Overview

• Global average CO2 rose by 3.5 ppm from 2023 to 2024 to about 424 ppm, the largest one-year increase since measurements began in 1957, the WMO’s greenhouse gas bulletin reports.
• Methane and nitrous oxide also reached record concentrations in 2024, with CO2 now roughly 52% above pre‑industrial levels, according to the WMO and partner scientists.
• The surge is tied to continued fossil fuel use, major wildfire emissions—especially in the Americas during the warmest year on record—and reduced uptake by carbon sinks during a strong El Niño.
• WMO officials warn that land and ocean sinks show signs of weakening, raising concerns about feedbacks that could leave more CO2 in the atmosphere and intensify extreme weather.
• The bulletin, based on data from roughly 500 monitoring stations, urges rapid emissions cuts and a focus on net‑zero CO2 as attention turns to next month’s COP30 in Belém, with UN leaders cautioning the current path risks about 3°C of warming.