Ocean acidification

According to the Science blog:

The U.S. Environmental Protection Agency has asked scientists how to revise the Clean Water Act to protect seas against ocean acidification from atmospheric carbon dioxide. Under the current rules, waters are designated as impaired if their pH deviates from naturally occurring levels by 0.2 units. But biologists say that some organisms are affected by smaller changes. A more complex approach would also take into account how organisms or ecosystems are affected differently by changing pH levels.