5:15 PM - 7:15 PM
[MIS15-P11] Comparison of Ocean Carbon Cycle During Different Interglacial Periods
Keywords:Ocean carbon cycle, Deep ocean circulation, Last Interglacial, Glacial-interglacial cycle
The ocean is one of the primary carbon reservoirs on Earth and significantly influences the long-term carbon balance of the climate system. However, many uncertainties remain regarding the changes in the ocean carbon cycle during past warm periods and the extent to which these mechanisms can be applied to future climate change.
In this study, we analyzed the response of the ocean carbon cycle and changes in atmospheric carbon dioxide concentration (pCO2) during the Last Interglacial (LIG, 129–115 ka), the Holocene (11 ka), and the pre-industrial period (PI). The numerical experiments showed that atmospheric pCO2 was highest in the order of PI (325.9 ppm) > LIG (310.7 ppm) > Holocene (305.1 ppm), with the increase in PI primarily attributed to a decrease in CO2 solubility due to rising sea surface temperatures (SST). On the other hand, the higher pCO2 in LIG compared to the Holocene was caused by differences in the ocean biogeochemical cycle, leading to changes in surface dissolved inorganic carbon (DIC) and alkalinity.
During LIG, the Atlantic Meridional Overturning Circulation (AMOC) was stronger than in the Holocene and PI, as it occurred immediately after an AMOC overshoot. As a result, the residence time of carbon in deep waters was shortened, reducing the efficiency of the biological pump and increasing surface DIC. Furthermore, these differences in circulation patterns influenced gas exchange, making the ocean more prone to releasing CO2 to the atmosphere in LIG than in the Holocene. The numerical experiments showed that atmospheric pCO2 was highest in the order of PI Differences in global temperature and deep ocean circulation thus contributed to variations in atmospheric pCO2 via the ocean carbon cycle.
Moving forward, we will validate the basin-scale responses through comparisons with proxy data and further analyze the roles of the carbon pump and AMOC during glacial–interglacial transitions. By comparing the transient responses of Termination 1 (the transition from the Last Glacial Maximum to the Holocene) and the preceding Termination 2, we aim to deepen our understanding of long-term changes in the ocean carbon cycle during warm periods.
In this study, we analyzed the response of the ocean carbon cycle and changes in atmospheric carbon dioxide concentration (pCO2) during the Last Interglacial (LIG, 129–115 ka), the Holocene (11 ka), and the pre-industrial period (PI). The numerical experiments showed that atmospheric pCO2 was highest in the order of PI (325.9 ppm) > LIG (310.7 ppm) > Holocene (305.1 ppm), with the increase in PI primarily attributed to a decrease in CO2 solubility due to rising sea surface temperatures (SST). On the other hand, the higher pCO2 in LIG compared to the Holocene was caused by differences in the ocean biogeochemical cycle, leading to changes in surface dissolved inorganic carbon (DIC) and alkalinity.
During LIG, the Atlantic Meridional Overturning Circulation (AMOC) was stronger than in the Holocene and PI, as it occurred immediately after an AMOC overshoot. As a result, the residence time of carbon in deep waters was shortened, reducing the efficiency of the biological pump and increasing surface DIC. Furthermore, these differences in circulation patterns influenced gas exchange, making the ocean more prone to releasing CO2 to the atmosphere in LIG than in the Holocene. The numerical experiments showed that atmospheric pCO2 was highest in the order of PI Differences in global temperature and deep ocean circulation thus contributed to variations in atmospheric pCO2 via the ocean carbon cycle.
Moving forward, we will validate the basin-scale responses through comparisons with proxy data and further analyze the roles of the carbon pump and AMOC during glacial–interglacial transitions. By comparing the transient responses of Termination 1 (the transition from the Last Glacial Maximum to the Holocene) and the preceding Termination 2, we aim to deepen our understanding of long-term changes in the ocean carbon cycle during warm periods.