Groundwater discharge as a driver of methane emissions from Arctic lakes

Lateral CH(4) inputs to Arctic lakes through groundwater discharge could be substantial and constitute an important pathway that links CH(4) production in thawing permafrost to atmospheric emissions via lakes. Yet, groundwater CH(4) inputs and associated drivers are hitherto poorly constrained because their dynamics and spatial variability are largely unknown. Here, we unravel the important role and drivers of groundwater discharge for CH(4) emissions from Arctic lakes. Spatial patterns across lakes suggest groundwater inflows are primarily related to lake depth and wetland cover. Groundwater CH(4) inputs to lakes are higher in summer than in autumn and are influenced by hydrological (groundwater recharge) and biological drivers (CH(4) production). This information on the spatial and temporal patterns on groundwater discharge at high northern latitudes is critical for predicting lake CH(4) emissions in the warming Arctic, as rising temperatures, increasing precipitation, and permafrost thawing may further exacerbate groundwater CH(4) inputs to lakes.