Large increases in methane emissions expected from North America’s largest wetland complex

Abstract

Natural methane (CH 4 ) emissions from aquatic ecosystems may rise because of human-induced climate warming, although the magnitude of increase is highly uncertain. Using an exceptionally large CH 4 flux dataset (~19,000 chamber measurements) and remotely sensed information, we modeled plot- and landscape-scale wetland CH 4 emissions from the Prairie Pothole Region (PPR), North America’s largest wetland complex. Plot-scale CH 4 emissions were driven by hydrology, temperature, vegetation, and wetland size. Historically, landscape-scale PPR wetland CH 4 emissions were largely dependent on total wetland extent. However, regardless of future wetland extent, PPR CH 4 emissions are predicted to increase by two- or threefold by 2100 under moderate or severe warming scenarios, respectively. Our findings suggest that international efforts to decrease atmospheric CH 4 concentrations should jointly account for anthropogenic and natural emissions to maintain climate mitigation targets to the end of the century.

Upscaling Wetland Methane Emissions From the FLUXNET‐CH4 Eddy Covariance Network (UpCH4 v1.0): Model Development, Network Assessment, and Budget Comparison

“…However, current emissions trajectories more closely track high emissions scenarios (Zhang et al, 2023). Since 2014, there has been an accelerating increase in the CH 4 growth rate that reached a record level in 2022, at 18.2 ppb y −1 (Lan et al, 2023), and these increases could continue as global temperatures rise (Bansal et al, 2023;Zhang et al, 2017).…”

“…Refined methods to evaluate CH 4 flux tower network representativeness along different dimensions of variability could result in improved estimates, as has been undertaken at regional scales (Malone et al, 2022;Villarreal & Vargas, 2021). Similarly, use of more finely resolved spatial forcing data can more accurately represent wetland conditions and may improve model functional responses (e.g., 30-m resolution in Bansal et al, 2023).…”

“…Spatial biases at global and landscape scales could be addressed in future work by improving the geographic and grid cell representativeness of CH 4 flux and predictor data, respectively. Developing methods to reconcile and integrate chamber flux data with tower flux data could be prioritized to gain information from the large amount of existing chamber data, such as in Bansal et al (2023), Kuhn et al (2021), andTuretsky et al (2014). Chamber methods offer a relatively inexpensive and accessible means to gather data in underrepresented regions (Harriss & Matson, 2009), may provide insights into patch-scale effects when paired with tower data via environmental response functions methods (Xu et al, 2017), and can extend the temporal representativeness of flux data (Chu et al, 2017).…”

Characterizing Performance of Freshwater Wetland Methane Models Across Time Scales at FLUXNET‐CH4 Sites Using Wavelet Analyses

“…In particular, a more advanced intercomparison protocol would help distinguish structural and parameterization limitations by (a) testing multiple parameterization schemes for major wetland processes (e.g., CH 4 production rate and transport); (b) running the models with inputs from FLUXNET-CH 4 local meteorological condition and local site information such as slope, drainage, and vegetation characteristics; and (c) including longer-term records and spatially representative observations with full uncertainty characterization from EC tower measurements. In addition, incorporating wavelet analysis into a more comprehensive framework that includes evaluation of other key variables and machine learning-based estimates (Bansal et al, 2023;McNicol et al, 2023) may help identify the factors influencing its performance at specific time scales more effectively. Modeling global-scale wetland CH 4 emissions is essential for accurately quantifying the contribution of wetland-CH 4 feedback to ongoing climate change within the contemporary global CH 4 budget, given their increasing role as potential contributors to the rise in atmospheric CH 4 concentration in recent years (Peng et al, 2022;Zhang et al, 2023).…”

Air temperature and precipitation constraining the modelled wetland methane emissions in a boreal region in Northern Europe

“…Methane production takes place in water-saturated soil layers with limited oxygen availability via anoxic decomposition of soil organic matter by methanogenic microbes. In addition, mineral lands can act as a source of methane if the soil is very moist or inundated (Lohila et al, 2016, Wolf et al, 2011, see also Bansal et al, 2023), with a significant contribution from the organic layer on top of the soil. There are accurate peatland maps for the northern regions based on in situ data of peat layer thickness (e.g.…”