Abstract
Background: The temporal emergence of major viral outbreaks has traditionally been regarded as largely
stochastic, with limited capacity for long-range anticipation. Increasing evidence from heliophysics and
atmospheric science suggests that Galactic Cosmic Ray (GCRs) flux—modulated by solar magnetic
activity and Earth–atmosphere coupling—constitutes a persistent background source of ionizing
radiation and may represent an overlooked environmental driver capable of organizing biological
phenomena across multiple timescales. As a ubiquitous component of the planetary radiation
environment, GCRs continuously interact with biological systems, providing a plausible environmental
context for large-scale temporal modulation without implying direct deterministic causation.
Methods: A total of 514 viral outbreak events (EM-DAT, 1964 to 2025) and GCRs intensity data (Oulu
Cosmic Ray Station) were analyzed using SARIMA forecasting, PELT change-point detection, Granger
causality, cross-spectral and Wavelet Transform Coherence (WTC), and a Vector Error Correction Model
with exogenous harmonic components (VECMX). These methods were applied within an environmental–
ecological time-series framework to evaluate whether large-scale GCRS variability aligns with population-
level viral outbreak dynamics. Harmonic structures corresponding to the Hale (~22-year), Schwabe (~11-
year), annual/semi-annual, and Quasi-Biennial Oscillation (QBO) cycles were incorporated to assess
phase synchronization, ecological timing cues, and long-range temporal alignment between cosmic
radiation variability and viral emergence patterns.
Results: GCRs variability signicantly Granger-caused viral outbreak occurrence across all tested lags up
to 12 months (p < 0.05), with maximal signicance within the rst four months (p < 0.0001), while no
reverse causality was detected. Spectral coherence revealed robust phase-locked coupling at the Hale
and Schwabe solar cycles (coherence = 0.91 and 0.85, respectively), indicating long-term
synchronization. Additional statistically signicant coherence was identified at quasi-biennial, annual,
and semi-annual timescales, consistent with GCRs secondary particles modulation by the Quasi-Biennial
Oscillation and seasonal atmospheric shielding. WTC demonstrated sustained coherence at the ≈11-
year Schwabe periodicity. Burst detection analysis further showed clustering of viral outbreak onsets
during periods of low solar activity, notably around the 2009 and 2019 solar minima. Conditional
harmonic VECMX and SARIMA projections indicate a renewed increase in GCRs intensity toward ~2030,
coinciding with the anticipated solar cycle A<0, 25/26 minimum and a corresponding phase-aligned rise
in viral outbreak activity.
Conclusions: Global viral outbreak dynamics exhibit statistically robust, multi-scale synchronization with
GCRs variability. While GCRs are unlikely to act as direct causal agents, they may function as
environmental timing cues or permissive triggers that modulate viral emergence or ecological
susceptibility windows. Incorporation of heliophysical indicators as contextual environmental risk
modiers may enhance early-warning systems and global outbreak preparedness when integrated with
conventional epidemiological surveillance frameworks.
