Communities Retreat as Oceans Swell, Coasts Erode

Erosion, rising seas, ferocious storms and other coastal perils have prompted the resettlement of more than 1 million people worldwide, with an exhaustive new analysis highlighting an emerging migration crisis that’s worsening as global warming overwhelms shorelines.

Researchers scoured journal papers, government reports and news articles for examples of what experts call “managed retreat,” analyzing 27 rules, programs and decisions that have led to the abandonment of homes and homelands from Louisiana, New York, and Alaska to Thailand, Brazil, and Australia.

“For a long time, the instinct has been to protect everything in place,” said Miyuki Hino, a PhD candidate at Stanford who led the research, published Monday in the journal Nature Climate Change.  “It’s only recently that we’re seeing a significant increase in societies in various forms deciding that isn’t the right choice for them.”

Coastal communities facing worsening flooding are responding in different regions by raising roads, rebuilding sand dunes, restoring marshes, upgrading building codes and elevating houses.

Compared to those options for adapting to a harsher climate, each of which can be expensive, the prospect of abandoning developed land can be particularly painful, vexing and divisive.

“Large migrations in response to climatic shifts are well-documented historically,” said Solomon Hsiang, a University of California, Berkeley researcher who has studied how communities and climates interact.  He wasn’t involved with the new analysis. “It wouldn’t be surprising for populations to begin moving around today as climate change significantly affects livelihoods.”
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Seas rose 5 inches in the 20th century and are projected to rise by several feet this century. A Climate Central analysis in late 2015 concluded that high future warming rates would eventually submerge land currently home to more than 470 million people.

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