Australia: The Land Where Time Began

A biography of the Australian continent 

Palaeocene-Eocene Thermal Maximum – 2 Massive Carbon Releases During the Onset of the PETM

About 55.5 Ma, During the Palaeocene-Eocene Thermal Maximum (PETM), the climate of the Earth warmed rapidly by 5-8^oC (Westerhold, Röhl & Laskar, 2012; McInerney & Wing, 2011). Associated with this warming, a massive release of carbon was added to the atmosphere-Ocean system. Estimates of the Earth system response to this perturbation have been complicated by estimates of the carbon release that vary widely, ranging from less than a year to tens of thousands of years. Also, the source of this carbon is still being debated, whether it was released as a single injection or several pulses (McInerney & Wing, 2011; Wright & Schaller, 2013; Cui et al., 2011). In this paper Bowen et al. present a new high resolution carbon isotope record obtained from the Bighorn Basin (Wyoming, USA)  that spans the PETM, and their interpretation of the record by the use of a carbon-cycle box model of the ocean-atmosphere-biosphere system. The beginning of the PETM is shown by their record to be characterised by 2 distinct events of carbon release that are separated by a recovery to background values. Their model required 2 discrete pulses of carbon that was released directly to the atmosphere, at rates averaging 0.9 Pg (billion tons of carbon, or 3.7 billion tons of CO₂ C per year, the first of the pulses lasting less than 2,000 years, to reproduce this pattern.. Their conclusion was that 1 or more reservoirs that were capable of repeated, catastrophic carbon release, and that during the PETM the rates of carbon release were more similar to those associated with modern anthropogenic emissions (Ciais et al., 2013) than have been suggested previously (Wright & Schaller, 2013; Cui et al., 2011).

Sources & Further reading

1. Bowen, G. J., B. J. Maibauer, M. J. Kraus, U. Röhl, T. Westerhold, A. Steimke, P. D. Gingerich, S. L. Wing and W. C. Clyde (2015). "Two massive, rapid releases of carbon during the onset of the Palaeocene-Eocene thermal maximum." Nature Geosci 8(1): 44-47.