Early Pliocene increase in thermohaline overturning : a precondition for the development of the modern equatorial Pacific cold tongue
Haug, Gerald H.
MetadataShow full item record
Unraveling the processes responsible for Earth's climate transition from an “El Niño–like state” during the warm early Pliocene into a modern-like “La Niña–dominated state” currently challenges the scientific community. Recently, the Pliocene climate switch has been linked to oceanic thermocline shoaling at ∼3 million years ago along with Earth's final transition into a bipolar icehouse world. Here we present Pliocene proxy data and climate model results, which suggest an earlier timing of the Pliocene climate switch and a different chain of forcing mechanisms. We show that the increase in North Atlantic meridional overturning circulation between 4.8 and 4.0 million years ago, initiated by the progressive closure of the Central American Seaway, triggered overall shoaling of the tropical thermocline. This preconditioned the turnaround from a warm eastern equatorial Pacific to the modern equatorial cold tongue state about 1 million years earlier than previously assumed. Since ∼3.6–3.5 million years ago, the intensification of Northern Hemisphere glaciation resulted in a strengthening of the trade winds, thereby amplifying upwelling and biogenic productivity at low latitudes.
Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 25 (2010): PA2202, doi:10.1029/2008PA001645.
Showing items related by title, author, creator and subject.
Cronin, Meghan F.; Bond, Nicholas A.; Fairall, Christopher W.; Weller, Robert A. (American Meteorological Society, 2006-02-01)Data from the Eastern Pacific Investigation of Climate Studies (EPIC) mooring array are used to evaluate the annual cycle of surface cloud forcing in the far eastern Pacific stratus cloud deck/cold tongue/intertropical ...
Particulate matter sinking to the deep-sea floor at 2000 M in the Tongue of the Ocean, Bahamas, with a description of a new sedimentation trap Wiebe, Peter H.; Boyd, Steven H.; Winget, Clifford L. (Woods Hole Oceanographic Institution, 1976-09)A sedimentation trap for use just above the deep-sea floor was free-fallen to a depth of 2050 m in the Tongue of the Ocean canyon on January 3, 1974. On March 6, it was successfully recovered with the assistance of ...
Taschetto, Andrea S.; Sen Gupta, Alexander; Jourdain, Nicolas C.; Santoso, Agus; Ummenhofer, Caroline C.; England, Matthew H. (American Meteorological Society, 2014-04-15)The representation of the El Niño–Southern Oscillation (ENSO) under historical forcing and future projections is analyzed in 34 models from the Coupled Model Intercomparison Project phase 5 (CMIP5). Most models realistically ...