Will 2024 be the first year that global temperature exceeds 1.5°C?

• Published in: Atmospheric science letters 2024-09, Vol.25 (9), p.n/a
• Main Authors: Dunstone, Nick J., Smith, Doug M., Atkinson, Chris, Colman, Andrew, Folland, Chris, Hermanson, Leon, Ineson, Sarah, Killick, Rachel, Morice, Colin, Rayner, Nick, Seabrook, Melissa, Scaife, Adam A.
• Format: Article
• Language: English
• Subjects: atmospheric and climate dynamics; change & impacts; Climate; Climate change; Climate policy; Climate prediction; climate variability; Datasets; Earth and Related Environmental Sciences; El Nino; El Nino events; El Nino phenomena; Emissions; Geovetenskap och miljövetenskap; global; Global temperatures; Global warming; Greenhouse gases; Mean temperatures; Paris Agreement; Salinity; scale; Southern Hemisphere; Statistical analysis; Surface temperature; Temperature; Temperature changes; Temperature forecasting; Trends; weather and climate prediction; Weather forecasting; weather/climate extremes
• ISSN: 1530-261X; 1530-261X
• DOI: 10.1002/asl.1254

Global mean near surface temperature change is the key metric by which our warming climate is monitored and for which international climate policy is set. At the end of each year the Met Office issues a global mean temperature forecast for the coming year. Following on from the new record in 2023, we predict that 2024 will likely (76% chance) be a new record year with a 1‐in‐3 chance of exceeding 1.5°C above pre‐industrial. Whilst a one‐year temporary exceedance of 1.5°C would not constitute a breach of the Paris Agreement target, our forecast highlights how close we are now to this. Our 2024 forecast is primarily driven by the strong warming trend of +0.2°C/decade (1981–2023) and secondly by the lagged warming effect of a strong tropical Pacific El Niño event. We highlight that 2023 itself was significantly warmer than the Met Office DePreSys3 forecast, with much of this additional observed warming coming from the southern hemisphere, the cause of which requires further understanding. Predictions of global mean surface temperature for 2024 are made showing for the first time a significant chance of exceeding 1.5°C above pre‐industrial. Whilst a one‐year temporary exceedance of 1.5°C would not be a breach of the Paris Agreement target, our forecast highlights how close we are now to this. This further motivates efforts to rapidly transition to net zero global emissions of greenhouse gases and to undertake research to better understand the recent jump in global temperature.