Dan Whaley, Climos. Courtesy SF Chronicle

Phytoplankton is one of Earth’s most abundant life forms and one of its best resources for soaking up carbon dioxide (CO2). The tiny photosynthetic organisms live in the ocean and, like land plants, combine sunlight and CO2 to create carbon compounds and oxygen. And compared with land-based plants, they’re faster at breaking down CO2 by a ratio of 40 to 1.

But it’s not just CO2 and sunlight that they need. Like land-based plants, a host of micro- and macronutrients play a role in the process, as well—including iron. Oceanographer John Martin was the first to suggest that iron was a key ingredient, when he noted that the tiny amounts of iron in the ocean varied slightly from place to place and that places with higher amounts of iron also had more fish and other sea life. Since most life in the ocean can be traced back to the availability of food, and phytoplankton are the basis of the ocean’s food chain, Martin proposed that adding iron to the ocean could boost phytoplankton growth.

Several studies and a few decades later, Martin’s hypothesis has been proven correct. So, the (not-so) new idea in climate science is this: Supercharge phytoplankton’s ability to pull in additional CO2 by juicing the oceans with a little extra iron.

It may seem logical, but the idea has been —and continues to be—controversial. As May came to a close, the United Nation’s Convention on Biological Diversity voted to halt ocean iron fertilization (OIF) projects without further research, in keeping with the International Maritime Organization’s London Convention’s recommendations, which also call for a precautionary approach and appropriate regulatory controls for OIF activities.