Are there basic physical constraints on future anthropogenic emissions of carbon dioxide?
Timothy J. Garrett* (Department of Atmospheric Sciences, University of Utah, Salt Lake City, UT, U.S.A.)
Received 12 November 2008; accepted 27 August 2009; published online 21 November 2009.
Abstract
Global Circulation Models (GCMs) provide projections for future climate warming using a wide variety of highly sophisticated anthropogenic CO2 emissions scenarios as input, each based on the evolution of four emissions “drivers”: population p, standard of living g, energy productivity (or efficiency) f and energy carbonization c (IPCC WG III 2007). The range of scenarios considered is extremely broad, however, and this is a primary source of forecast uncertainty (Stott and Kettleborough, Nature 416:723–725, 2002). Here, it is shown both theoretically and observationally how the evolution of the human system can be considered from a surprisingly simple thermodynamic perspective in which it is unnecessary to explicitly model two of the emissions drivers: population and standard of living. Specifically, the human system grows through a self-perpetuating feedback loop in which the consumption rate of primary energy resources stays tied to the historical accumulation of global economic production—or p×g—through a time-independent factor of 9.7±0.3 mW per inflation-adjusted 1990 US dollar. This important constraint, and the fact that f and c have historically varied rather slowly, points towards substantially narrowed visions of future emissions scenarios for implementation in GCMs.
*e-mail: tim.garrett@utah.edu
Link to abstract and free, open-access pdf file: http://www.springerlink.com/content/9476j57g1t07vhn2/
Link to free, open-access pdf file of complete article: http://www.springerlink.com/content/9476j57g1t07vhn2/fulltext.pdf
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