T23 Paleosols and Phanerozoic Climate: Geochemistry to Trace Fossils
Sunday, 27 October 2002
8:00 AM - 12:00 PM
WARM EOCENE CONDITIONS MAINTAINED BY METHANOGENESIS IN ARCTIC SOILS
Paper number: T23-12
Program: Technical Sessions
Time: 11:00 AM – 11:20 AM
Authors
Abstract
The strikingly large carbon isotope separation (d13Ccc - d13Com = 30.5 ‰) between fossilized wood and pedogenic carbonate intertwined in an unusually well-preserved Metasequoia stem of Eocene age from Axel Heiberg Island indicated an Arctic paleoenvironment in which 23% of soil-respired CO2 was enzymatically reduced to methane, prior to the precipitation of pedogenic carbonate. Using conservative estimates of biomass and litter paleoproduction for Metasequoia fossil forests, I calculated an annual methane release of 341 x 1012 gCH4/yr for the forested Arctic during the Eocene. This value is ~3x total modern natural methane emissions from soils, and would have drastically interfered with re-radiation of heat from the Earth's surface, and maintained the relatively mild Arctic temperatures evidenced by the fauna and flora of the Eocene.