Study Shows Southern Ocean May Be Poor Locale For Geo-engineering Plan

A controversial study to see if seeding the Southern Ocean with iron would remove large amounts of carbon dioxide from the atmosphere has shown that the frigid ocean does not appear to be a good locale for the geo-engineering scheme. Indian and German scientists, working aboard the vessel Polar Stern, spent 2 ½ months in the Southern Ocean for an experiment in which they dumped six tons of dissolved iron into a 116-mile patch of ocean. Based on earlier experiments in other oceans, the scientists believed iron fertilization would create large blooms of phytoplankton, or algae, that would absorb CO2 from the air and then sink to the bottom, sequestering the carbon and helping to slow global warming. But the recent experiments showed the fertilization created a type of phytoplankton that was quickly eaten by shrimp-like zooplankton called amphipods, leading to little sequestration. Scientists believed the iron seeding might create phytoplankton called diatoms, which have a hard silica shell and are not eaten by zooplankton. But because the Southern Ocean was low in the silicic acid needed to make the hard silica shells, regular phytoplankton formed and were consumed before they had a chance to sink.