I have often joked that the solution to increasing greenhouse gases was simple: simply invent a tabletop device (solar powered of course) that turns the CO2 in ambient air into diamonds and releases oxygen. While I am still awaiting this invention, the issue of “air capture” of CO2 is becoming less and less far-fetched. Whether or not air capture proves technologically, economically, or politically feasible in the long run, the technology, or more precisely the idea of the technology, has the potential to fundamentally transform debate on climate change.

The idea of air capture of CO2 is simple in principle: ambient air is taken in, CO2 is taken out, and air is released. (Those interested in an introduction to the technical details should see this PDF by David Keith and Minh Ha-Duong. For a look at a a prototype system see this PDF.)

Currently air capture of CO2 is a political third rail of climate policy. Here is why:

For most of those people opposed to greenhouse gas regulation advocating air capture would require first admitting that greenhouse gases ought to be reduced in the first place, an admission that most on this side of the debate have avoided. When so-called climate skeptics start advocating air capture (which I have to believe can’t be too far off), then you will have a sign that the climate debate is really changing.


If such a transformation occurs, then we have the irony of seeing the climate skeptics become the technology advocates and the greenhouse gas regulation advocates become technology skeptics. Why? For most of those people who support greenhouse gas regulations, even admitting the possibility of air capture is anathema, because it would undercut the entire structure of the contemporary climate enterprise. Consider that the Kyoto Protocol and all of its complex mechanisms would largely be rendered irrelevant. So too would be most research on carbon sequestration (though point source sequestration would likely remain of interest) and management, as well as much of research on reducing emissions in autos, homes, cities, etc.. As well, because among many much of the motivation for climate mitigation lies in changing peoples lifestyles, securing advantages in international economics, and changing energy policies, air capture represents a tremendous threat to such agendas. As a 2002 Los Alamos National Laboratory press release trumpets, “Imagine no restrictions on fossil-fuel usage and no global warming!”

Now for a moment imagine that the technological, economic, and political obstacles to air capture could be successfully overcome. For the record, I have no idea if this is in fact the case, however some very prominent researchers think that it is possible, see e.g., this PDF. What would this mean?

This would mean that policy makers could then tune the atmosphere to whatever concentration of CO2 that they desired, and people around the world could continue to consume fossil fuels with abandon. (The entire prospect of geoengineering would of course require some very, very careful thought that I am obviously overlooking for the moment.) Now of course, this argument presumes that the climate problem is one of stabilizing CO2 concentrations at a particular level, such as described in the Climate Convention, a framing that I have critiqued (e.g., here in PDF), but let’s go with it for purposes of discussion. The problem of increasing CO2 in the atmosphere would then simply be turned into a technical exercise in scrubbing the atmosphere clean, of course, at some cost.

Critics of air capture that I have spoken to dismiss air capture almost reflexively as undoubtedly forever remaining too costly and technologically infeasible. But given its potential to reshape the climate debate, I am amazed that air capture has not captured more attention from researchers and, especially, policy makers. For example, the recent IPCC report on Carbon dioxide Capture and Storage discusses capture from point sources, like power plants, but not from air. Should air capture start getting attention you can just about predict who will argue against it as being infeasible and work to keep it off of technology research agendas. (Question: Does anyone know how much research money is currently devoted to air capture?)

According to estimates by David Keith and colleagues, the costs of air capture are about one order of magnitude higher than the price that carbon trades for in the European carbon exchange. In the history of technological innovation, this is really not very far apart (think computers). Imagine if governments around the world set up a $50 billion prize for the first technology that demonstrated economic viability for air capture of carbon dioxide at, for instance, $20 per ton, $5 per ton or $1 per ton. The resulting investment in innovation would be massive. To scale the cost of awarding such a prize, it is a fraction of some projections of the annual costs of implementation of the Kyoto Protocol, which would deal with about 99% less of the problem than cost-effective air capture.

Can air capture solve the problem of increasing greenhouse gas emissions? I don’t know. But if scientists and policy makers frame the climate problem as one of stabilizing concentrations of atmospheric CO2, then given the potential payoff, air capture deserves to be at the center of international climate policy debate. Presently it is not, but I’d bet that it will be soon.

(Note: Thanks to David Keith for providing useful background information on air capture!)