Lighthouses have guided mariners to safety for centuries. As technology changed from candle wicks amplified by Fresnel lenses to high-intensity bulbs, as shoals moved with the shifting sands, lighthouses have stood their ground.
Except when they have to be moved.
Cape Poge Light on Martha’s Vineyard has guided ships at sea since 1801. Multiple structures have housed the light, and since 1900 it has been moved four times, as the bluffs on which it sits have progressively eroded. In 1987, it was picked up by a helicopter and carried landward. Parts of the old foundation are now hundreds of feet offshore where one of us remembers playing as a boy.
It is not just lighthouses. In 2018, a nor’easter took a large chunk of Nauset Beach on Cape Cod away, along with part of Liam’s, a local staple for fried seafood and onion rings that had been around for decades. Alas, Liam’s didn’t get a helicopter airlift; it was replaced by food trucks that now border the parking lot in summer. And in Chatham, the National Oceanic and Atmospheric Administration closed one of its weather stations in March because it will soon fall into the sea. The irony is noted.
What is behind all of this demolition and relocation? Part of the problem is the cycle of shifting sands and beach erosion. But human-induced climate change is now driving the processes. Sea level has risen by about half a foot over the last 50 years, and at an accelerating rate, driven by both melting ice sheets and the expansion of seawater as it warms. As the ocean warms, it also provides more energy for destructive storms affecting coastal communities.
How should rising seas be managed? One approach is to harden our defenses by building sea walls and raising houses. This is expensive and temporary, and merely buys some time against the inevitable. Other approaches include natural ones like rebuilding coral reefs, mangrove forests, and wetlands that soften some of the energy from larger storms. Yet many communities cannot afford to make these investments.
Another approach is to consider “managed retreat” — or “planned relocation” — a rational approach to the problem from a societal perspective, but one that is difficult to implement at the individual level.
There are examples where managed retreat has been effective. In 2016, the federal Department of Housing and Urban Development granted $48 million to Louisiana to move the entire town of Isle de Jean Charles to a new location, 40 miles northward. Given that much of the community holds ancestry related to the Biloxi-Chitimacha-Choctaw tribe and has been located there for generations, the social and other nonfinancial costs of resettlement are also profound.
Some would argue that the easiest building to move is the one that isn’t built in the first place. But curtailing development is a political challenge to communities who welcome new development and investment. Others argue that retreat may someday be required, so why try to impose it now? Still others may argue that retreat and relocation will have to happen whether we try to “manage” or “plan” for it or not. And the scale of the problem is enormous. Where will we move Miami? Or Wall Street? Or the Seaport?
Managed retreat may not be the answer for every situation, but there is an urgent need for consistency between all levels of government, since currently they are often in conflict. Consider this: The Federal Emergency Management Agency uses tax dollars to subsidize the National Flood Insurance Program, which offers some protection to homeowners who could not otherwise buy insurance. But flood insurance encourages people to stay in harm’s way rather than invest in climate resilient solutions.
And, while policy makers on both sides of the political aisle are considering reforming the NFIP, federal flood insurance is difficult to change. In March, FEMA delayed the rollout of new rates for insurance that would have brought them in line with actual climate risks. The problem? Pressure from homeowners who didn’t want to pay higher premiums. Yet FEMA also supports buy-back programs, in which residents are presented with options that encourage relocation and preservation of their investment, with the property not being reoccupied. But those programs are small and could never cover all of the potential properties at risk.
President Biden’s infrastructure plan offers a generational opportunity to hit the reset button and invest in a more resilient and economically sustainable future. It can cover the costs of some of the critical investments needed to protect coastal communities. But we cannot simply build our way out of facing the rising seas. We need to make difficult decisions — and now, based on our knowledge of how and why the seas are rising — to encourage people and communities to adapt to the new, future coast, without promises of a perfect safety net that we cannot afford.
The Cape Poge Light is still there, telling seafarers to stay away from danger. If only we could understand the true meaning of its beacon.
Richard W. Murray is deputy director and vice president for science and engineering at the Woods Hole Oceanographic Institution. Daniel P. Schrag is a professor of geology at Harvard University and director of the Harvard University Center for the Environment.