UN data confirms record high levels for three major greenhouse gases

The United Nations weather agency confirmed on Tuesday that global concentrations of the three primary greenhouse gases reached record highs in 2025. The World Meteorological Organization issued this finding in its 22nd annual Greenhouse Gas Bulletin. The report serves as a preliminary update before the COP31 climate summit begins on Nov. 9 in Antalya, Turkey.

Atmospheric measurements show carbon dioxide at 426.8 parts per million, methane at 1,948 parts per billion, and nitrous oxide at 339.1 parts per billion. These figures represent 153%, 267%, and 126% of pre-industrial levels, respectively. Carbon dioxide drives about 66% of the warming effect among these three gases. Methane contributes roughly 16% of the warming effect, while nitrous oxide makes up the remainder of the major gas group.

Ko Barrett, the WMO Deputy Secretary-General, described the findings as another year of new records. She explained that these gases trap heat and provide energy for extreme weather events. Barrett noted that the past 11 years have been the warmest on record. She emphasized that carbon dioxide remains in the atmosphere for long periods, meaning its effects will persist for decades or even centuries.

The increase in carbon dioxide levels slowed compared to the previous year. The global average rose by 2.8 parts per million from 2024 to 2025. This is lower than the 3.6 part per million jump seen between 2023 and 2024. Oksana Tarasova, a WMO senior scientific officer, attributed the smaller rise to the recovery of land carbon sinks and reduced fire emissions. These factors followed the strong El Nino event of 2023 and 2024.

Tarasova stated that 2.8 parts per million remains a substantial addition of carbon from fossil fuel burning. The current growth rate exceeds the decade average of 2.6 parts per million. For comparison, the growth rate in the 1960s was 0.8 parts per million. She expects further increases in 2026 due to continued fossil fuel use and the development of a powerful El Nino.

The bulletin also drew attention to two trace gases linked to electricity production. Molecular hydrogen and sulfur hexafluoride are potent but less abundant. Sulfur hexafluoride is used as a spark suppressant in electricity distribution and has risen steadily over three decades. The reason hydrogen levels have climbed over the past decade is unknown, though it has begun to be used as an energy storage medium.