Greenhouse gas levels hit new record in 2025, carbon dioxide reaches 426.8 ppm: WMO

Concentrations of the main heat-trapping gases in the atmosphere climbed to new record highs in 2025, the World Meteorological Organization (WMO) said in its annual Greenhouse Gas Bulletin, warning that the extra warming they cause will persist for generations.

The global average concentration of carbon dioxide reached 426.8 parts per million (ppm) last year, about 53% above pre-industrial levels of 1750. When the bulletin was first published in 2004, the figure stood at 377.5 ppm.

Slightly slower rise, but still high

Carbon dioxide rose by about 2.8 ppm between 2024 and 2025. That was smaller than the record jump of the previous year, but still above the average annual increase of the past decade. The WMO said the slowdown was largely because land ecosystems recovered some of their ability to absorb carbon after the drought and wildfires linked to the 2023-24 El Nino.

Methane, a powerful but shorter-lived greenhouse gas, reached about 1,948 parts per billion, more than two and a half times its pre-industrial level. Nitrous oxide climbed to about 339 parts per billion. The bulletin also recorded a sharp rise in sulphur hexafluoride, an extremely potent gas used in electrical equipment that can remain in the atmosphere for well over a thousand years.

Warning on El Nino

WMO Deputy Secretary-General Ko Barrett said each additional part per million matters because it traps more heat, and that the world is in effect supercharging the ocean and the atmosphere. The agency said monitoring station data indicate carbon dioxide levels kept rising in 2026, and that the strong El Nino developing this year sets the stage for another surge. It also cautioned that a warmer ocean may absorb less carbon dioxide in future.

The findings are expected to feed into the UN climate talks, COP31, due to be held in Antalya, Turkey, in November.

Why it matters for India

Rising greenhouse gas concentrations are linked by scientists to more intense heatwaves, heavy rainfall and stronger tropical cyclones, all of which India has experienced in recent years. A strong El Nino has historically been associated with weaker monsoons in India, adding to concerns over water and farm output, and the bulletin will add pressure on major emitters ahead of COP31.