Greenhouse gases hit new record highs in 2025, WMO says

In brief

• The World Meteorological Organization says greenhouse gas concentrations hit record highs in 2025.
• Carbon dioxide reached 426.8 ppm, up 2.8 ppm from 2024 and 153 percent of pre-industrial levels.
• Methane and nitrous oxide also rose to record levels, and the warming effect of long-lived gases has grown 56 percent since 1990.

Record CO₂ concentration

The World Meteorological Organization (WMO) said carbon dioxide levels in the atmosphere averaged 426.8 parts per million in 2025, the highest figure since measurements began (Greenhouse gases hit record highs, yet again – Phys.org) (Weltorganisation für Meteorologie - Klimaschädliche Treibhausgase in Atmosphäre steigen auf Rekordniveau – Deutschlandfunk). The concentration rose by 2.8 ppm compared with 2024 (CO₂ in der Atmosphäre steigt auf Rekordwert – DER SPIEGEL). The WMO said the growth rate was smaller than in previous years, but still considerable (WMO-Bericht: CO2-Konzentration in der Atmosphäre steigt 2025 auf neuen Höchststand – ZEIT ONLINE).

Methane and nitrous oxide also climb

Concentrations of methane and nitrous oxide, which also drive global warming, rose to record levels as well. WMO officials said the trend is likely to continue.

Long-lasting effects on climate

The WMO said the warming influence of long-lived greenhouse gases has increased by 56 percent since 1990 (Bericht der Weltwetterorganisation: Treibhausgase so hoch wie nie – tagesschau.de). Deputy Secretary-General Ko Barrett said the gases trap an unprecedented amount of heat and fuel extreme weather. Because carbon dioxide remains in the air for a long time, it will affect the climate for decades and centuries (Greenhouse gas levels hit new record highs in 2025: UN – Phys.org).

Sources of emissions

The gases come mainly from burning coal, oil and gas, as well as from agriculture and livestock farming. Climate researchers quoted by the German public broadcaster ARD said the fact that growth rates are not falling points to insufficient action. Sönke Zaehle of the Max Planck Institute for Biogeochemistry in Jena said the rise was not surprising but still worrying.

Key figures

• CO₂ concentration 2025: 426.8 ppm
• Annual increase in CO₂ (2024–2025): 2.8 ppm
• CO₂ relative to pre-industrial level (1750): 153 percent
• Increase in warming influence of long-lived greenhouse gases since 1990: 56 percent