Core-climate coupling: Changes in the Earth’s core dynamics driven by climatic processes

Changes in the Earth's global parameters—particularly variations in the length of day, $\Delta$LOD—are caused by a multitude of geophysical processes, including that of core dynamics. New signals have emerged in the recent space-geodetic record of $\Delta$LOD that are not explained solely based upon dynamics of the Earth's core. On the other hand, recent studies emphasize the increasing impact of climatic processes on $\Delta$LOD, yet even these fail to account for the mentioned emerging signals. Here we propose that these signals are explained once we account for ‘core-climate coupling’ (3C). For this purpose, we develop a new deep learning-based algorithm termed interpretable Bayesian physics-informed quantum deep learning (PIQDLIB) that takes into account all the possible connections between core and climate dynamics. Employing PIQDLIB and using the observations of $\Delta$LOD, global climate change, and core flow models, we unravel a 3C with a coupling strength of 4$\pm$2 %. This dynamic link elucidates nonlinear interactions between the climate and core processes. To explain the origin of this coupling, we propose a mechanism that accounts for 79$\pm$18 % of the coupling strength and is based upon the pole tide caused by the deviations of the Earth's rotational pole induced by climatic processes, namely, barystatic processes that result in continental-ocean mass redistribution as a result of polar ice sheet and global glaciers melting and shifts in terrestrial water storage. This newly discovered 3C phenomenon is manifested in $\Delta$LOD as a quasi-decadal oscillation with a main period of 12$\pm$1 year and amplitude of 0.1$\pm$0.02 milliseconds, though it also encompasses small-amplitude interannual and intradecadal periods in the range of $\sim$6–9 years. These results demonstrate the interplay between internal and external geodynamics, which is fundamental for a better understanding of global geophysics.