The interpretation and implications of the Knutson et al. 2020 projections of changes in the frequency and intensity of tropical cyclones under climate change. (8th June 2022)

• Record Type: Journal Article
• Authors: Jewson, Stephen
• Is Part Of: Quarterly journal of the Royal Meteorological Society. Volume 148:Number 746(2022)
• Page Start: 2219
• Page End: 2242
• Publication Date: 2022-06-08
• Subjects: climate change -- frequency -- hurricane -- intensity -- Knutson et al. 2020 -- tropical cyclone -- uncertainty; Meteorology -- Periodicals; 551.5
• DOI: 10.1002/qj.4299
• Languages: English
• ISSNs: 0035-9009

Abstract

Abstract: A recent meta‐study presented distributions of the possible impacts of climate change on the frequency and intensity of tropical cyclones for the six main tropical cyclone basins, summarizing many previous studies. However, it is not obvious how to interpret the distributions given in the meta‐study. I describe algorithms that can be used to interpret the changes in frequency and intensity in a mutually consistent way. I then investigate the nature of the relationships between the changes in frequency and intensity and find that the intensity changes are just a different way of looking at the information provided by the changes in frequency. The mean of the mean intensity distribution increases in all basins. In some basins this increase is associated mostly with an increasing frequency of the most intense tropical cyclones, while in other basins it is associated mostly with a decreasing frequency of less intense tropical cyclones. I consider the implications for a simple measure of risk that combines changes in frequency and intensity, and find that the most extreme risks increase for five out of six of the basins using this measure. The results of this study can be used to produce mutually consistent simulations of changes in tropical cyclone frequency and intensity. These can be used for further analysis of the effects of climate change on tropical cyclones. However, the results come with the major caveat that there are many uncertainties in the inputs and in the various steps of analysis. Finally, I give recommendations for which metrics could usefully be extracted from climate models in future studies of tropical cyclones under climate change to help with interpretation and impacts studies. Abstract : We consider the effects of climate change on tropical cyclones in all six major tropical cyclone basins, using the results from a recent meta‐study. We show how to interpret the results of that study so that the changes in frequency and intensity are mutually consistent, and consistent with historical distributions of intensity. We then analyse the relationships between changes in frequency, intensity and a simple measure of risk. We show that extreme risks are increasing in five out of six basins.