When it comes to global warming, it is not just carbon dioxide (CO2) that we talk about, but we also include other greenhouse gases (GHGs) such as methane, nitrous oxide and a few fluorinated gases. If we add up all GHGs in terms of their potential to make the planet warmer, no doubt CO2 is the most dominant, estimated at about 76%.
While CO2 can remain in the atmosphere for hundreds of years, the lifespan of gases such as methane is about 12 years and that of nitrous oxide is about 114 years. Fluorinated gases can survive for more than 250 years in the atmosphere.
Since the CO2 is the most dominant, when we speak of climate change issues, we tend to speak of CO2 only. Besides, the estimates of CO2 are more accurate and up to date when compared to other GHGs. The International Energy Agency (IEA) maintains detailed data on CO2 emissions on a countrywide/sector basis which are reasonably up to date as figures for 2019 for most countries are already available on their website.
According to the IEA, the G20 countries collectively accounted for 85% of the CO2 emissions for 2019, and this figure was actually about 92% in 1990. If we look at individual country CO2 emissions for 2019 (2018 for some countries since 2019 was not available), it ranged from 171 MTCO2e (Argentina) to 9,802 MTCO2e (China).
There are only five countries whose yearly CO2 emissions are more than 1,000 MTCO2e, and these are China (9,802), the USA (4,766), India (2,309), Russia (1,587) and Japan (1,066). These five countries account for almost 70% of the emissions from G20 countries, and about 58% of the world’s emissions.
Much of the climate change debate, however, is about which parameter to use—the absolute emissions or per capita emissions, since it has different implications for different countries. In terms of per capita, amongst the G20 countries