Inter-annual variability in fossil-fuel CO2 emissions due to temperature anomalies

Abstract

It is well known that short-term (i.e. interannual) variations in fossil-fuel CO₂ emissions are closely related to the evolution of the national economies. Nevertheless, a fraction of the CO₂ emissions are linked to domestic and business heating and cooling, which can be expected to be related to the meteorology, independently of the economy. Here, we analyse whether the signature of the inter-annual temperature anomalies is discernible in the time series of CO₂ emissions at the country scale. Our analysis shows that, for many countries, there is a clear positive correlation between a heating-degree-person index and the component of the CO₂ emissions that is not explained by the economy as quantified by the gross domestic product (GDP). Similarly, several countries show a positive correlation between a cooling-degree-person (CDP) index and CO₂ emissions. The slope of the linear relationship for heating is on the order of 0.5–1 kg CO₂ (degree-day-person)⁻¹ but with significant country-to-country variations. A similar relationship for cooling shows even greater diversity. We further show that the inter-annual climate anomalies have a small but significant impact on the annual growth rate of CO₂ emissions, both at the national and global scale. Such a meteorological effect was a significant contribution to the rather small and unexpected global emission growth rate in 2014 while its contribution to the near zero emission growth in 2015 was insignificant.