Swim out into the turquoise waters of the Caribbean, just beyond where the sandy sea floor gives way to massive rock formations, and a decades-long transformation has become apparent. Where a vibrant coral reef should be, there is a vast, colorless surface of almost nothingness.

Years of overfishing, boating and environmental degradation are causing coral reefs in the Caribbean—and around the world—to disappear. The erosion threatens not just fish and marine life that are supported by coral ecosystems, but a vast tourism economy that the National Oceanic and Atmospheric Administration (NOAA) says translates into a nearly $30 billion boost to the global economy.

The United Nations and conservation groups have sounded the alarm about the ecosystem's failure and its ripple effects, which include the mass extinction of thousands of species of animals.

"Coral degradation is a global problem," said Luis Solorzano, executive director at The Nature Conservancy, a nonprofit organization working in more than 35 countries and operating more than 100 marine conservation projects.

"Coral degradation is a global problem."

"Coral reefs help protect coastlines, which include coastal communities, hotels and other investments, from storms," Solorzano said. The stony substance secreted by millions of tiny animals minimizes the force of sea waves and helps protect an estimated 200 million people in islands and coastal states from storms and rising sea levels, according to researchers at Stanford University.

St. Martin's conundrum

In the turquoise waters off St. Martin, just out of reach from the sandy beach, a towering elkhorn coral comes into sight. A few fish can be seen huddling around its shadow, darting into the dark at signs of danger. Private boats and Jet Skis are frequent visitors.

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The vibrant scene, teeming with life, belies the fact that St. Martin's shores are actually locked in a life or death struggle.

In a study last year, Stanford scientists estimated that up to 60 percent of coral reefs around the world have been wiped out since the Industrial Revolution. There are indications that things could be getting worse in the Caribbean -- recent studies show the region may have lost 80 percent of its coral reefs.

Local economies, noted NOAA, "receive billions of dollars from visitors to reefs through diving tours, recreational fishing trips, hotels, restaurants, and other businesses based near reef ecosystems."

St. Martin is a third the size of Washington, D.C., and about 200 miles east of Puerto Rico. In the 1960s, it experienced a tourism boom that created "long-term degradation" of its corals, according to a recent study by the American Museum of Natural History.

Fast forward to now, and St. Martin's economy is so heavily reliant on tourism that the service industry makes up 84 percent of its gross domestic product, and 85 percent of the labor force is employed by the tourism industry, according to the Central Intelligence Agency's World Factbook. That reliance on tourism by St. Martin and other Caribbean islands, is hastening the demise of the ecosystem.

If tropical reefs and other ecosystems are destroyed, the oceans could lose $1 trillion in economic value "by the end of the century," according to a study published by Scientific American last October. For businesses that depend on tourist dollars, and for people whose income depends on those businesses, there is yet another storm gathering.

Flood insurance

In the U.S. alone, for example, there are 5.9 million flood insurance policies, with $1.3 trillion in total property exposure, according to insurance data by the Federal Emergency Management Agency. With coral reefs disappearing, the risk to coastal properties—and the sums it takes to safeguard them—is rising.

Protecting coral reefs "will become even more valuable in the future, as climate change results in more severe—and in some places, more frequent—weather events like hurricanes," said Solorzano.

Special interest groups and the need for cooperation among different nations have slowed coral conservation efforts, but in the Caribbean, for instance, that seems to be changing.

The Nature Conservancy is helping to lead an initiative to triple the coverage of marine habitats by 2020 through cooperation with nearly a dozen governments in the Caribbean. Other organizations, like the Nature Foundation St. Maarten on the island of St. Martin, have started coral nurseries with the hope to return them to their natural habitat.

Coral growth, however, is a slow process. In St. Martin, for instance, where a piece of the sea was turned into a marine park about five years ago, the American Museum of Natural History study could not yet see an "appreciable increase in coral cover since the establishment of the park." So might it be too late to save the coral?

"We are optimistic that corals are resilient and that we can help bring them back in the Caribbean and globally," said Solorzano, who thinks supporting reef-friendly businesses and practicing responsible diving, snorkeling and boating are a few things consumers can do to help.

"Ask the fishing, boating, hotel, aquarium, dive or snorkeling operators how they protect the reef," he said, and "do not touch the reef or anchor your boat on the reef."

A world without corals would not only have economic and social costs, added Solorzano, but "our planet would be a very sad place."