New ACP Letter: The 2023 global warming spike was driven by the El Niño–Southern Oscillation

10 Oct 2024

The rapid global warming of 2023 has led to concerns that it could be externally driven. Here the authors show that climate models subject only to internal variability predict such warming spikes but rarely (p~1.6 %). However, when a prolonged La Niña immediately precedes an El Niño, as occurred leading up to 2023, such spikes are not uncommon (p~10.3 %). Virtually all of the spikes occur during an El Niño, strongly suggesting that internal variability drove the 2023 warming.

Executive editor's statement: The rapid increase in global warming in 2023 has sparked fears that Earth has entered a new warm state. Possible explanations for a warming spike have included transient changes in radiative forcing or deficiencies in climate models. This study shows that the primary cause is a mode of natural climate variability – the El Niño/Southern Oscillation (ENSO). The authors show that, while the magnitude of global warming caused by ENSO was particularly large in 2023, it is not unprecedented in the historical record. The implication is that global warming is continuing at a steady average rate without dramatic acceleration.

The Science article can be found at: https://www.science.org/content/article/el-ni%C3%B1o-fingered-likely-culprit-record-2023-temperatures

Contact: Shiv Priyam Raghuraman (sraghur2@illinois.edu)