Climate Variability in the South Pacific: A Systematic Review of Key Drivers and Processes

This systematic review synthesizes current scientific knowledge on the drivers of climate variability and change across the South Pacific, with a particular focus on mechanisms influencing tropical cyclone behavior and regional hydroclimatic extremes. The review begins by contextualizing the unique vulnerabilities of Pacific Island nations, which arise from geographic isolation, socio-economic constraints, and extensive coastal exposures. It examines the foundational role of the South Pacific Convergence Zone in organizing regional convection and precipitation and explores the multi-scale climate oscillations that modulate environmental conditions across interannual, decadal, and intraseasonal timescales. The compounding effects of anthropogenic climate change—including rising temperatures, sea-level increase, shifting rainfall regimes, and changing storm characteristics—are critically assessed. Special attention is given to the complex interplay between natural variability and human-induced trends in altering tropical cyclone genesis, tracks, and intensity. The review identifies persistent knowledge gaps, such as data inhomogeneity, limited long-term records, and uncertainties in downscaled projections, and concludes with prioritized research directions aimed at enhancing predictive capacity and supporting climate-resilient adaptation across this highly vulnerable region.