Ray Pierrehumbert has a new article in Bulletin of the Atomic Scientists called There is no plan B for dealing with the climate crisis. The focus of the article is the possible use of geo-engineering, specifically solar radiation management, to deal with the effects of climate change. The basic conclusion of the article is that
because of the mismatch between the millennial persistence time of carbon dioxide and the sub-decadal persistence of stratospheric particles, albedo modification can never safely play more than a very minor role in the portfolio of solutions. There is simply no substitute for decarbonization.
The problem is that CO2 accumulates in the atmosphere, and this enhancement in atmospheric CO2 will persist for thousands of years. Hence, while we continue to emit CO2 it will continue to accumulate in the atmosphere, the climate will continue to change, and these changes will remain for many, many generations.
Solar radiation management works by injecting aerosol particles into the stratosphere that then reflect some of the incoming sunlight, hence the term albedo modification. The problem is that these aerosols precipitate within a few years. Hence, to maintain this would require continually repleneshing these particles. To counter-act the effects of climate change, we’d then need to continue doing this for thousands of years: a co-ordinated global effort that would need to last for longer than we’ve been able to maintain any advanced civilisation so far.
If we failed to maintain SRM, the particles would precipitate and we’d undergo what is known as a termination shock; the climate would catastrophically warm over a period of a few years. There are also potential geo-politcal issues. What if a powerful country decided that they preferred it slightly warmer. Maybe another would prefer to adjust it slightly so as to change the rainfall patterns in their region, but that such changes would then negatively impact another. The point is that something like solar radiation management isn’t a really viable plan B; we really need to focus on decarbonising the global economy.
However, a number on Twitter disagree and argued that even if it is something that we may never want to use, we should at least understand how it might work. If we do fail to sufficiently decarbonise the global economy then we may indeed want to consider something like solar radiation management. Additionally, the problems highlighted above may not be too big an issue if it’s only used to counteract a relatively small amout of global warming.
This, however, seemed to create another level of criticism. Essentially, solar radiation management will have a global impact and so studying it, and potentially implementing it, really needs to be inclusive; it can’t just be the wealthy developed world who decide if it’s something worth considering. Similarly, if we’re going to justify its use on the basis that economic growth in the developing world is likely to require increasing use of fossil fuels, we really should check if this is the path that such countries would like to follow. If we really do care about the developing world, maybe we should instead consider making the kind of sacrifices in the developed world that would lead to emission reductions, rather than studying a possible plan B.
I had intended that this might be some kind of open thread, but have written a bit too much. My own view is that Ray is essentially correct; there really is no substitute for decarbonisation. I don’t, however, have a major problem with studying a possibly geo-engineering solution, but I do think we have to be very careful that it doesn’t end up being used as an excuse to delay emission reductions and we would really need to ensure that the engagement with this is inclusive and not dominated by a minority in the developed world. Would, however, be interested to hear what other people think.