The Salinity, Temperature, and 
18O of the Glacial Deep Ocean
Jess F. Adkins,1*
Katherine McIntyre,1
Daniel P. Schrag2
We use pore fluid measurements of the chloride concentration and
the oxygen isotopic composition from Ocean Drilling Program cores to
reconstruct salinity and temperature of the deep ocean during the Last
Glacial Maximum (LGM). Our data show that the temperatures of the deep
Pacific, Southern, and Atlantic oceans during the LGM were relatively
homogeneous and within error of the freezing point of seawater at the
ocean's surface. Our chloride data show that the glacial
stratification was dominated by salinity variations, in contrast with
the modern ocean, for which temperature plays a primary role. During
the LGM the Southern Ocean contained the saltiest water in the deep
ocean. This reversal of the modern salinity contrast between the North
and South Atlantic implies that the freshwater budget at the poles must
have been quite different. A strict conversion of mean salinity at the
LGM to equivalent sea-level change yields a value in excess of 140 meters. However, the storage of fresh water in ice shelves and/or
groundwater reserves implies that glacial salinity is a poor predictor
of mean sea level.
1 MS 100-23, Department of Geological and
Planetary Sciences, California Institute of Technology, Pasadena, CA
91125, USA.
2 Department of Earth and Planetary
Sciences, Harvard University, Cambridge, MA 02138, USA.
*
To whom correspondence should be addressed. E-mail:
jess{at}gps.caltech.edu
