Falling Rate of CO2 Accumulation in Earth's Air

The Global Carbon Project has released its 2024 Carbon Budget, detailing where carbon dioxide originates and goes throughout the entire known carbon cycle on Earth. The report is the among first to project the total year values for carbon dioxide emissions by nation. The following chart presents the amount of CO₂ emissions by the world’s largest national producers of the greenhouse gas.

As it has been since 2006, China retains its title as the world’s largest emitter of carbon dioxide in 2024 by a widening margin with most nations. That includes India, whose emissions have been rising, but at a slower pace than China’s CO₂ output. The United States remains the second-largest national producer at about 41% of China’s 2024 emissions, even though its output of carbon dioxide emissions has been falling since 2005.

Changing to look at monthly data of how fast carbon dioxide emissions accumulate in the Earth’s atmosphere, the trailing twelve month average of the year-over-year change in atmospheric CO₂ levels peaked in January 2025. Since then, the rate of CO&8322; accumululation in the Earth’s air has fallen off sharply from January 2025′s record high pace.

This data is telling us something important about the state of Earth’s economy. Since China is such an outsize contributor to the carbon dioxide that is emitted into the atmosphere, it indicates that China’s economy has dramatically slowed since the end of 2024. And that happened before the U.S. imposed much higher tariffs on China’s exports to the U.S. on 2 April 2025, which have slowed China’s economy further.

In previous slowdowns, China’s government has responded by stimulating the country’s economy, resulting in higher CO₂ emissions to counter the slowing. Will 2025 be different?

References

National Oceanographic and Atmospheric Administration. Earth System Research Laboratory. Mauna Loa Observatory CO2 Data. [Online Data]. Updated 14 April 2025. Note: The NOAA appears to have changed its schedule for releasing atmospheric CO₂ concentration data from the Mauna Loa Observatory. Previously, they had regularly reported their revised and latest data during the first week of the month, but since March 2025, have been posting it in the middle of the month.

Image Credit: Friedlingstein, Pierre et al. Global Carbon Budget 2024. GtCO2 slidedeck PDF. 14 March 2025.