Michael Shellenberger has a recent Forbes article on [w]hy Deaths From Hurricanes And Other Natural Disasters Are Lower Than Ever. The article is based quite strongly on the work of a friend of this blog. The basic argument being that even though natural disasters are getting more expensive, it’s because we are so much richer, not because hurricanes and floods are so much more severe.
One problem is that not everyone agrees that the increase in damage costs is solely due to us being richer. Another friend of the blog is an author of a paper showing [e]conomic losses from US hurricanes consistent with an influence from climate change. Aslak Grinsted, and colleagues, also recently published a paper where they normalised in terms of equivalent area of total destruction and showed that [t]he frequency of the very most damaging hurricanes has increased at a rate of 330% per century.
Additionally, our understanding of how tropical cyclones will respond to global warming goes back more than 30 years. It’s well understood that increasing sea surface temperatures will increase the potential maximum intensity of tropical cyclones. We’re also very confident that anthropogenically-driven global warming (AGW) is the dominant cause of sea level rise, which can then impact storm surge. To date, sea level rise may not be that large, but as Gavin Schmidt pointed out, it’s the last foot that does the most damage. We also have examples where AGW almost certainly intensified tropical cyclone precipitation.Kossin et al. have also recently published a paper looking at tropical cyclone exceedance probability over the past four decades. As the figure on the right shows, globally there is a clear increase in the probability of a tropical cyclone exceeding major hurricane intensity (which they define as winds exceeding 100 knots). This is also consistent with the theoretical expectation that we’ll see an increase in the frequency and intensity of the strongest tropical cyclones, even if we don’t see an overall increase in the frequency of tropical cyclones.
Also, as Andrew Dessler highlights, the strongest tropical cyclones dominate the damages, and so an increase in the frequency and intensity of these extreme tropical cyclones can have an enormous impact on the future cost of natural disasters. To assume, as Shellengerger and his sources suggest, that disaster preparedness dwarfs the change in whatever your favorite hurricane metric is seems somewhat optimistic to me. What’s more, this seems to ignore that some regions may be more able to build resilience than others, and that tropical cyclones may start to impact regions that have never before – or rarely – seen such events.
Of course, the impact of AGW is not just about the increasing intensity and frequency of extreme tropical cyclones. If that’s all we were likely to face, we may well regard drastic emission reductions as an over-reaction. There’s also the increasing frequency and intensity of heatwaves, which could make some regions almost uninhabitable, and the increasing frequency and intensity of extreme precipitation events, which could impact flooding and agricultural practices. There’s sea level rise, which could substantially impact many coastal regions. There are already some impacts, such as the loss of tropical coral reefs, that are probably already unavoidable.
I realise that some do use tropical cyclones as a poster-child for the impacts of AGW and do sometimes exaggerate how climate change has impacted these events, or their impacts. I don’t, though, see how suggesting that AGW has had no impact is a suitable response to this. AGW will almost certainly have impacts that we may want to avoid. We can only really do so by limiting future CO2 emissions. That some regions may be able to deal with more intense tropical cyclones isn’t, in my opinion, a particularly good counter-argument.
Why Deaths From Hurricanes And Other Natural Disasters Are Lower Than Ever – Forbes article by Michael Shellenberger.
Economic losses from US hurricanes consistent with an influence from climate change – Estrada et al. 2015.
Normalized US hurricane damage estimates using area of total destruction, 1900−2018 – Grinsted et al. 2019.
Global increase in major tropical cyclone exceedance probability over the past four decades – Kossin et al. 2020.