Climate Program Office funds research to understand methane’s significance in the atmosphere

The Climate Program Office (CPO) is announcing eight new three-year projects in Fiscal Year 2023 (FY23) that aim to increase our understanding of methane’s significance in the atmosphere by exploring global, regional and local concentration and trends, modeling methane budgets and frameworks for measurement and verification of emissions. The competitively selected projects total $5.3 million in grants¹. These projects will improve understanding of atmospheric methane budgets (sources and sinks) in order to inform successful policies for reducing greenhouse gas emissions, address major sources of uncertainty in methane measurements and modeling, and ultimately reduce community-level methane emissions. 
Atmospheric methane (CH₄) is a potent greenhouse gas that has been steadily increasing since the beginning of the Industrial Area, much like CO₂, with a brief leveling off from 1999 to 2006, before resuming its increase from 2007 on. In 2021, global average methane concentrations increased by the highest amount since measurements had begun in 1983. 

The main sources and sinks of methane are both natural (wetlands, lakes, wild animals, termites and geological seeps) and human-caused (agriculture, waste management, fossil fuel exploitation and biomass burning). There are limited capabilities of quantifying, verifying and monitoring the sources and sinks which can make it difficult to understand and mitigate   methane emissions. An understanding of where methane comes from and how it’s removed from the atmosphere is critical for adopting successful policies for reducing greenhouse gas emissions.

Through the CPO Atmospheric Chemistry, Carbon Cycle and Climate (AC4) program FY23 competition, AC4 sought to measure and model methane across spatial and temporal scales. Within this framework, research proposals were requested to address one or more of the following topics:

• Explain the trends in global and regional methane concentrations.
• Improvements in process modeling of methane at a regional and global scale.
• Quantify urban methane across the U.S., including through collaboration with local communities.
• Understand Arctic methane, particularly in the larger context of carbon cycling and feedbacks.
• Demonstrate utility of current and potential future measurements to support monitoring, reporting and verification of emissions.

The Program received 38 proposals, and of these, eight projects were selected for funding, totaling $5.3 million in grants.The eight new projects funded by the AC4 program in FY23 are:

Explaining recent increases in global methane and their sectoral attribution using isotopic and remotely sensed measurements of atmospheric methane

• This study aims to clarify sources  of atmospheric methane (CH₄) by leveraging isotopologue measurements, which can distinguish between different CH₄ production mechanisms. Previous research suggests that microbial emissions are significant contributors, but the relative impact of natural versus anthropogenic sources is still debated. The proposed project will improve flux inversion models, enhance sectoral emission estimates using isotopologue data, and employ Observing System Simulation Experiments (OSSEs) to refine our understanding of CH₄ emissions, particularly from wetlands and agriculture. This research will provide critical insights for future emission reduction strategies and measurement network designs.
• PI: Xin Lan, Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder/NOAA Global Monitoring Laboratory, xin.lan@noaa.gov, 80305
• co-PI: Sourish Basu, Earth System Science Interdisciplinary Center, University of Maryland, (College Park, MD)
• co-PI: Sylvia Michel, Institute of Arctic and Alpine Research, University of Colorado (Boulder, CO)
• Award Amount: $672,543

Role of atmospheric chemistry in monitoring changes in the CH4 Budget

• CH₄‘s interaction with atmospheric chemistry, particularly its reaction with the hydroxyl radical (OH), complicates source attribution. Current studies focus on CH₄ sources, but detailed assessments of CH₄ sinks, incorporating atmospheric chemistry data, are lacking. Ignoring chemical feedbacks can introduce significant biases in methane source estimates. This project aims to integrate observational and modeling constraints on the chemical processes driving CH₄ loss, incorporating updated halogen chemistry and interactive atmospheric chemistry in the Community Atmosphere Model (CAM-chem). By using top-down estimates of CH₄ fluxes and focusing on inter-annual and seasonal variability, the project will develop an ensemble-based Earth system model to optimize CH₄ and CO measurements. This effort will enhance our ability to monitor, verify, and report CH4 emissions, supporting informed policy decisions related to air quality, energy, and environmental impacts.
• PI: Benjamin Gaubert, National Center for Atmospheric Research (NCAR) (Boulder, CO)
• co-PI: Avelino F. Arellano Jr., University of Arizona (Tuscon, AZ)
• Award Amount: $636,451

Constraining the local-to-global methane budget by simulating stable methane isotopologues within the NOAA GFDL AM4.1 model and comparing to new regional and existing global observational constraints

• A comprehensive understanding of methane (CH₄) budgets, crucial for effective greenhouse gas reduction policies, remains elusive due to the overlap of natural (wetlands) and anthropogenic (natural gas, agriculture, sewage, landfills) sources. To date, the isotopologues of methane (¹³CH₄ and CH₃D) have proven to be useful tools for providing information about local-to-global source attribution changes, but these have primarily been applied via local or global box models. This study will implement methane stable isotopologue chemistry online in order to use machine learning to develop low-cost methane chemistry emulators for global climate models. 
• PI: Lee T. Murray, University of Rochester (Rochester, NY)
• co-PI: Vasilii V. Petrenko, University of Rochester (Rochester, NY)
• co-PI: Larry Horowitz, NOAA Geophysical Fluid Dynamics Laboratory (Princeton, NJ)
• co-PI: Vaishali Naik, NOAA Geophysical Fluid Dynamics Laboratory (Princeton, NJ)
• Award Amount: $489,044

Methane Emissions from Energy Production to Consumption: multi-scale testbed in the Uinta and Salt Lake Basins

• Despite tremendous advances towards identifying hotspots in CH4 emissions from the energy infrastructure and the development of multiple observational platforms, critical knowledge gaps remain. This project aims to address three key questions: 1) What are the temporal dynamics of methane emissions? 2) How can multiple observations be combined to characterize emissions at multiple scales? 3) How do emissions in the production and consumption ends of the energy infrastructure compare to one another? The study will focus on the Uinta and Salt Lake Basins in Utah, linking multi-scale observations. The objectives include extending long-term in-situ CH₄ records in production and consumption regions, conducting drone-based aerial sampling of facilities and hotspots, modeling and synthesizing multi-scale observations, and engaging with stakeholders
• PI: John C. Lin , University of Utah (Salt Lake City, UT)
• co-PI: Shane Murphy, University of Wyoming (Laramie, WY)
• co-PI: Seth Lyman, Utah State University (Logan, UT)
• Award Amount: $627,179

Advancing NOAA’s CarbonTracker-CH4

• The NOAA in situ network CH4 observations are currently too sparse and infrequent to provide reliable estimates at these scales. This project proposes to improve the ability of Carbon Tracker- CH₄ (CT- CH₄) to quantify trends and attribute them to specific sources by including satellite datasets that have better spatiotemporal coverage and using them along with in situ observations. This project also seeks to improve CT- CH₄ by addressing major sources of uncertainty in CH4 flux inversion modeling including transport error, errors in stratospheric CH4, and errors in the chemical sinks.
• PI: Lori Bruhwiler, NOAA Global Monitoring Lab (Boulder, CO)
• co-PI: Daniel Jacob, Harvard University (Cambridge, MA)
• Award Amount: $683,401

Source attribution and interannual variability of the methane budget over the US Midwest

• Rapid changes in atmospheric mixing of methane (CH₄) are an important environmental concern that remains poorly understood. This project aims to advance the understanding of source attribution and interannual variability of the CH₄ budget in the US Midwest–a globally significant natural and anthropogenic CH₄ source region. The project will first expand on the lake and wetland measurements to provide critical observational data for land- water-atmosphere modeling and scaling of these natural CH₄ sources. Second, leverage tall tower observation systems that are positioned to support atmospheric inverse analyses of both wetland-dominated and agriculturally-dominated regions. Third, expand on the current development and testing of the Energy Exascale Earth System Land Model (ELM).
• PI: Timothy Griffis, University of Minnesota (Minneapolis, MN)
• co-PI: Dylan Millet, University of Minnesota (Minneapolis, MN)
• co-PI: James Cotner, University of Minnesota (Minneapolis, MN)
• co-PI: Fenghui Yuan, University of Minnesota (Minneapolis, MN)
• Award Amount: $738,105

Investigating changes in urban methane using a multiplatform approach

• Bottom-up emissions estimates tend to carry high levels of uncertainty and the range of fugitive CH₄ sources are difficult to detect effectively. This project aims to characterize multi-year trends in SF Bay Area urban CH₄ by extending the operation of a currently one-year funded stationary flux tower to at least three-years of operation (operational in Berkeley, CA as of April 2022). Then, use an intensive mobile monitoring campaign to evaluate the efficacy of this approach, identify fugitive sources, and better characterize major urban CH₄ emissions source categories and specific facilities. This project will work with community groups, building owners, and utility companies to mitigate any identified leaks within the flux tower observation range. 
• PI: Joshua Apte, University of California, Berkeley (Berkeley, CA)
• co-PI: Allen Goldstein, University of California, Berkeley (Berkeley, CA)
• Award Amount: $750,000

Hydrogen isotopes as tracers of urban and global methane sources

• This project proposes to use isotopes of hydrogen to track sources of methane globally as well as in the Cincinnati area. Researchers will collaborate with NOAA background monitoring sites to implement measurement of the stable hydrogen isotope in atmospheric methane. The second objective of the project is to construct a methane inventory in the Cincinnati area consisting of new measurements integrated with isotopic tracers; this will be compared to top-down measurements of stable isotopes made at high altitude to compare with the inventory. The third objective is to work with community groups to prioritize methane sources to mitigate and work with city leaders to enact policies and regulations in these areas in line with the city’s net zero emissions goals. 
• PI: Amy Townsend-Small, University of Cincinnati (Cincinnati, OH)
• Award Amount: $522,220

¹The funding will be distributed over the life of the projects and future-year funding is conditional on appropriations.

²At the time of publication, all awards may not have been accepted by recipient institutions