We examine an Arctic winter storm event, which led to ice break–up, the formation of open leads, and the subsequent freezing of these leads. The methane (CH₄) concentration in under–ice surface water before and during the storm event was 8–12 nmol L⁻¹, which resulted in a potential sea–to–air CH₄ flux ranging from +0.2 to +2.1 mg CH₄ m⁻² ...