Freshwater impacts recorded in tetraunsaturated alkenones and alkenone sea surface temperatures from the Okhotsk Sea across millennial-scale cycles

Type Article
Date 2008-07
Language English
Author(s) Harada Naomi1, Sato Miyako1, Sakamoto Tatsuhiko2
Affiliation(s) 1 : Japan Agcy Marine Earth Sci & Technol, Inst Observat Res Global Change, Yokosuka, Kanagawa, Japan.
2 : Japan Agcy Marine Earth Sci & Technol, Inst Res Earth Evolut, Yokosuka, Kanagawa, Japan.
Source Paleoceanography (0883-8305) (Amer Geophysical Union), 2008-07 , Vol. 23 , N. 3 / PA3201 , P. 1-14
DOI 10.1029/2006PA001410
WOS© Times Cited 39
Abstract [1] We present records of phytoplankton-produced alkenones down a long piston core, which reveal changes of sea surface temperature (SST) and sea surface salinity (SSS) in the southwestern Okhotsk Sea over the past 120 ka. Between 20 and 60 ka B. P., alkenone-derived temperatures typically increased by 6 degrees C-8 degrees C from periods corresponding, within a few hundred years, to stadials to those corresponding to interstadials recorded in Greenland ice cores. The abundance of C-37:4 alkenone relative to total C37 alkenones (percent C-37:4), a possible proxy for salinity, indicated that during most low SSS was associated with high SST. The warm freshwater events might be related to ( 1) a decline in the supply of saline water entering the Okhotsk Sea through the Soya Strait; ( 2) strengthening of the freshwater supply from the Amur River and precipitation over the Okhotsk Sea, associated mainly with increased Asian summer monsoon activity; and ( 3) the effect of melting sea ice. These findings increase our understanding of the close linkage between high and low latitudes in relation to climate change and the synchronicity of climate changes within a few centuries between the Pacific and the Atlantic sides of the Northern Hemisphere.
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