Research vessel. Courtesy LOHAFEX project website.
I blogged earlier this year about the German-Indian scientific experiment in the South Atlantic. They've seeded the ocean with iron in hopes of making the algae bloom and thus cause the ocean to absorb more CO2 from the atmosphere. They've spread their particles and the scientists have gone home, to wait for long-term results.
Early results were favorable. Here's one report: "10 tonnes of iron to a several hundred sq. kilometer patch of ocean. The iron was just the tonic the ocean needed and within days a verdant ocean pasture began to bloom. Ocean satellites picked up an image of the bloom on Valentines Day, what better gift for Mother Earth, than an ocean restored and growing nutritious plankton for every form of sea life from tiny krill to the great whales and everything in between fish, penguins, seals, and seabirds."
Here you can read the recent summary of the scientists' findings. The higher iron concentrations have definitely increased the plankton population and thus the absorption of CO2 in the treated area. This is the first large scale geo-engineering experiment aimed at coping with global warming and greenhouse gases.