Decreased Precipitation Intensity Across the South Pacific Convergence Zone During the Little Ice Age

S.N. Ladd; A.E. Maloney; D.B. Nelson; M. Peaple; A. Witt; P. Sobeck; M. Prebble; D. Sear; P.G. Langdon; N. Dubois; J.P. Sachs

doi:10.3997/2214-4609.202533119

oa Decreased Precipitation Intensity Across the South Pacific Convergence Zone During the Little Ice Age
Authors S.N. Ladd^1,2, A.E. Maloney^3,4, D.B. Nelson¹, M. Peaple⁵, A. Witt⁴, P. Sobeck⁴, M. Prebble⁶, D. Sear⁵, P.G. Langdon⁵, N. Dubois^2,7 and J.P. Sachs⁴
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¹ University of Basel, Switzerland ² Eawag, Switzerland ³ University of Colorado, USA ⁴ University of Washington, USA ⁵ University of Southampton, UK ⁶ University of Canterbury, New Zealand ⁷ ETH Zurich, Switzerland
Publisher: European Association of Geoscientists & Engineers
Source: Conference Proceedings, IMOG 2025, Sep 2025, Volume 2025, p.1 - 2
DOI: https://doi.org/10.3997/2214-4609.202533119

Abstract

Summary

The South Pacific Convergence Zone (SPCZ) is the most prominent precipitation feature in the southern hemisphere. Changes in SPCZ precipitation dynamics have major impacts on local and global scales. Despite its importance, the future trajectory of rainfall dynamics in the tropical south Pacific remains uncertain due to challenges in modeling the modern SPCZ and limited paleoclimate records. We present five new quantitative records of rainfall rates from sediment cores collected from freshwater lakes in the western portion of the SPCZ (Solomon Islands and northern Vanuatu), spanning the past ∼500 to ∼1000 years. Our records are based on the hydrogen isotope composition of the dinoflagellate biomarker dinosterol, which is quantitatively related to mean annual precipitation in these settings. We pair our reconstructions with previously published, comparable records from Samoa, Wallis, and southern Vanuatu.

Our networked reconstruction of precipitation rates throughout the SPCZ demonstrates a coherent, basin-wide reduction in precipitation intensity during the Little Ice Age (1450 - 1850 C.E.). These results suggest that changes in SPCZ precipitation dynamics during the past millennium have been thermodynamically controlled, and there were not large-scale positional reorganizations of the rainfall belt. Overall, this indicates a strengthening of Pacific Walker circulation associated with global warming.

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References

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Decreased Precipitation Intensity Across the South Pacific Convergence Zone During the Little Ice Age

Conference Proceedings 2025, 1 (2025); https://doi.org/10.3997/2214-4609.202533119

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oa Decreased Precipitation Intensity Across the South Pacific Convergence Zone During the Little Ice Age

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