Coastal wetlands, long recognized for their importance to local livelihoods and biodiversity, are also important natural carbon sinks. Mangroves, salt marsh, and seagrass beds, known collectively as “blue carbon” ecosystems, are especially efficient at removing carbon dioxide from the air and surrounding waters. Despite occupying less than 2% of the ocean, coastal wetlands store roughly 50% of all carbon known to be buried in global ocean sediments. These habitats also provide myriad other benefits, including protecting coastal communities against the full impact of storm surges, floods, sea level rise, and other climate change-related threats.
Countries and states are increasingly looking to their blue carbon ecosystems as nature-based allies in the fight against climate change. The latest United Nations Intergovernmental Panel on Climate Change (IPCC) “Climate Change 2022: Impacts, Adaptation, and Vulnerability” report delivers a grim outlook and urges nations to accelerate their efforts to reduce vulnerability to climate risks, as well as to drastically reduce emissions. The report, drafted by more than 270 leading experts from 67 countries, analyzes the feasibility of various climate adaptation measures and highlights coastal wetlands’ ability to protect against coastal erosion and flooding.
However, the report notes that to be most effective, these ecosystems need sufficient space to expand, or migrate, inland and warns that as sea levels rise, coastal wetlands such as salt marsh are at risk of being inundated and converted to open water. This would render them unable to store carbon or provide their other important benefits. To survive, wetlands must have enough space, free from barriers such as roads and seawalls, to migrate and avoid being overtaken by the ocean.
Protecting and restoring salt marshes, as well as creating space for them to move inland away from rising seas, are ways that countries and states can ensure that salt marsh persists in the face of climate change. In the U.S., the South Atlantic Salt Marsh Initiative, a collaboration among several southeastern states, the military, and coastal communities, including the Gullah/Geechee Nation, is working to protect a million acres of salt marsh stretching from North Carolina to northeast Florida. The region is home to more than 5.8 million coastal residents. Through creation of a collaborative conservation plan, the partners in the initiative aim to advance targeted restoration projects, conservation of adjacent open lands to allow salt marsh to migrate as sea levels rise, and coordinated, forward-thinking transportation and development efforts that minimize impacts on coastal wetlands.
And other U.S. states, particularly Oregon, California, Louisiana, and North Carolina, are at the forefront of measuring the carbon storage ability of their salt marsh and other coastal wetlands and incorporating them into natural and working lands strategies to help meet state greenhouse gas reduction goals.
Coastal wetlands in national climate plans
Like U.S. states, countries around the globe can also look to their salt marsh habitats to bolster coastlines against the effects of climate change. Incorporating salt marsh into their nationally determined contributions (NDCs) under the Paris Agreement can complement nations’ ambitious efforts to reduce greenhouse gas emissions and support adaptation efforts. Belize, Costa Rica, and Seychelles, among others, have made significant commitments to protect and restore coastal wetlands such as mangroves and seagrasses as nature-based solutions to climate change in their recently updated NDCs. These commitments—which are founded on robust scientific data and are the result of collaboration between national governments, in-country NGOs and universities, and local and international experts—set the stage for including these ecosystems in national greenhouse gas inventories and integrating coastal wetland conservation into coastal and marine spatial planning efforts.
The protection and restoration of coastal wetlands such as salt marsh present an opportunity for incorporating nature-based solutions on the state and national levels. The IPCC’s latest findings make clear that governments around the world must act now to protect coastal wetlands and create space for them to migrate inland in order to maintain their substantial climate benefits. As states and countries assess the role of various ecosystems in the fight against climate change, the conservation of salt marsh and other coastal wetlands stands out as a way to protect shorelines, store carbon, sustain biodiversity, and support local communities.
Alex Clayton is a principal associate with The Pew Charitable Trusts’ conserving marine life in the United States project, and Emily Owen is a manager with Pew’s protecting coastal wetlands and coral reefs project.