MESSING around with ecosystems is an unpredictable business. That proved true again this week when a group of Indian and German researchers gave their first report from the biggest ever experiment in geo-engineering: an expedition to pour iron into the Southern Ocean, a vast area that encircles Antarctica, to stimulate a giant bloom of phytoplankton.
Phytoplankton are tiny algae that absorb carbon dioxide when they grow and then lock up some of the greenhouse gas when they die and sink to the seabed. Stimulate the growth of more phytoplankton, the theory goes, and you might send more CO2 to the bottom of the ocean, where it cannot contribute to global warming. But the experiment did not quite turn out like that.
The voyage, a joint venture by Indiaâ€™s National Institute of Oceanography and the Alfred Wegener Institute for Polar and Marine Research in Germany, was controversial from the start. Some environmental groups claimed it was akin to pollution, and thus illegal. At one point, therefore, the German government ordered the Wegener Institute to suspend operations while it looked into the matter. Eventually, permission to continue was given and the research ship Polarstern made a two-and-half-month passage through stormy seas following the bloom that the researchers had created.