Roger Pielke Jr. recently asked whether we are seeing a “hurricane forecast bust of historical proportions” because the modelers and clever people who run them predicted we’d have a 2024 Atlantic hurricane season far above average, but here we are well into September and the goldanged climate refuses to cooperate. He cites Colorado State U hurricane expert Philip Klotzbach who says we haven’t had such a long period with no named storms since 1968. So why did the modelers say we’d have so many storms? Because, as one particularly famous expert on this (and everything else) Mannsplained, it’s the warming oceans, stupid. But lately some experts are thinking that maybe hurricanes have nothing to do with greenhouse gases and other short-term external causes. Maybe they just follow the beat of their own drummer, or long-term cycles, or non-linear processes in which tiny changes in initial condition can produce big changes in output and big changes in initial condition can fail to matter, and always have, so nothing unusual is going on. That’s the conclusion of 11 scientists who reconstructed hurricane activity back through the past thousand years and concluded... they’re driven by natural cycles, nothing to do with us. And if the true test of science is the quality of its predictions, well, you know from which direction the wind is blowing on this one.

The January authors examined records of sediment cores at locations up the US Atlantic coast, noting that hurricanes leave telltale debris layers in the sediment. This allowed them to deduce numbers of hurricanes every year back to AD900. The record looks like this:

The gray shaded area on the right is the modern era with observed hurricane records shown as the thick black line. The reconstruction matches the observed record kinda sorta but actually not really prior to 1900 so maybe the whole exercise is unsound. They also used a model-reconstruction of Sea Surface Temperatures (SST) to estimate hurricane counts by an alternate method, FWIW, and those results looked similar to the sediment-based record. If either method is genuinely capturing something valid, the authors point out what it means:

“The sediment-based reconstruction indicates substantial multi-decadal variability in hurricane frequency over the past millennium... Overall, the sediment-based reconstruction indicates that hurricane variability over the pre-industrial (PI) period (850–1851) was similar in amplitude to modern variability... Neither the sediment-based nor the SST-emulated hurricane reconstruction indicates that multidecadal hurricane frequency over the late twentieth century is outside the range seen over the past millennium.”

They also asked whether hurricanes are driven by natural variability or external forcing, which would include greenhouse gases but also volcanic eruptions. Since they couldn’t find any influence of volcanic eruptions on storm frequency, they concluded that variations in hurricane counts are driven by natural internal climate variations. And, they add:

“This is consistent with the lack of a clear trend in hurricane activity over the instrumental era despite a very strong external forcing from long-lived greenhouse gases. Taken together, our analysis offers limited prospects for 21st-century hurricane activity based on external forcings alone but does suggest that recent trends are within the range of variations experienced over the past millennium, to which natural and human systems were able to adapt.”

In other words, just because GHG levels are up doesn’t mean hurricanes will be too, and forecasters like Michael Mann who make it all about global warming are just blowing hot air.