New Study Supports Ocean-Nourishing Idea

Oct. 12 -- Last February, Matthew Charette and other scientists chugged through the icy, roiling waters of the Southern Ocean near Antarctica to conduct a very simple experiment.

“Basically we dumped a whole bunch of iron in the ocean and then waited to see what happened,” says Charette, an oceanographer at the Woods Hole Oceanographic Institute in Massachusetts.

The international team of scientists actually mixed just over 9 ½ tons of iron sulfate with water and then hosed the mixture into a 5-mile-wide stretch of ocean over the course of four days.

The experiment was the latest of three variations of its kind since 1993, when the late oceanographer John Martin declared, “Give me a half-tanker of iron, and I’ll give you an ice age.”

While Charette and his colleagues were hoping to learn more about what may have triggered ice ages of the past, some believe a large-scale dumping of iron in the ocean could curb the apparent warming of the world’s climate in the future.

What does iron have to do with a cooling planet? The answer begins with tiny, waterborne plants known as plankton.

A Pollution Sponge

Martin learned that ocean plankton are commonly iron-deprived, so by adding iron to the ocean, these tiny plants can flourish.

Sure enough, all three iron-nourishing experiments — even the most recent one in the normally barren Southern Ocean, that part of the Indian Ocean south of Australia — yielded booming populations of plankton. Like trees and plants on land, plankton plays a big role in soaking up carbon dioxide. And carbon dioxide, belched by factories and vehicles, is one of the main “greenhouse” gases that many fear is contributing to global warming by trapping heat inside the Earth’s atmosphere.

By adding iron, Martin suggested, you add plankton that absorb carbon dioxide. Tug the absorbed gas to the bottom of the sea as the plankton die and sink — and that cools the Earth.