Search

Abstract Bioenergy with carbon capture and storage (BECCS) is a key negative emission technology for climate mitigation. Some countries have made no commitment to carbon neutrality but are viewed as potential BECCS candidates (hereafter, non-CN countries). Here we analyze contributions of these countries to global climate mitigation with respect to BECCS using an Earth system model with explicit representations of bioenergy crops. Switchgrass cultivation in these non-CN countries can further remove atmospheric CO2 by 9.1 ± 2.8 and 19.9 ± 5.2 PgC in the low-warming and overshot scenarios, resulting in an extra biogeochemical cooling effect of 0.01 ± 0.04 to 0.02 ± 0.06 °C. This cooling is largely counterbalanced by the biophysical warming, but the net effect is still an extra cooling. The non-CN countries play a more important role in the low-warming scenario than in the overshoot scenario, despite the inequality of temperature change among countries. Our study highlights the importance of a global system for climate mitigation.

Abstract Bioenergy with carbon capture and storage (BECCS) is considered to be a key technology for removing carbon dioxide from the atmosphere. However, large-scale bioenergy crop cultivation results in land cover changes and activates biophysical effects on climate, with earth’s water recycling altered and energy budget re-adjusted. Here, we use a coupled atmosphere-land model with explicit representations of high-transpiration woody (i.e., eucalypt) and low-transpiration herbaceous (i.e., switchgrass) bioenergy crops to investigate the range of impact of large-scale rainfed bioenergy crop cultivation on the global water cycle and atmospheric water recycling. We find that global land precipitation increases under BECCS scenarios, due to enhanced evapotranspiration and inland moisture advection. Despite enhanced evapotranspiration, soil moisture decreases only slightly, due to increased precipitation and reduced runoff. Our results indicate that, at the global scale, the water consumption by bioenergy crop growth would be partially compensated by atmospheric feedbacks. Thus, to support more effective climate mitigation policies, a more comprehensive assessment, including the biophysical effects of bioenergy cultivation, is highly recommended.

Bioenergy crops has been proposed as a climate mitigation measure, but how the biophysical effects of large-scale cultivation would influence the climate is not well known. Here, the authors use models to show that large-scale cultivation could cool the global land by 0.03 to 0.08 °C.