HR: 14:20h
AN: PP22B-04 INVITED     [PDF]
TI: Global warming in the early Eocene: was it driven by carbon dioxide?
AU: * Beerling, D J
EM: d.j.beerling@sheffield.ac.uk
AF: David J. Beerling, Dept. of Animal and Plant Sciences, University of Sheffield, Sheffield, S11 9HF United Kingdom
AU: Valdes, P J
EM: p.j.valdes@bristol.ac.uk
AF: Paul J. Valdes, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 United Kingdom
AB: A wide variety of geological evidence indicates Earth experienced extreme global warmth 50 million years ago. But proxy indicators generally suggest carbon dioxide levels similar to today's value. What, then, drove global warming in the Eocene ? We present a process-based earth systems modelling analysis of this Eocene climatic puzzle. In our atmospheric chemistry calculations, trace gas emissions from terrestrial ecosystems lead to significantly higher atmospheric methane and tropospheric ozone levels compared to the pre-industrial situation. Climatic feedback experiments, quantifying the radiative forcing of these gases, and stratospheric water vapour, demonstrate substantial land surface warming. We suggest therefore that the trace gas composition of the ancient atmosphere provides a coherent climate forcing mechanism accounting, in large part, for the global warmth of the early Eocene.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 1610 Atmosphere (0315, 0325)
DE: 1615 Biogeochemical processes (4805)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting