Understanding the Patterns and Drivers of GHG emissions in Forests, Grasslands, Agricultural Ecosystems, and Waste Management
About My Research
Our lab was among the first to deploy continuous environmental sensing together with automated measurements of all three greenhouse gases (carbon dioxide, methane, and nitrous oxide) using the Picarro G2308 and G2508. The continuous data generated from this approach has given us new insights on the drivers of greenhouse gas fluxes. A recent paper published in Global Change Biology (Anthony and Silver 2021) reports on over 70,000 greenhouse gas flux measurements and found that short-term low redox events drive nitrous oxide fluxes and long-term anoxia stimulates net methane emissions. Results showed that peat-derived agricultural soils can be a very large regional source of nitrous oxide, and that IPCC-derived values may significantly underestimate this important source. Another study published during the most recent review period captured, in real time, the effects of a rare severe drought in a humid tropical forest (O’Connell et al. 2018). Our automated sensing network with high spatial and temporal resolution identified a threshold-type redox response to soil drying, as well as a suite of cascading effects including decreased phosphorus availability and increased soil respiration. The rapidity of the response, as well as the differential effects of topographic position had never before been documented. We found that humid tropical forest soils were more sensitive than expected to climate-change driven drought with feedbacks to greenhouse gas emissions. We used Picarro G2308 and automated sensing and found very rapid oxygen consumption and shifts in temperature that drove high methane bursts during composting.
Our research has provided key data on both fluxes and mechanistic drivers for regional, state, and national climate change mitigation planning. Our work provided scientific support for the following California legislation: SB 5 funding for healthy soils projects, SB 1383 limiting short-lived climate pollutants (waste-related methane from our work), AB 1045 which streamlined regulations on composting facilities. Our work provided scientific support for program development with the Natural Resource Conservation Service (Federal), the Carbon Cycle Institute, CalCAN, and others that led to the implementation of Healthy Soils Programs in California and several other states. The Marin Carbon Project, which I helped found, was called out as an example of climate change mitigation projects by the Obama White House in their Priority Agenda Enhancing the Climate Resilience of America’s Natural Resources. Our work has been covered extensively in the media including the New York Times, National Public Radio, the San Francisco Chronicle, and others.
How Picarro Analyzers Helped
Picarro greenhouse gas analyzers coupled with automated chambers have dramatically increased our lab’s ability to quantify greenhouse gas fluxes under field conditions. The corresponding datasets have fundamentally changed our understanding of the patterns and drivers of greenhouse gas emissions in forests, grasslands, agricultural ecosystems, and waste management. The ability of Picarro analyzers to be continuously deployed in the field over long periods with minimum calibration has radically altered our scientific approaches and research questions, enabling us to quantify the distribution of ecosystem greenhouse gas fluxes across space and time. We are using Picarro greenhouse gas data together with environmental sensing and intensive sampling to create machine learning models that significantly improve our ability to predict methane and nitrous oxide hot spots and hot moments, the main sources of these potent greenhouse gases over time. These combined data sets, anchored with Picarro greenhouse gas analyzers, are informing new biogeochemical theory and contributing to our understanding of management practices that can lower greenhouse gas emissions from land use and waste management activities, and ultimately help to mitigate climate change.