Experiments in the early 1990s that seeded a region of the Pacific Ocean with iron dust saw a phenomenal 20 fold increase in the local phytoplankton population, with a corresponding decline in atmospheric carbon dioxide by roughly 2,500 tons within a period of 2 weeks.
California-based Planktos Inc. believes this process can be repeated on a large scale to put a serious dent in our excess carbon dioxide problem.Since 1980, global levels of phytoplankton have dropped 25%. This is significant because phytoplankton, tiny floating surface algae, perform 50 percent of Earthís photosynthesis. The result of this is the production of 50 percent of our oxygen, and removed half of our carbon dioxide. At 1980 levels, this meant the metabolism of 50 gigatons of carbon dioxide each year. Since 1980, the loss in phytoplankton has resulted in a reduction of carbon dioxide metabolism of nearly 3 gigatons; equivilant to approximately half of all industrial and automotive emissions each year.
If this were carried out on a large scale, it could have the effect of reducing our atmospheric carbon dioxide outputs by up to 50 percent and locking it up forever as chalk on the ocean floor. This would need to be done very carefully though, as we still know relatively little about deep ocean ecosystems and the sudden influx of large amounts of calcified algae might have unintended side effects. However, compared with the alternative of unrestrained carbon dioxide emissions, this seems like a very good avenue to explore.