People tend to talk about climate change only along one axis: how much greenhouse gas we’re dumping into the atmosphere, and how much heating is likely to happen as a result. Less discussed is the possibility of trying to deliberately lower the Earth’s temperature. The economist Martin Weitzman has a paper out on the economics of this geoengineering:
A second less-familiar externality shows up in the scary form of geoengineering the stratosphere with reflective particles to block incoming solar radiation. This geoengineering-type externality is so relatively cheap to enact that it might in principle effectively be undertaken unilaterally by one nation feeling itself under climate siege, to the detriment of other nations. The challenge with this second global externality also appears to be enormous, because here too so much is at stake and it also seems difficult to reach an international governing agreement. If the first externality founders on the “free rider” problem of underprovision, then the second externality founders on what might be called the “free driver” problem of overprovision. If the first externality is the “mother of all externalities,” then the second externality might be called the “father of all externalities.” These two powerful externalities appear to be almost polar opposites, between which the world is trapped.
As Weitzman mentions, probably the most salient fact here is just how cheap it would be to attempt geoengineering. Preliminary estimates based on seeding the atmosphere with reflective chemicals have found a per-year cost in the single billions. What this means is that a single desperate nation of even moderate wealth could afford it. (Imagine, for example, a nation of low-lying islands whose medium-term existence is threatened by sea level rise.)
It should be said this is a wretched solution to climate change, a Hail Mary effort if all else fails. Among other things, it wouldn’t stop ocean acidification, and would wreck local weather patterns. But the United States of all countries should realize that nations which feel they are in mortal peril—as indeed many are—are prone to reckless action.
Ryan Avent has more.