South Pacific convergence zone dynamics, variability, and impacts in a changing climate

The South Pacific Convergence Zone (SPCZ) is a band of intense rainfall and deep atmospheric convection extending from the equator to the subtropical South Pacific. The variability in rainfall, tropical cyclone activity, and sea level due to displacement of the SPCZ affects South Pacific Island populations and surrounding ecosystems. In this Review, we synthesize recent advances in understanding of the SPCZ in regards to the physical mechanisms responsible for its location and orientation, interactions with the principal modes of tropical climate variability, regional and global impacts, and response to human-induced climate change. These advances begin to provide a coherent description of its character and variability on synoptic, intraseasonal, interannual, and longer timescales. However, further efforts are needed to better assess and quantify the impact of the SPCZ on regional and global weather and atmospheric circulation. While current-generation climate models capture some aspects of SPCZ behavior, significant biases and deficiencies remain that limit confidence in future projections. Both improved climate model skill and new methods for regional modelling may better constrain future SPCZ projections, aiding adaptation and planning among vulnerable South Pacific communities.