Global warming is making hurricanes like Ida more dangerous through stronger winds, higher storm surge, and much more precipitation.
But it also has begun to make them harder to forecast by increasing the speed with which they intensify.
Leading climatologist Michael Mann, author of The New Climate War: the fight to take back our planet, explains why in a tweet.
Lijing Cheng @Lijing_Cheng[1/8] 2020 ocean temperature (heat content) are formally released today by both IAP/CAS and NOAA/NCEI, both data show upper 0-20000m ocean heat content hit record high in 2020. With @MichaelEMann @jfasullo etc. https://t.co/y0wS9C8myi https://t.co/KKkPdzz7CV
Since Mann is one of our top climate communicators, I asked him to explain this hot take a little more. He emailed me:
One of the things we’ve learned over the last decade or two is that tropical storms tend to intensify rapidly over very warm oceans with deep layers of warm water where the mixing of sub-surface waters fails to bring cold water to the surface, cold water that otherwise dampens the strengthening of the storm. Human-caused climate change is leading to record heat content in the upper ocean (https://link.springer.com/article/10.1007/s00376-021-0447-x) and decreased mixing of cold sub-surface waters (https://www.nature.com/articles/s41558-020-00918-2), a double-whammy that favors rapidly intensifying monster storms like Ida.
Indeed, “storms are intensifying at a much more rapid pace than they used to 25 years back,” explained the author of a 2012 study on hurricane intensification trends. “They are getting stronger more quickly and also [to a] higher category. The intensity as well as the rate of intensity is increasing.”
And a 2015 study on the impact of sea-surface temperatures on the intensity of hurricanes in the North Atlantic found “intensification increases by 16 percent for every 1°C increase in mean SST.” And a 2016 study warned that “the vast majority (79 percent) of major storms” are rapid intensification storms,” and “the most intense storms” are those that undergo rapid intensification.
As climatologist and hurricane expert Greg Holland explained in 2017, “globally, the proportion of Cat 4 and 5 hurricanes has increased from ~20 percent of all hurricanes to around 40 percent due to climate change over the past 60 years.”
Bottom line: We are going to keep seeing more and more difficult-to-forecast super-hurricanes in the coming years and decades — until we get serious about slashing carbon pollution and stopping global warming.