Dorian was stronger than it would have been

What just happened to the Bahamas? There will be more of it.

While the science has yet to come in on the specifics of just how much worse climate change made Dorian, we already know enough to say that warming worsened the damage. Because it’s not a coincidence that Dorian was one of the strongest landfalling storms ever recorded in the Atlantic, with the strongest sustained peak winds east of Florida, and the strongest ever to hit the Bahamas. This comes less than a year after Florida withstood the first landfalling category 5 hurricane in decades, on 5 October – the latest ever in the season for a storm that strong.

On a basic physics level, we know that warm waters fuel hurricanes, and Dorian was strengthened by waters well above average temperatures. The fact that climate change has heated up our oceans means Dorian was stronger than it would have been had we not spent the past 150 years dumping carbon pollution into the atmosphere. Sea surface temperatures were more than 1C warmer in the region where Dorian formed and strengthened than they were before we started burning fossil fuels.

And the air is warmer too, and warmer air holds more moisture, which turns to torrents of rain in monster storms.

And we know that as climate change has melted glaciers and ice around the world, that water has gone into the oceans. The extra water, along with the expansion of water as it’s warmed, means that sea levels have been raised. That means when a storm like Dorian makes landfall, there’s more water for its storm surge, already bolstered by stronger winds, to push further inland.

All that extra water makes hurricanes even more deadly, since it’s generally not the wind but the water that kills people. So although Dorian’s 220mph gusts were incredibly dangerous (and sped up thanks to climate change), it was the 20-plus feet of storm surge and torrential rains that were the most destructive elements.

And neither one is something you actually want battering a small island.

Also hurricanes are getting worse more quickly and then staying put longer – worst of both worlds.

Had Dorian been moving at a regular pace of a few miles an hour, the devastation in the Bahamas would have been much less severe. But because it sat in place, basically stationary, the damage has been catastrophic. Again, Dorian is far from unique in moving slowly, as a study last year found a 10% decrease in speed for storms like this globally, while a similar study found a 17% decrease along the east coast of the US. While neither of these studies directly tie that slowdown to climate change, the theory that climate change is changing the jet stream in ways that would lead to stalling storms (a phenomenon one of us has researched) is growing increasingly convincing.

When all these factors combine in one storm, as it has for Dorian, it is truly a nightmare scenario – and a preview of the climate crisis to come. The only question is whether we have the foresight to address it.

Some of us do, but the ones in power, nope.

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