Another ocean issue

Oh, that's good. [Sarcasm] Another way in which ocean pH may be a problem:

Scientists already know that a drop in ocean pH affects the carbon cycle, reducing the carbonate ions that organisms like corals, mollusks and crustaceans use to build shells and external skeletons. Now, a new study shows that a CO2-induced increase in acidity also appears to disrupt the marine nitrogen cycle. The finding, to be published December 21 in the Proceedings of the National Academy of Sciences, could have ramifications for the entire ocean food web.

But what practical effect this may have is completely unclear:

Nitrification decreased, compared to controls, in all experimental cases, with the effect ranging from an 8 percent reduction to a 38 percent reduction. "What we saw is almost uniform across the ocean, or at least in all the experiments we conducted, which seems to suggest this is fairly consistent effect," says Beman. Importantly, in some cases the change was quite large. "So it could have a pretty substantial effect on how nitrogen is cycled in the ocean," he says.

One potentially positive effect could be a reduction of nitrous oxide—marine nitrification is a relatively big source of this greenhouse gas. "But the larger, much more difficult things to predict are the connections to other organisms and processes," says Beman. Less nitrification would make fewer nitrates available to the plants and other organisms that use them to make vital proteins, making it more difficult for them to thrive. This in turn means less food would be available to the animals that eat those nitrate-using organisms, and so on up the food web.