What happened: The World Meteorological Organization's Greenhouse Gas Bulletin, released Oct. 27, put the global average CO2 concentration at 426.8 parts per million in 2025, 153% of the pre-industrial level. Methane and nitrous oxide also reached record highs. CO2 rose 2.8 ppm from 2024 to 2025, after an exceptional 3.5 ppm jump the year before.

Why it matters: CO2 stays in the air for centuries, so each increase locks in more warming. The WMO expects concentrations to rise again in 2026 because of fossil fuel burning and a strong El Niño that weakens land carbon sinks. It also flags record growth in SF6, a gas used in electrical equipment with a warming effect about 24,300 times that of CO2.

How much agreement is there? Broad agreement. These are measurements from the WMO's global monitoring network; the debate is about policy, not the readings.

Could someone help? Students can follow measurement records like the Keeling Curve, and utilities and regulators can push for alternatives to SF6 as grids expand.