Wednesday, August 29, 2018

Far-Sighted Adaptation to Rising Seas Is Blocked by Just Fixing Eroded Beaches

June 2016’s devastating storms damaged beachfront homes on Sydney’s northern beaches. Some are calling for a seawall to be put in place. (Photograph Credit: Dean Lewins/AAP) Click to Enlarge.
Coastal communities around the world are struggling to adapt to rising sea levels and increasingly severe coastal storms.  In the United States, local governments are making investments to reduce those risks, such as protecting shorelines with seawalls, “nourishing” eroded beaches by adding sand and rerouting or redesigning roads and bridges.

In the short run, spending public money this way is economically rational.  But in the long run, many people who live near coastlines will probably have to relocate as seas continue to rise.

We have studied this problem by combining insights from our work in economics, coastal geomorphology and engineering.  As we have explained elsewhere, short-term actions to adapt to coastal flooding can actually increase risks to lives and property.  By raising the value of coastal properties, these steps encourage people to stay in place and delay decisions about more drastic solutions, such as moving inland.

Keeping millions in harm’s way
According to recent estimates, a 1-foot increase in sea levels will put about 1 million people in the United States at risk, and 3 feet will threaten about 4 million people.  Global sea levels currently are projected to rise 0.5 to 2.1 feet by 2050 and 1.0 to 8.2 feet by 2100.

As we see it, market forces and public risk reduction policies interact in unexpected ways, reducing incentives for communities to make long-term plans for retreating from the shore.  Nourishing beaches and building seawalls signal to individuals and businesses that their risks are lower.  This makes them more likely to build long-lasting structures in risky areas and renovate and maintain existing structures.  As a result, their property values increase, which reinforces economic and political arguments for more risk-reduction engineering.

Read more at Far-Sighted Adaptation to Rising Seas Is Blocked by Just Fixing Eroded Beaches

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