Coherent interdecadal cycles in global rainfall, temperature, and cloud cover with alignment to Jovian orbital periods

Abstract Interdecadal cycles repeatedly appear in global climate variables such as rainfall, temperature, and the climate modes, yet their origin remains unresolved and is most often attributed either to quasi-periodic artefacts of internal climate variability and red-noise fluctuations, or external lunisolar drivers. Previous studies have often focussed on specific regions, singular variables or aggregated datasets. Here we identify significant coherent 12.9- and 19.9-year cycles in globally gridded datasets of rainfall, surface temperature, and cloud cover across ~40% of sites using the Gaussian clustering of wavelet amplitude power spectrum (GC-WAPS) method. Regional clusters of positive and negative correlation are largely balanced spatially meaning these cycles represent a redistribution of energy rather than an overall heating or cooling effect. These signals appear to align closely with orbital dynamics of the Jovian planets with a consistent lag of approximately two years. The observed phase, amplitude, and cross-variable consistency suggest a working hypothesis in which gravitational perturbations modulate interplanetary dust influx, potentially driving subtle observed downstream changes in total cloud cover (~2%), radiative balance (~0.4°C), and rainfall (~10%). These findings empirically suggest that a significant fraction of interdecadal variability may be externally paced, as opposed to arising solely from internal stochastic processes with potential implications for long term rainfall forecasting.