Pushed by environmentalists, the US Environmental Protection Agency has formally opened the door to regulation of ocean acidification, which is yet another consequence of carbon dioxide emissions. (Greenwire, Christian Science Monitor)

The move came in response to a 2009 lawsuit from the Tucson, Arizona-based Center for Biological Diversity, which argued that Washington state’s coastal waters were legally impaired due to acidification. Such a determination would trigger some kind of regulatory program for addressing the issue. The settlement stops well short of outright regulation but does create a public pathway for addressing the issue within the EPA, which could decide to act at a later date.

As with global warming, it’s not really clear how to adequately address ocean acidification without turning off the carbon emissions. Much of the carbon dioxide pumped into the atmosphere each year is absorbed into the oceans, which changes the pH. The resulting acidification affects coral reefs and other organisms that rely on calcification to produce shells. Although it’s not entirely clear at what level of acidification different organisms would cease to exist, the outlook isn’t particularly good several decades out.

This is part of a multi-pronged effort to spur climate regulation in the United States. A second prong focused on the automobile sector, which ended in a Supreme Court decision declaring that EPA has the authority under the Clean Air Act to regulate greenhouse gases from automobiles – and by extension anything else. A third focused on the polar bear, which was declared threatened under the Endangered Species Act due not to its current population but the future threat of global warming.

The Center for Biological Diversity called the settlement a “crucial step” toward using the Clean Water Act to combat carbon dioxide’s impact on the oceans. “Ocean acidification is global warming’s evil twin, and CO2 pollution is one of the biggest threats to our marine environment,” Miyoko Sakashita, who heads up the oceans policy, said in an announcement on the center’s website. “We need prompt action to curb CO2 emissions to avoid the worst consequences of acidification.”