Atypical warming pattern of strong 2023-24 El Niño boosts global temperatures to new 1.5 °C record

During the 2023-24 El Niño, the July 2023–June 2024 average global mean surface temperature peaked at 1.58 °C above pre-industrial levels, associated with a record 0.36 °C year-over-year rise. Here we use statistical models and a Green’s Function method to explore the causes for this rise. We show that sea surface temperature accounts for ~92% of the interannual warming, highlighting the critical role of El Niño diversity. Unlike typical El Niños, dual tropical Pacific warming centers in 2023-24 and an eastward-extended North Atlantic jet stream synergistically amplified sea surface temperatures across tropical basins, accelerating the pace of global warming. From an energy balance perspective, ocean heat content accumulated during the preceding La Niña and a continuous increase in absorbed shortwave radiation over the ocean drove sea surface temperature rise. Accelerated warming may push the climate system closer to critical tipping points, emphasizing the need for enhanced monitoring, mitigation, and adaptation strategies. The 2023-24 El Niño event led global mean surface temperatures to surpass 1.5 degrees above pre-industrial levels, according to analysis of surface air temperature and ocean heat content data.