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What Climate Change Taught Us About Hurricanes

Cities torn apart. Thousands of people displaced. Impassable roads and a search for the missing and the dead in rubble that stretches for miles. Anyone reading the news following Hurricane Michael’s landfall on Wednesday knows how devastating a single hurricane can be. So it’s no surprise that, until relatively recently, forecasters’ emphasis was on individual storms — whether a hurricane would form, where it might go and when to issue an evacuation order.

But today researchers are also able to think of hurricanes collectively, as a series of connected events. Over the last 30 years, we’ve become better able to predict hurricane risk — both in terms of individual storms and the risk a full season might bring. We can prepare for hurricanes more effectively today than we could a generation ago. And, experts say, climate change is partly to thank for that.

Or, rather, climate change research.

This change in our understanding of how hurricanes work really began with the work of William Gray, who developed the first data-driven seasonal hurricane forecasts in the early 1980s, said James Elsner, a professor at Florida State University who researches hurricanes and tornadoes. Although Gray was famously a skeptic of the idea that humans caused climate change, he was one of the first people to make connections between large-scale climate variations and the number and intensity of hurricanes that form in a season.

For instance, Gray was the first to note that hurricane activity in the Atlantic fell during El Nino years and he hypothesized that this was due to the way rising hot air over the Pacific Ocean increased westerly winds high above the Atlantic. Those changes in wind speed and direction in the upper atmosphere — known as wind shear — can alter the process of storm formation. In this case, those westerly winds seem to inhibit hurricanes from forming. Basically, wet and stormy El Nino weather in one part of the world created dryer, less-stormy weather elsewhere. “Before that, there was no sense that hurricanes participated in the climate system in any meaningful way,” Elsner said. “That’s how we got started.”

Our understanding of how hurricanes and climate systems are linked has expanded significantly over the last two decades, said Lucas Harris, a weather and climate dynamics expert at the National Oceanic and Atmospheric Administration. For example, thanks largely to the work of MIT physicist Kerry Emanuel, we know today that warmer waters in the Atlantic are strongly associated with stronger hurricanes in that region.

These discoveries about how the physics of climate systems work, and how those systems help to create and steer hurricanes, has drastically improved the models we use to predict these storms, said Suzana Camargo, executive director of the initiative on extreme weather and climate at Columbia University. In the past, hurricane models were statistical guesses based on historical data about past storms. Today, they’re more likely to involve dynamic models based on current climate-system physics.

The result is better predictions and the ability to make predictions on longer time scales. Take seasonal predictions, which we started making in the early 1990s. They are now accurate enough that insurance companies and emergency managers use them to help assess risk and plan for the year. These forecasts aren’t perfect — unpredictable short-term weather variations still matter a lot. In August, forecasters thought this season would be quieter than average, and while this season may turn out to be more active than they thought, even if it matches the predictions exactly, that accuracy doesn’t mean much if your house just got flattened by Michael. But Camargo and Elsner were both excited about these forecasts’ growing ability to make predictions about which broad regions might be subject to the most risk in a given season (that is, will the Atlantic coast be more at risk, or should the Gulf coast prepare to take the brunt?). “You start having a more tailored forecast, and that’s where you have a lot of value,” Camargo said.

Climate change research has also improved the quality of the models that we use for individual hurricane tracking, Camargo said. Today, forecasters are increasingly relying on the dynamic models that use high-speed computing and knowledge of climate and weather physics to predict how storms will grow and where they will travel. Five-day forecasts now are as good as two-day forecasts were 20 years ago.

This knowledge, and these models, might eventually have existed without climate change research, Camargo told me. But the short-term predictive powers we have today were ultimately born out of our pressing long-term concerns. “I don’t think the community would have pushed and been there so fast if it wasn’t trying to simulate climate change,” she said.

Maggie Koerth-Baker is a senior science writer for FiveThirtyEight.

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