Lateral CH₄ inputs to Arctic lakes through groundwater discharge could be substantial and constitute an important pathway that links CH₄ production in thawing permafrost to atmospheric emissions via lakes. This study unravels the important role and drivers of groundwater discharge for CH₄ emissions from Arctic lakes. Spatial patterns across lakes suggest groundwater inflows are primarily related to lake depth and wetland cover. Groundwater CH₄ inputs to lakes are higher in summer than in autumn and are influenced by hydrological (groundwater recharge) and biological drivers (CH₄ production). This information is critical for predicting lake CH₄ emissions in the warming Arctic.

Carolina Olid, Valentí Rodellas, Gerard Rocher-Ros, Jordi Garcia-Orellana, Marc Diego-Feliu, Aaron Alorda-Kleinglass, David Bastviken, Jan Karlsson