The famous islands of Martha's Vineyard and Nantucket in Massachusetts are facing serious impacts from rising sea levels and more powerful coastal storms driven by climate change, a new environmental report released Wednesday warns.
The "State of the Coast" report by the Trustees, a prominent Massachusetts conservation group, says the popular tourist destinations off Cape Cod risk losing hundreds of acres of marshlands to flooding and billions of dollars in coastal homes, buildings and infrastructure to erosion.
What's more, roughly 900 structures on the two islands may experience daily tidal flooding by 2050 as sea levels are predicted to rise more than 2.5 feet, the organization said.
"The impacts of flooding and erosion on these beloved Islands will affect thousands who live and work there, and the thousands more who visit each summer," said Tom O'Shea, a managing director at the Trustees.
The island communities, which also include the small and sparsely populated Elizabeth islands, also known as Gosnold, are taking climate change seriously, the organization says in its report.
Island communities have hired staff focused on climate change and begun resiliency work, from redesigning harbors, to replenishing sandy beaches, raising roads, and creating living shorelines to protect against coastal erosion.
"This is encouraging, but many climate-related projects are in the planning phase, and more needs to be done," the Trustees said. "We may have only 10 to 20 years before climate change forces our hand."
U.S. Senator Edward Markey said in a statement the report "magnifies the importance of taking bold steps now" to "protect these irreplaceable and invaluable wild treasures."
One challenge for the islands is limited options for retreat inland.
Less than 10% of Martha's Vineyard's remaining land is considered available for development, and less than 9% is available on Nantucket, according to the report. And since the late 1800s, the two islands have lost nearly 3,300 acres of beaches, dunes, and other coastal areas combined — an area equivalent to about 2,500 football fields, the organization said.
The Trustees warn the consequences of inaction are stark: Nearly 800 homes, businesses and other structures valued at more than $4.6 billion are at risk of being lost to coastal erosion on the islands, which were formed by retreating glaciers and collectively contain nearly 200 miles of beaches.
Nantucket alone could lose more than 500 acres of high salt marsh, or an area roughly 11 times the size of Boston Common, the organization said.
On Martha' Vineyard, the Menemsha docks — one of a number of island locations famously featured in the 1975 blockbuster movie Jaws — could be underwater at high tide every 5.5 days.
"Difficult decisions lie ahead to confront a turbulent future and adapt our coastal landscapes," the Trustees said in its report. "Time is running out."
Wednesday's report is the latest in an annual series delving into the threat and possible solutions to climate change in a different coastal region of the state.
Last year's inaugural report looked at Cape Ann and the North Shore, home to the historic fishing port of Gloucester as well as Salem, the site of the notorious colonial-era witch trials.
The Trustees, considered the state's largest private coastal landowner, owns more than 120 miles of coastline, including eight reservations on Martha's Vineyard and more than 900 acres on Nantucket.