Difficulty in Containing Carbon Dioxide Concentrations as Climate Targets at Risk

The increase in atmospheric carbon dioxide (CO2) concentrations this year is at risk of exceeding levels compatible with the climate warming trajectories necessary to meet the 1.5-degree Celsius limit outlined in the Paris Agreement, according to a study by the UK Met Office, based on data from a reference station in Hawaii. The 2015 Paris Agreement aims to keep the increase in global average temperature well below the 2-degree Celsius threshold compared to pre-industrial levels and to continue efforts to limit this temperature increase to 1.5 degrees Celsius. However, experts find it increasingly challenging to maintain the most ambitious limit-a sustained average temperature over a period of at least 20 years. "The estimated increase in atmospheric carbon dioxide concentrations for this year is well above the three scenarios compatible with the 1.5-degree Celsius limit highlighted in the IPCC report," summarized Richard Betts, a researcher at the Met Office, referring to the Intergovernmental Panel on Climate Change (IPCC). The study's authors relied on three scenarios from the IPCC that would make it possible to adhere to the most ambitious limit outlined in the Paris Agreement. Their conclusions are based on the predictions of a "relatively significant" increase in CO2 at the Mauna Loa station in Hawaii, considered a good indicator of global trends. Scientists also wanted to analyze the projected developments for this year without considering the current meteorological phenomenon El Niño, associated with a rise in global temperatures and negatively impacting carbon reservoirs such as tropical forests. "Even if we set aside the temporary effects of El Niño, we find that human-caused emissions will lead to an increase in CO2 in 2024 up to the absolute limit of trajectories to respect the 1.5-degree Celsius threshold," emphasized Richard Betts. The current climate already indicates a warming of about 1.2 degrees Celsius or 1.3 degrees Celsius compared to the period 1850-1900. At the current emission rate, the IPCC estimates a 50% chance of reaching the 1.5-degree Celsius threshold on average between 2030-2035.