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Abstract Meridional shifts of the North Atlantic Subtropical High (NASH) western edge create a dipole that drives hydroclimate variability in the southeastern United States and Caribbean region. Southwest displacements suppress rainfall in the southern Caribbean. Northwest displacements drive southeast United States and northern Caribbean drying. Projections for the 21st century suggest a more meridionally displaced NASH, which jeopardizes Caribbean island communities dependent on rain‐fed aquifers. While recent work indicates that Atlantic and Pacific Ocean‐atmosphere variability influenced the NASH during the instrumental period, little is known about NASH behavior and subsequent hydroclimate responses over longer timescales. To address this limitation, we developed a ∼6000‐years long rainfall record through the analysis of calcite raft deposits archived within sediments from a coastal sinkhole in the northeast Bahamas (Abaco Island). Increased (decreased) calcite raft deposition provides evidence for increased (decreased) rainfall driven by NASH variability. We use simulations from the Community Earth System Model to support this interpretation. These simulations improve our understanding of NASH behavior on timescales congruous with the reconstruction and suggest an important role for the state of the Pacific Ocean. Furthermore, model simulations and a compilation of regional hydroclimate reconstructions reveal that the NASH‐driven dipole dominates northern and southern Caribbean rainfall on centennial timescales. These results bring Holocene Caribbean hydroclimate variability into sharper focus while providing important context for present and future changes to regional climate. Additionally, this study highlights the need for improved future predictions of the state of the Pacific Ocean to best inform water scarcity mitigation strategies for at‐risk Caribbean communities.
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This content will become publicly available on July 1, 2026
The Influence of Carbon Dioxide and Precession on Western North American Hydroclimate and Pacific Sea Surface Temperature During the Holocene
Abstract Model‐based projections of hydroclimate in western North America (wNA) remain uncertain and depend on how Pacific sea surface temperature (SST) will evolve in the future. However, whether climate models can accurately capture Pacific SST changes and its relationship with wNA hydroclimate in the future remains elusive. Here, we use a synthesis of proxy records and idealized model simulations to elucidate the spatiotemporal evolution and the forcings that drive wNA hydroclimate and Pacific SST during the Holocene (past ∼11,000 years), when the boundary conditions are different from the present. We find that wNA hydroclimate and Pacific SST co‐evolved during the Holocene, where wNA became wetter while the eastern equatorial Pacific and the north Pacific became warmer toward the present. We attribute changes in wNA hydroclimate to precession and carbon dioxide changes, but we are unable to attribute Pacific SST changes unambiguously to any forcing. Our analysis offers a framework to understand the relationship between wNA hydroclimate and Pacific SST and provides an empirical assessment of how these two regions are related over time.
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- Award ID(s):
- 2432287
- PAR ID:
- 10623842
- Publisher / Repository:
- American Geophysical Union (AGU) / Wiley
- Date Published:
- Journal Name:
- Paleoceanography and Paleoclimatology
- Volume:
- 40
- Issue:
- 7
- ISSN:
- 2572-4517
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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