The World Meteorological Organization (WMO) reported that the increase in carbon dioxide levels from 2023 to 2024 represents the largest one-year rise since records began in 1957. Published on October 15, 2025, and updated shortly thereafter, the UN highlighted that last year’s surge in atmospheric carbon dioxide was unprecedented.
According to the WMO, all three major greenhouse gases—carbon dioxide (CO2), methane, and nitrous oxide—saw further increases in 2024, each reaching new record highs. This alarming trend was detailed in a report released ahead of the COP30 UN climate summit scheduled for November 10-21 in Belem, Brazil, which specifically addressed greenhouse gas concentrations in the atmosphere.
A forthcoming UN report next month is expected to reveal further increases in emissions, continuing the trend as global reliance on oil, gas, and coal persists. This rise contradicts the commitments made under the 2015 Paris Agreement, which aimed to limit global warming to “well below” 2°C above pre-industrial levels, with an aspiration to keep it below 1.5°C.
The WMO expressed “significant concern” that both land and oceans are becoming less effective at absorbing CO2, resulting in higher concentrations of this potent greenhouse gas in the atmosphere. WMO Deputy Secretary-General Ko Barrett emphasized that the heat trapped by CO2 and other greenhouse gases is exacerbating climate change and leading to more extreme weather events. “Reducing emissions is therefore essential not just for our climate but also for our economic security and community well-being,” Barrett stated.
Additionally, the WMO noted that last year was the warmest on record, surpassing the previous high set in 2023.