Methane fluxes during the initiation of a large‐scale water table manipulation experiment in the Alaskan Arctic tundra

Much of the 191.8 Pg C in the upper 1 m of Arctic soil of Arctic soil organic mater is, or is at risk of, being released to the atmosphere as CO 2 and/or CH 4 . Global warming will further alter the rate of emission of these gases to the atmosphere. Here we quantify the effect of major environmental variables affected by global climate change on CH 4 fluxes in the Alaskan Arctic. Soil temperature best predicts CH 4 fluxes and explained 89% of the variability in CH 4 emissions. Water table depth has a nonlinear impact on CH 4 efflux. Increasing water table height above the surface retards CH 4 efflux. Decreasing water table depth below the surface has a minor effect on CH 4 release once an aerobic layer is formed at the surface. In contrast with several other studies, we found that CH 4 emissions are not driven by net ecosystem exchange (NEE) and are not limited by labile carbon supply.