Steve Wofsy
ATMOSPHERIC AND ENVIRONMENTAL CHEMISTRY
Prof. Wofsy’s work focuses on measuring, modeling, and mitigating the vast impacts that human beings have on the atmosphere. Combustion of fossil fuel, clearing of forests, agriculture, and chemical industry have caused concentrations of the most important atmospheric trace gases (CO2, CH4, N2O) to increase over the past 200 years, with accelerating change in the last 50 years. Emissions of industrial halocarbons (CFCs, such as CF2Cl2, "CFC-12") caused stratospheric ozone declines and formation of the Antarctic ozone “hole”. These changes have serious impacts on the environment of the earth and on society, such as climatic warming and global, regional and urban air pollution. Professor Wofsy’s research over many years has been motivated by the need for scientific information and analysis to make wise decisions on the future development and conservation of the world's resources.
The main efforts of the Wofsy group are directed towards making measurements defining the sources and sinks for important atmospheric gases, including developing new measurement paradigms and analysis approaches to enable deeper understanding of underlying processes and of the rates for chemical transformations and transport in the atmosphere. The work covers many environments, ranging widely in spatial scales and temporal durations, including:
- Exchanges of atmospheric gases with vegetation, soils, and oceans;
- long-term measurements of greenhouse gas fluxes in forests and urban areas;
- ecosystem response to climate change and air pollution;
- global distributions of trace gases and pollutants;and most recently,
- remote sensing of methane emissions from aircraft and satellites.
Prof. Wofsy has led several global atmospheric measurement programs, including the 1995 STRAT mission to sample the global stratosphere and the 2009 – 2011 HIPPO and recent 2016 - 2020 Atom missions measuring trace gases across the entire globe. Some images from ATom. The group also maintains a long-term measurement programs studying greenhouse gas and pollutant emissions in the Boston region, in collaboration with Prof. Lucy Hutyra at Biston University and Prof. Róisín Commane at Columbia University, and long term eddy flux measurements at the Harvard Forest LTER, for which Bill Munger is Principal Investigator.
A major focus of the group presently is the development and deployment of the MethaneSAT satellite observatory, and its companion aircraft instrument (MethaneAIR). Starting in 2016, we began developing the instrument concept and design for MethaneSAT in collaboration with TEMPO group (SAO) and engineering group at the Harvard Center for Astrophysics/Smithsonian Astrophysical Observatory, supported by, and in collaboration with, the Environmental Defense Fund (Chief Scientist Steven Hamburg). This is a science mission intended to measure the concentrations of methane over oil and gas production regions worldwide, and to deliver reliable emissions data for the whole regions and for the major point sources in each region. It is also more than a science mission: EDF will take the data into the realm of industry, government, and advocacy, with the goal to incentivize 45% reduction of methane releases by 2025 and 70% by 2030. Launch is scheduled for Q1/Q2 2023.
The MethaneAIR sensor simulates MethaneSAT measurements, and flew an extended mission in the summer of 2021. You can view a colloquium discussing MethaneSAT and MethaneAIR (Nov. 2021). Future missions are planned to examine oil and gas provinces across the US, as well as other major sources of methane to the atmosphere, such as landfills and agriculture. Once MethaneSAT is on orbit, MethanAIR will provide the primary testing and validation data for the satellite project.
Selected recent publications
Alvarez, R.A., D. Zavala-Araiza, R. R. Lyon, D. T. Allen, Z. R. Barkley, A. R. Brandt, K. J. Davis, S. C. Herndon, D. J. Jacob, A. Karion, E. A. Kort, B K. Lamb, T. Lauvaux, J. D. Maasakkers, A. J. Marchese, M. Omara, S. W. Pacala, J. Peischl, A. L. Robinson, P. B. Shepson, C. Sweeney, A. Townsend-Small, S. C. Wofsy, S. P. Hamburg, Assessment of methane emissions from the US oil and gas supply chain, Science 361, 186-188, DOI: 10.1126/science.aar7204, 2018.
Commane, R., J. Lindaas, J. Benmergui, K. A. Luus, , R. Y.-W. Chang, B. C. Daube, S. E. Euskirchen, J. M. Henderson, A. Karion, J. B. Miller, S. M. Miller, N. C. Parazoo,, J. T. Randerson, C. Sweeney, P. Tans, K. Thoning, S. Veraverbeke, C. E. Miller, and S. C. Wofsy, Steven C., Carbon dioxide sources from Alaska driven by increasing early winter respiration from Arctic tundra, PNAS 114, 5361 - 5366, 10.1073/pnas.1618567114, 2017.
Floerchinger, C., P. B. Shepson, K. Hajny, B. H. Stirm, B. C. Daube, C. Sweeney, and S. C. Wofsy, Measurement of the Fraction of Methane Emissions Derived from Natural Gas for Seven U. S. Cities, Elementa 9, 1. DOI: https://doi.org/10.1525/elementa.2021.000119, 2021.
Gonzalez, Y., Commane, R., Manninen, E., Daube, B. C., Schiferl, L., McManus, J. B., McKain, K., Hintsa, E. J., Elkins, J. W., Montzka, S. A., Sweeney, C., Moore, F., Jimenez, J. L., Campuzano Jost, P., Ryerson, T. B., Bourgeois, I., Peischl, J., Thompson, C. R., Ray, E., Wennberg, P. O., Crounse, J., Kim, M., Allen, H. M., Newman, P., Stephens, B. B., Apel, E. C., Hornbrook, R. S., Nault, B. A., Morgan, E., and Wofsy, S. C.: Impact of stratospheric air and surface emissions on tropospheric nitrous oxide during ATom, Atmos. Chem. Phys. 21, 11113-11132, doi: 10.5194/acp-21-11113-2021, 2021.
Shekhar, Ankit, J. Chen, J. C. Paetzold, F. Dietrich, X. Zhao, S. Bhattacharjee, V. Ruisinger, and S. C. Wofsy, Anthropogenic CO2 emissions assessment of Nile Delta using XCO2 and SIF data from OCO-2 satellite, Environ. Res. Lett. 15, https://doi.org/10.1088/1748-9326/ab9cfe, 13pp, 2020.