More efficient North Atlantic carbon pump during the Last Glacial Maximum

Area of Science:

• Paleoceanography
• Climate Science
• Geochemistry

Background:

• The Last Glacial Maximum (LGM) saw substantial carbon sequestration in the global ocean.
• The Southern Ocean's reduced CO2 outgassing is the primary explanation for LGM carbon storage.
• The North Atlantic Ocean's role as a carbon sink during this period has been less explored.

Purpose of the Study:

• To investigate the North Atlantic Ocean's contribution to atmospheric CO2 drawdown during the LGM.
• To quantify the carbon pump efficiency in the North Atlantic during the LGM compared to the Holocene.

Main Methods:

• Utilized a novel proxy approach combining carbonate ion and nutrient reconstructions.
• Analyzed multiple sediment cores from the North Atlantic region.
• Estimated air-sea CO2 exchange signals during the LGM.

Main Results:

• North Atlantic carbon pump efficiency was nearly double during the LGM compared to the Holocene.
• Evidence suggests enhanced CO2 absorption by the North Atlantic.
• This process contributed to the reduction of atmospheric CO2 during glacial periods.

Conclusions:

• The North Atlantic Ocean played a significant role in atmospheric CO2 reduction during the LGM.
• Combined with Southern Ocean processes, North Atlantic carbon uptake was crucial for glacial CO2 drawdown.
• Revises understanding of ocean carbon cycle dynamics during past ice ages.