Unexpected Changes to the Global Methane Budget over the Past 2000 Years (original) (raw)

We present a 2000-year record of stable carbon isotope measurements in atmospheric methane derived from Antarctic ice cores. The data reveal significant variations in the methane budget during the late preindustrial Holocene, with substantial enrichment and subsequent depletion of d 13 CH 4. Our analysis shows that emissions from biomass burning were higher than previously estimated from 0 to 1000 A.D. and declined sharply thereafter. We argue that both human activities and natural climate variations played a critical role in influencing these emissions and that past research may have understated their impact on the global methane budget.