Biased sampling of methane release from lakes and ponds: A problem for extrapolation

Abstract:

Lakes and ponds at high latitudes are important sources of atmospheric methane (CH₄). However, their overall contribution is largely unconstrained, partly due to sampling campaigns with short measurement periods and few sampling locations against a backdrop of high spatiotemporal variations in the emissions. Using CH₄ emission data from a total of 49 studies, we point out that high-end fluxes that average above 200 mg CH₄ m^-2 d^-1 were measured during sampling intervals of 1 week or less. The range of these short-term fluxes is also twice that of those measured during sampling intervals of 3 months or longer. Further, measurements of small shallow thaw ponds are overrepresented in the literature, which adds error and complexity when scaling CH₄ emissions regionally and globally. We use these and other examples to suggest improved sampling strategies that will reduce biases of CH₄ emission estimates from high latitude inland waters.