Understanding Drivers of Decoupling of Global Transport CO2 Emissions from Economic Growth :Evidence from 145 Countries

This paper examines the extent to which countries have succeeded in decoupling transportemissions from economic growth, and how changes in emissions intensity, economic growth, and population growth havecontributed to changes in transportation-related emissions. The paper employs a modified version of the Tapio decouplingmodel, and demonstrates that over the 1990–2018 study period only 12 of 145 countries achieved “absolute decoupling,”defined as reducing emissions while growing gross domestic product. The majority of the top emitters remain in a“relative decoupling” state, with emissions growing more slowly than gross domestic product. Many of the middle- andlow-income countries have not achieved decoupling; their emissions are growing as fast as or faster than grossdomestic product. To understand the driving factors of transport-related carbon emissions, the paper conductsindex-decomposition and an econometric analysis. The results reveal that while transportation emission intensity hasdeclined in most countries, economic growth and population growth have offset these declines. If these patternscontinue, achieving the goals of the Paris Agreement with improvements in efficiency alone seems unrealistic. Thepaper also shows evidence that higher energy prices are associated with strong emissions reduction.