Abstract:
Annual global CO2 emission forecasts at 2100 span 10 to 40 billion tonnes. Modeling work over the past decade has not narrowed this range nor provided much guidance about probabilities. We examine the time-series properties of historical per capita CO2 emissions and conclude that per capita global emissions are stationary without trend, and have a constant mean of 1.14 tonnes per person with standard deviation of 0.02. With estimates of 21st century peak population levels in the 8-10 billion range, this implies that most emissions scenarios currently used for global warming forecasts are unrealistically high.