CO2 growth rates have now tripled since the 1960s, and reached levels not seen in at least 800,000 years

Heat-trapping carbon dioxide in Earth’s atmosphere increased by the largest amount ever recorded last year, reaching levels not seen at any point in human civilization and drastically accelerating climate change, the United Nations weather agency reported Wednesday.

In its annual greenhouse gas bulletin released ahead of the U.N. climate summit, the World Meteorological Organization (WMO) said that carbon dioxide growth rates have now tripled since the 1960s and are at concentrations not observed in at least 800,000 years.

The report attributes the surge to ongoing emissions from coal, oil, and natural gas, as well as increases in wildfires, describing a “vicious climate cycle.” Human activities continue releasing CO₂ while the planet’s oceans and forests — which normally absorb carbon pollution — are losing their capacity to do so.

WMO said the jump in average global CO₂ concentration from 2023 to 2024 was the largest single-year increase since measurements began in 1957. Annual CO₂ growth has risen from an average of 2.4 parts per million (ppm) between 2011 and 2020 to 3.5 ppm from 2023 to 2024.

Bill Hare, CEO of Climate Analytics, called the findings “deeply alarming.” While fossil fuel emissions were “relatively flat” last year, he said the data indicates an accelerating buildup of CO₂ in the atmosphere, pointing to positive feedback loops driven by record heat — warming oceans and burning forests releasing even more carbon.