Iron on Troubled Waters

Sept. 25, 2007 — -- The climate change argument isn't over; it hasn't even begun. Sure, we have already resolved two questions -- is global climate change happening (yes), and do humans cause (yes) -- to the satisfaction of all but a handful of fringe naysayers, but this consensus merely sets the stage for the real argument over what to do. And sailing right into the center of this storm is the Weatherbird II, the research flagship of Silicon Valley-based company Planktos.

Planktos proposes to remove climate-damaging carbon dioxide (CO2) from the atmosphere by dispersing powdered iron magnetite (think rust the texture of talcum powder) into the ocean hundreds of miles from shore. The iron will act as a fertilizer, triggering a massive bloom of phytoplankton that will soak up carbon dioxide and sequester it as sediment formed by the corpses of the dead organisms settling on the deep seabed. Because phytoplankton account for more than half the carbon fixation on the planet, and iron dispersal is so easy compared with other methods of carbon capture such as injection into old oil wells, ocean-based sequestration could be a cheap and effective solution to the planetary carbon problem.

This theory has been tested experimentally, and later this fall, the Weatherbird II will conduct the first of several medium-scale pilot tests in the Tropical Eastern Pacific, dispersing a hundred tons of iron dust over an area of ocean the size of Connecticut. Planktos considers this a benign and conservative process, noting that the iron dispersal rate will be in the parts per trillion, a level comparable to that dumped by a storm carrying iron-rich dust from the Chinese mainland over the Pacific.

But others disagree, and the Weatherbird II is thus certain to become a lightning rod in the argument forming around how to respond to global warming. On one side are "engineers," people convinced that we must work our way out of the climate crisis by engaging in planet-scale efforts like sequestering carbon, unfurling orbital sunshades, tossing dust high in the atmosphere to block sunlight, or moving wholesale to nuclear power to eliminate coal-based emissions. On the opposite side are individuals --