There’s been quite a lot of recent coverage of a paper suggesting that climate endgames, such as global societal collapse or human extinction, have been dangerously unexplored. For those who recall the contentious RCP8.5 debate, this may seem a surprising suggestion.
I’ve now had a chance to read the paper, and it mostly seems reasonable. There are possible feedbacks that haven’t necessarily been studied in as much detail as maybe they should have been. There are possible tipping points that we may want to understand better. Plus, we can’t rule out that climate sensitivity may actually end up being on the high side of the range. I agree that these are things that we should be looking at. I’d be surprised, though, if we significantly reduced the uncertainty about these outcomes any time soon.
They then discuss how climate change can impact our societies, suggesting that climate change could exacerbate vulnerabilities and cause multiple, indirect stresses (such as economic damage, loss of land, and water and food insecurity) that coalesce into system-wide synchronous failures. Again, it does seem worth studying these potential outcomes.
A couple of general comments, though, that I may not explain as well as clearly as I’d like. How the impact of climate affects societies depends on many factors, some of which we can influence. Hence, the outcome isn’t deterministic in the same way as it might be for a physical system. Of course, this doesn’t mean that one shouldn’t consider these type of scenarios, but they’ll almost always be conditional. So, we probably have to be careful of suggesting that climate change will cause some kind of societal response, rather than it might do so if we fail to take appropriate action.
The other issue is that we already largely know what we should be doing to reduce the risks associated with climate change. Essentially, collectively we need to limit how much is emitted and we need to invest in developing resilience and reducing vulnerabilities. Nothing wrong, of course, with considering what might happen if we fail to do so, or do so badly. Of course, if we’re already failing to do what should probably be done, it’s hard to see how more (uncertain) information is going to do much to change that.
This Realclimate post probably sums it up pretty well.
To get to the worst cases, two things have to happen – we have to be incredibly stupid and incredibly unlucky.
We can’t really do much about the unlucky part, other than trying to better constrain things that are uncertain. We can try to not be stupid and maybe highlighting what might happen if we are will help to avoid that. On the other hand, as someone who was involved in the RCP8.5 debate about a supposed focus on worst-case scenarios, I’m not convinced that it will have the desired effect.
Climate Endgame: Exploring catastrophic climate change scenarios, by Kemp, Xu, Depledge, and Lenton.
The never-ending RCP8.5 debate – one of my posts about a contentious discussion about worst-case scenarios.
The best case for worst case scenarios – Realclimate post by Gavin.