“Hurricane Matthew was likely more destructive because of climate change,” Clinton said. “Right now the ocean is at or near record high temperatures, and that contributed to the torrential rainfall and the flash flooding that we saw in the Carolinas. Sea levels have already risen about a foot, one foot, in much of the southeast, which means that Matthew’s storm surge was higher, and the flooding was more severe.”
Gore went into even more scientific detail when he took the stage to emphasize what he said were two messages — climate change is a core issue at stake in the election, and every vote counts (he should know).
“It spun up from a tropical storm into a category 5 hurricane in just 36 hours. That’s extremely unusual,” Gore said of Matthew. He later added that “Just since Hurricane Andrew, the sea level, and the waters around Florida, have gone up 3 inches.” Hurricane Andrew struck South Florida in 1992 as a Category 5 storm (but a small sized one).
The back-to-back assertions suggest that it has become less politically treacherous to talk about extreme weather events in a climate change context than it was during, say, the time of Hurricane Katrina 11 years ago. And at the same time, Gore’s appearance reinforces that the Clinton campaign views the climate as a winning campaign issue.
That is especially the case in Florida and especially Miami, surrounded by the rising ocean. Neither Clinton nor Gore mentioned Jill Stein, the Green party candidate who threatens to siphon votes away from Clinton in Florida. Yet a subtext of the event was to signal to Bernie Sanders supporters, who might be thinking of voting for Stein, that Clinton takes climate change very seriously — and that such a vote could help elect her opponent, who does not.
But what about these claims about a linkage between some aspects of Hurricane Matthew and climate change?
One climate scientist whom I quickly reached, Michael Mann of Penn State University, called Clinton’s quotation above “absolutely” accurate. Mann added that it “mirrors” remarks he gave in a recent interview with Democracy Now on the subject (link here).
Gore and Clinton are probably on the safest ground when talking about sea level. There’s a broad scientific consensus that the seas are rising, and that a warming climate is responsible. And while there are regional variations in how the oceans are distributed across the Earth, the fact remains that on average, this means a hurricane that strikes Florida or the U.S. East Coast today will be doing so atop higher seas, with more potential to hurl the water inland.
As for Matthew’s rapid intensification, Gore is right to note that it is “unusual,” although he may have pushed it a bit far. As Atlantic hurricane expert Philip Klotzbach noted for Capital Weather Gang, “Hurricane Matthew underwent a remarkable rapid intensification of 80 mph in 24 hours, intensifying from a Category 1 hurricane to a Category 5 hurricane. This was the third-strongest rapid intensification in a 24-hour period for any Atlantic hurricane on record, trailing only Hurricane Wilma (2005) and Hurricane Felix (2007).”
In other words, Matthew’s rapid intensification is certainly noteworthy, but not unprecedented. It’s the kind of feature that is worrisome, but it is hard to say it is definitive proof of anything at this point.
If there’s anything wrong with Clinton’s and Gore’s remarks, it’s what they didn’t say — there are many caveats and nuances to this issue. They didn’t note, for example:
That no storm is “caused” by climate change — a common misconception that scientists don’t consider supportable. Neither Clinton or Gore claimed this — but they didn’t debunk the misconception, either.
That while scientists expect hurricanes to become more intense, on average, as the world warms, overall storm numbers may actually decrease.
That scientists don’t fully understand what’s driving hurricane activity in the Atlantic, and whether the signal of a global warming influence is yet detectable in hurricane trends.
Most of all, the event demonstrated that Clinton, clearly, thinks the climate issue helps her win. “We cannot risk putting a climate denier in the White House,” Clinton said.
Update: On Facebook, Michael Mann, quoted above, had some critiques of this article. When it came to Matthew’s rapid intensification, for instance, he wrote that “Mooney seems to dismiss the clear connection between climate change, ocean heat content, and rapid intensification as incidental. It’s not.”
I’m not sure we really disagree on this one. When I see a hurricane rapidly intensify as Matthew did, I definitely wonder whether I’m looking at an indicator of a changed climate, and in my prior and more thorough piece on Matthew and global warming, I noted that rapid intensification and long life at a strong intensity were “certainly the kinds of attributes we’d expect to see more often as a warming climate heats the oceans and provides more fuel for the most intense hurricanes.” If I was somewhat more hesitant above, it’s just that with only three recent storms cited as having gone through intensifications that were quite this rapid, I figured that some scientists might be hesitant about drawing broader conclusions about trends.
Mann makes another interesting point, which is that Gore and Clinton were right not to even bother clarifying that the storm wasn’t “caused” by climate change, since of course it wasn’t and “even discussing the connections in those terms buys into the ‘single cause fallacy.'” I guess I’d counter that most people still think, rightly or wrongly, in a single-cause framework, so I think it remains helpful to clarify.
That said, Mann’s last point is certainly fair. He writes that “criticizing Gore and Clinton for not spending their available time expounding on the subtleties, caveats and nuances of the science seems plain over the top to me.” Fair enough. It was a stump speech. I don’t expect them to use it for the purposes of a dissertation, and I agree that on the points they did make, they were pretty accurate.