HurricanesIrma spared America, but still had a big effect on it

“LIMITED menu, cash only!” said the owner of Luna Rosa, a seaside restaurant that opened for business on September 11th, hours after Hurricane Irma stopped lashing Delray Beach on Florida’s eastern coast. Police limited access to those who could prove they lived along the shoreline road, which was cluttered with debris, uprooted palm trees and fallen power lines. Running on its propane-fuelled generator, Luna Rosa served an early lunch. Business at the bar in particular was brisk. On the beach, just across the road, intrepid surfers revelled in the churning waters left behind by Hurricane Irma.

Irma’s landfall was preceded by one of the largest peacetime evacuations in America’s history. Around 6.5m people were ordered to move by the state government, including 650,000 in Miami-Dade County, Florida’s largest (a small fraction obeyed). Yet thanks to Irma’s unexpected path, Miami was spared the worst of the flooding. Some evacuees found themselves in areas on Florida’s west coast that were hit more severely.

Deciding whether or not to evacuate is tricky, in particular for the frail and elderly. A botched evacuation of Houston ahead of Hurricane Rita in 2005 left 90 dead as they succumbed to heat exhaustion during traffic jams on highways. The panic was due to the carnage wrought by Hurricane Katrina earlier that year, which had caused the deaths of some 1,400 mostly old, poor and black residents in New Orleans.

Irma disrupted most of Florida’s power lines. By nightfall on September 11th two-thirds of Florida’s 10.5m homes were without power. As the hurricane moved north, lights went out in another 1m homes in Georgia. Getting them back on could take weeks, according to the power companies. The disruption equals the record set by Hurricane Sandy in 2012, which left 8m homes without power for an average of eight days.

The shifting of America’s population to coastal communities, where 39% of the population live, means Americans are more vulnerable to rising tides. One in 12 lives in a home that can expect a 1% chance of flooding in any given year, according to data published in the Annals of the American Association of Geographers in June. Urban development on floodplains slowed between 2001 and 2011, though not in Manhattan and Miami. Around 15% of Manhattan and 40% of Miami are in flood-risk zones.

Miami’s seas have risen ten inches (25cm) over the past 100 years which, coupled with storm surges, makes it extremely vulnerable. Southern Florida can expect to be battered by a category-three hurricane (one with wind speeds over 95 knots, or 176km per hour) every five years. Though climate models predict global warming will not increase the frequency of storms, it will make them more severe. The collective sigh is likely to be one of only temporary relief.