Coastal perilRising seas: to keep humans safe, let nature shape the coast
Even under the most conservative climate change scenarios, sea levels 30cm higher than at present seem all but certain on much of the U.K.’s coast by the end of this century. Depending on emission scenarios, sea levels one meter higher than at present by 2100 are also plausible. The knee-jerk reaction to sea level rise has traditionally been to maintain the shoreline’s position at all cost, by building new flood defense structures or upgrading old ones, but this traditional approach of “grey” engineered sea defenses locks society into ever increasing costs of replacement and maintenance. The alternatives are “nature-based solutions” to coastal flooding and erosion, which work with natural processes to reduce flood risk and incorporate ecosystems into flood defense.
Even under the most conservative climate change scenarios, sea levels 30cm higher than at present seem all but certain on much of the U.K.’s coast by the end of this century. Depending on emission scenarios, sea levels one meter higher than at present by 2100 are also plausible.
The knee-jerk reaction to sea level rise has traditionally been to maintain the shoreline’s position at all cost, by building new flood defense structures or upgrading old ones. More than US$10 billion per year is already spent worldwide on “grey” infrastructure such as concrete walls and levies to protect against coastal flooding. Equally large are the costs incurred when coastal defenses fail.
The United Nations has called on governments to relocate public facilities and infrastructure from flood-prone areas, while the U.K. Climate Change Committee has urged the government to “set out how and when the hard choices that have to be made on the coast are going to happen”.
Letting nature decide
The traditional approach of “grey” engineered sea defenses locks society into ever increasing costs of replacement and maintenance. The alternatives are “nature-based solutions” to coastal flooding and erosion, which work with natural processes to reduce flood risk and incorporate ecosystems into flood defense.
Rather than seeing the coast as a static line, these alternatives rethink the coastlines as zones with valuable habitats such as beaches, dunes and wetlands that act as carbon stores, places for recreation and natural buffers against the waves.
Schemes such as the Wild Coast Project at Wallasea on the U.K.’s east coast have restored salt marshes where land had been reclaimed for agriculture years earlier. The tide and waves now regenerate salt marsh where it had been embanked and drained. If designed well, such schemes create new habitat which can reduce the height and intensity of storm surges and lower flood risk.
