Greenhouse gases: how to read the new atmospheric records
· BehindLines newsroom
The World Meteorological Organization's bulletin, released on 27 October 2026, reports new atmospheric records for three gases in 2025. The corresponding annual averages are 426.8 ppm for carbon dioxide, 1,948 ppb for methane and 339.1 ppb for nitrous oxide. An AFP report carried by Peninsula gives the same figures, attributing them to WMO.
A level is different from its rate of increase
The World Data Centre for Greenhouse Gases table allows annual averages to be compared: carbon dioxide rose from 424.0 ppm in 2024 to 426.8 ppm in 2025. The difference is 2.8 ppm. A smaller rise than in the preceding year can still produce a fresh high. The amount continues to grow even when the pace of that growth slows.
Units matter too. Parts per million and parts per billion describe different proportions. Placing the three numbers side by side does not directly rank the gases by abundance, let alone by their contribution to warming. The unit must be read along with the number.
What is in the air, rather than an emissions inventory
The WMO announcement distinguishes atmospheric concentrations from annual emissions. Concentrations describe the amount present in the air, whereas emissions concern releases over a period. Uptake by land and oceans also affects the balance. Treating a concentration as the total released during that year would confuse two different measurements.
Another distinction concerns comparisons with 1750. For nitrous oxide, the bulletin's publication page gives an increase of 26%, equivalent to a level at 126% of that reference. It does not mean a 126% increase.
The global table supplies uncertainties and warns that quality control can lead to revisions of earlier values. Following the trend therefore requires comparisons between compatible years, units and methods. These worldwide averages cannot serve as a measurement of the air in a particular city or as a forecast of tomorrow's weather. Reading the scale, reference period and quantity being measured together is essential to understanding what the record actually says.