Last year saw the biggest ever recorded annual increase in carbon dioxide in the atmosphere, locking in more long-term global temperature increases, according to a new report from the Wold Meteorlogical Organisation (WMO).
The WMO says "continued emissions of CO2 from human activities and an upsurge from wildfires were responsible, as well as reduced CO2 absorption by "sinks" such as land ecosystems and the ocean – in what threatens to be a vicious climate cycle".
"The heat trapped by CO2 and other greenhouse gases is turbo-charging our climate and leading to more extreme weather. Reducing emissions is therefore essential not just for our climate but also for our economic security and community well-being," WMO Deputy Secreatry General Ko Barrett warned.
Concentrations of methane and nitrous oxide also rose to record levels.
When the bulletin was first published in 2004, the annual average level of CO2 measured by WMO's Global Atmosphere Watch network of monitoring stations was 377.1 ppm. In 2024 it was 423.9 ppm.
Growth rates of CO2 have tripled since the 1960s, accelerating from an annual average increase of 0.8 ppm per year to 2.4 ppm per year in the decade from 2011 to 2020. From 2023 to 2024, the global average concentration of CO2 surged by 3.5 ppm, the largest increase since modern measurements started in 1957.
The likely reason for the record growth between 2023 and 2024 was a large contribution from wildfire emissions and a reduced uptake of CO2 by land and the ocean in 2024 - the warmest year on record, with a strong El Niño.
During El Niño years, CO2 levels tend to rise because the efficiency of land carbon sinks is reduced by drier vegetation and forest fires - as was the case with exceptional drought and fires in the Amazon and southern Africa in 2024.
"There is concern that terrestrial and ocean CO2 sinks are becoming less effective, which will increase the amount of CO2 that stays in the atmosphere, thereby accelerating global warming.
"Sustained and strengthened greenhouse gas monitoring is critical to understanding these loops," said Oksana Tarasova, a WMO senior scientific officer.
