We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Mid-Pliocene shifts in ocean overturning circulation and the onset of Quaternary-style climates.
- Authors
Sarnthein, M.; Prange, M.; Schmittner, A.; Schneider, B.; Weinelt, M.
- Abstract
A major tipping point of Earth's history occurred during the mid-Pliocene: the onset of major Northern Hemisphere Glaciation (NHG) and pronounced, Quaternary-style cycles of glacial-to-interglacial climates, that contrast with more uniform climates over most of the preceding Cenozoic, that and continue until today. The severe deterioration of climate occurred in three steps between 3.2Ma (warm MIS K3) and 2.7Ma (glacial MIS G6/4). Various models and paleoceanographic records (intercalibrated using orbital age control) suggest clear linkages between the onset of NHG and three steps in the final closure of the Central American Seaways (CAS), deduced from rising salinity differences between Caribbean and East Pacific. Each closing event led to enhanced North Atlantic meridional overturning circulation and strengthened the poleward transport of salt and heat (warmings of +2-3°C). Also, the closing resulted in a slight rise in the poleward atmospheric moisture transport to northwestern Eurasia, which led to enhanced precipitation and fluvial run-off, lower sea surface salinity (SSS), and increased sea-ice cover in the Arctic Ocean, hence promoting albedo and the build-up of continental ice sheets. Most important, the closing of CAS led to greater steric height of the North Pacific and thus doubled the low-saline Arctic Throughflow from the Bering Strait to the East Greenland Current (EGC). Accordingly, Labrador Sea IODP Site 1307 displays an abrupt but irreversible EGC cooling of 6°C and freshening by ~1 psu from 3.16-3.00 Ma, right after the first but still reversible attempt of closing the CAS.
- Subjects
NORTHERN Hemisphere; PLIOCENE paleoclimatology; ATMOSPHERIC circulation; CLIMATE change; CLIMATOLOGY; PALEOCEANOGRAPHY
- Publication
Climate of the Past Discussions, 2009, Vol 5, Issue 1, p251
- ISSN
1814-9324
- Publication type
Article
- DOI
10.5194/cpd-5-251-2009