Largest global emitters of carbon dioxide 2021, by country

China was the biggest emitter of carbon dioxide (CO₂) emissions in 2021, accounting for nearly 31 percent of the global emissions. The world's top five largest polluters were responsible for roughly 60 percent of global CO₂ emissions in 2021.

Cumulative emissions

Although China currently emits the highest levels of CO₂ annually, it has emitted far less than the United States over the past three centuries. Since 1750, the United States has produced more than 400 billion metric tons of cumulative carbon dioxide emissions. Since the birth of the Industrial Revolution, global CO₂ emissions have increased dramatically, and reached a record high in recent years.

Impact of COVID-19 on emissions

Throughout history, major events such as wars and recessions have caused emission levels to fall. In 2020, COVID-19 led to a drop in emissions as governments enforced strict lockdowns. Travel bans around the world meant the transportation sector experienced significant emission reductions. By April 2020, aviation emissions had fallen 60 percent, relative to annual mean daily emissions in 2019.