My favorite form of geoengineering is the kind where we leave most of the coal buried and see what happens: bit.ly/SAPhK1— David Roberts (@drgrist) November 1, 2012
Andrew Sullivan pulled together some thoughtful posts on geoengineering as a tactic for addressing excess CO2 in the atmosphere.
Scott Rosenberg at Grist reports on a recent debate over geoengineering:
Both men agree that the climate is in peril and we must move quickly to reduce carbon emissions. But that doesn’t seem to be happening. So is it time to begin serious geoengineering research? That’s where the disagreement kicks in.
Caldeira argues that we should be doing the research now so that when calls for a technofix rise at some moment of future crisis, we can at least know what we’re doing, instead of fumbling blindly. He admits that 15 years ago he thought the idea was “loony” and recognizes the possibility of unintended consequences and unforeseen disasters. But he believes the chance that geoengineering could be a lesser-of-evils for our warming world is worth exploring. He likens it to “chemotherapy for the planet”: Poison is poison, but sometimes you resort to it to cope with something even worse.
One concern is that by investing heavily into geoengineering research "people will stop contemplating difficult choices to reduce carbon emissions if they think technology will make the pesky problem vanish."
I think this is a valid concern and raises a problem with the entire debate about geoengineering.
Lawrence Krauss at Slate writes that "in addition to undertaking dramatic global efforts to reduce present and future CO2 emissions, we need a strategy for addressing the carbon already up there."
There are two parts to the extraction process. First, one removes CO2 from the air by using a sorbent, which is a material that can absorb gasses. Next, the CO2 has to be extracted from the sorbent and sequestered, presumably by pumping it deep underground at relatively high concentration or by binding it to minerals—a bit like how we handle nuclear waste. But another possibility includes actually converting it back into fuel. One particularly attractive possibility that has been proposed involves using an “exchange resin” sorbent which binds CO2 when dry and releases it when wet. In this way the evaporation of water could actually be used to help reduce the energy burden associated with binding and subsequently extracting the CO2.
Note that direct air capture is also not to be confused with so-called “geoengineering,” which attempts to lessen the impact of climate change using other global (and potentially environmentally hazardous) interventions, unrelated to the root cause. Put another way, direct air capture would treat the disease, not merely the symptoms.
It is worth-noting that Krauss wants this concept to be seen as different from geoengineering. Too often the discussion is framed as a question of "should we do geoengineering or not?" Should we dump iron into the ocean? Should we launch reflective particles into the upper atmosphere? And so on.
In this way, this process of extracting existing carbon from the atmosphere is better thought of as an attempt to reverse the unintentional geoengineering we've been doing since the dawn of the Industrial Revolution. And as David Roberts makes clear in the tweet above, geoengineering can be more than doing stuff to the environment. We could try leaving it alone.