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Abstract

The global growth rate of CO₂ emissions from fossil fuel burning and other industrial processes has been accelerating from 1.1% year−1 in 1990–1999 to more than 3% year−1 in the period 2000–2004 (Raupach et al. 2007). This increase has contributed to an observed increase in the atmospheric growth rate of CO₂; during 1990–1999, the atmospheric CO₂ growth rate was estimated at 3.1 Pg C year−1; for the period of 2000–2005, this is estimated at 4.2 Pg C year−1 (Denman et al. 2007). The increase in emissions has put the growth rates of atmospheric carbon in recent years at the top end of the SRES (Special Report Emission Scenarios) prepared by the Intergovernmental Panel on Climate Change (IPCC) (Nakicenovic et al. 2000). These scenarios are the most important forcing agents used in current climate models to predict the effects of greenhouse gases and aerosols on the Earth’s climate. The dominant factor causing the imbalance appears to be a faster increase in fossil fuel emissions relative to the sink capacity of the land and oceans.
The analysis of Raupach et al. (2007) and the various chapters of this book point to the clear need to continue observing the carbon cycle as a means of both to verify and to fingerprint the source of emissions. Raupach et al. furthermore suggest that increased understanding of where the emissions are accelerating, and where decarbonisation of energy use takes place, has important implications for global equity and burden sharing in the costs of global change. This makes understanding the global carbon balance an issue of direct and fundamental relevance to society.