A while ago I wrote a post about a paper by Luke Kemp, and colleagues, suggesting that we should put more effort into exploring catastrophic climate change scenarios. There’s now been a response by Burgess et al. suggesting that Catastrophic climate risks should be neither understated nor overstated and a response to the response pointing out that
Counting the Shared Socioeconomic Pathway (SSP) SSP3-7.0 and SSP5-8.5 scenarios used in the Intergovernmental Panel on Climate Change AR6 Working Group II report is not a good proxy for catastrophic climate risk assessment.
I have my own concerns about the arguments in the original Kemp et al. paper, but I don’t think the Burgess et al. response does a particularly good job of engaging with their arguments, even if it is clear that we should neither understate, nor overstate, catastrophic climate risks.
As I understand it, the original Kemp et al. paper was making a subtler argument than simply suggesting that we should focus more on high-emission/warming scenarios. They were referring to considering how societies might respond to the potential impacts, and not simply those associated with the high-emission/warming pathways.
For example, what would happen if some regions had temperatures and humidities that made working outside difficult? What would happen if some regions experienced some major climate-change-driven agricultural failure? What would happen if we crossed some tipping point that led to rapid changes, such as substantial sea level rise on a timescale of decades? What about compound events, the increasing possibility of multiple extreme events happening at the same time? How would climate change impact society’s ability to recover from a major societal event, such as a war?
I should also stress that the idea isn’t to simply understand the possibility of the above occuring, but to try to understand how these outcomes would actually impact society. Even though I agree with the Burgess et al. response that we should be cautious of overemphasizing apocalyptic futures, I don’t think they really engaged with the deeper arguments being made in the Kemp et al. paper and mostly just suggested that there is already a lot of focus on the high-emission/warming pathways and that catastrophic outcomes are not all that likely along the other pathways.
For what it’s worth, my own concern with the suggestions in the Kemp et al. paper is that it’s extremely challenging to do what they suggest, and it’s hard to know how to do it in way that would be methodologically robust. Also, societal systems are not deterministic, so it would be very difficult to use this type of work to make any kind of prediction. Additionally, it seems unlikely that this type of analysis would substantially change what we should do; limit how much more is emitted and invest in improving resilience and reducing vulnerabilities.
Of course, this doesn’t mean that I don’t think this work should be done, just that I’m not quite sure how one would do it, which – admittedly – is probably not a good argument for not doing it.
Something I should probably have realised, but didn’t, is that there is quite a strict word-limit for PNAS responses. According to Matthew Burgess, it’s only 500 words. So, it was going to be tricky to address the nuances in the Kemp et al. argument in such a short response.