The iron fertililty controversy

The German government has at least temporarily suspended an experiment that would see 20 tonnes of iron dust dumped into the ocean between Argentina and Antarctica in hopes of inducing plankton bloom that sucks up atmospheric CO2, according to Nature. First, says the government, you have to do an environmental impact study. But the very experiment itself is a study in environmental consequences. After all, if it works, then we might have at our disposal a simple way to draw down as much as 10% of the atmospheric carbon that's heating the planet. But wait.

There's this international convention that amounts to a voluntary moratorium on ocean fertilization activities until there is "an adequate scientific basis on which to justify such activities." Seems like a bit of a Catch-22, don't you think? We're never going to get a scientific basis nailed down until we've carried out a fair number of pilot projects.

Now, maybe the good people at the Alfred Wegener Institute, which is leading the attempted experiment, should have floated some trial balloons first. Maybe they did. William Connelley says he can find no good reason for not letting them go head with the thing, and I'm tempted to agree, even with all my reservations about geoengineering schemes.

Dumping iron into the ocean may sound like pollution, but if it can actually draw down serious amounts of CO2, then we should be dumping money into such things as fast was we can. There are lots of unknowns at this point. A couple of years back, a long list of researchers published a review of the issue in Science. They wrote that:

A major unknown in the geological past is the fate of Fe incorporated into phytoplankton blooms. Was dust-mediated Fe supply lost to the deep ocean as declining blooms sank [as aggregates], or was it efficiently recycled by biota in the subsurface ocean and subsequently upwelled?

This is the key question. In theory, plankton fall to the bottom of the ocean when they die and take the carbon they've metabolized from the air with them. It's all part of the Earth's eons-long geochemical cycle, the one that we've accelerated by several orders of magnitude by sucking up fossil fuels and spewing the carbon back into the air from whence it came. But no one really knows if this will work in artificially induced circumstances, and there some hints it might not.

So we need to know. This is one of the more attractive geoengineering ideas. Unlike spraying sulfates into the stratosphere or lauching millions of mirrors into space, is relatively straightforward and inexpensive. Let's find at way to let the Germans go about their ocean dumping business.