Flood damage would double without coral reefs

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

Coupled with projected sea level rise driven by global warming, reef decline could see flooding increase fourfold by century's end, they reported 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 dollars, the team calculated.

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

“Unfortunately, we are already

Coral reefs serve as natural, submerged breakwaters that reduce flooding by breaking waves and reducing wave energy. Michael Beck, lead scientist for The Nature Conservancy research and environmental group

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 told AFP.

Not all coral reefs are declining, and reefs can recover from bleaching, overfishing and storm impacts, Beck noted.

“But the overall pattern of signficant losses across geographies is clear.”

Much of the world's 71,000 kilometres of coastline with shallow reefs — concentrated in the tropics — 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.

A marine heatwave in 2016, for example, killed off nearly 30 per cent of Australia's iconic Great Barrier Reef.

Damage from yet another bout of destructively warm water in 2017 has yet to be assessed.

Global coral reefs risk catastrophic die- offs if Earth's average surface temperature increases two degrees Celsius above pre- industrial levels, earlier research has shown.

The 196- nation Paris Agreement seeks to cap global warming ‘ well below' that threshold, but the planet has already warmed by more than 1 degrees Celsius.

Combining coastal f looding and economic models, the new study calculated — country by country — the value of coral reefs as a barrier against stormrelated wreckage.

Globally, seaside f looding is estimated to cause nearly US$ 4 billion dollars ( 3.4 billion euros) a year in damages.

With the erosion of the top metre of coral reefs worldwide, that figure rises to US$ 8 billion, Beck and his colleagues found.

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

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

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

— Reuters photo File photo show corals at the Great Barrier Reef. The world’s largest coral reef – under threat from Australia’s surging coal and gas shipments, climate change and a destructive starfish – is declining faster than ever and coral cover could fall to just 5 per cent in the next decade, a study shows.