Unexpected changes to the global methane budget over the past 2000 years

We report a 2000-year Antarctic ice-core record of stable carbon isotope measurements in atmospheric methane (delta13CH4). Large delta13CH4 variations indicate that the methane budget varied unexpectedly during the late preindustrial Holocene (circa 0 to 1700 A.D.). During the first thousand years (...

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Bibliographic Details
Published in:Science
Main Authors: Ferretti, DF, Miller, JB, White, JWC, Etheridge, DM, Lassey, KR, Lowe, DC, MacFarling Meure, CM, Dreier, MF, Trudinger, CM, van Ommen, TD, Langenfelds, RL
Format: Article in Journal/Newspaper
Language:English
Published: Amer Assoc Advancement Science 2005
Subjects:
Earth Sciences
Geology
Marine Geoscience
Antarctic
Antarc*
ice core
Online Access:https://doi.org/10.1126/science.1115193
http://ecite.utas.edu.au/112096
Description
Summary:We report a 2000-year Antarctic ice-core record of stable carbon isotope measurements in atmospheric methane (delta13CH4). Large delta13CH4 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.), delta13CH4 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 approximately 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.

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