A new study shows that “living” shorelines can help sequester CO2 and potentially help combat climate change. The National Oceanic and Atmospheric Administration study, published last month in the journal PLOS One, is the first to quantify the amount of carbon that can be sequestered in living shorelines, which usually are engineered using natural materials such as plants, sand and rock. Using core samples, researchers measured the amount of carbon stored in salt-marsh sediments and compared storage rates in marshes of different ages in North Carolina’s Newport River Estuary. The researchers concluded that the long-term potential of sandy, living shorelines is similar to natural marshes in the Southeast—75 grams of carbon per sq meter.
Jenny Davis, the study’s lead author and a scientist with NOAA’s National Center for Coastal Ocean Sciences, told ENR, “Any of these sites makes a small contribution on its own, but when you start looking at the cumulative impacts, using this approach to shore stabilization can become significant” in reducing carbon emissions. For example, the 124 living shorelines in North Carolina store enough carbon to offset 64 metric tons of CO2 annually. Converting even 10% of North Carolina’s 850 miles of shores to living shoreline could yield an annual CO2 offset of 870 metric tons, the study’s authors report.
Stacy Small-Lorenz, climate adaptation and resilience specialist at the National Wildlife Federation, says living shorelines and other natural resiliency and restoration solutions already have been shown to have value. This study “is one more piece of ... evidence of why we should be prioritizing natural infrastructure, or green-gray hybrid solutions, over strictly hard armoring,” such as seawalls and bulkheads.
Carter Strickland, a former New York Dept. of Environmental Protection commissioner, says projects that incorporate natural elements are becoming more prevalent. “You know it’s a real concept and going mainstream if the Army Corps has a term for it—‘natural and nature-based infrastructure,’ ” he says. Now a vice president with HDR, he says a typical project might incorporate a berm on the land side and a dune-wetland system on the water side.