부산대학교 도서관

We report a 2000-year Antarctic ice-core record of stable carbon isotope measurements in atmospheric methane ( δ[sup.13]C[H.sub.4]). Large δ[sup.13]C[H.sub.4] variations indicate that the methane budget varied unexpectedly during the Late preindustrial Holocene (circa 0 to 1700 A.D.). During the first thousand years (0 to 1000 A.D.), δ[sup.13]C[H.sub.4] was at least 2 per rail enriched compared to expected values, and during the following 700 years, an about 2 per rail depletion occurred. Our modeled methane source partitioning implies that biomass burning emissions were high from 0 to 1000 A.D. but reduced by almost ~40% over the next 700 years. We suggest that both human activities and natural climate change influenced preindustrial biomass burning emissions and that these emissions have been previously understated in late preindustrial Holocene methane budget research.
Methane is an important greenhouse gas, and measurements of its atmospheric concentration, [C[H.sub.4]], from ice cores demonstrate a slow increase over the late preindustrial Holocene (the LPIH, circa 0 to [...]