Impacts Projected to Occur By 2050 

DEVELOPED COAST 

• PROPERTY DAMAGE A 10-year storm in Nantucket may flood up to 1,436 (10%) structures, and a 100-year storm up to 1,932 (13%) [CIT. 3]. At significant risk is the town’s historic downtown district, Brant Point, and Madaket. 

• ROAD FLOODING About 69 miles (15%) of roadway may flood in a 10-year storm and an estimated 95 miles (21%) in a 100-year storm. Washington and Easy Streets, among others, already see high tide flooding [CIT. 3]. 

• HARBOR AND WATERFRONT DAMAGE This area is at extreme risk of future flooding and storm damage. The Steamship Authority terminal, Hy-Line terminal, and shipping channel have been cited as critical vulnerabilities. Downtown street flooding significantly disrupts travel and commerce, including routes to the ferry terminals and between commercial docks and the rest of the Island.  

NATURAL COAST

• EROSION Parts of the south coast have receded up to 1,800 feet since the 1800s, with maximum short- and long- term annual rates of 17 and 11 feet, respectively [CIT. 5]. Beach erosion could be particularly severe along the south shore, potentially affecting one wastewater treatment plant and the airport. Great Point is migrating west, while erosion impacts Siasconset and Jetties Beach. 

• MARSH LOSS Regular flooding may transition 569 of 863 acres (66%) of high marsh to low marsh, while total marsh (high and low) may lose 50 acres (5%) [CIT. 2]. 

• HABITAT CHANGES Estuarine beach/tidal flats and estuarine open water may increase by 225 acres (91%), and 108 acres (2%), respectively [CIT. 2].