The Center for Biological Diversity has notified the U.S. Environmental Protection Agency of its intent to file a lawsuit to force EPA to act on speculative claims of ocean acidification. Some scientists say such acidification may occur as a result of higher concentrations of atmospheric carbon dioxide.
The group’s notice, delivered November 13, argues EPA should use its regulatory powers under the federal Clean Water Act to force reductions in U.S. carbon dioxide emissions.
Small Change Causes Suit
Since the dawn of the Industrial Revolution, the pH of waters at the surface of the oceans has fallen from 8.2 to 8.1, which means the ocean surface has become more acidic, according to the October 30 issue of Science Daily. EPA has determined a pH decline of 0.2 would not result in significant negative consequences, but the Center for Biological Diversity argues otherwise.
“Unless we take steps now to stop ocean acidification, it could cause the collapse of our marine ecosystems,” asserted the group’s lawyer, Miyoko Sakashita, in a November 13 press release. “EPA needs to take prompt action to address this serious water-quality threat facing our oceans.”
Studies Show Healthier Ecosystems
Contrary to the group’s claims, a variety of studies have shown higher atmospheric carbon dioxide concentrations have little or no impact on ocean ecosystems, except for the effect of making life more abundant.
Eight Czech and Israeli scientists, for example, reported in the February 2007 issue of the science journal Global Change Biology that higher carbon dioxide levels create conditions more conducive to oceanic life.
After experimenting with ocean water in atmospheres of 250 parts per million of CO2 (corresponding to pre-Industrial Revolution conditions), atmospheres with 400 parts per million of CO2 (corresponding to current conditions), and atmospheres with 900 parts per million (corresponding to conditions speculated as being possible more than a century from now), the scientists observed higher CO2 levels correlated with better growth conditions for oceanic life.
The highest CO2 concentrations produced “higher growth rates and biomass yields” than the lower CO2 conditions. Higher CO2 levels may well fuel “subsequent primary production, phytoplankton blooms, and sustaining oceanic food-webs,” the authors concluded.
Similarly, a 2005 study reported in the scientific journal Geophysical Research Letters examined trends in chlorophyll concentrations, which are the building blocks of ocean life. The French and American scientists reported “an overall increase of the world ocean average chlorophyll concentration by about 22 percent” during the preceding two decades of increasing atmospheric carbon dioxide concentrations.
Resiliency Confirmed
And in a 2008 study reported in the scientific journal Biogeosciences, a team of eight European scientists subjected marine organisms to varying concentrations of CO2, including abrupt changes of CO2 concentration.
The scientists reported the ecosystems were “surprisingly resilient” to changes in atmospheric CO2, and “the ecosystem composition, bacterial and phytoplankton abundances and productivity, grazing rates and total grazer abundance and reproduction were not significantly affected by CO2-induced effects.”
These and other studies show increasing amounts of atmospheric carbon dioxide are causing a net benefit for, or at worst no net effect on, ocean ecosystems and will likely continue to do so.
Concern over Small Subset
Allies of the Center for Biological Diversity speculate a small subset of marine shellfish might not benefit as much as the rest of the aquatic ecosystem. One of the authors of the Biogeosciences study mentioned such concerns.
“A change in seawater pH will affect marine ecosystems in many ways, most prominently by making it more difficult for calcifying organisms to build their calcium carbonate shells and skeletons,” said Dr. Ulf Riebesell, a professor of biochemistry at the University of California at Santa Barbara.
“Calcium carbonate is a primary building material among many marine taxa—such as corals, mollusks, snails, sea urchins, crayfish, many groups in the plankton, but also fish. It appears that larval and early life stages are most vulnerable to ocean acidification.”
If true, the asserted negative effects of higher CO2 on some shellfish will pose a regulatory dilemma: If an elevation of atmospheric CO2 benefits most marine animals and ecosystems but burdens a much smaller number, EPA regulations to cut carbon dioxide emissions could impede the overall ecosystem for the benefit of a small few species.
EPA and the courts would then have to decide whether the well-being of a relatively small number of species should override concerns for the overall ecosystem, in addition to the human economic consequences.
