China emits the most CO2 today, 2.5 times as much as the United States in 2024, but the United States has emitted far more over time: 434.9 billion tonnes of fossil CO2 since 1750, against China's 285.1 billion. Five new charts, based on the Global Carbon Budget and the "National contributions to climate change" dataset as published by Our World in Data, look at who caused the warming so far. For how per-person figures change the picture, see our post on per-capita and total emissions.
Who has emitted the most
The historical fossil CO2 chart puts the United States first with 23.5 per cent of the 1,849 billion tonnes emitted since 1750. Adding deforestation and other land use, in the chart that includes land use, lifts Brazil to fourth place with 139.4 billion tonnes, although it is only 19th on fossil fuels alone.
Who caused the warming
In the share of global warming chart, greenhouse gases emitted from 1851 to 2024 had warmed the planet by 1.68°C, and the United States accounts for 17.65 per cent of that, China for 12.95 per cent and Brazil for 5.25 per cent. These shares count methane and nitrous oxide as well as CO2.
Methane and forests today
China was also the largest methane emitter in 2024, with 1,591 million tonnes of CO2-equivalent out of the world's 9,499, as the methane chart shows. The land-use chart is led by Brazil, whose net emissions from deforestation and land use, 1,600 million tonnes, were 34.9 per cent of the world total.
| Chart | Top | Value |
|---|---|---|
| Countries With the Largest Historical CO2 Emissions, 1750-2024 | United States | 434.9 bn t |
| Historical CO2 Emissions Including Deforestation, 1850-2024 | United States | 560.5 bn t |
| Countries' Share of Global Warming, 1851-2024 | United States | 17.65% |
| Methane Emissions by Country 2024 | China | 1,591 Mt CO2e |
| CO2 Emissions From Deforestation and Land Use by Country 2024 | Brazil | 1,599.7 Mt |
How certain are these numbers?
Fossil CO2 estimates are the most reliable; land-use and methane figures are much less certain. As a check, the European Commission's EDGAR inventory ranks the same top four methane emitters and the same top three countries for deforestation emissions, though its exact values differ. All totals are counted by today's borders.