Overview

• The WMO Greenhouse Gas Bulletin finds a 3.5 ppm year-over-year jump in atmospheric CO2 in 2024, the largest increase since modern measurements began in 1957.
• Global mean CO2 reached 423.9 ppm in 2024, while methane rose to 1,942 ppb and nitrous oxide to 338 ppb, both setting new highs.
• The analysis attributes the surge primarily to continued human emissions and increased forest fires during a year shaped by a strong El Niño and record global heat.
• Natural sinks weakened as warmer oceans absorbed less CO2 and drought reduced land uptake, leaving a larger share of emissions in the atmosphere.
• WMO leaders warn the buildup will extend planetary warming and intensify extreme weather, urging swift emissions cuts as governments convene in Belém for COP30.