Washington Sea Grant-supported Research Quantifies the Climate Benefits of Coastal Wetland Restoration

With funding from Washington Sea Grant, researchers conducted one of the first-ever studies on sediment carbon stock and carbon sequestration rates for restored and natural salt marshes. They analyzed 13 wetland sites across the Stillaguamish River estuary, including four sites within a tidal marsh that had been recently restored. The researchers found that the rate of carbon sequestration in the recently restored marsh is currently twice the rates found in the adjacent natural marshes. The restoration site is expected to accumulate approximately 4,500 to 9,000 tonnes of carbon before it reaches equilibrium with adjacent marshes, equivalent to removing 3,500 to 7,000 cars from the road for one year. Using the national average carbon offset price, this amount of carbon is worth $65,000 to $165,000. These findings indicate wetland restoration has significant and immediate benefits and could be a valuable tactic to help mitigate future climate change. The salt marshes adjacent to the delta distributary are also all accreting at rates that exceed the rate of sea level rise, indicating the additional potential of wetland restoration for climate resiliency.