Preprints
https://doi.org/10.5194/egusphere-2024-1937
https://doi.org/10.5194/egusphere-2024-1937
08 Jul 2024
 | 08 Jul 2024
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

The 2023 global warming spike was driven by El Niño/Southern Oscillation

Shiv Priyam Raghuraman, Brian Soden, Amy Clement, Gabriel Vecchi, Sofia Menemenlis, and Wenchang Yang

Abstract. Global-mean surface temperature rapidly increased 0.27 ± 0.05 K from 2022 to 2023. Such an interannual global warming spike is not unprecedented in the observational record with previous instances occurring in 1956–57 and 1976–77. However, why global warming spikes occur is unknown and the rapid global warming of 2023 has led to concerns that it could have been externally driven. Here we show that climate models that are subject only to internal variability can generate such spikes, but they are an uncommon occurrence (𝑝 = 2.6 ± 0.1 %). However, when a prolonged La Niña immediately precedes an El Niño in the simulations, as occurred in nature in 1956–57, 1976–77, 2022–23, such spikes become much more common (𝑝 = 16.5 ± 0.6 %). Furthermore, we find that nearly all simulated spikes (94 %) are associated with El Niño occurring that year. Thus, our results underscore the importance of El Niño/Southern Oscillation in driving the occurrence of global warming spikes such as the one in 2023, without needing to invoke anthropogenic forcing, such as changes in atmospheric concentrations of greenhouse gases or aerosols, as an explanation.

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Shiv Priyam Raghuraman, Brian Soden, Amy Clement, Gabriel Vecchi, Sofia Menemenlis, and Wenchang Yang

Status: open (until 08 Aug 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-1937', Anonymous Referee #1, 08 Jul 2024 reply
  • RC2: 'Comment on egusphere-2024-1937', Mika Rantanen, 16 Jul 2024 reply
  • CC1: 'Comment on egusphere-2024-1937', Ales Kuchar, 19 Jul 2024 reply
Shiv Priyam Raghuraman, Brian Soden, Amy Clement, Gabriel Vecchi, Sofia Menemenlis, and Wenchang Yang
Shiv Priyam Raghuraman, Brian Soden, Amy Clement, Gabriel Vecchi, Sofia Menemenlis, and Wenchang Yang

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Short summary
The rapid global warming of 2023 has led to concerns that it could be externally driven. Models subject only to internal variability rarely predict such warming spikes (p~3 %). However, when a prolonged La Niña immediately precedes an El Niño, as occurred leading up to 2023, such spikes are not uncommon (p~17 %). Virtually all of the spikes occur during an El Niño, strongly suggesting that internal variability drove the 2023 warming.