The Largest Contributors to Climate Change
I discussed the impact of greenhouse gases on our climate previously (here and here). In this post, I will address a popular question. Which countries are the largest emitters of greenhouse gases?
A single metric is not adequate to discuss the relative contributions from the different countries. Instead, three metrics are commonly used.
Metric 1: Recent Emissions
Most countries in the world have net zero targets¹. The metric, recent emissions, tells us about the extent of greenhouse gas reduction that will be required by each country to meet net zero goals.
The five countries that currently emit the largest amount of greenhouse gases are shown in Figure 1. The contribution from the rest of the world is also included for reference.
The top emitters based on their recent greenhouse gas emissions are China, United States, EU-27 countries, India, and Russia²𝄒³. These top emitters have a 59% share in terms of the recent contributions to global greenhouse gas emissions.
The relative contribution of the countries has changed over the decades (Figure 2)². For example, the emissions from China and India have increased markedly, while that from the United States and EU-27 countries have decreased over the past couple of decades. The emissions of most countries have increased in recent decades.
EU27 countries and United States are past their peak emissions. But most countries in the world are yet to reach peak emissions. The combined share of the EU27 countries and United States to the global emissions is 18%. So, even if these countries could somehow, very rapidly, cut their emissions to zero, the global emissions will reduce only by 18%. This reveals the importance of the role of all the countries across the globe.
Metric 2: Emissions Per Capita
The metric we discussed earlier focused on the total greenhouse gas emissions of the countries. The next metric we will review is the greenhouse gas emissions per capita. This data is obtained by dividing the total greenhouse gas emissions of the country by its population for the desired year. This metric allows a comparison between countries that have different population sizes.
The top five countries in terms of the highest greenhouse gas emission per capita are Qatar, Palau, Bahrain, Kuwait, and Trinidad & Tobago⁴. Most middle eastern countries are very high contributors by this metric.
Qatar has almost ten times more emissions per capita relative to the world average. The difference is especially glaring when compared to the least emitter countries. Qatar has 100 times higher emissions per capita than Democratic Republic of Congo and Burundi, which were the lowest emitter countries by this metric.
What about the emissions per capita of the top five emitters based on metric 1?
India has much lower greenhouse gas emissions per capita than the world average (Figure 3). The other countries have larger emissions per capita than the world average. The emissions per capita of China are over 50% of the world average, while those of Russia and United States are more than twice the world average.
Metric 3: Cumulative emissions
Climate change depends on the amount of greenhouse gases in the atmosphere. The greenhouse gases have long lifetimes and accumulate in the atmosphere⁵. So, the metric, cumulative emissions, is very important to discuss the relative contribution from countries.
The cumulative emissions from a country are estimated by adding all its greenhouse gas emissions from the earliest year for which data is available. CO₂ is used as a proxy for the greenhouse gases because it is the major component and historical CO₂ data is available.
The data is shown in Figure 4. The top emitters based on the cumulative contribution to CO₂ emissions are United States, EU-27 countries, China, Russia, and Japan⁶. These top emitters have a 66% share in terms of cumulative contributions to the global CO₂ emissions.
Final Remarks
Each of the metrics provides useful information related to the contribution of the different countries to climate change.
The metric of current emissions tells us about the level of reduction that will be required by each country to reach net zero. This will especially be challenging for China because of its massive current emissions. It produces 60% more emissions than the United States and EU27 countries combined.
But the current emissions alone do not provide the complete picture. The metric of cumulative emissions informs us about the total contribution from each country to climate change. While China has been the largest emitter in recent decades, the EU27 countries and United States have larger cumulative emissions. This means that United States and EU27 countries have contributed more to climate change than China.
Another important metric is the emissions per capita. This allows comparison of the contribution from countries with different population sizes. Middle eastern countries have extremely large emission per capita. Amongst the top five emitters based on the recent emissions metric, only India has lower emissions per capita than the world average.
The overall data shows that United States, EU27 countries, China and the middle eastern countries are the largest contributors to greenhouse gas emissions. These countries will need to play a leading role in cutting greenhouse gas emissions. But efforts from the largest contributors alone will not be adequate. If only the largest contributors reduced their greenhouse gas emissions to zero, this will reduce the global emissions by about 60%. This means that all the countries across the globe will need to take part in drastically reducing emissions.
Note: This is a modified excerpt from my book “The Climate Misinformation Crisis: How to move past the mistruths to a smarter energy future.
References & Notes
[1] United Nations. Climate action. https://www.un.org/en/climatechange/net-zero-coalition
[2] EDGAR (Emissions database for global atmospheric research) GHG database. https://edgar.jrc.ec.europa.eu/report_2023
[3] PBL Netherlands Environmental Assessment Agency 2021 Report. Trends in global CO₂ and GHG emissions. https://www.pbl.nl/en/publications/trends-in-global-co2-and-total-greenhouse-gas-emissions-2021-summary-report
[4] EDGAR GHG emissions of all world countries. 2023 Report. https://edgar.jrc.ec.europa.eu/report_2023?vis=ghgpop#emissions_table
[5] United Nations Climate Change. Global warming potentials. https://unfccc.int/process/transparency-and-reporting/greenhouse-gas-data/greenhouse-gas-data-unfccc/global-warming-potentials
[6] Global carbon budget, 2022. https://www.icos-cp.eu/science-and-impact/global-carbon-budget/2022
