Sounds like a horror movie, but it’s not. It’s a strategy for removing carbon dioxide emissions from the atmosphere (“Seeding the Ocean,” Audubon, March-April 2009).

Here is the idea: Plants called phytoplankton use carbon from surface waters to make food for themselves. When they take carbon out of the ocean, the ocean responds by removing carbon from the air. If the phytoplankton die and sink, then they take carbon with them into the ocean depths. Congratulations: you’ve just figured out how to reduce the amount of atmospheric carbon!

In order to grow, phytoplankton need iron. So, we fertilize the ocean with iron and let the phytoplankton do their thing. Good-bye, global warming.

Sounds like everyone would want to go along, don’t you think? But no.

The private sector seems intrigued. The article mentions a San Francisco–based company called Climos that wants to cash in on this process, but the website seems a little out of date. Another company, Planktos, has gone out of business.

To some environmentalists, the idea of casting a bunch of iron into the ocean is horrific. A little iron stimulates the growth of phytoplankton; a lot does … well, who knows? Just what the ocean needs, another man-made experiment.

From 1993 to January 2009, there were 13 experiments in iron seeding, according to the article mentioned above. An article in the Guardian (“Ocean Iron Plan Approved,” January 28, 2009) mentions research by the University of Southampton and the Alfred Wegener Institute in Germany. It also mentions an article in Nature, which I have not yet read. I did find this press release from the Alfred Wegener Institute dated March 23, 2009. (There seems to be some confusion with dates in the article. I think the date in the first paragraph should be January 17, not March 17.) The iron did cause the phytoplankton to grow more quickly, but predators took so many of the plankton that only a few of them sank into the ocean depths, carrying carbon with them. Earlier experiments had indicated that the process might sequester more carbon in the deeps.

While surfing the web, I found a 6-part series in Oceanus, the magazine of the Woods Hole Oceanographic Institution. According to the first article (the only one I’ve read so far), which was published in November 2007 (before the 2009 experiment with AWI), the plan is to keep trying. At the end of the first article, the following list of questions was presented:

Unresolved Questions (from Oceanus, posted November 13, 2007)

Twelve small experiments [13 after the one mentioned above] have shown that blooms of phytoplankton consistently result from intentional addition of iron to the ocean. But the efficacy and ecological impacts of iron fertilization remain uncertain, particularly with larger-scale experiments. If and when a new round of experiments is begun, these questions will be first on the list: