Ocean Science Experiment Could Fight Acidification

Today we emit more than 3.3 billion tons of carbon from coal burning alone. That number is projected to climb to 16-28 billion tons per year by 2100 if we continue "business as usual."

Harvey also examined the energy requirements of mining, grinding and shipping the limestone.

"You wouldn't want to be supplying grinding energy from an inefficient coal-fired power plant," he said. He imagines putting this approach into place after society has made the switch to renewable energy, when energy needs would not offset the carbon gains of adding limestone.

And would the approach have unwanted ecological consequences? Large zooplankton would be likely to eat the limestone as it fell through the surface layer, which would probably be harmful to them, but Harvey noted that the limestone would only be present in their habitat for a few hours a year.

"I look at this paper as detailing a theoretical possibility, but not one that's likely to be implemented," said Ken Caldeira of the Carnegie Institution of Washington in Stanford, Calif. "You could imagine engineering the water of a specific bay to maintain coral reef growth, but the attempt to use calcium carbonate to change the whole ocean chemistry is a bit unrealistic."

To engineer a bay would probably require adding already-dissolved calcium carbonate, he added, because reefs occur at depths too shallow to allow limestone powder to dissolve. Caldeira and others have considered using CO2 from power plant emissions to dissolve calcium carbonate, and then to apply the resulting solution to the ocean.

Such an approach might be useful for a small-scale project like altering the chemistry of a bay, Caldeira noted.

Harvey has mixed feelings about the feasibility of his scheme.

"My conclusion is that it might work," he said. "Sometimes I've thought this was a crazy idea, but it might be a valid thing to do once you've dealt with the root source of the problem" -- burning fossil fuels and emitting CO2. "If you don't, the problem is hopeless."

Related Links:

Jessica Marshall's blog: EnvironMental Case

NOAA on Ocean Acidification

More on Ocean Acidification

Planet Green

How Stuff Works: How Adding Iron to Oceans Could Slow Global Warming