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This content will become publicly available on June 24, 2026

Title: Abrupt shift of El Niño periodicity under CO 2 mitigation
Removing CO2from the atmosphere is emerging as a viable strategy to mitigate global warming, yet the responses of the climate system to CO2reduction remain uncertain. One of the most uncertain aspects of El Niño behavior is the change in periodicity in response to CO2forcing [O. Alizadeh,Earth-Sci. Rev.235, 104246 (2022)]. In this study, we show that climate models consistently project an abrupt shortening of El Niño periodicity once CO2reductions commence in ramp-up and ramp-down CO2experiments. Besides the contribution of slow mean state changes, this phenomenon is shown to be driven by a southward shift of the Intertropical Convergence Zone (ITCZ) [J.-S. Kug,et al.,Nat. Clim. Chang.12, 47–53 (2022)] and the consequent narrowing of El Niño’s spatial pattern, which enhances the effectiveness of ocean heat recharge/discharge processes, thereby shortening its periodicity. This suggests that the abrupt shift in El Niño periodicity results from a cascading reaction involving ITCZ dynamics and El Niño’s spatial configuration. These findings highlight the critical role of the global energy balance in shaping El Niño characteristics.  more » « less
Award ID(s):
2219257
PAR ID:
10639470
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
Proceedings of the National Academy of Sciences
Date Published:
Journal Name:
Proceedings of the National Academy of Sciences
Volume:
122
Issue:
25
ISSN:
0027-8424
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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