Precipitation intensity increased across the South Pacific Convergence Zone in the Industrial Age

S. Nemiah Ladd; Ashley E. Maloney; Daniel B. Nelson; Mark D. Peaple; Julie N. Richey; Amanda Witt; Polly Sobeck; Matthew Prebble; David A. Sear; Peter G. Langdon; Nathalie Dubois; Julian P. Sachs

doi:10.1029/2026gl122187

USGS · 70277122

Precipitation intensity increased across the South Pacific Convergence Zone in the Industrial Age

S. Nemiah Ladd·Ashley E. Maloney·Daniel B. Nelson·Mark D. Peaple·Julie N. Richey·Amanda Witt·Polly Sobeck·Matthew Prebble·David A. Sear·Peter G. Langdon·Nathalie Dubois·Julian P. Sachs

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Abstract

The position, strength, and variability of precipitation in the South Pacific Convergence Zone (SPCZ) remain challenging for coupled ocean-atmosphere climate models to represent, leaving future rainfall projections in this dynamically important region uncertain. Here, we present quantitative records of mean annual precipitation (MAP) spanning the past 1,000 years using sediment cores from five freshwater lakes on different islands in the western portion of the SPCZ. Precipitation reconstructions are based on the hydrogen isotope composition of the dinoflagellate biomarker dinosterol, which is inversely correlated with MAP. We show that MAP in the western tropical Pacific increased over the past ∼300 years, with a significant increase beginning in 1,820 ± 75 C.E., coincident with a warming trend in the Western Pacific Warm Pool. These results contrast with the expected drying associated with reduced Pacific Walker Circulation as global temperatures increase in many climate models. Future warming may promote more intense SPCZ precipitation.

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S. Nemiah Ladd, Ashley E. Maloney, Daniel B. Nelson, Mark D. Peaple, Julie N. Richey, Amanda Witt, Polly Sobeck, Matthew Prebble, David A. Sear, Peter G. Langdon, Nathalie Dubois, Julian P. Sachs. 2026-07-10. Precipitation intensity increased across the South Pacific Convergence Zone in the Industrial Age. https://doi.org/10.1029/2026gl122187

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