Modelling CO2 emissions from passenger cars for Swedish municipalities

Sammanfattning: The ratification of the Paris agreement has motivated nations to investigate howsubstantial greenhouse gas emission reductions can be accomplished for limiting globalwarming under two degrees Celsius. In Sweden, the magnitude of CO2 emissionsfrom domestic transportation is approximately one third of all other emission sectorscombined. It is therefore crucial for Sweden to stimulate substantial reductions in thissector. Local actors' possibilities to contribute to climate change mitigation arecentral to succeed albeit constrained in the transportation sector due to data andresource limitations. With the intention to benefit local climate change mitigationwork, a model capable of estimating the tailpipe CO2 emissions from passenger carswas created. The modelling exploited traffic work data from mandatory vehiclechecks conducted in Sweden for calculating CO2 emissions per car and year for theperiod of 1999-2017, to thereafter be aggregated for a municipality, i.e. a bottom-upapproach. The model and model results have been validated with official data andemission factors from HBEFA, whereas model configurations have also beencontrolled with sensitivity analyses. The model was applied for a case-study, Järfälla, amunicipality who recently had a carbon budget developed. Model results illustrated anincreasing trend in CO2 emissions for the period of 1999-2017 and were alsopresented over fuel technology, mass and car age. Moreover, the model was appliedto produce CO2 estimates per postal codes in the municipality for 2017 and toquantify the effect of explorative scenarios, i.e. policy goals, on CO2 emissions.