Unexpected Changes to the Global Methane Budget over the Past 2000 Years

• Published in: Science
• Main Authors: Ferretti, D. F., Miller, J. B., White, J. W. C., Etheridge, D. M., Lassey, K. R., Lowe, D. C., Meure, C. M. MacFarling, Dreier, M. F., Trudinger, C. M., van Ommen, T. D., Langenfelds, R. L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Association for the Advancement of Science (AAAS) 2005
• Subjects: Antarctic; Antarc*; ice core
• Online Access: http://dx.doi.org/10.1126/science.1115193; https://www.science.org/doi/pdf/10.1126/science.1115193

We report a 2000-year Antarctic ice-core record of stable carbon isotope measurements in atmospheric methane (δ 13 CH 4 ). Large δ 13 CH 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 13 CH 4 was at least 2 per mil enriched compared to expected values, and during the following 700 years, an about 2 per mil 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.