species that represent the very base of marine food webs, and the disappearance of these microscopic plant species will cascade throughout the entire ocean with devastating consequences.
"Most small and/or juvenile organisms can't survive even small decreases in pH," says Green.
The workshop, sponsored by the National Science Foundation and National Oceanic and Atmospheric Administration, gathered oceanographers together in the hope of shaping future research, standardizing methods and promoting collaboration among key scientists.
"It was designed to get people talking about ocean acidification and immediately formulate research strategies to deal with this potentially catastrophic problem," Green states.