Our new California-China Climate Institute brief summarizes how wetlands contribute to climate change mitigation and factors that affect greenhouse gas flux in wetlands. Lessons and experiences from the Sacramento-San Joaquin Delta, California provide insights for other regions on best practices that could be adopted, as well as existing gaps and challenges. 

Wetlands play an important role in mitigating climate change: vegetation and sediment in wetlands can absorb carbon dioxide (CO2) from the atmosphere, which makes wetland restoration a compelling approach to mitigate climate change. At the same time, research shows that under some conditions wetland soils produce another potent greenhouse gas, methane. As a result, wetland restoration is sometimes seen as controversial in mitigating climate change. However, careful analysis shows that concerns about methane should not serve as an argument against wetland restoration and protection.

A significant body of scientific research has characterized the mechanisms that lead to reduced greenhouse gas emissions from wetlands. Results show that oxygen levels, soil temperature, and vegetation coverage are key factors affecting wetland CO2 and methane emissions. In addition to the literature, on-the-ground wetland restoration projects have demonstrated that wetland restoration is an effective measure to mitigate greenhouse gas emissions in the long term, even with the trade-offs between methane and CO2 emissions.

Wetland restoration projects in the Sacramento-San Joaquin Delta, California are good examples of greenhouse gas mitigation in wetlands. Through land-use changes, greenhouse gas monitoring, and carbon offset credit acquisition, these projects demonstrate a pathway to mitigate greenhouse gas emissions while also supporting biodiversity, delivering economic benefits, and reversing ground subsidence. Some best practices from these projects include (1) converting agricultural lands to a rice-wetland mosaic, (2) quantifying baseline greenhouse gas emissions through model estimation and eddy covariance techniques, and (3) Incorporating more wetland restoration projects into the carbon market.

• Read the Full Brief in English