Earth & Space
UC Santa Cruz team helps California Air Resources Board better understand how wetlands sequester carbon and improve air quality
Atmosphere-monitoring towers operated by the Paytan Lab will tell the tale of two very different Southern California wetlands over the next two years
The UC Santa Cruz team building an eddy covariance tower at Seal Beach National Wildlife Refuge during high tide.
Photo by Jacqueline Jabuka
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Key takeaways
- UC Santa Cruz scientists have installed sophisticated monitoring towers at two contrasting wetlands to compare how much carbon dioxide each absorbs versus how much methane they release.
- These coastal habitats can store carbon in their soil up to 10 times more efficiently than land-based forests, offering a “shovel-ready” natural solution to help California reach its net-zero emissions goal by 2045.
- The project fills a major data gap for the region: Most monitoring has focused on Northern California’s Delta. But because Southern California’s climate and plants are different, this new local data will help eliminate a blind spot for state air-quality regulators.
- The findings will guide billions of dollars in state funding. By providing high-quality science on how restoration affects carbon storage, the study helps state officials decide where to invest in nature-based projects that protect both the environment and local property.
To support the state’s climate change mitigation efforts, as well as its goals for clean air and sustainable environments, researchers from the University of California, Santa Cruz, have recently started monitoring the atmosphere at two very different wetlands to measure how much carbon they store and emit.
Earth and planetary sciences professor Adina Paytan and members of her lab are partnering with the California Air Resources Board (CARB) and AmeriFlux to study two wetlands in Southern California. One is the Los Cerritos Wetlands, an estuary in Long Beach that is highly degraded from industrial use. The other is neighboring Seal Beach National Wildlife Refuge, one of the largest and most pristine wetlands in Southern California.
Coastal wetlands can remove carbon dioxide (CO2) from the atmosphere and store the carbon in their plants and soils much more efficiently than forests on land—up to 10 times more by some estimates. That’s because carbon in submerged wetland sediments can be protected from decomposition, staying in the soil for decades to millennia. Coastal wetlands also protect shorelines and property, while preserving habitats for many species.
But wetlands are also dynamic environments that both store carbon, but can also at times emit greenhouse gases like methane (CH4). The Paytan Lab‘s focus on biogeochemical processes and goal of identifying links between ecosystem changes and climate change—and her extensive work on wetlands at Elkhorn Slough—make her team well suited to monitor these marshes.
A shovel-ready solution
California has committed to reducing greenhouse gas emissions and achieving carbon neutrality by 2045. To reach this goal, Paytan says we need to directly remove CO2 from the air. “Restoring wetlands is one of the most effective, shovel-ready, nature-based carbon dioxide removal solutions,” she said. “In my lab, we are excited to provide high-quality, science-based data that could be used to inform the design of restoration projects that maximize carbon sequestration along with other co-benefits.”
The partnership with CARB and AmeriFlux has allowed the team to deploy two eddy covariance towers, monitoring systems that will continuously measure the exchange of CO2 and CH4 between the wetlands and the air above. This will provide long-needed measurements that can refine California’s estimates of wetland emissions. This work will also provide data that could be used to upscale estimates to other sites using models, as well as quantify the atmospheric effects of restoring a wetland like Los Cerritos to something like its healthier neighbor.
CARB has emphasized that measurements such as these are important for monitoring the effectiveness of its strategies and for helping direct additional research towards nature-based solutions. This partnership between the University of California and the state is important work intended to study and protect our environment.
CARB seeks to strengthen emission estimates through the collection of continuous, high-quality data, high-resolution spatial mapping, and improved modeling of wetland ecosystems. The board’s Natural and Working Lands Carbon Inventory quantifies greenhouse gas emissions of CO2 and CH4, as well as carbon stored in soils.
Coverage beyond the Delta
For wetlands, almost all monitoring towers were concentrated in the San Joaquin Bay Delta until recently—more towers, in fact, than in any other land category in the state. As a result, a large data gap exists for Southern California’s vast coastal wetlands. Filling that gap is essential for refining emissions modelling because the climate and vegetation of Southern California wetlands differ considerably from Delta systems.
And that’s where the Paytan Lab comes in, with two new coastal wetlands monitoring towers in Southern California. “We’re trying to understand, under what conditions, can we maximize the sequestration of CO2. Wetlands and sloughs are amazing ecosystems,” Paytan said. “The more wetland settings we have data for, the better we can understand how these complex systems function.”
Paytan will be collaborating with researchers at both UC Irvine and the Smithsonian Environmental Research Center. Adding to the Paytan Lab’s measurements of greenhouse-gas emissions, Alex Guenther of UC Irvine is refining measurements of biogenic volatile organic compounds (BVOCs) from vegetation. This research will show where and when the state’s ecosystems emit BVOCs, such as ground-level ozone and fine particulate matter, which are important precursors to pollutants that harm air quality.