Friday, October 19, 2012

Geoengineering for the sake of the climate?

As atmospheric CO2 concentrations continue to rise, and efforts to slow emissions are stuck in "Park," schemes to scrub CO2 out of the atmosphere seem like a viable solution. Of course, we already depend on tree growth, particularly in places like the tropics, or the accumulation of dead carbon in bogs and the arctic to take carbon out of the atmosphere - or "sequester" it. There are also  much more ambitious plans that fall under the general heading of "geoengineering" - manipulating geological, chemical, or biological processes so as to draw down CO2 emissions. Regardless of how we do reducing what we put into the atmosphere, the thinking goes, we'd be prudent to also try to actively take it out.

One of the more oft-cited versions of this is to "fertilize" the ocean with iron. Dump iron filings onto the ocean's surface, and plankton would bloom by the millions, taking up CO2 as they do it. (The CO2 they take up would be from the ocean, but it would be replaced by CO2 from the atmosphere). Once the plankton die, they would drift to the bottom the ocean, taking the carbon they incorporated into their bodies with them. And, presto! We've "stored" some carbon at the bottom of the ocean and reduced the amount in the atmosphere.

Actually, the science behind this seems pretty strong - several small-scale experiments have indeed seen the expected planktonic bloom and a decline in local ocean CO2 levels. And the eruption of Mt. Pinatubo in the Philippines in 1991 dropped ~40,000 tons of iron dust, and led to a global decline in atmospheric CO2.

All of this is in the news because it was just reported that an entrepreneur has dumped 100 tons of iron dust in the Pacific Ocean off the coast of Canada. He has done it in exchange for $2.5 million from a "native Canadian group" according to the NY Times. It has been criticized from numerous corners. The opposition derives from, among other things, the unregulated nature of the action - it was not cleared by Canadian, US, or International regulators - the scale of the project, and the potential harms it could cause via pollution.

But I think we're going to see more and more of this. As a price gets placed on carbon, and the market for carbon "offsets" grows, we will see more and more companies and individuals looking to offer their services to sequester C. Given how little we know about the long-term consequences of this method for the ecology or chemistry of the ocean - or even the long-term effectiveness in storing carbon - we should be worried. But I'm sure we can count on our governments to step up and properly regulate future large-scale geoengineering projects, right?...Right?...Hello???

Posted by Prof. Jeff Corbin

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