The Canadian Arctic has the potential for enhanced atmospheric methane (CH4) source regions as a response to the ongoing global warming. Current bottom-up and top-down estimates of the regional CH4 flux range widely. This study analyses the recent observations of atmospheric CH4 from five arctic monitoring sites and presents estimates of the regional CH4 fluxes for 2012–2015. The observational data reveal sizeable synoptic summertime enhancements in the atmospheric CH4 that are clearly distinguishable from background variations, which indicate strong regional fluxes (mainly wetland and biomass burning CH4 emissions) around Behchoko and Inuvik in the western Canadian Arctic. Multiple regional Bayesian inversion modelling systems are applied to estimate fluxes for the entire Canadian Arctic and show relatively robust results in amplitude and temporal variations even across different transport models, prior fluxes and sub-region masking. The estimated mean total CH4 annual flux for the Canadian Arctic is 1.8 ± 0.6 Tg CH4 yr−1. The flux estimate in this study is partitioned into biomass burning, 0.3 ± 0.1 Tg CH4 yr−1, and the remaining natural (wetland) flux 1.5 ± 0.5 Tg CH4 yr−1. The estimated summertime natural CH4 fluxes show clear inter-annual variability that is positively correlated with surface temperature anomalies. This indicates that the hot summer weather conditions stimulate the wetland CH4 emissions. More data and analysis are required to statistically characterise the dependence of regional CH4 fluxes on climate in the Arctic. These Arctic measurement sites should help quantify the inter-annual variations and long-term trends in CH4 emissions in the Canadian Arctic.
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Ishizawa et al. (2018) studied this question.