A noted oceanographer once quipped that if you gave him a tanker half-filled with iron, he could give you an ice age. He was only half-joking.
Adding iron to the ocean can cause blooms of algae, which have the potential to take huge amounts of carbon dioxide out of the air and by so doing, cool the planet. And a report in Nature magazine now offers some support for that idea.
The premise of this experiment is that algae growing in the oceans around Antarctica can't grow fast because it's starved of an essential nutrient: iron. Victor Smetacek at the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany, says iron in the ocean is as precious as water is for plants on the land.
"Where you have heavy rainfall you have forests, and where you have no rainfall you have deserts," he says. "And you have the same thing with iron falling from the atmosphere on the oceans."