Global concentrations of carbon dioxide, methane and nitrous oxide climbed to unseen levels in 2023, underlining climate crisis

The levels of the three most important heat-trapping gases in the atmosphere reached new record highs again last year, US scientists have confirmed, underlining the escalating challenge posed by the climate crisis.

The global concentration of carbon dioxide, the most important and prevalent of the greenhouse gases emitted by human activity, rose to an average of 419 parts per million in the atmosphere in 2023 while methane, a powerful if shorter-lasting greenhouse gas, rose to an average of 1922 parts per billion. Levels of nitrous oxide, the third most significant human-caused warming emission, climbed slightly to 336 parts per billion.

The increases do not quite match the record jumps seen in recent years, according to the National Oceanic and Atmospheric Administration (Noaa), but still represent a major change in the composition of the atmosphere even from just a decade ago.