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Biology‐mediated temperature control on atmospheric p CO 2 and ocean biogeochemistry
Author(s) -
Matsumoto Katsumi
Publication year - 2007
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 - 10.1029/2007gl031301
Subject(s) - glacial period , biogeochemistry , deep sea , interglacial , environmental science , ocean heat content , oceanography , carbon cycle , atmospheric sciences , climate change , climatology , sea surface temperature , geology , ecology , ecosystem , geomorphology , biology
The remarkable correspondence between glacial‐interglacial changes in atmospheric CO 2 levels and global climate over much of the Pleistocene suggests that CO 2 is also a key climate change driver. However, there is as yet no widely accepted explanation of the low glacial CO 2 levels. Here I use an intermediate‐complexity climate model to show that glacial cooling, acting on the rates of organic carbon production and decay in the ocean, can explain a significant portion of the glacial CO 2 lowering. New model results show that cooling strengthens the vertical transport of organic carbon from the surface ocean to the deep ocean, reduces atmospheric p CO 2 , and shifts nutrients from the Atlantic basin to the Indo‐Pacific basins. The overall vertical transport is increased because the cooling effect on reducing the degradation rate of sinking particulate organic carbon is greater than on reducing the export production. This net temperature effect on atmospheric p CO 2 mediated by biology is comparable to the temperature effect on atmospheric p CO 2 driven by solubility, which is almost always mentioned as a large factor in the glacial CO 2 levels. An implication for the future is that higher ocean temperatures will act as a positive feedback on atmospheric CO 2 by reducing the vertical transport of carbon to the deep ocean and thereby increasing CO 2 degassing from the ocean.