Climate change alters teleconnections

manuscript submitted to GRL Climate change alters teleconnections E. Vos1, P. Huybers2, E.Tziperman2 1Laboratoire de M´et´eorologie Dynamique/IPSL, Sorbonne Universit´e, ENS,PSL Research University, Ecole Polytechnique, CNRS, Paris France. 2Department of Earth and Planetary Sciences and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA. Key Points: • Anthropogenic climate change has altered large-scale climate teleconnections, af- fecting regional temperatures. • Changes to the teleconnections of ENSO, the IOD, and PDO between 1960–1990 and 1990–2020 are robustly observed. • Future climate change is projected to further alter teleconnection patterns, am- plifying their regional influence. Corresponding author: Eran Vos, eran.vos@gmail.com –1– arXiv:2512.22678v1 [physics.ao-ph] 27 Dec 2025 manuscript submitted to GRL Abstract Internal modes of climate variability, such as El Ni˜no and the North Atlantic Oscilla- tion, can have strong influences upon distant weather patterns, effects that are referred to as “teleconnections”. The extent to which anthropogenic climate change has and will continue to affect these teleconnections, however, remains uncertain. Here, we employ a covariance fingerprinting approach to demonstrate that shifts in teleconnection pat- terns affecting monthly temperatures between the periods 1960–1990 and 1990–2020 are attributable to anthropogenic forcing. We further apply multilinear regression to assess the regional contributions and statistical significance of changes in five key climate modes: the El Ni˜no–Southern Oscillation, North Atlantic Oscillation, Southern Annular Mode, Indian Ocean Dipole, and the Pacific Decadal Oscillation. In many regions, observed changes exceed what would be expected from natural variability alone, further implicating an an- thropogenic influence. Finally, we provide projections of how these teleconnections will alter in response to further changes in climate. Plain Language Summary Large-scale patterns in the climate system, such as El Ni˜no and the North Atlantic Oscillation, can have strong influences upon distant weather patterns, effects that are referred to as “teleconnections”. However, it is unclear to what degree anthropogenic cli- mate change is altering these teleconnections. We show that shifts in these climate con- nections between 1960–1990 and 1990–2020 cannot be explained by natural variability alone and can be attributed to human influence. We examine five major climate modes and find that their effects on remote regional temperatures have already changed, im- pacting many parts of the world. Finally, we provide projections showing how these cli- mate teleconnections are likely to further evolve in a warming future. 1 Introduction Modes of internal variability such as the El Ni˜no-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Southern Annular Mode (SAM), Indian Ocean Dipole (IOD), and the Pacific Decadal Oscillation (PDO) are recurring large-scale oceanic and atmo- spheric patterns. These patterns influence local and remote temperatures, precipitation, and extreme weather events (Karoly, 1989; Wallace & Gutzler, 1981; Alexander et al., 2002; Hobeichi et al., 2024; Casanueva et al., 2014; Wang & Schimel, 2003; Yeh et al., 2018; Reboita et al., 2021; Simon Wang et al., 2015; Casselman et al., 2023) with sig- nificant environmental, social, and economic impacts (Zebiak et al., 2015; Wang & Schimel, 2003; Hardiman et al., 2020; Kurths et al., 2019). Projecting changes to the effects of these modes in a warmer future climate is critical for adaptation efforts (Gillett et al., 2003; King et al., 2010; Paeth & Pollinger, 2010). Teleconnections are typically induced by atmospheric Rossby waves (Hoskins & Karoly, 1981; Hardiman et al., 2020; Reboita et al., 2021; Casselman et al., 2023) that are trig- gered by anomalies of sea surface temperature or surface heat fluxes, often via the me- diation effects of atmospheric convection. The teleconnection pattern of a given variabil- ity mode (for example, ENSO) can change between events because differences in the state of the ocean and atmosphere can affect wave propagation, including due to other modes that can exert a modulating effect on the teleconnections (Gershunov & Barnett, 1998; Hardiman et al., 2020; Joshi et al., 2021). Previous studies (Yeh et al., 2018) found in- dications of changes in teleconnection patterns since the 1990s, including in the effect of ENSO on North American precipitation (Simon Wang et al., 2015) and the effects of the Indian Ocean warming on the NAO (Hoerling et al., 2004). As climate change con- tinues, such teleconnections may be further affected, as suggested for ENSO (Lieber et al., 2024; Beverley et al., 2024). Some modes and the relation between them may change –2– manuscript submitted to GRL in the future, as projected for the NAO and AO under extensive climate warming (Hamouda et al., 2021). Observational anal

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