Waves breaking on a coral reef crest off the coast of Hawaii.

Waves breaking on a coral reef crest off the coast of Hawaii.

Waves breaking on the Great Mesoamerican Reef.

An over-under shot shows soft and hard corals growing next to a mangrove swamp in the coastal waters at Kofiau. Kofiau is part of the Raja Ampat Islands of Indonesia located in the Coral Triangle, an area containing what may be the richest variety of marine species and corals in the world.

The lagoon coral reef and shore at Ant Atoll, Pohnpei, Federated States of Micronesia. Life in Micronesia has been shaped by the islands’ remoteness and the rich resources of their lands and seas.

Brandon Bourke of The Nature Conservancy dives under a breaking wave at the reef crest near Pengiun Spit withing Palmyra Atoll in the equatorial Northern Pacific.

Gray Angelfish among healthy corals. Shot in Exuma Cays Land and Sea Park, Bahamas.

Conservancy Marine Chief Kydd Pollack and Brandon Bourke dive under a breaking wave at the reef crest near Pengiun Spit withing Palmyra Atoll in the equatorial Northern Pacific. The Nature Conservancy and the U.S. Fish & Wildlife Service are partnering to protect the Atoll while the Palmyra Atoll Research Consortium is developing it as a center for scientific study.

Wave breaking over a healthy coral reef in Tumon Bay Marine Preserve, Guam, Mariana Islands

2014-06-03

Co.Exist

The Cheapest, Most Effective Way To Protect Coastal Cities From Storms? Natural Reefs

Build all the flood walls you want: Nature already found the best way to protect from growing storm surges and climate change. Bonus: They're also cheaper.

As coastal cities prepare for rising waters, they should keep in mind that sometimes natural solutions can be the most effective.

In a recent study, researchers found that coral reefs could dramatically decrease the effects of waves and storm surges made worse by climate change. In fact, they cut down on wave energy—a measure of the energy transferred in the ocean from wind to waves—by 97% At $1,290 per meter for restoration projects, coral is also significantly cheaper than other forms of protection, like artificial breakwaters, which break down to a cost of $19,791 per meter.

© Tim Calver for The Nature Conservancy

The study, published in Nature, is the first to look at how coral reefs can contribute to climate change mitigation and adaptation across the world's oceans. The researchers used data from 255 studies that gauged the link between coral reefs in the Atlantic, Pacific, and Indian Oceans and reductions in wave energy.

The three reef environments they analyzed—reef flat, reef crest, and whole reef—were all effective, with each dissipating 65% of wave energy, 86% of wave energy and 97% of wave energy respectively. They each also dramatically cut down on wave height.

© Jeff Yonover for The Nature Conservancy

While the researchers found that coral reef restoration is cheaper to implement than artificial protections against rising tides, they admit that a full cost-benefit analysis is still needed.

They write:

As living structures, reefs have the potential for self-repair and thus lower maintenance costs as compared with artificial structures, but reef restoration is still a comparatively new field. Most measures of reef restoration projects are limited to just the time period in which a project is constructed (that is, one funding cycle) particularly in developing countries where most reef restoration occurs. The addition of ecosystem benefits and considerations of maintenance costs in a full benefit:cost analysis would likely add to the relative cost effectiveness of reefs for coastal defence.

Maddeningly enough, coral reefs are deeply threatened by climate change. So in addition to restoration, anyone concerned about the future of coastal cities also needs to think about coral reef conservation.

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