David Keith sends in this thoughtful response to my recent post on air capture.

Author: David Keith

While Roger raises some interesting points, I think the original post overstates the near-term importance of air capture. In speculating about the potential importance of air capture, I find myself caught between two very different possible futures.

In one future, which we might call the linear future, I assume that we live in a world in which carbon prices/constraints are (roughly) equal across economic sectors and in which they increase gradually, and in which they gradually apply to a larger and larger set of countries. This world is the subject of most economic models of the climate problem. In this world, it will be a very long time before air capture technologies become economically competitive, if indeed they ever do.

There is however, an alternative, nonlinear future. It has been 40 years since the climate problem was first brought to the attention of policymakers (the first report to a US president that stated the climate problem in modern terms was to Johnson in 1965). We have done very little. Despite the best efforts of many of us, it seems to me plausible that little but talk will be achieved in the next few decades. This may be particularly likely if some other major problem (e.g., a global pandemic) helps to keep climate off the front burner. When the world finally ask seriously to manage the climate problem, it may do so in a climate of crisis. Perhaps spurred on by scientific findings such as evidence of impending ice sheet collapse and rapid sea level rise. In such a world we might manage the climate problem by spending 5% or 10% of world GDP for a decade or two rather than addressing the problem slowly and smoothly at a rate of 1% of GDP over most of the century as is typically assumed in climate policy discussions. In such a world, options like air capture might be useful because they could be implemented comparatively quickly precisely because they are partially decoupled from the worlds energy infrastructure.

While I, of course, prefer the first world. The second seems plausible, however, given that governments often find themselves able to manage only a few problems at once and operate by ignoring problems until some combination of circumstances puts them at the top of the policy agenda.

Such a world might well consider not only air capture but more radical approaches such as albedo geoengineering. I think geoengineering is among the more credible claimants to the title of “the third rail of climate policy”

Roger: thanks for getting this discussion started.

Cheers, David

N.B., Our Air Capture paper is now available on the Climatic Change website.

For some thoughts on geoengineering see: 37. D. W. Keith (2001). Geoengineering. Nature, 409, p. 420. PDF 26. David W. Keith (2000). Geoengineering the Climate: History and Prospect. Annual Review of Energy and Environment, 25, p. 245-284. PDF here.