Coral reefs may offer a cost-effective alternative to artificial coastal defences in many parts of the world, suggests a study published in Nature Communications. The findings suggest that nearly 200 million people who live in coastal areas could receive risk reduction benefits from reefs or, in contrast, bear the cost if reefs are lost or degraded.
Social, ecological and economic loss associated with inundation and flooding from rising sea levels and storms are expected to increase with worsening climatic change. Huge investments are being made in coastal hazard management, with the cost of dikes alone predicted to increase to between 12-71 billion US dollars per year by the year 2100. It is widely agreed that cost-effective, nature-based solutions are needed to help relieve this financial burden.
Michael Beck and colleagues assess the potential role and effectiveness of coral reefs as a form of natural coastal defence. The team perform a global synthesis and analysis of published records and show that coral reefs can dissipate up to 97% of the wave energy that would otherwise impact shorelines. They find that coral reefs can deliver wave reduction benefits similar to or greater than artificial structures, such as low crested breakwaters, at a significantly lower cost in tropical environments. However, the authors warn that reef restoration is still a comparatively new field, with many gaps in our understanding.
The authors conclude that coral reefs provide a first line of defence for millions of people at risk from rising sea levels and increased storminess, yet unless global action is taken, this valuable defence could collapse under growing threats from coral mining and coastal development.
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