Ocean carbon sequestration during glacial climates due to combined Antarctic sea ice expansion and ocean circulation change.

Expansion of Antarctic sea ice combined with ocean circulation changes sequesters carbon in the ocean abyss, causing a decline in atmospheric carbon dioxide during glacial periods.

• Why it matters: Understanding the mechanisms behind atmospheric carbon drawdown during glaciations is crucial for comprehending Earth's climate system and past climate transitions.
• What they did: The study used models to show that Antarctic sea ice expansion and circulation changes together enhance biological carbon storage by reducing ocean-atmosphere fluxes in the Southern Ocean, without external drivers.
• The result: This combined effect inhibits outgassing of remineralized carbon and promotes its resubduction into the abyss, revealing a feedback linking atmospheric cooling, sea ice expansion, and carbon sequestration.