Decomposing the decoupling of road-based traffic emissions and economic growth: Regional disparities between the national and city-level in Germany during 1999-2013

Sammanfattning: The process of decoupling is often considered to fulfil the prediction by the Environmental Kuznets Curve hypothesis that negative environmental externalities diminish with increasing income. Recent research has found many instances of delinking between economic growth and environmental harm on the national level across the globe. This study examines the development of the relationship between economic growth and carbon dioxide emissions from road traffic for the case of Germany during 1999-2013. Additionally, it adds a geographical dimension by investigating decoupling in the three German cities Stuttgart, Frankfurt a. M. and Berlin. To explain the delinking that is uncovered by the decoupling analysis, a subsequent Shapley decomposition of the carbon emissions from road traffic on five underlying factors is conducted. The study shows that decoupling occurred in Germany and the cities throughout the entire period, except for recessive coupling in 2000 in Berlin. Nevertheless, periods of desirable decoupling, with increasing GDP and decreasing emissions, were only prevalent in Germany for nine years, in Berlin for seven, in Frankfurt for six and in Stuttgart for four years. The emission factor, representing the carbon intensity of traffic activities, was the most impactful factor in the total period, resulting in a significant decline in road traffic carbon emissions. Furthermore, the study revealed that the factors that are influencing on-road carbon emissions vary substantially between different regions and time periods. Consequently, the results suggest that the development of carbon emissions ffrom road traffic changes over time and is subject to regional characteristics.