I wrote about Solar Radiation Managment, or solar geoengineering, earlier this year. It’s become a rather contentious topic, with some regarding it as worth exploring, and others almost seeming to regard it as something we should avoid at all costs. The latest saga involves a group of scholars signing a letter arguing for an international solar geoengineering non-use agreement, which is partly based on this paper. Their main reason for proposing this is that they regard it as being virtually impossible to develop a suitable governance framework.
As a result of this, I ended up in a brief Twitter discussion with Dan Miller, who then asked me to join their clubhouse discussion that took place yesterday evening. It was an interesting discussion, but a little tricky as I was there to partly defend the call for a non-use agreement, which I hadn’t signed and don’t completely agree with. I do, however, share many of their concerns.
On the other hand, Dan and his colleagues, Stacey and Ely, seem fairly convinced that there is a high risk of us crossing a tipping point soon and that this means that we should be seriously considering actually implementing some kind of solar radiation management now.
Although I don’t completely agree with all of what seems to be being proposed in the call for a non-use agreement, I do not think that we should be seriously considering the use of solar geoengineering. One reason is that even though I agree that there are risks of us crossing some tipping points, I think these become much more likely if we warm beyond 2oC. Consequently, I think our focus should be on limiting emissions so that we give ourselves a good chance of keeping warming below 2oC, rather than implementing some kind of solar geoengineering.
The other reason is because of the risk of what is called a termination shock. If we were to implement solar geoengineering now so as to keep global warming close to today’s level while continuing to emit CO2 into the atmosphere, solar geoengineering could end up masking quite a lot of unrealised warming. If for some reason we were unable to sustain this solar geoengineering, this unrealised warming could then materialise on a timescale of a few years, which could have catastrophic consequences.
So, I do think we should be very cautious of actively implementing such technology. In fact, I would suggest that we really shouldn’t be aiming to implement anything like this at the moment, or any time soon. I also think the governance issues highlighted in the letter are valid concerns, and there may well be no easy way to overcome them. On the other hand, I think it’s probably still worth understanding this option, even if it is something we never actually want to use. In some sense, the cat is already out of the bag (we know that there are ways to artificially cool the planet) so it’s probably better to be informed, than not.
Links:Solar geoengineering non-use agreement
Solar geoengineering: The case for an international non-use agreement, paper by Biermann et al.
As highlighted by Alastair McIntosh on Twitter, solar geoengineering also doesn’t directly address ocean acidification, which is another reason for focussing on emission reductions, rather than implementing something like solar radiation management.