Closure of the Panama Seaway during the Pliocene: Implications for climate and Northern Hemisphere glaciation

• Main Authors: Ian C. Rutt, D. J. Lunt, A. Haywood, I. C. Rutt
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Pacific; Ice Sheet; North Atlantic Deep Water; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.366.3353; http://homepages.see.leeds.ac.uk/~earamh/Files/PAGES_Pliocene/Key references/Luntetal2008.pdf

Abstract The ‘‘Panama Hypothesis’ ’ states that the gradual closure of the Panama Seaway, between 13 million years ago (13 Ma) and 2.6 Ma, led to decreased mixing of Atlantic and Pacific water Masses, the formation of North Atlantic Deep water and strengthening of the Atlantic thermohaline circulation, increased temperatures and evaporation in the North Atlantic, increased precipitation in Northern Hemisphere (NH) high latitudes, culminating in the intensification of Northern Hemisphere Glaciation (NHG) during the Pliocene, 3.2–2.7 Ma. Here we test this hypothesis using a fully coupled, fully dynamic oceanatmosphere general circulation model (GCM) with boundary conditions specific to the Pliocene, and a high resolution dynamic ice sheet model. We carry out two GCM simulations with ‘‘closed’ ’ and ‘‘open’ ’ Panama Seaways, and use the simulated climatologies to force the ice sheet model. We find that the models support the ‘‘Panama Hypothesis’ ’ in as much as the closure of the seaway results in a more intense Atlantic thermohaline