I understand your point about oscillations as an alternative cause, but we have enough data for at least a single full cycle of NAO. While skimming some of the

I understand your point about oscillations as an alternative cause, but we have enough data for at least a single full cycle of NAO. While skimming some of the related work, I found a line in this paper (https://journals.ametsoc.org/view/journals/bams/100/10/bams-d-18-0189.1.xml https://journals.ametsoc.org/view/journals/bams/100/10/bams-...) which roughly estimated six decades of data required to assess a modest (10%) increase in frequency of severe hurricanes in the Atlantic, taking into account natural variability from a range of sources. I don’t know how comprehensive that is, though. The big picture view I have on this is that the skeptic perspective on this article has a big hurdle to overcome, namely that physical theories do support the empirical finding here. I think it is reasonable to keep alternate causes in mind here, but I don’t see too many that seem viable globally.