CO2 concentrations this year threaten limit of 1.5°C warming, study warns

The study by the British Meteorological Service is based on readings from a reference station in Hawaii. The limit of temperature increase to 1.5°C is considered increasingly unattainable by scientific experts.

Yet another alert. The increase in CO2 concentrations in the atmosphere in 2024 is expected to be higher than levels compatible with climate warming trajectories respecting the limit of 1.5°C, according to a study by the Met Office, the British meteorological service, made public Friday January 19. It is based on the records of the Mauna Loa station in Hawaii, which is considered a good indicator of the global trend.

The 2015 Paris Agreement aims to keep the increase in global average temperature well below 2°C compared to pre-industrial levels and to continue efforts to limit the temperature increase to 1.5°C. vs. But this most ambitious limit (which is understood as an average temperature over at least 20 years) is considered increasingly difficult to maintain by experts.

No substantial slowdown in perspective

“The estimated increase in atmospheric concentrations of carbon dioxide for this year is well above the three scenarios compatible with the 1.5°C limit described in the IPCC report”, explains Richard Betts, researcher at the Met Office. The authors of the study in fact relied on three scenarios from the IPCC, the climate experts mandated by the UN, which would make it possible to respect the most ambitious limit of the Paris agreement.

The scientists also sought to look at this year’s forecast without taking into account the current El Niño weather phenomenon, which is associated with an increase in global temperatures, and which also weakens carbon sinks like tropical forests. “Even putting aside the temporary effects of El Niño, we find that human-caused emissions will push the CO2 increase in 2024 to the absolute limit of the trajectories to meet 1.5°C”underlines Richard Betts.

The current climate already shows a warming of around 1.2°C or 1.3°C compared to 1850-1900. And at the current rate of emissions, the IPCC predicts that the threshold of 1.5°C has a one in two chance of being reached on average by the years 2030-2035. “To keep warming below 1.5°C, CO2 accumulation will have to slow down substantially in the coming years and stop by the middle of the century. But the forecast for 2024 does not show such a slowdown”warned Richard Betts.