Hurricane Beryl and other superstorms would pose a far greater threat without the presence of these iconic ocean animals.
Hurricane season has begun, and it’s off to a frightening start.
On Monday night, Beryl, the first named hurricane of the year, intensified into a dangerous Category 5 storm as it moved northwest toward Jamaica. Earlier in the week, it battered islands in the southeast Caribbean, including St. Vincent and the Grenadines, destroying homes and resulting in at least one fatality.
Expected to weaken later on Tuesday, Beryl has already set records. It is the earliest Category 5 storm ever recorded in the Atlantic, and it intensified at unprecedented speeds, leaping from Category 1 to Category 4 in under 24 hours.
Caribbean nations are particularly vulnerable to hurricanes, as these storms frequently lie in their paths. Hurricanes typically form in the Atlantic Ocean, west of northern Africa, and then travel westward toward the Caribbean and the Southeastern US.
However, Caribbean islands possess one of the world’s best natural defenses against superstorms like Beryl: coral reefs. These reefs, hidden beneath the waves, form a colorful patchwork surrounding many Caribbean nations. Functioning as natural seawalls, coral reefs help dampen waves and reduce flooding. Research shows that coral reefs help dozens of countries avert billions of dollars in flood damage each year, both in the Caribbean and globally.
The pressing issue now is that these lifesaving ecosystems are vanishing, driven by the same factors that make hurricanes more destructive.
An All-Natural Hurricane Defense System
Each piece of coral on a reef is a colony of tiny animals called polyps. These polyps build skeletons out of calcium carbonate, similar to how a snail grows a shell, forming the reef's structure. These coral skeletons are crucial in safeguarding coastlines during storms.
When waves crash into coral reefs, they lose energy. The bigger and taller the reef, the more wave energy it dissipates, much like how coastal cities use rock breakwaters to protect shorelines. Remarkably, studies show that coral reefs can dissipate more than 90 percent of wave energy. Reduced wave energy means smaller, slower waves that cause less damage when they reach the shore.
Even small changes in a reef’s height can significantly impact flood risk. Flood risk is often measured by the 100-year flood zone—an area with a 1 percent chance of flooding in any given year. If coral reefs in the US lose 1 meter of height, a study found, that zone would expand by 104 square kilometers (about 26,000 acres, nearly twice the size of Manhattan), putting approximately 51,000 more people at risk of flooding.
This natural service provided by coral reefs is invaluable. Across the US, including Puerto Rico and other Caribbean islands, coral reefs help safeguard the homes of more than 18,000 people and avert $1.8 billion in flood damage annually, according to a 2019 US Geological Survey (USGS) study. Globally, this number exceeds $4 billion.
“Without reefs, annual damages would more than double,” wrote the authors of the latter study, published in Nature Communications.
Caribbean nations benefit significantly from coral reefs and the damage they prevent. In the Nature Communications study, researchers ranked countries by how much flood damage coral reefs avert relative to their GDP. Eight of the top ten are Caribbean nations. Grenada, where Hurricane Beryl made landfall Monday, ranks third.
Vanishing Reefs
The financial and life-saving benefits provided by reefs make their loss particularly alarming. Unfortunately, reefs are rapidly vanishing, especially in the Caribbean’s warming waters.
The area of live hard corals on Caribbean reefs has decreased by about 80 percent in recent decades. In some regions, like the Florida Keys, the declines are even steeper. Compared to the 1970s, most Caribbean reefs are nearly unrecognizable today.
Elkhorn coral, a species known for its wave-weakening abilities, has been particularly affected. In the 1970s, it covered more than 30 percent of Caribbean reefs. By the 1980s, coverage had fallen to less than 2 percent, and it has likely declined even further since then.
Several human activities, such as coastal construction and fishing, have destroyed Caribbean coral, as have some natural threats like disease. However, the most enduring and existential problem is climate change.
Warming ocean water disrupts the relationship between coral and the symbiotic algae that live inside the polyps, causing the coral to turn white—or “bleach”—and starve. Bleached corals often struggle to survive other threats and may die.
This means climate change not only makes tropical storms more severe but also weakens our natural defenses against them. A warming ocean makes storms more dangerous not just because they intensify faster or drop more rain but also because, in places like the Caribbean, we’re losing the resilience that iconic ecosystems provide.
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