Where We Stand on Iron Fertilization

atlantic ocean off argentina

Image courtesy of NASA

The leading éminences grises of science, policy and industry convened a few weeks ago to hash out what has become one of the thorniest issues in climate science today: the place for iron fertilization as a strategy to combat global warming. At issue were relevant concerns about the ecological consequences of the practice and the current absence of any clear regulations for conducting these experiments at sea.

While many of the participants raised concerns about the efficacy and safety of large-scale iron fertilization, others seemed to acknowledge that the urgency of the climate crisis warranted the continuation of carefully designed experiments—pointing out that, if done appropriately, they could provide a win-win for both scientists and businesses interested in selling carbon offsets. "We're in a learning process that involves a balance of science, commercial, and a whole variety of social activities and interests. We've got to set up a measured process for moving forward," said Tony Michaels, director of the Wrigley Institute for Environmental Studies at USC.

SeaWIFS image

Image courtesy of Institute of Ocean Sciences

As has been noted in much of the recent literature, the problem is that iron fertilization hasn't yet proved its efficacy as a long-term strategy to sequester more carbon dioxide in the oceans—at best, it has proven to be a successful, though ultimately short-lived, way to stimulate large phytoplankton blooms and only in certain regions of the world. They key, scientists explain, lies in ensuring that a sufficiently high enough percentage of organic carbon produced during the blooms reaches middle-depth waters, at which point it would remain in deeper underwater currents for decades.

This would be good enough to buy us more time to come up with more efficient, permanent solutions to global warming, argue its advocates. Other scientists are worried about the changes "downstream" of the areas where iron is added; the huge phytoplankton blooms would consume not only iron, but also other vitally important nutrients—including nitrate and phosphate—necessary for the basic rungs of life (and, consequently, for higher trophic levels). In addition to altering marine food webs, iron fertilization could produce greenhouse gases more potent than carbon dioxide, such as nitrous oxide and methane, or block sunlight needed by deep coral reefs.

However, they could also coax phytoplankton into producing more dimethylsulfide (DMS), a gas that is known to promote cloud formation, thus helping cool the atmosphere and countering some of effects of global warming. Proponents correctly point out that, so far, none of the iron addition experiments have led to the above-mentioned repercussions; some say this might simply be because the experiments haven't been conducted on a large enough scale yet.

Companies such as Climos and Planktos, though they acknowledge the potential impacts, urged the participants to not let uncertainty "preclude careful research". "There are plenty of ways to do it wrong, but done right, [iron fertilization] does actually sequester carbon for hundreds of years in the place that it would ultimately end up anyway," remarked Andrew Watson, a biogeochemist at the University of East Anglia.

As the science continues to advance, Michaels explained, researchers will need to team up with private interests to conduct similar, carefully designed addition experiments. "We have to evolve a set of skills within our community to have those kinds of roles. Who else should be figuring that out but us?"

Via ::WHOI Oceanus: Fertilizing the Ocean with Iron (magazine)

See also: ::International Team Of Scientists To Test South Atlantic Carbon Sink In 2009, ::Planktos to Begin Ocean Seeding, ::Planetary Engineering For Climate Crisis: What Are The Choices?