Nantucket

Winter storm Grayson might have had a genteel name, but it packed a punch in the winter of 2018. Floodwaters approaching three feet deep roiled Nantucket’s downtown streets, totaling cars, swamping homes and businesses, and surrounding Brant Point lighthouse.

Fast forward to June 2021, and all signs indicate that the island heeded the wake-up call. A year after Grayson, the community gathered for its first official resilience building workshop, which led to acceptance of an MVP and Hazard Mitigation Plan in 2019, and hosted a two-day workshop on Keeping History Above Water. Nantucket has since hired a full-time Coastal Resilience Coordinator and contracted an engineering firm to develop a comprehensive coastal resilience plan, expected to be finalized this fall. An updated harbor management plan and a sediment transport study for both harbors is planned to be undertaken in the next few years, among other initiatives. 

Organizations across the island — from the Nantucket Conservation Foundation, Land Bank, Land Council, and Preservation Trust to the Nantucket Shellfish Association, ACKlimate, and ReMain Nantucket, among others — are increasingly galvanized to raise public awareness and find ways to accommodate, protect or retreat. In a recent survey (Envision Resilience Nantucket Challenge Survey Report), more than 70% of residents and regular visitors said they are “very worried” about climate impacts. They know the challenges are great. 

To live on Nantucket is essentially to live on a boomerang-shaped beach, the dynamic remnants of a glacier’s retreat thousands of years ago. It makes for 81 miles of wondrous sandy shoreline, visited by thousands each summer. And yet the island’s greatest asset — a low-lying pristine coast, with glorious beaches — may also be its greatest liability. 

With a population of about 11,000 that swells more than fourfold in-season, the median home value is about $1.08 million and median household income more than $107,000, 2019 census data shows. But wealth is no match for water. Since the tide gauge was installed in 1965, the mean sea level in Nantucket Harbor has risen by approximately 8 inches [CIT. 20]. Seas may rise 2.62 feet around Nantucket by 2050, and 4.42 feet by 2070 [CIT. 1]. The highest point of the island is a mere 111 feet above sea level, just south of Sankaty Head Light. 

Climate change, or even a sudden severe storm, could dramatically impact the island’s natural and developed coast and its historic character as well as the outposts of Tuckernuck and Muskeget, which experience severe erosion. High tide flooding already impacts low-lying areas and downtown streets, even on sunny days. Roads have closed, and beaches have eroded along the south-facing shore, which is losing up to 15 feet per year [CIT. 5]. 

For a mere 48 square miles, Nantucket has much to protect and more critical infrastructure than most towns its size. At stake is its access to the mainland by multiple harbors, ferries, and an airport. At risk by 2050 is $2.6 billion in parcel values, according to FEMA data, plus historic resources, uniquely preserved architecture, and an economy reliant on global tourism and outdoors recreation. The island also harbors one of the greatest concentrations of rare and endangered species in Massachusetts [CIT. 17], from the New England blazing star to the Nantucket moth and northern long-eared bat. 

Over 50% of the County (including Tuckernuck and Muskeget) is protected and preserved, which leaves limited opportunities for retreat and requires a strategic realignment of resources among a wide range of landowners — as well as a leap of imagination. ReMain Nantucket’s Envision Resilience Challenge in June provided a sweeping exercise in what creative adaptation might look like: Floating piers and canals. Artificial reefs and barrier islands. Boardwalks as deployable barriers. Front lawns as detention basins. Sponge parks and marine gardens. And modular, mobile structures and vertical spaces that share space with nature, and let the waters in. 

As one of the event speakers noted, “It’s not one big fix, and we all go home happy. It’s a new way of thinking and living that will be with us and our children for a long time to come.” 

THE ENVISION RESILIENCE NANTUCKET CHALLENGE, a spring 2021 design studio run by non-profit organization ReMain Nantucket, tasked teams from design programs at five leading universities to reimagine the Nantucket harborfront using the latest sea level rise projections. Led by Carolyn Cox of the Florida Climate Institute, students worked with 24 local and regional advisors with expertise in a wide range of disciplines, from conservation and architecture to civil engineering and historic preservation, to identify threats, research solutions and propose adaptive designs. Their innovative models, presented to a jury in late April and the public in June, featured flip-up boardwalks, permeable surfaces, vertical buildings, and absorptive parks.

ABOVE: One team’s “Living with Water” proposal for a model residence along Brant Point’s Hubert Avenue creates an interconnected living and mobility network by using a layered system of shoreline hydro-ecology, dune restoration, elevated boardwalks, and yard space transformed into a retention pond circled by dense native plantings.

THE COSKATA-COATUE WILDLIFE REFUGE is a dynamic barrier beach system that has experienced natural erosion and accretion events over the last century. However, over the last century, the beach has experienced a net loss of 63 acres of sand and has migrated in a westerly direction because of its direct exposure to coastal processes. Looking to the future, Coskata-Coatue is likely to see continuous westward migration, overwash of dunes, and a narrowing of barrier beach in places due to sea level rise and erosion. Boston University researchers also found that breaches could occur in the future at certain locations [see circled areas on graphic] [CIT. 19].