Greenhouse gas concentrations reached a new high in 2025, according to the World Meteorological Organization's latest Greenhouse Gas Bulletin. Carbon dioxide averaged 426.8 parts per million, methane reached 1,948 parts per billion, and nitrous oxide hit 339.1 parts per billion. CO2 is now about 53% above pre-industrial levels. The annual rise in CO2 slowed to 2.8 ppm between 2024 and 2025, down from a record 3.6 ppm the year before. The WMO attributes part of that to stronger land carbon absorption and lower wildfire emissions, but warns that 2026 could still see another increase. The report also flags sulfur hexafluoride, a gas used in electrical equipment, for a record rise despite its global warming potential being thousands of times higher than CO2. The full bulletin underscores the gap between current emission trends and the pace needed to limit global warming. It also points to overlooked risks like hydrogen leaks and the long atmospheric lifetime of CO2, which will keep affecting the climate for centuries.
