In the US, about 16% of the immediate coastline (within 1km of the shore) is classified as “high hazard” area. These coastlines are home to 1.3 million people and US$300 billion worth of residential property.
Millions under threat
Sea level rise is predicted to increase the amount of highly threatened people and property by 30-60% by 2100.
A recent study found that 147-216 million people – more than a quarter of them in China – live on land that will be below sea level or regular flood levels by the end of the century.
Responding to a harsher nature
To minimize the potential economic and social losses, governments and other organizations are investing in infrastructure and developing management plans to respond and adapt to these hazards.
The traditional approach has been to construct levees and seawalls (so-called “grey” infrastructure). But these are expensive to build and maintain and often have consequences for the benefits that natural systems provide to people.
Ecosystems as our line of defense
Recently, interest has increased in “green infrastructure” investments, such as restoration of coastal habitats – wetlands, coastal forests, mangroves, seagrass meadows, coral and oyster reefs.
The aim is to protect people and property while improving quality of life by maintaining the full suite of benefits these ecosystems provide.
Focus on the U.S.
In the aftermath of Hurricane Sandy, which devastated the northeast US in October 2012, the US government is investing millions of dollars in coastal defence projects along the Eastern Seaboard.
These include restoring oyster and wetland habitats in New York and combining natural and engineered strategies for protection in Louisiana.
In 2013, the Natural Capital Project mapped the entire US coast to identify where green infrastructure has the greatest potential for reducing risk from coastal hazards now and in the future.
On a national scale, the number of people most exposed to hazards can be reduced by half if existing coastal habitats remain fully intact. Regionally, coastal habitats defend the greatest number of people and total property value in Florida, New York and California.
Grave risks globally
In other parts of the world, coastal defence planning has slowly begun to incorporate ecosystems alongside physical structures. Many poor coastal communities in countries like the Philippines, Indonesia and small island developing states face grave risks of hurricanes, tsunamis and sea level rise.
These communities largely depend on fishing for their food and income: if their fisheries are in poor health, it is hard for them to bounce back from disaster.
Multi-stakeholder efforts in these countries are combining community-based and large-scale initiatives to restore natural habitats, to both strengthen fisheries and help buffer coastal communities from floods and storms.