2002), Did Antarctic sea-ice expansion cause glacial CO2 decline?, Geophys

• Main Authors: M. A. Morales Maqueda, S. Rahmstorf
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; The Antarctic; Antarc*; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.477.1230; http://instaar.colorado.edu/~marchitt//moralesmaqueda02.pdf

[1] Recently, Stephens and Keeling [2000] have put forward an appealing theory for explaining the decrease in glacial atmospheric CO2. They argue that a compact sea-ice cover extending southward of 55 S trapped large amounts of CO2 beneath the sea surface, thus accounting for the lower atmospheric concentrations. An atmosphere-ocean box model in which sea-ice area is prescribed allows them to simulate 80 % of the CO2 drawdown. However, glacial CO2 levels can be attained in their model only when the fraction of ice-covered area southward of the Antarctic Polar Front rises to 99–100%. We present simulations with a coupled sea ice-upper ocean model indicating that ice-area fractions so large might have not prevailed even under rather extreme glacial conditions. The combination of our glacial ice-coverage estimates with the ice area-CO2 relation derived by Stephens and Keeling suggests that CO2 sequestration under sea ice could account for at most 15–50% of the total glacial CO2 decline. INDEX TERMS: 4267