Overview

• The global average rose by 3.5 ppm from 2023 to 423.9–424 ppm in 2024, the biggest annual jump since measurements began in 1957 and part of a long‑term acceleration since the 1960s.
• Concentrations of methane and nitrous oxide also reached all‑time highs in 2024, with global averages around 1,942 ppb and 338 ppb, according to the WMO.
• Continued fossil fuel burning, a surge in wildfire emissions, and reduced uptake by land and ocean sinks drove the spike, compounded by a strong El Niño and the warmest year on record.
• WMO scientists cautioned that forests, soils and oceans appear less able to absorb carbon, raising the risk of feedback loops that keep more CO2 in the atmosphere and speed warming.
• Officials called for rapid emissions cuts, progress toward net‑zero CO2, and strengthened greenhouse‑gas monitoring, with the bulletin released to inform COP30 talks in Belém, Brazil.