The coming storm. Rising sea levels are forcing tough decisions about where and how to build near water

by Richard W. Murray & Daniel P. Schrag, Boston Globe Correspondents, February 17, 2013

DAVID L RYAN/GLOBE STAFF

Homes on Turner Road in Scituate were circled by water from the ocean during last week’s blizzard.

A FEW miles off the shore of Wellfleet are the remnants of the community of Billingsgate Island. Nearly 100 years ago, this was a typical New England coastal settlement. Yet today most people have never heard of Billingsgate; the community is simply gone. Sea level rise, storms, and erosion gradually made life on the island untenable, and people moved away. What was once a bustling community is now known as “Billingsgate Shoal.”

Billingsgate’s fate may be an omen for how some coastal communities will react to climate change. Today, we armor our shorelines with seawalls, raise coastal homes on pilings, and begin to plan for sea level rise. But as climate change continues, some people will simply move away. It will require serious public discussion, and tough choices, about when to fight and when to flee.

Climate change is raising the sea level — right now a little faster than an eighth of an inch per year. Most of that is due to the expansion of seawater as the ocean slowly warms. Within 30 years, we could see the high tide mark advancing upwards as fast as a few inches per decade.

The rise in sea level is gradually making coastal communities more vulnerable to flooding, but that is only a part of the problem. Climate change is also affecting the intensity of storms, increasing both their size and the amount of rainfall and snow they bring. The storm surge from Hurricane Sandy in New York City was 13 feet, 4 feet greater than from Hurricane Irene the previous summer, and far higher than what New Yorkers had ever experienced. Storms like last week’s — akin to the famed Blizzard of ’78 — are likely to become more frequent.

Consider Scituate, which owes much of its identity to its location by the sea. In 1976, there were about 40 homes built on pilings or in dunes on Peggotty Beach. Today there are fewer than 20. The Blizzard of ’78 destroyed 189 homes in Scituate and damaged another 402, and the Peggotty Beach community was hit hard. Local legend has it that a harbor seal was pulled out of the second story of a Peggotty house. Scituate and the surrounding communities of Marshfield, Cohasset, and Norwell, were once again slammed during the most recent storm, with power outages for nearly the entire region lasting more than four days. Hundreds of people were evacuated.

And it is not only homes along the beach that are in danger. In Boston Harbor, the storm surge from the ’78 blizzard came within 16 inches of topping the newly built Charles River Dam. Inland communities remain dependent on that concrete structure near the Museum of Science, which will eventually be incapable of stopping the advancing seas.

So what choices do we have? Immediately after a big storm, there is an urge to design new systems of protection, raise the sea walls higher, and make them stronger. This will be very expensive, and will provide only temporary protection. Seawalls cost around $10 million per mile. Some new sea walls may be necessary, but there are other options.

The best chance of success in minimizing the effects of sea level rise and increasing storm frequency and intensity will collectively involve industry, government, and individual citizens making challenging decisions that are likely to deviate from historical practices and assumptions. If such measures are not taken, then what happened to Billingsgate will not be an isolated story.

One strategy, complementary to constructing expensive sea walls, is to invest in resilience. This means acknowledging that flooding will occur, but making sure that after the storm recedes, our buildings can be pumped dry, and that we can recover with only minimal damage. This will require new building codes and some significant costs, although not the massive public investment required for large infrastructure.

Another option is a coordinated plan for managed retreat. After the Blizzard of ’78, nearly 10 homes on Peggotty Beach were purchased through a federal program and the land turned over to the Town of Scituate to be kept as open space. Such programs, teamed with enhancing environmental regulations to preserve open space and marshland buffers, can play a role toward managing the growing vulnerability of coastal communities. Insurance companies can also contribute to the solution, as many current policies encourage people to live in harm’s way.

Finally, we need to think differently about what we will pass along to future generations via inheritance; the family home by the ocean may in fact not be there to pass on. “Terra firma” is indeed not so “firma” after all. Just ask the descendants of a Mr. Henry Daniels, if you can find them. He was one of the last beacon keepers on Billingsgate Island.

Richard W. Murray is professor of earth and environment at Boston University and a selectman in Scituate. Daniel P. Schrag is a professor of geology and director of the Harvard University Center for the Environment.

http://www.bostonglobe.com/opinion/2013/02/17/after-blizzard-new-framework-for-coastal-settlements/BxEVNtmbojoHpzQIbMwJvM/story.html