Supposedly the very active Atlantic hurricane season in 2020 was more proof that global warming is upon us. As you will recall, when there was a long hiatus in major hurricanes making landfall in the United States the theory was fine-tuned to say warming decreases hurricanes. But then a string of hurricanes hit and the theory switched back. Except for one small thing: last year was actually a quiet one for… um… hurricanes.
As Paul Homewood writes on his Not A Lot of People Know That blog, or mostly shows in pictures worth thousands of words, the total number of hurricanes recorded by early September 2020 with wind speed over 64 knots was 42 and the number with wind speed over 96 was 18. And while neither number is unprecedented, they are certainly toward the low end of the range from 1980 on. Just as the U.S. saw fewer tornadoes than usual last year. (And for that matter wildfires are down not up over the past few decades; stand by for news that warming reduces wildfires and it’s bad.)
At least 11 years since 1980 saw 60 or more hurricanes recorded globally with wind speed over 64 knots, and at least that many saw 30 or more with wind speed over 96 knots. The period from 1990 to 1998 seems to have been especially bad, if one regards hurricanes as in some way “bad”. (Yes, we realize you don’t want one hitting your home town. But ecosystems are complicated things and it may well be that a healthy planet is one that sees periodic destructive wind storms. Again beware the alarmist trope that all effects of warming are bad and all bad things are effects of warming.)
The overall pattern is, you will not be surprised to hear, complicated. There seems to be a downward trend from the mid-1980s at least until 2014, with a bit of a bump in 2016 and another in 2019.
Some alarmists solved that problem the old-fashioned way, namely by ignoring it. Thus in his lyrical pro-lockdown piece in the Guardian (see below) their global environment editor Jonathan Watts raved about how “2020 saw record smoke plumes from bushfires in Australia, a freakishly protracted heatwave in Siberia, the most tropical storms ever registered in the Atlantic, devastating blazes in Brazil’s Pantanal wetlands, the highest flood levels recorded in east Africa, unusually devastating cyclones and typhoons in India, Indonesia and the Philippines, the hottest northern hemisphere summer in history, and temperature records in the Antarctic and the Arctic, where winter ice formation was delayed for longer than in any season in the satellite era.” But we predict a more subtle approach.
The consensus view will be that warming decreases hurricanes except when it increases them. And which way the switch is thrown at any given point will depend not on trends, careful measurement or rigorous analysis of causation but basically on whatever seems to be happening right now.