Fertilized ocean algae are a natural carbon sink

Nature : In an effort to find a way to limit global warming, researchers are reanalyzing an experiment conducted in 2004 in which an area of ocean was fertilized with iron sulphate. Victor Smetacek of the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany, and colleagues found that the added iron encouraged the growth of algae, which in turn captured carbon dioxide through photosynthesis. The researchers’ paper was published yesterday in Nature. When the algae died, they became a natural carbon sink as they and the carbon they captured sank to the sea floor. Although some geoengineering advocates think this carbon-sequestration mechanism might help mitigate present-day climate change, an international convention in 2007 discouraged ocean-fertilization efforts because of the potentially harmful side effects to marine ecosystems. “But just because we don’t know all the answers, we shouldn’t say no to further research,” said Ken Buesseler of the Woods Hole Oceanographic Institution, whose News and Views article also appeared online yesterday in Nature.