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Modeling the oxygen‐isotopic composition of the North American Ice Sheet and its effect on the isotopic composition of the ocean during the last glacial cycle
Author(s) -
Sima Adriana,
Paul André,
Schulz Michael,
Oerlemans Johannes
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl026923
Subject(s) - ice sheet , last glacial maximum , geology , glacial period , seawater , isotopes of oxygen , oceanography , greenland ice sheet , ice sheet model , sea ice , holocene , ice stream , climatology , geomorphology , geochemistry , cryosphere
We used a 2.5‐dimensional thermomechanical ice‐sheet model including the oxygen‐isotope ratio 18 O/ 16 O as a passive tracer to simulate the isotopic composition (δ 18 O) of the North American Ice Sheet (NAIS) during the last glacial cycle. This model allowed us to estimate the NAIS contribution to the change of seawater δ 18 O (δ w ) between the Last Glacial Maximum (LGM) and the Holocene and to evaluate the effect of nonequilibrium isotopic composition of the NAIS on the relationship between ice‐volume variations and the ocean isotopic enrichment. The enrichment due to the NAIS at the LGM was 0.63‰, corresponding to ∼60% of the LGM sea‐level lowstand and to a mean δ 18 O of the NAIS of approximately −31‰. The modeled NAIS volume variations and the induced δ w changes over the past 120,000 years indicated no significant time lag. The inaccuracy associated with linearly inferring ice‐volume variations from δ w changes was generally less than 10%.