Carbon dioxide emissions of transport sector transformation pathways considering CO2 emission budget allocation approaches

The IPCC's assessment report 6 shows a lack of ambition between global climate targets and what would be needed to keep global warming well below 2°C. However, while climate change is a global phenomenon, energy planning mainly occurs on national level. In order to bridge the gap between climate and energy research, we quantify cumulative emissions from 2020 up to GHG neutral provision of electricity, heat and power in Germany based on a reference and two target scenarios. Focusing on the transport sector transformation, we include end-user behavior and social and infrastructural inertia. We find cumulative emissions of between 7.2 and 12.7 Gt for the provision of German power, heat and transport energy demands. Transport sector is found to emit between 1.6 and 2.1 Gt in the analyzed scenarios, a range mainly shaped by end-user assumptions on car sales decisions. Main differences in transport sector defossilization scenarios show until 2030. Depending on value-driven allocation methods, the German share of the remaining global carbon budget is around -50 Gt (holding Germany accountable for historic emissions), 10 (if only today's population counts) or 80 Gt (if only today's emissions count). The German 1.5°C-compatible budget may be depleted very soon and neither political targets nor projections are in line with the 2°C target.