But treating all nations the same, as a single unit, has weaknesses as a measure. The population size of nations varies greatly. Population estimates for the top five emitting nations are greatly varied. China has a population of around 1.44 billion. That’s more than four times that of the US at 331 million. India, the third-largest emitter has the second largest population in the world at 1.38 billion. Russia’s 2020 population is estimated to be about 146 million and Japan’s 126 million. Treating each nation as a single unit obscures the vastly different population sizes and unfairly implies that a billion people and a hundred million people should be held responsible for GHG emissions in a similar fashion. Fiji, a sovereign nation has a population of less than a million. Should Fiji’s emissions be compared to Brazil’s emissions when Brazil has a population of 212 million? Should China, with four times the population be equated with the US? Per capita units of measure by country account for the variation of population sizes.
If we utilize 2017 per capita emissions as our unit of analysis, national contributions to GHG emissions among four of the top five highest emitting nations plus the UK looks like this:
Instead of China being the leading emitter, the US emits the most carbon dioxide on average per person. One person in China emits the equivalent of less than half of what one person in the US emits (6.96mt compared to 16.24mt). Each person in the US does not literally emit just over 16 metric tons of CO2, but the per capita measure is calculated by taking the total emissions of a nation and dividing by the population size. India, the third leading overall emitter, emits less than 2mt (1.84) of CO2 per person. That means that it takes eight Indians to emit the same level of CO2 as just one person in the US. Other, poorer nations have much smaller per capita levels of emissions compared to the US.
The graphic below illustrates how many people from each country it takes to equal the same level of CO2 in a year as ONE person from the US:
There are countries with higher per capita emissions than the US. They include oil-producing nations like Qatar, Kuwait, United Arab Emirates, and Saudi Arabia. Many of these countries have small populations so their overall emissions are relatively low. Australia also has similar levels of CO2 emissions per capita as the US. To explore every countries’ per capita emissions see the tools here and here.