In a groundbreaking advance for urban environmental science, researchers at the University of California, Irvine have developed a novel technique that leverages the radiocarbon signature found in turfgrasses to precisely map fossil fuel-derived carbon dioxide (CO2) emissions across metropolitan landscapes. This innovative approach offers cities an invaluable tool to measure real progress in reducing greenhouse gases—an urgent priority as municipalities strive to meet ambitious decarbonization targets amid mounting climate change concerns.
The critical role of fossil carbon dioxide emissions in driving global warming is well established. However, until now, urban centers have faced significant challenges in accurately quantifying local emissions and discerning whether mitigation strategies are effectively curbing carbon output. UC Irvine’s earth system scientists, spearheaded by Claudia Czimczik, recognized that plants integrate atmospheric CO2 during photosynthesis, leaving a distinct radiocarbon fingerprint that can be analytically disentangled to distinguish fossil-derived carbon from biogenic sources. This insight underpins their pioneering methodology.
The research team conducted extensive sampling of managed turfgrasses throughout urban and rural areas of Southern California. Turfgrass, unlike wild or invasive species, offers a reliable proxy due to its regular maintenance and growth cycles, providing a consistent temporal window reflecting atmospheric conditions over a short but meaningful interval. By harvesting the uppermost layers of frequently mowed grass—typically cut every one to two weeks—the scientists ensured each sample captured approximately a fortnight of carbon assimilation, tightly aligning biological and atmospheric measurements.
Simultaneously, high-precision greenhouse gas monitoring instruments, provided through collaboration with Manvendra Dubey of Los Alamos National Laboratory, were deployed to obtain concurrent atmospheric CO2 concentration data. This integrative approach allowed the team to correlate radiocarbon signals extracted from the plant tissue with contemporaneous airborne CO2 metrics, thereby refining the spatial resolution and accuracy of emission maps.
The results revealed well-defined “carbon dioxide domes” over Los Angeles, a phenomenon rooted in the region’s unique topography where surrounding mountain ranges confine pollutants within the basin. This effect creates localized atmospheric pockets with elevated fossil fuel CO2 concentrations. Critically, the new turfgrass radiocarbon mapping method effectively captured these complex spatial patterns, suggesting strong applicability for evaluating emission control policies.
Importantly, this methodology addresses previous gaps in urban carbon monitoring infrastructure, providing a cost-effective yet precise tool adaptable for cities with limited resources. By harnessing vegetation as an intrinsic environmental archive, municipalities gain access to a scalable system capable of delivering fine-grained data necessary to track decarbonization efficacy across diverse neighborhoods and jurisdictions.
Extending beyond prior studies executed during the COVID-19 pandemic—which relied on invasive grass samples collected by citizen scientists and demonstrated stark emission fluctuations during lockdown and reopening phases—this work represents a methodological evolution. Shifting focus to managed turfgrasses enables year-round surveillance, eliminating seasonal sampling bias and enhancing temporal continuity. Additionally, the integration of atmospheric measurement experts has elevated analytical rigor, ensuring robust interpretation of complex radiocarbon dynamics.
Despite the promising outcomes, researchers caution that the interplay of local meteorology and urban form influences fossil carbon distribution. Los Angeles’s basin-mountain setting, which traps emissions, affords a relatively stable scenario for detecting fossil CO2. In contrast, cities subject to strong and consistent wind transport may present challenges for signal retention in vegetation and require calibration of the approach to account for increased atmospheric mixing.
Looking forward, the research team envisions broad implementation of their radiocarbon turfgrass technique as an indispensable component of urban climate strategy toolkits. By furnishing high-resolution emission maps with temporal sensitivity, local governments can precisely evaluate the impact of specific policies such as transportation electrification, building efficiency upgrades, and industrial emission reductions. This capacity will empower data-driven decision-making to accelerate progress toward carbon neutrality.
This innovative scientific effort underscores the transformative potential of interdisciplinary collaboration across earth system science, atmospheric chemistry, and urban ecology. With support from the U.S. National Science Foundation and in cooperation with partners from UC Riverside and the University of Utah, the UC Irvine team exemplifies how environmental measurement innovations can translate into actionable insights for climate mitigation.
To summarize, UC Irvine’s research charts a compelling new frontier in urban greenhouse gas monitoring by deploying radiocarbon analysis of managed turfgrass as an accurate, practical, and scalable surrogate for fossil fuel CO2 emissions. This breakthrough promises to enhance transparency, accountability, and efficacy in municipal climate initiatives, fueling momentum for meaningful emission reductions in American cities and beyond.
Subject of Research: Not applicable
Article Title: Not provided
News Publication Date: November 3, 2025
Web References:
https://doi.org/10.1029/2025JD043336
References:
The study published in the Journal of Geophysical Research: Atmospheres, October 27, 2025.
Image Credits: Not provided
Keywords:
Earth systems science, Greenhouse gases
