This post is partly motivated by something I think I either heard Michael Shellenberger say, or write, but I can’t find it anymore. I have tried reading some of the articles again, and listening to some of the podcasts again, including the Heartland Institute one – where Micheal Shellenberger thanks them for what they’re doing – and the one with Alex Epstein, where Michael Shellenberger suggests that one of the Chapters in the book was motivated by some of what Alex Epstein promotes. If you’re not sure why I’m highlighting this, it might be worth looking up the Heartland Institute and Alex Epstein.
My memory is that Shellenberger was suggesting that precipitation changes would be modest, so it would be relatively straighforward to develop adaptation strategies to cope with these changes. I may have remembered incorrectly, but it is still a topic worth highlighting.
Depending on one’s definition of modest, it is probably true that the overall change in precipitation will be modest; the change in mean precipitation is estimated to be around 2% per K. The problem, though, as this paper points out, is that
the intensity of extreme precipitation increases more strongly with global mean surface temperature than mean precipitation
[g]lobally, the observed intensity in daily heavy precipitation events, i.e. the rainfall per unit time, increases with surface temperature at a rate similar to that of vapour pressure (6–7% per K).
In other words, even though mean precipitation will only increase by about 2% per K, the intensity of extreme precipitation events will increase by more than this, largely (as I understand it) because the vapour pressure increases by 6-7% per K.The paper then goes on to point out that it’s not just the intensity of extreme events that changes, but also their frequency. For example, the figure on the right suggests that the most extreme precipitation events could double with every degree of warming, while their intensity also increases by more than 10% per degree of warming.
So, the changes in the frequency and intensity of the most extreme precipitation events are certainly not small. What’s more, this also means that – as we warm – we’ll shift the distribution of precipitation towards more extreme events; i.e., more and more precipitation will occur in what we, today, would regard as an extreme event.
Given that the events that impact us the most are the extreme events, it seems a bit overly optimistic to think that we can easily deal with quite large changes in both the intensity and frequency of such events. As the paper itself even says:
Such large increases are not taken into account by adaptation management, and our findings imply that society may not be adequately prepared for the coming changes in extreme rainfall.
We will, of course, have to adapt to some of the changes we’re facing. However, there is a difference between recognising that some amount of adaptation is unavoidable, and suggesting that adaptation will be sufficient to effectively cope with any possible change we might experience. At the end of the day, it’s going to be a combination of mitigation, adaptation and suffering, and
we’re going to do some of each. The question is what the mix is going to be. The more mitigation we do, the less adaptation will be required and the less suffering there will be.
Frequency of extreme precipitation increases extensively with event rareness under global warming, paper by Myhre et al. (2019).