Coral reef loss may double flood damages worldwide

LOS ANGELES: Rapid loss of coral reefs around the world would double the annual expected damages from flooding, and triple the costs from frequent storms, a study has found.


When coupled with sea level rise, flooding could quadruple, according to researchers at the University of California, Santa Cruz in the US.


The study, published in the journal Nature Communications, shows that coral reefs cut the cost of all flood-related damages around the world in half.

Coral reefs serve as natural, submerged breakwaters that reduce flooding by breaking waves and reducing wave energy.

The study compared the flooding that occurs now with the flooding that would occur on coastlines with coral reefs if just the topmost one metre of living coral reef were lost.

Without living coral reefs, the annual expected damages from flooding would double, increasing by $4 billion. The costs from frequent storms would triple, researchers said.

If coupled with sea level rise, flooding could quadruple. For the big 100-year storms, flood damages could increase by 91 per cent to $272 billion, they said.

"We built the best global coastal flooding model, and then we added reefs to estimate flood risk overall and the benefits provided by these habitats," said Inigo Losada from the University of Cantabria in Spain.

"This represents the first global application of a coastal protection model that probabilistically estimates risk and the benefits of coastal ecosystems," said Losada.

The countries with the most to gain from reef conservation and restoration are Indonesia, Philippines, Malaysia, Mexico, and Cuba; annual expected flood savings exceed $400 million for each of these nations, researchers said.

The US also receives many benefits from coral reefs (ranking 8th globally), with almost $100 million annually in direct flood reduction benefits, they said.

In addition to helping alleviate costs related to flooding, coral reefs also offer other economic benefits from tourism and fisheries.

Per capita, the study found that reefs provide the most benefits to small island states, including the Cayman Islands, Belize, Grenada, Cuba, Bahamas, Jamaica, and the Philippines.

In just the past few years, tropical storms such as Hurricanes Irma and Maria and Typhoon Haiyan have had devastating impacts, and the effects of such storms would be even worse without coral reefs, researchers said.

Reef habitats across the world have been significantly degraded and face growing threats from coastal development, sand and coral mining, destructive and excessive fishing, storms, and climate-related bleaching events, they said.