CO2 emissions, CO2 concentration and mean surface temperature increase, for 2 ° C targets (left) and 1.5 ° C targets (right)
Figure 1. CO2 emissions, CO2 concentration and mean surface temperature increase, for 2 ° C targets (left) and 1.5 ° C targets (right). Cases shown are: fossil CCS with ceiling targets (light blue), fossil CCS with overshoot targets (dark blue), fossil CCS and BECCS with ceiling targets (light green) and fossil CCS and BECCS with overshoot targets (dark green). Ceiling cases for the 1.5 ° C target are infeasible in our model.
In order to meet stringent temperature targets, active removal of CO2 from the atmosphere may be required in the long run. Such negative emissions can be materialized when well-performing bioenergy systems are combined with carbon capture and storage (BECCS). Here, we develop an integrated global energy system and climate model to evaluate the role of BECCS in reaching ambitious temperature targets. We present emission, concentration and temperature pathways towards 1.5 and 2 ° C targets. Our model results demonstrate that BECCS makes it feasible to reach temperature targets that are otherwise out of reach, provided that a temporary overshoot of the target is accepted. Additionally, stringent temperature targets can be met at considerably lower cost if BECCS is available. However, the economic benefit of BECCS nearly vanishes if an overshoot of the temperature target is not allowed. Finally, the least-cost emission pathway over the next 50 years towards a 1.5 ° C overshoot target with BECCS is almost identical to a pathway leading to a 2 ° C ceiling target.