PNNL

Abstract

This paper explores the implications of delays associated with currently formulated climate policies (compared to optimal policies) for long-term transition pathways to limit climate forcing to 450ppm CO2e on the basis of the AMPERE Work Package 2 model comparison study. The paper highlights the critical importance of the 2030-2050 period for ambitious mitigation strategies. In this period, the most rapid shift to non-greenhouse gas emitting technology occurs. In the delayed response emissions mitigation scenarios, an even faster transition rate in this period is required to compensate for the additional emissions before 2030. Our physical deployment measures indicate that, without CCS, technology deployment rates in the 2030-2050 period would become considerably high. Yet the presence of CCS greatly alleviates the challenges to the transition particularly after the delayed climate policies. The results also highlight the critical role that bioenergy and CO2 capture and storage (BECCS) could play. If this technology is available, transition pathways exceed the emissions budget in the mid-term, removing the excess with BECCS in the long term. Excluding either BE or CCS from the technology portfolio implies that emission reductions need to take place much earlier.