EPA Will Analyze the Effects of CO2 Emissions on Water Quality
Ocean acidification results from the ocean's absorption of excess CO2 in the atmosphere, which increases the acidity of the ocean and changes the chemistry of seawater. The primary known consequence of ocean acidification is that it impairs the ability of marine animals—including coral reefs—to build and maintain the protective shells and skeletons they need to survive.
The Center for Biological Diversity sought to compel the EPA to impose stricter pH standards for ocean water quality and publish guidance to help states protect U.S. waters from ocean acidification. The pH water-quality criterion is relevant to preventing ocean acidification because it is the measure of seawater acidity against which many states gauge the need to impose regulations on pollution.
The EPA's formal response to the center's petition sets out a public process to evaluate ocean acidification's impacts on water quality, as well as to determine whether the current water-quality criterion for pH should be modified to address ocean acidification. The EPA also agreed to develop biological assessment methods and other technical guidance relating to evaluation of the health of coral reefs, which are particularly threatened by ocean acidification.
"Global warming’s evil twin, ocean acidification, is the most insidious threat to our ocean ecosystems," said Miyoko Sakashita, an attorney with the Center for Biological Diversity's oceans program. "EPA's commitment to review its water-quality criterion in light of ocean acidification marks an important step toward taking action under the Clean Water Act to begin to address this perilous threat."
Ocean acidification is emerging as a primary threat to our oceans. In the past few decades, the oceans have absorbed approximately 30 percent of the CO2 released by human activities. The world’s oceans store about 50 times more CO2 than the atmosphere, and most CO2 released into the atmosphere from the burning of fossil fuels will eventually be absorbed by the ocean. As the ocean absorbs CO2 from the atmosphere it changes the chemistry of seawater by lowering its pH. Surface ocean pH has already dropped by about 0.1 units on the pH scale from 1750 to 1994—a rise in acidity of about 30 percent.
Ocean acidification is already degrading seawater quality with adverse impacts on marine ecosystems. For example, it threatens to erode away coral reefs within our lifetime. Scientists have also found that some plankton, which form the base of marine food webs, suffer from weaker and thinner shells due to ocean acidification. Nearly every marine animal with a shell is vulnerable to the impacts of ocean acidification.
"In just a few decades, ocean acidification will unravel a delicate balance of underwater diversity that took millions of years to build," said Sakashita. "Absent quick regulatory action to address ocean acidification, we will likely see catastrophic impacts on our ocean ecosystems, including the near-complete loss of coral reefs."
In 2007, the Center for Biological Diversity filed a formal petition asking the EPA to impose stricter pH standards for ocean water quality and to publish guidance to help states protect U.S. waters from ocean acidification. The federal Clean Water Act requires the EPA to update water-quality criteria to reflect the latest scientific knowledge. However, the agency has not updated its pH criterion since 1976. Now it has agreed to reevaluate this pH criterion in light of the new information on ocean acidification.
If the EPA strengthens the pH water-quality criterion for oceans, then the Clean Water Act requires states to adopt a water-quality standard at least as protective as the one established by the EPA. Moreover, states are required to designate water bodies that do not meet water-quality standards as “impaired” and take action to limit their pollution. Here, stronger water-quality standards for pH could translate into measures that regulate CO2 pollution, the primary cause of ocean acidification.