title: Pliocene oceanic seaways and global climate.
abstract: Tectonically induced changes in oceanic seaways had profound effects on global and regional climate during the Late Neogene. The constriction of the Central American Seaway reached a critical threshold during the early Pliocene ~4.8-4 million years (Ma) ago. Model simulations indicate the strengthening of the Atlantic Meridional Overturning Circulation (AMOC) with a signature warming response in the Northern Hemisphere and cooling in the Southern Hemisphere. Subsequently, between ~4-3 Ma, the constriction of the Indonesian Seaway impacted regional climate and might have accelerated the Northern Hemisphere Glaciation. We here present Pliocene Atlantic interhemispheric sea surface temperature and salinity gradients (deduced from foraminiferal Mg/Ca and stable oxygen isotopes, δ18O) in combination with a recently published benthic stable carbon isotope (δ13C) record from the southernmost extent of North Atlantic Deep Water to reconstruct gateway-related changes in the AMOC mode. After an early reduction of the AMOC at ~5.3 Ma, we show in agreement with model simulations of the impacts of Central American Seaway closure a strengthened AMOC with a global climate signature. During ~3.8-3 Ma, we suggest a weakening of the AMOC in line with the global cooling trend, with possible contributions from the constriction of the Indonesian Seaway.
authors.affiliation: Goethe-University Frankfurt, Altenhoeferallee 1, 60438, Frankfurt am Main, Germany.|Biodiversity and Climate Research Centre (BIK-F), Senckenberganlage 25, 60325 Frankfurt am Main, Germany.|GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstrasse 1-3, 24148 Kiel, Germany.|Lamont Doherty Earth Observatory, Palisades, NY 10964, USA.
authors.forename: Cyrus
authors.initials: C
authors.lastname: Karas
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstrasse 1-3, 24148 Kiel, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Nürnberg
authors.affiliation: Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 234, 69120 Heidelberg, Germany.
authors.forename: André
authors.initials: A
authors.lastname: Bahr
authors.affiliation: Center for Marine Environmental Sciences (MARUM), University of Bremen, Klagenfurter Strasse, 28359 Bremen, Germany.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Groeneveld
authors.affiliation: Goethe-University Frankfurt, Altenhoeferallee 1, 60438, Frankfurt am Main, Germany.|Biodiversity and Climate Research Centre (BIK-F), Senckenberganlage 25, 60325 Frankfurt am Main, Germany.
authors.forename: Jens O
authors.initials: JO
authors.lastname: Herrle
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Tiedemann
authors.affiliation: Lamont Doherty Earth Observatory, Palisades, NY 10964, USA.
authors.forename: Peter B
authors.initials: PB
authors.lastname: deMenocal