Tripling since the 1960s
The latest WMO Greenhouse Gas Bulletin shows that CO₂ growth rates have tripled since the 1960s, accelerating from an average annual increase of 0.8 parts per million (ppm) to 2.4 ppm per year, in the decade from 2011 to 2020.
The rate increased by a record 3.5 ppm between 2023 and 2024. the largest increase since monitoring began in 1957.
Average concentrations reached 423.9 ppm in 2024, up from 377.1 ppm when the bulletin was first published in 2004.
Approximately half of the CO₂ emitted remains in the atmosphere, while the rest is absorbed by land and oceans; storage that is weakening as warming reduces ocean solubility and worsens drought.
The 2024 peak was likely amplified by an increase in wildfires and a reduction in CO₂ uptake by land and ocean in 2024, the warmest year on record, with a strong effect from the El Niño weather pattern.
“There is concern that terrestrial and oceanic CO₂ sinks are becoming less effective, which will increase the amount of CO₂ that remains in the atmospherethus accelerating global warming. Sustained and strengthened greenhouse gas monitoring is critical to understanding these cycles,” said Oksana Tarasova, a WMO senior scientific officer who coordinates the bulletin’s research.
Other all-time highs
Methane and nitrous oxide (the second and third long-lived greenhouse gases) also set new emissions records.
Methane levels rose to 1,942 ppb, 166 percent above pre-industrial levels, while nitrous oxide reached 338 ppb, a 25 percent increase.
“Heat trapped by CO2 and other greenhouse gases is accelerating our climate and causing more extreme weather conditions.. Reducing emissions is therefore essential not only for our climate but also for our economic security and community well-being,” said WMO Deputy Secretary-General Ko Barrett.
Monitoring and action
The WMO released the report ahead of the COP30 climate conference in Belém, Brazil, starting in November, emphasizing that sustained global monitoring is vital to guide climate action.