Long-term trends

Global emissions of carbon dioxide have risen by 88% since 1971 and are projected to rise by another 52% by 2030. In 1971, the current OECD countries were responsible for 66% of the total. As a consequence of rapidly increasing emissions in the developing world, the OECD contributed 49% to the total in 2004, but this is expected to fall to 38% by 2030. By far, the largest increases in non-OECD countries occurred in Asia, where emissions in China have risen by 5.5% per annum between 1971 and 2004. The use of coal in China increased levels of CO₂ by 3.2 billion tonnes over the 33-year period.

Two significant downturns can be seen in OECD CO₂ emissions, following the oil shocks of the mid-1970s and early 1980s. Emissions from the economies in transition declined over the last decade, helping to offset the OECD increases between 1990 and the present. However, this decline did not stabilise global emissions as emissions in developing countries grew.

Disaggregating the emissions data shows substantial variations within individual sectors. Between 1971 and 2004, the combined share of electricity and heat generation and transport shifted from one‑half to two‑thirds of global emissions.

Fossil fuel shares in overall emissions changed slightly during the period. The relative weight of coal in global emissions has remained at approximately 40% since the early 1970s. The share of natural gas has increased from 15% in 1971 to 20% in 2004. Oil’s share decreased from 49% to 40%. Fuel switching and the increasing use of non-fossil energy sources reduced the CO₂/total primary energy supply (TPES) ratio by 7% over the past 33 years.