The Caribbean has a defense system against deadly hurricanes – but it is disappearing

Hurricane season has begun, and it’s off to a scary start.

On Monday night, Beryl, the first named hurricane of the year, strengthened into a dangerous Category 5 storm as it moved northwest toward Jamaica. Earlier in the week, it hit islands in the southeastern Caribbean, including St. Vincent and the Grenadines, destroying homes and leaving at least one person dead.

The storm, which is expected to weaken later Tuesday, is already a record. Beryl is the earliest Category 5 storm on record in the Atlantic. It also intensified at a record speed for a hurricane earlier in the year, jumping from Category 1 to Category 4 in less than 24 hours.

Caribbean nations are particularly vulnerable to hurricanes, for the obvious reason that these storms often lie in their paths. Hurricanes typically form in the Atlantic Ocean, west of northern Africa, and then travel west toward the Caribbean and the southeastern United States.

But the Caribbean islands also have one of the best defense systems in the world against superstorms like Beryl. That system is hidden under the waves, it’s free, and it’s completely natural. They are coral reefs.

Indeed, most Caribbean nations are surrounded by a colorful patchwork of coral reefs, communities of living animals that function together as natural sea walls. These strong, rock-like creatures help dampen waves and reduce flooding. Research shows that coral reefs help dozens of countries avoid billions of dollars in flood damage each year, in the Caribbean and around the world.

The problem, more pressing now than ever, is that these lifesaving ecosystems are disappearing—for the same reason hurricanes are becoming more destructive.

Each piece of coral on a reef is actually a colony of tiny animals, called polyps. These polyps build skeletons from calcium carbonate, not unlike a snail growing a shell, that form the structure of reefs.

It is these coral skeletons that protect the shores during a storm.

Simply put, waves lose energy when they crash into coral reefs. The bigger and higher the rock, the more wave energy is dissipated, for the same reason that coastal cities use breakwaters made of rocks to protect the coastline. Amazingly, studies show that coral reefs can dissipate more than 90 percent of wave energy. Waves with less energy are smaller and slower and do not cause as much damage when they reach the shore.

Even a small change in the height of a cliff can make a big difference in risk. Flood risk is often measured by what is called a 100-year flood zone—an area in which the chance of a flood in a given year is 1 percent. If US coral reefs lose 1 meter of height, according to one study, that area in the US will increase by 104 square kilometers (or about 26,000 hectares, nearly twice the size of Manhattan), putting about 51,000 more people at risk of flooding . .

This service – which Coral Reefs provides for free – is worth a lot.

Across the U.S., including Puerto Rico and other Caribbean islands, coral reefs help protect the homes of more than 18,000 people and prevent $1.8 billion in flood damage each year, according to a 2019 study by the Service US Geological Survey (USGS). A slightly older study found that, globally, that number is more than $4 billion.

“Without reefs, annual damages would double,” the authors of the latest study, published in Nature Communications, has written

Caribbean nations are among those who benefit the most from coral reefs and the damage they prevent. IN Nature Communications The study, published in 2018, researchers ranked countries by how much flood damage coral reefs prevent, relative to their GDP. Eight of the top 10 are Caribbean nations.

Number 3 is Grenada, where Hurricane Beryl made landfall on Monday.

All the financial and potentially life-saving benefits that reefs provide make their loss all the more frightening. And we really are losing them, especially in the warm waters of the Caribbean.

The area of ​​hard living coral on Caribbean reefs has declined by about 80 percent in recent decades. In some regions, such as the Florida Keys, the declines are even steeper. Compared to the 1970s, most of the Caribbean’s reefs are almost unrecognizable today.

Elkhorn coral – a species that resembles plague horns, known for its wave-attenuating abilities – is particularly at risk. By the 1970s, it had grown to more than 30 percent of Caribbean reefs. By the 1980s, coral cover had dropped to less than 2 percent, a number that is likely to have declined further in the years since.

A variety of human behaviors have destroyed Caribbean corals, from coastal construction to fishing, as well as some seemingly natural threats, such as disease. However, the most enduring and existential problem is climate change.

Warming ocean water disrupts the relationship between corals and a type of symbiotic algae that lives inside the polyps. This disruption causes corals to bleach – or “bleach” – and starve. Bleached corals often have more difficulty surviving other threats and die.

This means that climate change is not only making tropical storms more severe, but may also weaken our natural defenses against them. And that’s an important, scary point: ocean warming makes storms more dangerous, not just because they’re intensifying faster or raining more, but because, in places like the Caribbean, we’re losing the stability they provide iconic ecosystems.

Update, July 2, 9:10 a.m. ET:This story was originally published on July 1 and has been updated with the latest information about Hurricane Beryl.