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Could sprinkling iron across the oceans prevent global warming? Sadly, it appears not. Since phytoplankton are the largest carbon dioxide sink on earth, larger than even all terrestrial plants, one idea was to dust the oceans with iron to feed phytoplankton. Scientists hoped the little organisms would quickly sink to about 300 meters, beyond the reach of that zooplankton, one level up on the food chain. Unfortunately, small-scale tests found that instead of sinking to the sea floor, the extra phytoplankton get quickly eaten by zooplankton, who metabolize and re-emit the carbon. Too bad. Still, a research ship is seeding waters around Galapagos anyway, just to bring attention to the role of phytoplankton in climate change.
