State of the Coast: The Islands
ABOVE: The Islands of Martha’s Vineyard and Nantucket were formed by retreating glaciers that left mixed sediment deposits in their wake. These simplified USGS geology maps show the unique composition of each island divided into three broad categories based on the type of deposit: beach and dune, coarse stratified deposits, including glacial outwash material, and glacial moraine deposits, which contain till, and coarse stratified deposits. This graphic also shows island vulnerability to the natural processes of erosion due to the nature of their landscapes. Sandy beach and stratified glacial outwash deposits along the coastlines are extremely vulnerable to erosion through wave action and large storm events. Meanwhile, glacial moraine deposits of mostly soil and rock, which typically form the higher elevated terrain, are more stable and less prone to erosion. While many factors are at play including lack of intense development pressure and orientation to storms, and less wave exposure than south- and east-facing coasts, the west coast of Martha’s Vineyard may be less vulnerable to erosion due to its glacial moraine footprint.
Generations of Martha’s Vineyard, Gosnold (Elizabeth Islands), and Nantucket inhabitants understand that oceanfront landscapes are among the most dynamic, changing with winds, seasons, storms, and tides. The Islands have been buffeted for centuries by powerful tempests, from early floods that cut them off from the mainland and the Great Hurricane of 1635 to winter storm Riley (March 2018) and Tropical Storm Isaias (August 2020).
Today, these enduring and beloved places face the intensifying and accelerating impacts of climate change — ocean warming and acidification, flooding from sea level rise, and stronger storms and wave energy. These are unprecedented threats to all that exist on the shore, and they make clear that we need to make smart choices today about how to respond.
We want to continue to live, work, and play on the shoreline, as we have for years. For some people it may feel like climate change is too enormous to confront, and resources to respond to it too scarce.
And yet…
If you know the Vineyard or Nantucket, you’ve likely experienced downtown areas and access roads flooded, harbor areas inundated, ferries canceled, water supplies threatened, and homes damaged or lost. You’ve seen beaches narrow from Edgartown to Siaconset, salt marshes shrink, barrier beaches breached, and estuaries and salt ponds threatened. Consider:
SINCE 1887 Martha’s Vineyard and Nantucket combined have lost 3,295 acres of coastal areas, or about 5.1 square miles due to erosion — roughly the size of Aquinnah, or about 2,500 football fields [CIT. 5]. Based on a review of historic maps, affected coastal areas largely appear to be beaches, dunes, and coastal banks.
BY 2050 Nantucket could lose nearly 569 acres of high salt marsh — an area 11 times as big as Boston Common [CIT. 2] — and 50 acres of total marsh. Menemsha docks could be underwater at high tide every 5 1/2 days [CIT. 15].
LESS THAN 10% of Martha’s Vineyard remaining land is considered available for development, while only a reported 8.6% is available for development on Nantucket [CIT. 16], presenting a challenge for retreat from rising seas and erosion.
NEARLY 800 STRUCTURES — including homes, businesses and infrastructure — are at risk of being lost by 2050 to erosion on land with a total appraised value of more than $4.6 billion, FEMA data shows. More than 44 miles of roads on both Islands are also at risk.
ROUGHLY 900 STRUCTURES on Martha’s Vineyard and Nantucket may experience daily flooding from tides in 2050, given an expected increase in sea level of more than 2.5 feet.
We may have only 10 to 20 years before climate change forces our hand. Do we adapt and accommodate change, or resist it? Do we avoid impacts or accept loss? Managing expectations now for the future and leveraging short-term adaptation can act as a bridge to transformational change.
WHAT IS STATE OF THE COAST?
““There are really, truly magic things that can be done if you think about what it is to live with water instead of fight against it.””
Executive Director of ReMain Nantucket
Our annual report, now in its second year, is an analytical and qualitative assessment of coastal conditions in Massachusetts, region-by-region. This year’s focus on Martha’s Vineyard, Nantucket, and the Elizabeth Islands (Gosnold) offers a glimpse at on-the-ground techniques and future-facing opportunities to create more resilient and healthier coasts. Most of the data is based on High Sea Level Rise projections, to be consistent across all levels. (Please see citations for more detailed information.)
The report is a guiding resource that can stimulate discussion, action, and collaboration among public officials, conservation partners, residents, and others. Designed to be both information-rich and highly visual, graphics include a coastal matrix and beach erosion chart offering a visual comparison of community impacts, along with maps of flooding impacts and illustrations explaining coastal processes.
WHY US?
As the largest private coastal landowner and conservation organization in Massachusetts, The Trustees has witnessed firsthand the widespread effects of climate change up and down the coast, with some of the highest erosion rates in the state on the Vineyard and Nantucket.
We are in a unique position to share a long-term perspective that speaks to our mission, values, and philosophy — and underscores the urgent need for new coastal strategies. We see this report as a framework for conversation, partnership building, and proactive island-wide strategies in the next 5, 10 and 20 years. Calls and meetings with local stakeholders reinforced our view that now is the time for collaborative, forward-looking adaptations to accelerating climate change.
The report highlights two significant climate-related hazards — sea level rise and coastal storms. Both are anticipated to accelerate after 2050 with widespread effects on coastal areas. We need to start thinking now about how to transform crisis into opportunity.
Formed by retreating glaciers, the diverse shorelines of Martha’s Vineyard and Nantucket face different impacts, and their edges are being constantly redefined. As such, they present unique opportunities for the Islands to innovate and test potential solutions. In other words, we believe these frontline communities can be frontrunners, developing resiliency strategies and taking actions that may serve as models for the rest of the world
THE MAIN CHALLENGES AND OPPORTUNITIES
As Islanders know, and our latest data indicates, challenges are everywhere:
BEACH EROSION will accelerate, with sand moving offshore and alongshore, overwashing beaches, and shorelines narrowing.
WITHOUT ROOM TO MIGRATE INLAND many salt marshes will turn into tidal flats and open water.
SIGNIFICANTLY ACCELERATED FLOODING of coastal homes and businesses, transportation networks, and critical infrastructure may require short-term adaptive design and relocation.
COASTAL BANKS may erode more rapidly, helping to nourish nearby shorelines with much needed sediment deposits, but also jeopardizing structures and hidden cultural and prehistoric resources.
HABITATS, which play critical roles in sustaining island ecosystems and economies, may continue to decline and degrade unless they are restored and managed in sustainable and innovative ways.
““We have to look at the common good as opposed to our individual interests in order to make this all work.””
for Martha's Vineyard
Island communities have already begun projects on the ground, from living shorelines to elevated structures. Several partnerships between island communities have been forged, and two new island-wide, climate-focused positions filled. This is encouraging, but many climate-related projects are in the planning phase, and more needs to be done. Another challenge is that islands are finite spaces — limiting options for retreat. After all, adaptation and retreat require having somewhere to adapt or retreat to.
It will not be enough to craft solutions parcel by parcel, or town by town. Each island as a whole — and the Islands together — must be considered, from discussing whether interior uplands can serve as refuge for vulnerable areas and people to targeting the places with the greatest chances for resiliency. Self-reliant by nature and necessity, Islanders must now look outward to one another — and beyond — to conserve and protect these fragile landscapes. What is needed now is transformative innovation and broad collaboration.
WHAT YOU CAN DO TO HELP
This is a call to be imaginative and forward-thinking. Making strategic choices and sacrifices, educating our communities, advocating for change, and engaging as stakeholders and volunteers will go a long way toward creating models of resiliency that other places will want to follow.
Only by acting together can Martha’s Vineyard, Nantucket, and Gosnold — among the most treasured and iconic places in the world — prepare to confront the turbulence that lies ahead.
This conceptual illustration, based off the Bruun Rule, illustrates how sea level rise can result in erosion to sandy shorelines. The Bruun Rule does not include additional factors contributing to beach erosion, including but not limited to storms, changes in the wave environment, limitations on sediment supply, and the movement of sand by near-shore ocean currents.