Screenshot of Data Explorer interactive map

Blue carbon stocks, including eelgrass meadows and tidal marsh, from Long Island, New York, to southeastern Massachusetts, as shown on the new Northeast Ocean Data Portal map layer.

In response to the New England Governors and Eastern Canadian Premier 2017 Climate Change Action Plan recommendation to “manage blue carbon resources to preserve and enhance their existing carbon reservoirs,” the U.S. Environmental Protection Agency (EPA), with assistance from the Northeast Regional Ocean Council (NROC), convened a New England Blue Carbon Inventory Workgroup (comprised of a variety of federal, New England state, academic, and non-profit organizations) to develop an inventory of blue carbon stocks from Maine to Long Island, New York.

The Workgroup focused its inventory efforts on salt marshes and eelgrass meadows, leveraging existing regional habitat maps available on the Northeast Ocean Data Portal. Additional existing data for soil organic carbon stocks were then used to calculate blue carbon stock estimates. For visual display purposes, sediment carbon heat maps were developed to highlight areas of greatest carbon accumulation. The heat maps can also be accessed on the Northeast Ocean Data Portal in the Data Explorer under Habitat > Blue Carbon. The Workgroup created heat maps for eelgrass and tidal marsh habitats individually as well as a heatmap showing blue carbon reservoirs for both coastal vegetation types together.

Screenshot of eelgrass and tidal marsh vegetation classification map layers

Eelgrass & Tidal Marsh Vegetation Classification

Screenshot of Blue Carbon Stocks (MgC) – Eelgrass Meadows & Tidal Marsh

Blue Carbon Stocks (MgC):
Eelgrass Meadows & Tidal Marsh

Using the regional habitat data and soil organic carbon samples, the Workgroup found that the northeast region (from Maine to Long Island) has an estimated 218,222 acres of eelgrass meadows, salt marsh and saline Phragmites, which are estimated to provide a reservoir of 7,523,568 megagrams of blue carbon, or the equivalent to the annual carbon emissions from over 5,944,024 passenger vehicles. Due to data limitations, the carbon stock estimate represents a mere fraction of the actual quantity of accumulated carbon in these habitats.

The findings from the Workgroup’s efforts and the resulting map products can help inform land and coastal management policies, fisheries management, and climate change mitigation practices. Further refinements and expansion of data are needed, including more detailed habitat maps, deeper soil core data for soil organic carbon content, and inclusion of more marine flora into calculations. The Workgroup will continue refining blue carbon data products in 2023-2024 through NROC’s Coastal and Ocean Ecosystem Health Committee.

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