Dream-World: A Simple Model of Energy-Related Carbon Emissions in the 20th and 21St Centuries

Abstract

This paper describes “DREAM-World”, a simple model of global carbon emissions using logistic equations to describe the variations, over the period 1900–2100, in world population, GDP per capita, energy intensity and carbon intensity. The resulting simulations of historical and projected future carbon emissions are in reasonably good agreement with both the historical emissions data and with three published future emission scenarios, chosen to reflect a wide range of possibilities. The use of logistic equations highlights the need to consider when the inflection points in key variables, such as GDP per capita, will occur in future. The modelling exercise also highlights the fact that, because energy intensity cannot in principle reach zero whereas carbon intensity can, energy efficiency improvements can only “buy time” in the carbon abatement process: a shift to carbon-free energy sources is ultimately required – if global economic growth is to continue.