El Nino and the AMO Sparked the Astonishingly Large Margin of Warming in the Global Mean Surface Temperature in 2023

In 2023, the majority of the Earth witnessed its warmest boreal summer and autumn since 1850. Whether 2023 will indeed turn out to be the warmest year on record and what caused the astonishingly large margin of warming has become one of the hottest topics in the scientific community and is closely connected to the future development of human society. We analyzed the monthly varying global mean surface temperature (GMST) in 2023 and found that the globe, the land, and the oceans in 2023 all exhibit extraordinary warming, which is distinct from any previous year in recorded history. Based on the GMST statistical ensemble prediction model developed at the Institute of Atmospheric Physics, the GMST in 2023 is predicted to be 1.41 degrees C +/- 0.07 degrees C, which will certainly surpass that in 2016 as the warmest year since 1850, and is approaching the 1.5 degrees C global warming threshold. Compared to 2022, the GMST in 2023 will increase by 0.24 degrees C, with 88% of the increment contributed by the annual variability as mostly affected by El Nino. Moreover, the multidecadal variability related to the Atlantic Multidecadal Oscillation (AMO) in 2023 also provided an important warming background for sparking the GMST rise. As a result, the GMST in 2023 is projected to be 1.15 degrees C +/- 0.07 degrees C, with only a 0.02 degrees C increment, if the effects of natural variability-including El Nino and the AMO-are eliminated and only the global warming trend is considered.