Imagine a world where dying forests are actually making climate change worse. Sounds counterintuitive, right? But that's exactly what's happening with "ghost forests," and NASA's Student Airborne Research Program (SARP) is on a mission to understand why. This research, spearheaded by faculty advisors Stacey Hughes from the University of New Hampshire and graduate mentors Katherine Paredero from the Georgia Institute of Technology and Kaylena Pham from the University of Southern California, delves into the complex relationship between dying vegetation, methane emissions, and our atmosphere.
Wetlands, those soggy, vibrant ecosystems, are surprisingly major players in the global methane cycle. They're like natural methane factories, producing this potent greenhouse gas through a process called methanogenesis, which occurs in oxygen-deprived sediments. Think of it as the byproduct of decomposition in these waterlogged environments. But here’s where it gets controversial: as coastal wetlands face increasing threats from rising sea levels and severe storms, saltwater intrusion is creating "ghost forests" – expanses of dead trees, stark reminders of ecological change. The critical question is: how are these ghost forests affecting methane emissions?
Traditional estimates of wetland methane emissions often overlook these ghost forests. This prompted a closer look at two similar wetland ecosystems: the Great Dismal Swamp and the Alligator River. The core idea? To compare methane emissions across wetlands with varying levels of vegetation stress. Using data collected during the 2025 NASA SARP flight campaign, researchers utilized the Dynamic Aviation B-200 aircraft equipped with a highly sensitive PICARRO Gas Concentration Analyzer to measure methane and carbon monoxide levels. To understand vegetation health, they also incorporated satellite imagery from the Terra satellite’s MODIS instrument, specifically the Normalized Difference Vegetation Index (NDVI), which acts like a health indicator for plants. Higher NDVI values indicate lush, healthy vegetation, while lower values suggest stress or death.
Carson Turner from the University of North Dakota focused his research specifically on the Great Dismal Swamp (GDS), straddling the border of Virginia and North Carolina. Methane is a greenhouse gas with roughly 28 times the warming potential of carbon monoxide, making it a critical focus for climate research. Wetlands are the biggest natural source of methane, contributing 20-40% of global emissions. However, accurately modeling these emissions is challenging due to a lack of on-the-ground measurements and a limited understanding of how factors like soil moisture and temperature influence methane production. Turner's study leveraged data from two SARP flights over the GDS in June 2025. He calculated methane flux (the rate of methane release) using a mass balance approach. Interestingly, he found lower methane flux on the day with higher temperatures, contradicting some previous research. This is the part most people miss: environmental systems are incredibly complex, and simple correlations don't always hold true. Consider, for instance, that higher temperatures might lead to increased decomposition, but also to drier soil conditions that inhibit methanogenesis. Turner's future work aims to refine models by incorporating these flux measurements and further investigating the relationship between methane emissions and soil moisture. What factors do you think contribute to the complexity of modelling methane emissions, and how can we make our current models more accurate?
Back to the overarching comparison between the Alligator River and Great Dismal Swamp: The team observed significantly greater vegetation stress in the Alligator River, along with wider variations in methane concentrations in areas with higher stress. In contrast, the Great Dismal Swamp showed less vegetation stress and more consistent methane levels. Though it may seem counterintuitive, the Great Dismal Swamp actually exhibited a slightly higher mean methane concentration (2.11 ppm) compared to the Alligator River (1.96 ppm). This highlights the complexity of wetland methane dynamics. It's a reminder that ecosystem stress is only one piece of the puzzle. The researchers emphasized the crucial need to better understand the specific vegetation conditions that contribute to methane enhancements in wetlands. Could it be that initial decomposition in the ghost forests releases a burst of methane, followed by a decrease as the readily available organic matter is consumed? Or perhaps the changing soil conditions in these areas favor different types of methane-producing microbes?
On a related note, urban air quality is also under investigation by SARP. Alek Libby from Florida State University focused on ozone pollution in Mid-Atlantic cities like Baltimore, Richmond, and Norfolk. Ground-level ozone, a harmful air pollutant, forms from reactions involving volatile organic compounds (VOCs) and nitrogen oxides (NOₓ) in sunlight. The EPA's standard for ozone is 70 ppb (8-hour average), and while exceedances have decreased, understanding the specific emission profiles of different cities is still vital. Libby analyzed VOC composition and ozone formation dynamics in these cities using air samples collected during the 2024 SARP campaign. The analysis revealed that Baltimore had lower levels of key anthropogenic VOCs compared to the other cities. VOC/NOₓ ratios suggested that Richmond and Norfolk were NOₓ-limited, while Baltimore was in a transitional zone. But here’s the kicker: Baltimore still experiences more ozone exceedance days, likely due to elevated NO₂ levels. This suggests that reducing NOₓ emissions might be more effective for ozone mitigation in Baltimore than reducing VOCs alone. Future research will use the 2025 SARP dataset, collected on hot, stagnant days conducive to ozone formation, to further investigate these patterns. Is reducing NOₓ emissions the only way to solve the ozone problem or should we consider a multi-pronged approach?
Hannah Suh from the University of California, Santa Cruz, further explored VOCs, emphasizing their role in tropospheric photochemistry and their impact on air quality and human health. Her study focused on identifying VOC sources in Baltimore using SARP data from June 24th flights. By analyzing VOC ratios and using Positive Matrix Factorization (PMF), she identified oil and natural gas, biogenic sources, and vehicular emissions as major contributors to Baltimore's VOC profile. The presence of mixed plumes of industrial and urban emissions, indicated by correlations with ethyne, further complicated the picture. A logical next step would be to compare VOC signatures across multiple years to assess temporal trends. With the increasing transition to electric vehicles, how will this impact Baltimore's VOC's profile?
Finally, Aashi Parikh from Boston University tackled the issue of air pollution in Hopewell, VA, home to a cluster of major chemical facilities. Concerns about air pollution and health disparities have been raised by neighboring communities. Parikh's study investigated the distribution of VOCs in Hopewell's industrial corridor, comparing air samples collected there to those from the rest of the flight path during the 2024 SARP campaign. The analysis revealed significantly elevated levels of aromatics (benzene, toluene, and styrene) in Hopewell, VOCs linked to serious health problems. In fact, aromatics were approximately 5 times higher than in other areas. The EPA states that there is no safe threshold for chronic exposure to these carcinogenic compounds. Underserved communities are disproportionately affected by these health risks in Hopewell. Future research will compare VOC concentrations from the 2025 SARP campaign to the 2024 baseline to assess the effectiveness of emissions reductions efforts. Chemical facilities bring economic growth, but at what cost? How can we balance industrial development with public health and environmental justice?
These SARP projects highlight the critical role of atmospheric chemistry research in understanding and addressing pressing environmental challenges, from climate change to air pollution. By combining cutting-edge technology with dedicated student researchers, NASA is providing valuable insights into the complex interactions between ecosystems, emissions, and our atmosphere. What other solutions can we implement to better understand and address the issues of air quality?
