Attack of the extreme floods
On 8 September 2017, Thomas Wahl checked in at London’s Gatwick Airport for a nearly-empty flight to Orlando, Florida. A coastal engineer at the University of Central Florida, Wahl knew what was heading for his hometown: category-5 Hurricane Irma, which had already battered much of the Caribbean. He got on the plane anyway. “It was me, the pilot and a few Disney tourists who just didn’t care,” he says.
Irma’s heavy rains and powerful winds killed dozens of people across Florida. For Wahl, who rode out the storm in his family’s one-bedroom apartment, the experience was a rare chance to witness first-hand a phenomenon he has long worried about: extreme sea levels — what happens when storm surges, high tides and waves combine.
Extreme sea-level events can send water pouring over coastal barriers, swamping people’s homes and drowning crucial infrastructure. They’ve happened, for example, in New Orleans in Louisiana and the surrounding region — still recovering from more than US$100 billion in damages caused by Hurricane Katrina in 2005 — and in Jacksonville, Florida, where Irma swamped parts of the city under 2 metres of water, trapping residents and closing bridges and the city’s international airport.