Despite covering just 2% of the ocean, coastal wetlands — such as tidal salt marshes, mangrove forests and seagrass beds — are responsible for storing nearly half of all carbon found in ocean sediment. These “blue carbon” ecosystems naturally absorb vast amounts of carbon dioxide (CO2) from the atmosphere and bury it deep within their soil.
But rising sea levels — projected to increase by up to a meter by 2100 — threaten to disrupt the water’s chemistry and the delicate balance of microorganisms essential for carbon cycling. Rising tides could also transform marshes into mudflats, releasing stored carbon back into the atmosphere and exacerbating climate change.
With support from the USC Wrigley Institute for Environment and Sustainability’s new Carbon and Climate Initiative, USC researchers are studying this threat through a two-part project in the tidal salt marshes of Upper Newport Bay Ecological Reserve, an estuary along Orange County’s 42-mile-long coastline in Southern California. Spanning over 600 acres of wetlands, this area supports populations of shorebirds, waterfowl, native plants and several rare and endangered species.
The research team is examining how sea level rise may affect the marsh’s microbial communities, which ultimately influence carbon capture and storage, through a combination of field observations, laboratory experiments and advanced modeling techniques. Doing so will give the team a clearer picture of the marsh’s potential vulnerability to climate change.
“Salt marshes, like those at Upper Newport Bay, can actually store as much carbon as the Amazon rainforest or any other forest in the world, making them powerful allies in the fight against climate change,” said David Bañuelas, a USC Presidential Sustainability Solutions Fellow and the project’s lead researcher. The fellowship is a key component of the research goals of the Assignment: Earth framework, introduced by USC President Carol Folt in 2022 as a “moonshot” to ensure the university remains a leader in sustainability operations, research and education.