Image: Dr. Silver’s lab is studying techniques to increase the carbon stored within soils, starting with California grasslands in coordination with the Marin Carbon Project. Image by: Kris Daum
Script by: Sophie Wenzlau Blurb by: Amanda Neslund Audio Editing by: Marie Hogan
Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide to slow the pace of climate change. There are two major types of carbon sequestration: geologic and biologic. Geological carbon sequestration injects carbon dioxide captured from an industrial or energy-related source into underground geologic formations. Biological carbon sequestration refers to the storage of atmospheric carbon in vegetation, soils, woody products, and aquatic environments. While carbon dioxide (CO2) is naturally captured from the atmosphere through biological, chemical, and physical processes, some artificial sequestration techniques exploit the natural processes to slow the atmospheric accumulation of CO2.
Soil Carbon Sequestration and Climate Change
The exchange of carbon between soils and the atmosphere is a significant part of the world’s carbon cycle. Carbon, as it relates to the organic matter of soils, is a major component of soil and catchment health. However, human activities including agriculture have caused massive losses of soil organic carbon, leading to soil deterioration. California’s Healthy Soil Initiative is one program in the state working to promote the development of healthy soils in efforts to increase the state’s carbon sequestration, prevent soil deterioration and reduce overall greenhouse gas emissions.
Soil carbon sequestration is a process in which CO2 is removed from the atmosphere, primarily mediated by plants through photosynthesis, with carbon stored in the form of soil organic matter. Many scientists agree that regenerative agricultural practices can reduce atmospheric CO2 while also boosting soil productivity and health and increasing resilience to floods and drought.
UC Berkeley researchers found that low-tech agricultural management practices such as planting cover crops, optimizing grazing, and sowing legumes on rangelands, if instituted globally, could capture enough carbon from the atmosphere and store it in the soil to reduce global temperatures 0.26 degrees Celsius – nearly half a degree Fahrenheit – by 2100. However, because biological sequestration isn’t permanent and can be hard to measure, most agree that it’s only one part of the climate solution and not a substitute for reducing emissions.
Dr. Whendee Silver is the Rudy Grah Chair and Professor of Ecosystem Ecology and Biogeochemistry in the Department of Environmental Science, Policy, and Management at U.C. Berkeley. She received her Ph.D. in Ecosystem Ecology from Yale University. Her work seeks to determine the biogeochemical effects of climate change and human impacts on the environment, and the potential for mitigating these effects. The Silver Lab is currently working on drought and hurricane impacts on tropical forests, climate change mitigation potential of grasslands, and greenhouse gas dynamics of peatlands and wetlands. Professor Silver is the lead scientist of the Marin Carbon Project, which is studying the potential for land-based climate change mitigation, particularly by composting high-emission organic waste for soil amendments to sequester atmospheric carbon dioxide.
- The potential of agricultural land management to contribute to lower global surface temperatures
- Technical options for sustainable land and water management
- Soils help to combat and adapt to climate change by playing a key role in the carbon cycle
- The solution to climate change is just below our feet
- Soil as Carbon Storehouse: New Weapon in Climate Fight?
- Soil Carbon Sequestration Impacts on Global Climate Change and Food Security
- Silver Lab, UC Berkeley
- Carbon Management and Sequestration Center, Ohio State University
- Food and Agricultural Organization, the United Nations
- Collaborating with farmers on climate-friendly practices, with Alameda County Resource Conservation District
Ethan Elkind: I’m Ethan Elkind, and you’re listening to Climate Break. Climate solutions in a hurry. Today’s proposal: adding compost to grasslands to help solve climate change. Whendee Silver, a biogeochemist at UC Berkeley, explains how the soil on farms and ranches can be used to capture and store carbon that otherwise would end up in the atmosphere.
Dr. Whendee Silver: If you look at the ecosystems globally that are managed that store the most carbon, it’s grasslands. And most of the grasslands globally are degraded with regard to their carbon, but it was like a bathtub that was half full that maybe we could start to fill up again.
Ethan Elkind: One source of excess carbon that can be used to restore grasslands is compost from food waste. Instead of throwing away food scraps, they can be injected underground to capture the carbon and methane that would otherwise escape into the air from landfills. According to Dr. Silver, this practice has the potential to enhance soil health and significantly reduce global temperatures.
Dr. Whendee Silver: We found that if you combined all the practices that we know sequester carbon in soils, we could technically lower global temperatures by about 0.3 degrees Celsius, and that doesn’t seem like much, but if you think we’ve already warmed one degree and we’re trying to keep it to 1.5, if we can get 0.3, that’s 60% of the way there.
Ethan: To learn more about how adding compost to grasslands can promote soil health and help solve climate change, visit climatebreak.org.