EAR-Climate: Collaborative Research: Methane Dynamics Across Microbe-to-Landscape Scales in Coastal Wetlands

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Methane (CH4) is a gas that, although it has a much lower concentration in the atmosphere compared to carbon dioxide (CO2), possesses a much more potent greenhouse effect, possibly accounting for 20-25% of global warming since the Industrial Revolution. Methane has a short residence in the air, so that regulating the emission of this gas can have rapid and profound results for mitigating climate change. The amount of methane in the atmosphere has increased despite reductions in anthropogenic sources; accordingly, the processes of methane production in natural environments must be accurately assessed. Coastal wetlands account for ~40% of global methane emissions and these regions are in constant flux owing to sea-level rise, sediment accumulation, ecological shifts, and landscape dynamics. This project will investigate the present-day controls on methane emissions in coastal wetlands, assess their variability due to sea-level rise, and use field observations and experiments to develop models that integrate the numerous factors that control methane emissions from these environments. The study site will be in coastal Louisiana, which has ~40% of all coastal, tidally influenced fresh and saltwater wetlands in the U.S., and these wetlands experience some of the highest relative sea-level rise rates in the world. Nearly 1 billion people around the globe live in proximity to similar coastal wetlands, so that the results of this research will have broad applicability to solving large-scale problems. The project’s educational and outreach activities will leverage ongoing programs at the participating universities and further include the development of new resources that will be available to students and the public.The proposed spatiotemporal framework will combine field, experimental, and model-based approaches to determine methane emissions from a range of settings (e.g., elevation, salinity, distance from waterways, hydroperiod, temperature, vegetation, soil organic carbon) and time scales (decadal–centennial– millennial) in the Terrebonne-Timbalier Estuary of coastal Louisiana. Some of these vegetated wetland soils emit more methane annually than the soil carbon that they sequester. The research objectives will: i) assess spatiotemporal variability of methane inventories and emissions, ii) quantify soil and organic carbon age and sedimentation history, iii) determine the microbial and functional diversity from soils at different spatiotemporal scales and across geochemical gradients, iv) experimentally assess methane flux due to flooding (e.g., duration, frequency, depth) regime changes, v) integrate landscape change into hydrodynamic and biogeochemical models that account for changes in wetland configuration and sea-level, and iv) evaluate the best numerical parameters to simulate methane dynamics across microbe-to-landscape scales.This project is jointly funded by the Frontier Research In Earth Sciences (FRES) program, the Established Program to Stimulate Competitive Research (EPSCoR), and the Ecosystem Sciences program in the Division of Environmental Biology (DEB).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.