WMO Greenhouse Gas Bulletin

The Greenhouse Gas Bulletin has been published annually since 2004. This publication presents the latest analysis of observations from the WMO Global Atmosphere Watch (GAW) Programme on concentrations of long-lived greenhouse gases in the atmosphere for 2023.

The Bulletin reports globally averaged surface mole fractions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). It compares these values to those of the previous year and pre-industrial levels. Additionally, it provides insights into changes in radiative forcing — the warming effect on the atmosphere by long-lived greenhouse gases and details the contribution of individual gases to this effect.

The Greenhouse Gas Bulletin is released yearly to inform the United Nations Climate Change negotiations, the annual Conference of the Parties (COP).

Key messages

• CO2 concentrations have increased 11.4 % in just 20 years
• Long lifetime of CO2 in atmosphere locks in future temperature increase
• El Niño and vegetation fires fuel surge in later part of 2023
• Effectiveness of carbon sinks like forests cannot be taken for granted
• Improved understanding of carbon-climate feedbacks is needed