Comment on "Carbon farming in hot, dry coastal areas: an option for climate change mitigation" by Becker et al. (2013)

Abstract. Becker et al. (2013) argue that an afforestation of 0.73 × 10⁹ ha with Jatropha curcas plants would generate an additional terrestrial carbon sink of 4.3 PgC yr⁻¹, enough to stabilise the atmospheric mixing ratio of carbon dioxide (CO₂) at current levels. However, this is not consistent with the dynamics of the global carbon cycle. Using a well-established global carbon cycle model, the effect of adding such a hypothetical sink leads to a reduction of atmospheric CO₂ levels in the year 2030 by 25 ppm compared to a reference scenario. However, the stabilisation of the atmospheric CO₂ concentration requires a much larger additional sink or corresponding reduction of anthropogenic emissions.