Enhanced precipitation in the Gulf of Mexico during the Eocene–Oligocene transition driven by interhemispherical temperature asymmetry

Abstract Studies reveal that the sea-surface temperature (SST) of Northern Hemisphere decreased at a smaller amplitude than Southern during Eocene–Oligocene transition (EOT). This interhemispheric asymmetry has been associated with intensified Atlantic Meridional Overturning Circulation (AMOC) may have driven enhanced precipitation and weathering in low latitudes subsequent drawdown atmospheric carbon dioxide. However, no quantitative constraints on paleo-precipitation reported to characterize AMOC effect across EOT. Here, we present results high-resolution (ca. 6 k.y. per sample) isotopic biomarker records from Gulf Mexico. Reconstructed using leaf wax isotopes shows an increase 44% EOT (34.1–33.6 Ma), which is accompanied by secular SST ~2 °C latest Eocene. We attribute Mexico northward shift Intertropical Convergence Zone was enlarged polar-tropic gradient invigorated AMOC. Our findings link changes meridional large-scale oceanic circulation lowlatitude terrestrial hydroclimate provide paleohydrological evidence supports CO2-weathering feedback “greenhouse” “icehouse” transition.