EGU21-9623, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-9623
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Southern control of interhemispheric synergy on marine carbon sequestration during glacial cycles   

Jinlong Du1, Xu Zhang2,3, Ying Ye4, Christoph Völker4, and Jun Tian1
Jinlong Du et al.
  • 1State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China (dujinlong@tongji.edu.cn)
  • 2Key Laboratory of Western China’s Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Center for Pan Third Pole Environment (Pan-TPE), Lanzhou University, Lanzhou,730000,China
  • 3CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences (CAS), Beijing 100101,China.
  • 4Alfred Wegener Institute, Helmholz Centre for Polar and Marine Research, Bremerhaven, Germany

The mechanisms of atmospheric CO2 draw-down by ~90 ppm during glacial cycles have been one of the most contentious questions in the past several decades. Processes in the Southern Ocean (SO) have been suggested to be at the heart, while the North Atlantic (NA) is recently proposed to be critical during glacial periods as well. However, in a full course of glacial cycles, the individual and synergic roles of these two regions remain enigmatic. Using a state-of-the-art biogeochemical model (MITgcm-REcoM2) associated with an interactive CO2 module, we examined the impact of the onset of individual mechanisms and combinations of them on atmospheric CO2. Here we show that SO controls carbon sequestration in both hemispheres. In sensitivity runs with respect to mechanisms happening during glacial inceptions, cooling in SO contributes to a larger portion of CO2 draw-down than cooling in NA, by shortening the surface water exposure time, while the early sea ice expansion tends to weaken the carbon uptake. The efficiency of surface carbon storage in the North Atlantic depends on the volume of Antarctic bottom water and reaches its maximum when the glacial stratification is well developed during glacial maxima.  SO cooling and sea ice expansion strongly promote the formation of AABW and the full development of the glacial stratification. Furthermore, increased dust deposition during the glacial maxima raises the contribution of the Southern Ocean in the global biological carbon pump, leading to a higher efficiency of the biological carbon pump. And the maximal expanded sea ice suppresses local carbon leakage.

 

 

 

How to cite: Du, J., Zhang, X., Ye, Y., Völker, C., and Tian, J.: Southern control of interhemispheric synergy on marine carbon sequestration during glacial cycles   , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9623, https://doi.org/10.5194/egusphere-egu21-9623, 2021.

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