Melting Arctic glaciers expose new sources of planet-warming methane

Retreating glaciers in the Arctic are exposing groundwater springs containing very high concentrations of methane, which may add significant quantities of the greenhouse gas to the atmosphere.

“This is a novel methane emissions pathway that we hadn’t identified before,” says Gabrielle Kleber at the University of Cambridge.

Hundreds of springs have emerged at the base of retreating glaciers across the Norwegian Arctic archipelago of Svalbard. Kleber was intrigued by the springs, partly because of their “sulphuric, eggy smell”. Although methane is odourless, microbes in high-methane conditions sometimes produce gases like hydrogen sulphide that have this distinctive smell. “We knew …