As all correct-minded people know, anthropogenic climate change is responsible for the increasing severity and frequency of hurricanes. It is also responsible for that time a few years ago when there were hardly any hurricanes worth noticing, which came on the heels of Al Gore’s post-Katrina warning that “the science is extremely clear now, that warmer oceans make the average hurricane stronger, not only makes the winds stronger.”
I hope you got all that, because things are about to get even more complicated.
If global warming and/or climate change is responsible for the ever-increasing frequency and severity of hurricanes, then it follows that global warming and/or climate change must also be responsible for the fact that hurricanes have actually become less frequent and less severe over the past half-century.
University of Colorado-Boulder professor and author Roger Pielke in Forbes today vivisected an alarming new study on hurricanes, which he calls “fatally flawed.” He writes:
Earlier this week a paper published by the Proceedings of the National Academy of Sciences (PNAS) by a team of authors led by Aslak Grinsted, a scientist who studies ice sheets at the University of Copenhagen, claimed that “the frequency of the very most damaging hurricanes has increased at a rate of 330% per century.”
The press release accompanying the paper announced that United States mainland “hurricanes are becoming bigger, stronger and more dangerous” and with the new study, “doubt has been eradicated.”
Sounds bad, eh? It would be even worse if it were even the slightest bit true. But as Pielke notes, the peer-reviewed study “contains several major errors” and ought to be retracted.
Why? For starters, it looks like Grinsted and his crew plucked their hurricane counts out of thin air. Pielke tweeted:
In other words, they undercounted the number of hurricanes in the 1900-1958 period by 25 — a nearly 30% error. But it gets worse. They overcounted the number of hurricanes from 1959-2017 by 64 — a whopping 70% inflation of the real figure. How did a study this terribly flawed and so easy to disprove ever pass peer review?
Now I know I already said that the study got worse, so from here I guess it gets… worser.
The conclusion that hurricanes have gotten more severe also doesn’t hold up, according to the NOAA’s precise — and easy to find — numbers.
Category 1 landfalls declined by nearly a quarter from the 1900-1959 era to the present era, and Cat 3 landfalls are down by almost 19%. Are we supposed to believe that Grinsted & Co.’s claim of a 330% increase was some kind of rounding error? Not quite. Here’s how they did it:
Part of this difference can be explained by the fact that G19 focus on economic damage, not hurricanes. If a hurricane from early in the 20th century resulted in no reported damage, then according to G19 it did not exist. That’s one reason why we don’t use economic data to make conclusions about climate. A second reason for the mismatched counts is that G19 counts many non-hurricanes as hurricanes, and disproportionately so in the second half of the dataset.
And as Pielke noted elsewhere in his piece, “anyone wanting to understand trends in U.S. mainland hurricanes should look at data on U.S. mainland hurricanes, not economic data on losses.” Indeed. A Cat 3 storm hitting a barely-populated Florida coast in 1900 is going to cause far less economic damage than a smaller, weaker Cat 1 crashing today into metropolitan Miami. Damage is a silly metric for storm size, since that’s really a measure of human activity, rather than Mother Nature’s doings. On the other hand, doing so does push a popular political narrative — something that the peer-review process is supposed to find and eliminate. Oops.
Nevertheless, everyone from The Weather Channel to ABC News to Science Daily to Business Insider to Phys.org and many others all ran alarming stories uncritically repeating Grinsted’s bad science to a mostly gullible public.
Mission accomplished, I guess.