(De)coupling and (De)carbonizing in the economies and energy systems of the G20

Reducing emissions will require significant changes in the production and consumption of emissions-intensive energy. These changes will necessitate two broad sets of actions: first, energy-intensive end-use sectors must reduce their demand for energy by becoming more energy efficient, and second, energy systems and the energy supplies they use must become less carbon-intensive. In this paper, we describe a set of emissions analysis methods to distinguish between these two actions, showing whether an end-use sector (represented by a jurisdiction’s economy) is coupled with or decoupled from the energy system, or the energy system and its energy supplies are carbonizing or decarbonizing, or some combination of (de)coupling and (de)carbonizing. We then apply the method to the changes in the economy, energy supply, and emissions of the members of the G20 between 2008 and 2017. The results show that 14 members experienced a degree of coupling and that for 18 members, and globally, the principal reason for any degree of emissions decline was demand reduction as opposed to changes to their energy systems. We conclude by suggesting significant decarbonization efforts are needed through the replacement and restructuring of energy systems and their energy sources.