Blue carbon in Massachusetts:
A Tool to Prevent and Prepare for Climate Change
September 2016
Background
Coastal and inland wetlands cover over half a million acres of Massachusetts1. From the calcareous wetlands in
the Berkshires that are home to some of our few remaining bog turtle populations, to the salt marshes along Cape
Cod that are a popular spot for anglers, an acre of wetland produces more economic value in ecosystem services
than an acre of most upland systems. Massachusetts’ policy has long given wetlands significant protections in
recognition of their ability to reduce flood risk and damage, control mosquitoes, filter pollutants out of drinking
water, and help reduce the impacts of coastal storms.
Coastal wetlands play a critical role in fighting climate change. Blue carbon refers to the long-term storage of
carbon within plant habitats growing in coastal lands and near-shore marine environments2. Blue carbon
ecosystems are among the most productive in the world for carbon sequestration. In Massachusetts, we have two
types of blue carbon ecosystems: salt marshes and seagrass beds. Plants in salt marshes and seagrass beds draw in
carbon as they grow, and transfer much of this carbon into the rich organic soils formed by their roots. Protecting
and restoring blue carbon systems keeps hundreds to thousands of years of stored carbon safely in the soil.
Degrading or destroying these systems, on the other hand, releases many years’ worth of carbon, while destroying
the capacity of these systems to store carbon. Although the acreage of blue carbon systems in Massachusetts is
small, their role in fighting climate change is not:
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Salt marshes studied in Nauset Bay, MA store 105-155 g of carbon per square meter per year3, while
seagrass beds globally store an average of 83 g of carbon per square meter per year2, but vary widely.
In New England, salt marsh sediments are 3-5 meters thick, 3,000-4,000 years old, and are composed of
up to 40% carbon4.
Scaling up, blue carbon systems cover less than 2% of the area of the world’s oceans, but sequester at
least half of the carbon stored in ocean sediments5.
Fortunately, very few acres of wetland are completely converted to development in Massachusetts each year. The
biggest current threats to wetlands are from degradation, including through nutrient pollution, improperly sized or
sited road-stream crossings that alter hydrology, and climate adaptation actions that build up and harden
coastlines and do not allow coastal wetlands to move with sea level rise.
Massachusetts Clean Energy and Climate Plan
Massachusetts is a leader in recognizing the serious threats climate change presents to humans and the
environment upon which communities depend. Under the Global Warming Solutions Act (GWSA), the state has
established goals of reducing greenhouse gas emissions by 25% by 2020 and 80% by 2050. The 2015 Update to
the Clean Energy and Climate Plan for 2020 recognized the value of blue carbon in reaching these goals, the
recent improvements in measurements of blue carbon with the state’s Blue Carbon Calculator, and the difficulty
of reaching our GWSA goals if we fail to protect blue carbon systems and therefore release their accumulated
carbon stocks into the atmosphere. The substantial contribution that blue carbon systems can make to
offsetting GHG emissions, the emissions released when blue carbon systems are degraded or converted,
and the benefits of all wetlands in reducing damage and costs from flooding and storms, should be
highlighted in the Commonwealth’s efforts to prevent and prepare for climate change.
1
U.S. Department of Agriculture. 2015. Summary Report: 2012 National Resources Inventory, Natural Resources
Conservation Service, Washington, DC.http://www.nrcs.usda.gov/technical/nri/12summary
2
Commission for Environmental Cooperation. 2016. North America’s Blue Carbon: Assessing Seagrass, Salt Marsh, and
Mangrove Distribution and Carbon Sinks.
3
Chmura et al. 2003. Global carbon sequestration in tidal, saline wetland soils. Global Biogeochem. Cycles, 17(4), 11111122.
4
Johnson et al. 2007. Middle to late Holocene fluctuations of C3 and C4 vegetation in a Northern New England Salt Marsh,
Sprague Marsh, Phippsburg Maine. Organic Geochemistry, 38: 394–403.
5
Nellemann et al. 2009 in Commission for Environmental Cooperation. 2013. North America Blue Carbon Scoping Study.
Cross-Cutting Benefits of Wetland Conservation:
Emissions reduction: Protection and restoration of blue carbon systems through avoided conversion, reduction of
nitrogen and other pollution, and restoration projects that restore natural flow and allow coastal wetlands to move
with sea level rise are key to achieving Massachusetts’ Global Warming Solutions Act goals.
 Every acre of salt marsh or seagrass bed lost can result in the release of decades to centuries of carbon
stored in soils, as well as the loss of future carbon sequestration.
 Inland and coastal wetlands can avoid the need to build costly (and carbon-intensive) gray infrastructure
to filter water and defend against floods and storms.
 Restoration of wetlands improves the ability of those systems to sequester carbon, while generating
significant economic benefits. $1 million spent in Massachusetts on restoration of wetland systems
returns an estimated 12.5 jobs and $1.75 million6.
Adaptation: Blue carbon systems and inland wetlands also play critical roles in climate change adaptation. As
climate change brings increased precipitation and more severe floods and storms, more than ever before we need
to find ways to reduce risk along coasts and rivers.
 One acre of inland wetland can hold ~1 million gallons of water in times of flooding, and Massachusetts’
coastal wetlands provide an average of $643 million in storm protection services each year7.
 Blue carbon systems, if we keep them healthy, can migrate and expand over time, providing increased
protection against storms and avoiding the need to constantly build seawalls and other gray infrastructure
higher and stronger as sea levels rise.
Action Recommendations:
Recognize the role of blue carbon systems and inland wetlands in policies and carbon accounting stemming
directly from the Global Warming Solutions Act as well as in state agency actions across the board. Align
policies across agencies, and increase attention on and support for action at the municipal level. Consider new
programs and expansion of existing programs to prevent both destruction and degradation of blue carbon systems.
Specific areas recommended for focus include the following:
1. Protect all remaining blue carbon systems and consider strengthening the mitigation requirements for
inland wetlands:
 Prevent any further infilling or other conversion of salt marshes and eelgrass beds.
 Recognize that current compensatory mitigation requirements for conversion of wetlands do not
adequately account for greenhouse gases, and revise them to reflect best-available science.
2. Increase restoration efforts to secure existing blue carbon stocks and improve the ability of blue carbon
systems to sequester carbon:
 Provide additional funding for the Division of Ecological Restoration and Office of Coastal Zone
Management, directed towards restoration projects that have the biggest greenhouse gas benefit.
Explore the potential for carbon credits using the Verified Carbon Standard methodology for tidal
wetland and seagrass restoration.
 Assist municipalities in reducing upstream pollution from nitrogen and sediment that can degrade
blue carbon systems, by providing technical assistance to municipalities, sharing successes from other
municipalities, and encouraging protection of buffers along coasts and rivers to filter pollutants.
3. Wherever possible, use blue carbon systems and inland wetlands, or use a mix of green and gray
infrastructure, rather than building gray infrastructure to reduce risk from floods and storms.
 Ensure that permitting and incentives enhance opportunities for green infrastructure.
For more information, contact:
Steve Long
617-532-8367 • [email protected]
6
Massachusetts Department of Fish and Game, Division of Ecological Restoration. 2012. Economic Impacts of Ecological
Restoration in Massachusetts.
7
The Trust for Public Land. 2013. The Return on Investment in Parks and Open Space in Massachusetts.