A stacked area chart showing annual global fossil CO2 emissions. Emissions have been steadily rising since 1959, hitting an estimated 36.3 gigatons in 2023. The U.S. has maintained emissions of around 4 to 5 gigatons a year since the 1970s. China’s annual emissions have grown from under 1 gigaton in the 1960s to 11 gigatons in 2023.