About 50 people heard how coastal resilience will impact the future of Falmouth during a public presentation held October 24. The natural resources committee of the League of Women Voters of Falmouth hosted the informational event at the Falmouth Public Library.
Charles T. McCaffrey, chairman of the Falmouth Coastal Resiliency Action Committee and Falmouth’s member of the Cape Cod Commission, presented his committee’s work on several funded research studies, including the Surf Drive Vulnerability Assessment. The study’s goal is to predict the locations of coastal flooding and to reduce damage to vulnerable infrastructure.
Erin Perry, deputy director of the Cape Cod Commission, introduced the Resilient Cape Cod project and an online coastal planner the commission has developed in partnership with several other groups, to explore the potential impact of sea-level rise at many points around the Cape, along with efforts to protect these areas.
Also in attendance were Richard Johnson, chairman of the league’s natural resources committee; selectwoman Susan L. Moran; and members of the Falmouth water quality management and coastal resiliency action committees.
To provide the scientific basis for the coastal changes, Mr. McCaffrey referred the audience to a special report last month from the United Nations Intergovernmental Panel on Climate Change on the ocean and cryosphere in a changing climate. The report can be found online.
“The ‘cryosphere’ is frozen water in the environment, so it’s the Antarctic, Arctic and Greenland,” he said. “The report indicates that ocean warming has more than doubled since 1993. Worst-case projections for global mean sea-level rise are higher than thought, and a two-meter rise by 2100 cannot be ruled out.”
Sea-level rise on the North Atlantic coast, the Cape’s shoreline, will probably be greater than in any other place in the world, Mr. McCaffrey said.
“It is likely to be worse in this part of the world because we’re also experiencing subsidence of the land. In the studies we’re doing we’re assuming four feet of sea-level rise by 2070,” he said, calling that estimate “high but conservative.”
Another important report is the November 2018 National Climate Assessment from the US government, which can be found at www.globalchange.gov, Mr. McCaffrey said.
“It was not interfered with in any way by the [Trump] administration. This is a solid study based on experts and science professionals in the federal government from a wide range of agencies, and they very clearly outlined the risk that exists for communities from sea-level rise,” he said.
Two reports from the now-defunct Falmouth Coastal Resources Working Group more than a decade ago are still valid, and their findings will inform the recommendations of the current coastal resiliency action committee, the chairman said.
Over the past two years that newer committee has sought to understand how natural forces such as erosion will affect changes in the physical forms of the landscape that will, in turn, affect differing levels of flooding.
“For things like roads being inundated, the ‘bathtub model’ [in which the water-level rise does not depend on the changing character of the landscape] works fine, but as we need to design and redesign our shoreline, we need more sophisticated data,” Mr. McCaffrey said.
In early December the committee will host a public information forum on the Surf Drive Vulnerability Assessment. The date and location are still being determined.
“In terms of adaptive management, we could raise Surf Drive and that would protect it for five years, but after five years you need something more radical. We need to change our approach to resiliency depending on the extent of the risk, and the risk will change and increase over the years, so it may make sense to do something today that does not make sense in the long term,” Mr. McCaffrey said.
Decision makers must weigh the costs and benefits of short-term actions against their long-term effectiveness, he said.
“Many of our roads have a questionable life without major expenditure to make them into causeways, raise them, or to expand bridges. In some cases that may be worthwhile; in some cases that may not be,” he said.
Any approach to coastal resiliency in Falmouth “is going to rely on sand,” which researchers call an area’s “sediment budget,” and understanding how and where the sand will move and how and where it should be replenished, Mr. McCaffrey said.
On the policy side, the coastal resiliency action committee will work with the planning board in the next year to strengthen bylaws that relate to coastal resiliency.
“We have 95 miles of shoreline in Falmouth, and it’s characterized by very distinct communities, both naturally and in terms of development. We need to think about how we make the communities resilient, particularly those that are low-lying and are threatened with the loss of a significant number of homes, which may be inevitable,” Mr. McCaffrey said. “What mechanisms do we have to allow a community to adjust and redevelop in ways that maintain the community’s character?”
Finally, Mr. McCaffrey questioned how Falmouth will maintain its AAA bond rating given that the town has $1 billion of infrastructure at risk from climate change.
After his presentation Ms. Perry spoke about the Cape Cod Coastal Planner, an online tool of the recently completed Resilient Cape Cod project that was funded through a grant from the National Oceanographic and Atmospheric Administration.
The interactive, geographic-information-system-based planner, which can be found at www.capecodcoast.org, can assist communities in making difficult decisions related to the coastal impacts of sea-level rise, storm surge and erosion, Ms. Perry said.
“The planner is a communication and decision support tool that illustrates the costs and benefits of various adaptation strategies,” she said, noting it allows a user to compare scenarios—for example, taking no action versus taking a specified action—along any segment of the Cape Cod shoreline.
Ms. Perry demonstrated how the planner combines information on resiliency strategies with socioeconomic analyses and GIS data layers, including the flood zones and the mean high tide line, in one place.
During the question-and-answer period Stephen B. Leighton, a member of the water quality management committee, asked the presenters about the effects of the increased frequency and severity of storms in Falmouth due to climate change.
“Have you thought about the political, economic and legal implications of using to your advantage the wiping out of a huge number of residences, or would you propose to just rebuild them and have the same problem to deal with?” he asked, adding that catastrophic storms will likely “come long before the time scales of the sea-level rise.”
Mr. McCaffrey agreed that there will will be more storms and that the storms will be more severe.
“We should be doing this even if there were no climate change because we were always subject to major storms and we never prepared for them until now, until we heard that it was going to get worse,” he said.
In low-lying areas that will likely be permanently inundated in the next 50 years, the main strategy to protect buildings has been to elevate them and to make them stronger.
“That doesn’t do you any good if there’s going to be two feet of water at low tide around your house and there isn’t any road access,” he said.
A “rebuild” strategy might not be the best option in those low-lying areas, whereas rebuilding might make more sense at higher elevations that are hit by a major hurricane or 100-year storm, Mr. McCaffrey said.
The increasing incidence of five-year or 20-year storms will begin to change the development patterns in Falmouth, Mr. McCaffrey said.
“Smaller flooding will begin to happen so frequently that it will be a disincentive to development. If you get flooding in your yard every month, that’s going to begin to change your perception. It doesn’t mean your house is going to be [destroyed], but you’re not going to want to live there,” he said.
“We need to develop mechanisms, mainly in the land-use or planning area, on how we encourage redevelopment so that areas that are uninhabitable or that people don’t want to inhabit can be removed in ways that are accessible to our legal and cultural system. This is not impossible.”