Paleoceanographic Evolution of the Antarctic Southern Ocean since the Mid-Pleistocene Transition ...

• Main Author: Hasenfratz, Adam P.
• Format: Thesis
• Language: English
• Published: ETH Zurich 2017
• Subjects: PALEOCEANOGRAPHY; BIOGEOCHEMISTRY; info:eu-repo/classification/ddc/550; Earth sciences; Antarc*; Antarctic; Sea ice; Southern Ocean
• Online Access: https://dx.doi.org/10.3929/ethz-b-000181636; http://hdl.handle.net/20.500.11850/181636

The Pleistocene epoch was characterized by orbitally-forced climate oscillations between warm stages and ice ages. The concentration of atmospheric CO2 (pCO2) has varied in step with these so-called glacial-interglacial cycles over at least the last 800 thousand years (kyr), with consistently 80–100 parts per million per volume (ppmv) lower pCO2 during ice ages. The Southern Ocean, a large water body that entirely encircles the Antarctic continent, exerts a dominant control on the partitioning of CO2 between the ocean interior and the atmosphere through its leverage on the efficiency of the biological pump. In the modern Southern Ocean, nutrient- and CO2-rich deep waters ascend to the surface ocean where iron limitation restricts the fixation of the major nutrients by phytoplankton, allowing for the evasion of deeply sequestered carbon to the atmosphere. In the Antarctic Zone of the Southern Ocean, south of the Antarctic Polar Front, the evasion of CO2 was reduced during ice ages by increased sea- ice cover ...