From the NYTimes, this considered opinion, which we appreciate, along with the "scientists are reluctant" disclaimer tucked in here for that all-important CYA moment:
Q: Can the intensity of this year’s tornadoes be blamed on climate change?
A: Probably not. Over all, the number of violent tornadoes has been declining in the United States, even as temperatures have increased, making it likely that this year’s twister outbreak is simply a remarkable and terrifying — but natural — event. Climate science has long predicted that global warming will cause more weather extremes, however, and statistics suggest that this has started to happen. In most areas of the world where good weather data is available, instances of heavy precipitation are rising, often leading to flash flooding. And the same thing is true of heat waves; in the United States, new high-temperature records for a given date now occur twice as often as record lows. That said, scientists are reluctant to attribute any specific weather event to global warming. And, at least so far, only a handful of studies have suggested that tornadoes are likely to become more frequent or more intense on a warming planet. Frustratingly, it is likely to be a year or two before we get good published analyses of the causes for this season’s strange weather — and it may be decades before science can conclusively demonstrate whether or not human-driven warming is affecting tornado frequency. — JOHN COLLINS RUDOLF and JUSTIN GILLIS