Emissions intensity is a composite indicator of two other major factors contributing to a country’s emissions profile: energy intensity and fuel mix.

Energy intensity, or the amount of energy consumed per unit of GDP, reflects both a country’s level of energy efficiency and its overall economic structure, including the carbon content of goods imported and exported. An economy dominated by heavy industrial production, for instance, is more likely to have higher energy intensity than one where the service sector is dominant, even if the energy efficiencies within the two countries are identical. Likewise, a country that relies on trade to acquire (import) carbon-intensive goods will—when all other factors are equal—have a lower energy intensity than those countries that manufacture those same goods for export.

Fuel mix refers to the carbon content of the energy consumed in a country. Coal has the highest carbon content, followed by oil and then natural gas. Accordingly, if two nations are identical in energy intensity, but one relies more heavily on coal than the other, its carbon intensity will be higher. The breakdown of fuel mixes, shown above for selected countries, varies widely and is highly correlated with countries’ natural endowments of coal, oil, natural gas, and hydropower capacity. “Other renewables” (which includes solar, wind, and geothermal) accounts for no more than 4 percent of total primary energy supply in any of the major emitting countries.