With Hurricane Florence bearing down on the Carolinas, our attention is focused where it needs to be — evacuating the coast, stocking our shelves, and making plans to keep our families safe. But while we do those things, we should be aware that this storm, like others, is partially of our creating.
Climate change has changed the way that scientists conceive of extreme events like hurricanes. There no longer are pure “Acts of Nature,” but through climate change, human activities have some role in altering the weather system. We now must assess the probabilities of extreme events, how those probabilities have changed in a warming world, and how they will change in the future.
But the press is generally reluctant to talk in these terms.
No one event like Hurricane Florence is caused by climate change, and it would be irresponsible for the press to claim as such. But it is also irresponsible to cover the hurricane without mentioning the role of climate change to make such events more likely. And that is what has happened — huge attention is devoted to hurricanes without uttering the words “climate change.”
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How does climate change affect severe storms? One influence is easy. Sea-level rise raises the baseline onto which a storm surge is added, increasing the coastal flooding of any storm. More generally, climate change affects the atmosphere and global meteorology so that severe storms are more likely. In particular, warmer air holds more water vapor, so rainfall events generally release more rain. Also, warmer ocean surface waters can increase the power of hurricanes with greater peak wind speeds, greater storm surges, and more rainfall.
Climate observations over the past several decades have indicated that hurricanes have become more powerful. We have also observed that the average rainfall event produces more intense rainfall.
In a study of Hurricane Harvey that flooded Houston in August 2017, professor Kerry Emanuel of MIT used a computer model to compare the probability of getting the rainfall from Harvey in a climate of the recent past and in the future. He estimated that Harvey’s rainfall was about six times more likely in 2017 than it was in 1981-2000, as a result of climate change that has already happened. Under a scenario in which climate change is not addressed, it becomes about 18 times more likely by 2081-2100. These studies are now becoming more common and accepted in climate science.
Similarly, if taking steroids makes a baseball player hit more home runs, we cannot say that any single home run is caused by the steroids. But we can say that the steroids make a home run more likely in any at-bat. Climate change is like putting our weather on steroids.
This discussion focuses on the changing meteorological hazard from climate change. We are also changing our vulnerability to these hazards through the ways we develop the coast, and in that way we also affect the damages of hurricanes.
So as Hurricane Florence approaches, do all the things we’re doing to get ready. And the press should do what it does — inform people to stay safe, send windswept reporters to the coast, and assess damage.
But we should also be aware of, and the press should talk openly and responsibly about, the roles of climate change in making events like Hurricane Florence more likely or severe. That climate change is happening now and impacts our lives. That climate change will continue to get worse. And that we know good ways to solve it.