Research Themes
Methane Emissions from Dairy Farms
Dairies are the single largest source of methane emissions in California. Dairies have been targeted for mitigation by statewide efforts to reduce methane emissions coming from manure management. However, we currently lack an understanding of the processes leading to methane emissions from dairy farms. We use a variety of techniques and tools to quantify emissions and improve process understanding and representation in models. Ultimately, this work will enable researchers to verify emissions reduction efforts on dairy farms.
Mobile Van at a SoCal Dairy
Collection Chamber on Lagoon
Mobile Van at a SoCal Dairy
Publication
R.R. Thiruvenkatachari, V. Carranza, F. Ahangar, A. Marklein, F. Hopkins, A. Venkatram (2020). Uncertainty in using dispersion models to estimate methane emissions from manure lagoons in dairies. Agricultural and Forest Meteorology, https://doi.org/10.1016/j.agrformet.2020.108011
Mapping Methane Emission Sources
Unlike carbon dioxide, methane is often released from fugitive emission sources. By definition, we do not understand where in space or time fugitive emissions will appear. We make observations of methane enhancements from on-road and airborne platforms to detect fugitive and super-emitter sources in the environment. Identifying these methane hotspots is the first step to mitigating these emissions.
Publication
T. Rafiq, R.M. Duren, A.K. Thorpe, K. Foster, R. Patarasuk, C.E. Miller, F.M. Hopkins (2020). Attribution of Methane Point Source Emissions using Airborne Imaging Spectroscopy and the Vista-California Methane Infrastructure Dataset. Environmental Research Letters. https://daac.ornl.gov/NACP/guides/NACP_Vista_CA_CH4_Inventory.html
R.M. Duren, A.K. Thorpe, K.T. Foster, T. Rafiq, F.M. Hopkins, V. Yadav, B.D. Bue, D.R. Thompson, S. Conley, N.K. Colombi, C. Frankenberg, I.B. McCubbin, M.L. Eastwood, M. Falk, J.D. Herner, B.E. Croes, R.O. Green, C.E. Miller (2019). California’s Methane Super-Emitters. Nature. https://doi.org/10.1038/s41586-019-1720-3.
F.M. Hopkins, S.E. Bush, J.R. Ehleringer, C.T. Lai, E.A. Kort, D.R. Blake, J.T. Randerson (2016). Spatial patterns and source attribution of urban methane in the Los Angeles Basin. Journal of Geophysical Research-Atmospheres, 121, doi:10.1002/2015JD024429.
Urban Greenhouse Gas Emissions
Cities are major hotspots for greenhouse gas emissions, and many are eager to reduce their impact. In order for cities to better control their emissions, new measurements that keep track of urban emissions over time and better understand the mix of sources are needed. We contribute to monitoring and source apportionment of methane emissions in the Los Angeles Megacity. We also map locations where emissions are likely to occur. We are interested in building partnerships with emitters and cities to tackle the challenge of mitigation.
Publication
V. Carranza, T. Rafiq, I. Frausto-Vicencio, F. Hopkins, K.R. Verhulst, P. Rao, R.M. Duren, C.E. Miller (2018). Vista-LA: Mapping methane emitting infrastructure in the Los Angeles megacity. Earth Syst. Sci. Data, https://doi.org/10.5194/essd-2017-65.
F.M. Hopkins, J.T. Randerson, S.E. Bush, C.T. Lai, Y.-K. Hsu, V. Carranza, J.R. Ehleringer (2016). Mitigation of methane emissions in cities: how new measurements and partnerships can contribute to emissions reduction strategies. Earth’s Future, 4, 408-425, doi:10.1002/2016EF000381.
Urban CH4 Partnership
Urban CH4 Conceptual Diagram
Urban CH4 Partnership
Soils and Climate Change
Soils are the largest stock of terrestrial carbon and have the potential to amplify climate change through feedback effects. We use carbon isotopes and manipulation experiments to better understand how soils respond to global changes like warming and changes in atmospheric composition.
Publication
F.M. Hopkins, T.R. Filley, G. Gleixner, M. Lange, S.M. Top, S.E. Trumbore (2014). Increased belowground carbon inputs and warming promote loss of soil organic carbon through complementary microbial responses. Soil Biology & Biochemistry, 76, 57-69.
F.M. Hopkins, M.S. Torn, S.E. Trumbore (2012). Warming accelerates decomposition of decadal-cycling soil carbon. Proceedings of the National Academy of Sciences, 109, E1753-E1761.
Communicating Climate Change Impacts in California
Californians of all ages can benefit from learning the best science of how we expect our environment to change with a warming climate, particularly in underserved areas of the state. We participate in many different types of public outreach about climate change impacts and the science of the Earth System in the Anthropocene.
Publication
Francesca Hopkins. (University of California, Riverside). 2018. Inland Deserts Summary Report. California’s Fourth Climate Change Assessment. Publication number: SUM-CCCA4-2018-008. http://www.climateassessment.ca.gov/regions/docs/20180827-InlandDeserts.pdf
