The ocean’s soft tissue carbon pump is thought to be responsible for a large part of the glacial to interglacial difference in atmospheric CO2(2). We present a novel box model approach that can evaluate in isolation or combination the effects of circulation changes and nutrient utilization changes on the soft tissue carbon pump.(1) Solutions are filtered by comparison with observations.
Key results :
- This statistical box model approach avoids the pitfall of only assessing the sensitivity of one or a few best guest control states.
- The glacial CO2 is very sensitive to circulation changes while the interglacial CO2 is very sensitive to nutrient utilization changes.Southern Ocean winds and/or buoyancy flux forcing do not reduce atmospheric CO2 through changes in the Ekman or Eddy flux exchange between the AA and Sub-AA regions.
- Winds and/or buoyancy may reduce CO2 by reducing AABW.
- Increased nutrient utilization in the Antarctic would reduce CO2 but this is not consistent with export production proxies.
- Nutrient utilization increase north of 40°S helps reduce CO2 although mechanisms for this does not explain tight coupling of CO2 with Antarctic temperature.