Sea Level Rise Affects Coastal Access

As a journalist, I have written a lot about the coast, and I am at work on my second book about coastal land use in an era of rising seas. So I was interested to read Wilko Graf von Hardenberg’s essay, “Our Bases Are Precarious!” (Issues, Winter 2025).

His discussion of how people have struggled to understand what is meant by “sea level” is rich, surprising, and fascinating. There is so much we don’t know!

On the other hand, as Yogi Berra’s famous saying goes, “You can observe a lot by just watching,” as I have learned at my home on Chappaquiddick, a small island off the larger island of Martha’s Vineyard, in Massachusetts.

For example, until recently, the three-car barge ferry that makes the 90-second voyage between “the big island” and Chappy has run reliably through good weather and bad, even when Hurricane Bob made a direct hit in 1991. Now, though, when the moon is full and the wind is from the northeast, the landing stages are often awash. You could drive through but you won’t. Nothing corrodes an undercarriage like salt water. So you plan grocery runs by the wind direction and the phases of the moon.

But there is another sea level issue—little-known but potentially very important—that cries out for more study, and more data: the fate of the so-called public trust lands along the nation’s saltwater coasts.

According to legal principles dating from the sixth century Roman emperor Justinian and descended to Americans via colonial-era British common law, certain elements of nature like the air, the seas, and “the shores of the seas” are covered by a public trust, a kind of easement that allows members of the public to use them. “Public trust” beaches are typically defined as the area seaward of the high tide line, the so-called wet beach. Frequent “No Trespassing” signs notwithstanding, people have a legal right to stroll these lands and, depending on the state, to fish, gather seaweed, hunt waterfowl, or even swim.

As coastal development increases, these lands can offer precious coastal access for many. But they are coming under threat as sea level rises and property owners build walls or other structures to protect their buildings. When rising seas reach this armor, the public trust beach is drowned.

Environmental activists argue that the wet beach must be allowed to shift inland to higher ground. And some jurisdictions already bar armor or even require the removal of structures that end up on public trust beaches. But everything depends on enforcement, which can be erratic. So the activists are suing. Recently, some have asserted that structures built years ago should be removed to allow the wet beach to emerge where it would naturally have migrated. But where, exactly, is that?

That is a good question for coastal geologists.

Cornelia Dean