In testimony before the British Parliament, Ken Caldeira has done a good job of expressing what I consider to be the appropriate perspective on geoengineering: the deliberate modification of the climate system, intended to counteract anthropogenic climate change. While it may well be possible to reduce the degree of temperature increase – or even reduce atmospheric levels of greenhouse gasses – though geoengineering, it seems nearly certain that doing so will produce harmful and unintended effects. There is also the danger that simply exploring the prospect of geoengineering will encourage us to use it as a perceived quick fix, rather than actually reducing greenhouse gas emissions.
Those things being said, there is a strong counter-argument. We know from the paloeclimatic record that there have been times in history when climate changed violently, over the span of decades. We also know that we are pushing the climate system farther and farther from the equilibrium it was at prior to the Industrial Revolution. As such, the risk of abrupt or runaway climate change is very real and potentially catastrophic. This is especially true if the climate system is actually as sensitive as climatologist James Hansen has suggested in his recent work.
For the sole purpose of having a fall-back if disaster seems imminent, it seems sensible to investigate possible geoengineering technologies, assessing them in terms of probable effectiveness, secondary consequences, and overall risks. As Caldeira explains:
“Only fools find joy in the prospect of climate engineering. It’s also foolish to think that risk of significant climate damage can be denied or wished away. Perhaps we can depend on the transcendent human capacity for self-sacrifice when faced with unprecedented, shared, long-term risk, and therefore can depend on future reductions in greenhouse gas emissions. But just in case, we’d better have a plan.”
If we find ourselves suddenly on the cusp of the disintegration of Greenland or West Antarctica, the abrupt drying and burning of the Amazon, or the failure of the Asian monsoon, we may find ourselves glad to have conducted this research in advance, even if the ultimate result of that research is the knowledge that geoengineering is actually technically impossible or unacceptably risky. Better to learn that in advance than to roll the die at a time when no room for deliberation remains.