North Siberian Lakes: A Methane Source Fueled by Pleistocene Carbon

The sizes of major sources and sinks of atmospheric methane (CH 4 ), an important greenhouse gas, are poorly known. CH 4 from north Siberian lakes contributes ∼1.5 teragrams CH 4 year −1 to observed winter increases in atmospheric CH 4 concentration at high northern latitudes. CH 4 emitted from these lakes in winter had a radiocarbon age of 27,200 years and was derived largely from Pleistocene-aged carbon.