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The cause of the glacial to interglacial atmospheric CO 2 change: A Polar Alkalinity Hypothesis
Author(s) -
Broecker Wallace S.,
Peng TsungHung
Publication year - 1989
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/gb003i003p00215
Subject(s) - alkalinity , glacial period , interglacial , geology , oceanography , polar , deglaciation , chemistry , paleontology , physics , organic chemistry , astronomy
In an attempt to create a scenario for the cause of the glacial to interglacial CO 2 change recorded in air trapped in polar ice, we call on an increase in the alkalinity of polar surface waters. In this way we circumvent a major deficiency of the polar nutrient scenarios of Sarmiento and Toggweiler (1984), Siegenthaler and Wenk (1984) and Knox and McElroy (1984). Namely, our scenario does not require a drop in the nutrient content of polar surface waters in conformity with the demonstration by Boyle (1988a, b) that the cadmium content of planktonic foraminifera from polar regions did not decrease from late glacial to Holocene time. The rise in alkalinity required by our model is a natural consequence of the demise, during glacial time, of North Atlantic Deep Water as a major force in ocean circulation and of the nutrient maximum deepening of Boyle (1988b). Rather than being original, our hypothesis builds on the concept basic to the polar nutrient hypotheses, namely that the CO 2 partial pressure in polar waters controls that for both the atmosphere and warm surface ocean. It also requires the alkalinity increase in surface waters produced by Boyle's nutrient deepening.