Share of global transportation sector CO₂ emissions 2023, by country

The United States is the biggest contributor to global transportation-related CO₂ emissions by far, accounting for approximately 21 percent of the world's total in 2023. That year, the U.S. transportation emissions totaled 1.71 billion metric tons of carbon dioxide (GtCO₂). The second-largest emitter was China, which produced around 13 percent of global transportation CO₂ emissions in 2023. Together, these 10 countries were responsible for just over half the world's total transportation-related CO₂ emissions in 2023.