A multi-year estimate of methane fluxes in Alaska from CARVE atmospheric observations

Published

October 9, 2016

Author(s)

Anna Karion, Scot Miller, Anna Michalak, Rachel Chang, Steven Dinardo, Jakob Lindaas, Colm Sweeney, Roisin Commane

Abstract

Methane (CH4) fluxes from Alaska and other arctic regions may be sensitive to thawing permafrost and future climate change, but estimates of both current and future fluxes from the region are uncertain. This study estimates CH4 fluxes across Alaska over a three year period using aircraft observations from the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) and a geostatistical inverse model (GIM). We find that a simple flux model based on daily soil temperature maps and a static map of wetland extent can reproduce the atmospheric CH4 observations more effectively than state of the art process-based models. This result points to a simple and effective way of representing wetland CH4 fluxes at regional spatial scales. It further suggests that contemporary process-based models can improve the representation of key processes that control fluxes at regional scales, and that more complex processes included in these models cannot be evaluated given the information content of available atmospheric CH4 observations. In addition, we find substantial CH4 emissions from the North Slope regions of Alaska, representing 24% of the total flux. Contemporary process models, on the other hand, only attribute an average of 3% of the total flux to this region. We hypothesize that the mismatch is due to a shutdown of CH4 fluxes within the process-based models at low soil temperatures. Our results suggest that CH4 emissions from high-latitude tundra ecosystems could be higher than in global-scale, process-based estimates. These regions could be a larger contributor to the natural global CH4 budget, and future projections based upon these models may underestimate CH4-climate feedbacks in cold soil tundra ecosystems. Lastly, we find that the seasonality of CH4 fluxes varied during 2012-2014, but that the total annual emissions did not differ significantly among years, despite substantial differences in temperature and precipitation. These results suggest that observed, short-te

Citation

Global Biogeochemical Cycles

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Journals

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Keywords

A simple model of soil temperature and wetland distribution can reproduce CH4 observations. ¿ The largest CH4 fluxes in Alaska occur in lowland tundra – in the south- west and North Slope. ¿ We do not find evidence for large inter-annual variability in the total Alaska CH4 budget.

Citation

Karion, A. , Miller, S. , Michalak, A. , Chang, R. , Dinardo, S. , Lindaas, J. , Sweeney, C. and Commane, R. (2016), A multi-year estimate of methane fluxes in Alaska from CARVE atmospheric observations, Global Biogeochemical Cycles, [online], https://doi.org/10.1002/2016GB005419 (Accessed April 23, 2024)