Journal ArticleDecadal oscillations in the ocean’s largest oxygen-deficient zoneDuprey, N N [Max Planck Institute for Chemistry (Otto Hahn Institute), Mainz, Germany.] (ORCID:0000000211090772); Foreman, A D [Max Planck Institute for Chemistry (Otto Hahn Institute), Mainz, Germany.] (ORCID:0000000250825786); Carriquiry, J D [Terracoast Environmental Consultants, Ensenada, Baja California, México.]; Charles, C D [Scripps Institution of Oceanography, La Jolla, CA, USA.] (ORCID:0000000340162365); Sanchez, S C [Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO, USA.] (ORCID:0000000219231218); Vonhof, H [Max Planck Institute for Chemistry (Otto Hahn Institute), Mainz, Germany.] (ORCID:0000000208978244); Rubach, F [Max Planck Institute for Chemistry (Otto Hahn Institute), Mainz, Germany.] (ORCID:0000000261442799); Rabenstein, R [Messel Research and Mammalogy, Senckenberg Research Institute, Frankfurt am Main, Germany.] (ORCID:0000000314216446); Rohr, M [Rohr Foundation, Dallas, TX, USA.]; Reyes-Bonilla, H [Departamento Académico de Ciencias Marinas Y Costeras, Universidad Autónoma de Baja California Sur, La Paz, Baja California Sur, Mexico.]; Marconi, D [Department of Geosciences, Princeton University, Princeton, NJ, USA.]; Sigman, D M [Department of Geosciences, Princeton University, Princeton, NJ, USA.] (ORCID:0000000279231973); Haug, G H [Department of Earth and Planetary Sciences (D-EAPS) ETH Zürich Sonneggstrasse 5, Zürich, Switzerland.] (ORCID:0000000175344420); Martínez-García, A [Max Planck Institute for Chemistry (Otto Hahn Institute), Mainz, Germany.] (ORCID:0000000272065079)<p>The impact of global warming on the ocean’s oxygen-deficient zones (ODZs) is uncertain, partly because of a lack of data on past changes. We report monthly resolved records of coral skeleton–bound nitrogen isotopes (CS-δ¹⁵N) to reconstruct denitrification in the Eastern Tropical North Pacific (ETNP) ODZ over the last 80 years. The data indicate strong decadal variation in ETNP denitrification, with maxima during the cool North Pacific phase of Pacific Decadal Variability. The maxima in denitrification (and thus oxygen deficiency) were likely due to stronger upwelling that enhanced productivity leading to greater oxygen demand in the thermocline. Prior findings of multidecadal-to-centennial ODZ trends were likely biased by this variability. ODZ evolution over the next century will depend on how global warming interacts with the decadal oscillations.</p>Science2024-11-2910658856Science38667251019 to 10240036-8075https://doi.org/10.1126/science.adk49651736652; 2049416National Science Foundation