Carbon Burial in Deep-Sea Sediments and Its Impact on Oceanic Carbon and Alkalinity During Glacial Cycles

The study of carbon burial in deep-sea sediments is crucial for understanding the dynamics of the oceanic carbon and alkalinity inventories during glacial cycles. The atmospheric CO2 reservoir interacts with various carbon pools, including oceanic and terrestrial systems. This interaction is vital for climate regulation. The document emphasizes that the active carbon inventory is influenced by geological processes, particularly the burial of carbon in marine sediments. The authors argue that the traditional view of glacial–interglacial cycles, which posits a stable active carbon inventory, is challenged by evidence of significant geological CO2 supply rate variations. This highlights the need for a comprehensive understanding of carbon removal rates from the system, primarily through sediment burial. The reconstruction of carbon and alkalinity burial over the last glacial cycle provides insights into the effects of burial flux changes on global inventories. The findings suggest that reduced carbonate burial in the Atlantic was not fully offset by increased burial in the Pacific, leading to a gradual alkalinity buildup in the ocean. This section sets the stage for a deeper exploration of the implications of these findings for climate science.

The dynamics of carbon and alkalinity burial in deep-sea sediments are complex and influenced by various factors. The document presents a global reconstruction of these burial processes, revealing significant uncertainties. The authors note that the burial of calcium carbonate (CaCO3) plays a pivotal role in the air-sea partitioning of the active carbon inventory. The burial processes are categorized into two forms: organic carbon (Corg) and CaCO3. While Corg burial primarily removes carbon, CaCO3 burial also affects alkalinity levels. The interplay between these processes is crucial for understanding the long-term carbon cycle. The authors highlight that increased alkalinity enhances CO2 solubility in seawater, which can lead to carbon transfer from the ocean to the atmosphere. This section underscores the importance of marine burial fluxes in regulating the active carbon inventory and their implications for climate change. The findings suggest that variations in burial rates can significantly alter oceanic carbon concentrations, impacting global climate systems.

The implications of carbon burial dynamics for climate change are profound. The document discusses how anthropogenic carbon emissions are rapidly altering the marine carbon cycle, affecting air-sea partitioning. The authors argue that understanding natural changes in the geological past can inform future climate projections. The study highlights that decreased CaCO3 burial during glacial periods may have contributed to lower atmospheric CO2 concentrations. This relationship suggests that changes in ocean circulation and biological production could significantly impact deep ocean DIC levels. The authors emphasize the need for further research to quantify these processes and their effects on the carbon cycle. The findings have practical applications for climate modeling and policy-making, as they provide insights into the mechanisms driving climate change. By understanding the historical context of carbon burial, scientists can better predict future trends and develop strategies to mitigate climate impacts.