Thu, Jun 14, 2018 - Page 6 News List

Flood damage to double without coral reefs: study


Loss of coral reefs around the world would double the damage from coastal flooding and triple the destruction caused by storm surges, researchers said on Tuesday.

Coupled with projected sea level rise driven by global warming, reef decline could see flooding increase four-fold by the century’s end, they wrote in the journal Nature Communications.

Without coral to help absorb the shock, a once-in-a-century cyclone would wreak twice the havoc, with the damage measured in the tens of billions of US dollars, the team said.

“Coral reefs serve as natural, submerged breakwaters that reduce flooding by breaking waves and reducing wave energy,” said Michael Beck, lead scientist at the Nature Conservancy and a professor at the University of California, Santa Cruz.

“Unfortunately, we are already losing the height and complexity of shallow reefs around the world, so we are likely already seeing increases in flood damages along many tropical coasts,” he added.

Not all coral reefs are declining and reefs can recover from bleaching, overfishing and storm impacts, but “the overall pattern of significant losses across geographies is clear,” Beck said.

Much of the world’s 71,000km of coastline with shallow reefs has been decimated by coastal development, sand mining, dynamite fishing and runoff from industry and agriculture. Coral is also highly sensitive to spikes in water temperature, which have become sharper and more frequent with climate change.

Global coral reefs risk catastrophic die-offs if the Earth’s average surface temperature increases 2°C above pre-industrial levels, earlier research has shown.

Combining coastal flooding and economic models, the study calculated — country by country — the value of coral reefs as a barrier against storm-related wreckage.

Globally, seaside flooding is estimated to cause nearly US$4 billion a year in damages.

With the erosion of the top 1m of coral reefs worldwide, that figure rises to US$8 billion, the researchers found.

“The topmost living corals will die and can break off very quickly,” Beck said.

The countries most at risk from coral reef loss are Indonesia, the Philippines, Malaysia, Mexico and Cuba, each of which could avoid US$400 million in damage per year if reefs are maintained.


Taiwan, Saudi Arabia, the US and Vietnam would also become significantly more vulnerable to flooding with severe coral erosion.

The researchers estimate that Taiwan would see 595 people flooded every year, the 16th most in the world, and would face US$1.83 billion in built capital damages from flooding over 100 years, the 13th highest among the nations studied, mostly concentrated in the southwest.

“When we consider the devastating impact of tropical storms in just the past few years — Hurricanes Irma and Maria, Typhoon Haiyan — the effects would be much worse without coral reefs,” Beck said.

Additional reporting by staff writer

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