Spatial and Temporal Variability of Eastern Pacific Radiocarbon and Carbon Chemistry From the Ice Age to Today
Year: 2026
Type: article
Abstract: Proxy records of seawater radiocarbon ( 14 C/C) provide strong constraints on how changes in ocean ventilation contributed to the increase in atmospheric CO 2 during the termination of the last ice age (≈18,000‐to‐12,000 years ago). One outstanding problem, however, is the existence of anomalously low deglacial benthic foraminiferal 14 C/C in the intermediate‐depth Eastern Tropical North Pacific (ETNP) near the Gulf of California (GoC). This deglacial ETNP 14 C/C anomaly is hypothesized to reflect either (a) an artifact of the proxy record, (b) the advection of low 14 C/C seawater, or (c) the input of 14 C/C‐depleted geologic carbon related to local seafloor volcanism. To test these hypotheses, we first use new sediment‐trap and seaweed 14 C/C to establish a new baseline understanding of ETNP seawater 14 C/C, which suggest that anomalously low 14 C/C is upwelled in the modern GoC. We then apply new geochemical experiments to test and ultimately validate the utility of the benthic foraminiferal 14 C/C as a proxy for seawater 14 C/C. Finally, we present a compilation of published and new glacial‐interglacial benthic foraminiferal 14 C/C records, specifically developed to map the spatial and temporal variability of the intermediate‐depth water mass containing the deglacial ETNP 14 C/C anomaly. These results clearly show that the ETNP deglacial 14 C/C anomaly develops near the GoC mouth, concomitant with local hydrothermal systems. Considering these results and those of our companion paper (Green et al., 2026, https://doi.org/10.1029/2025pa005217 ), we argue that the input of pH‐neutral geologic carbon from hydrothermal vents near and within the GoC could explain the anomalous intermediate‐depth 14 C/C values both during the deglaciation and today.
DOI: 10.1029/2025pa005265
Institutions: University of South Florida, University of South Florida St. Petersburg, University of California, Santa Cruz, Universidad Nacional Autónoma de México, University of Arizona, University of South Carolina, Instituto de Ciencias del Mar y Limnología, University of California, Santa Barbara, University of Michigan, Centro de Investigación Científica y de Educación Superior de Ensenada, Laboratoire des Sciences du Climat et de l'Environnement, University of Washington, University of St Andrews, University of California, Irvine
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,070
Funder: National Science Foundation
Awards: RCN: Improving reconstructions of Cenozoic pCO2 and temperature change, G267202307, Collaborative Research: Uncovering marine carbon chemistry dynamics during the deglaciation with boron isotopes and radiocarbon, Collaborative Research: Uncovering marine carbon chemistry dynamics during the deglaciation with boron isotopes and radiocarbon, Eastern Pacific carbon chemistry after the ice age: gaining insight to a persistent carbon cycle mystery
OpenAlex ID: W7160448120