Welcome to DU!
The truly grassroots left-of-center political community where regular people, not algorithms, drive the discussions and set the standards.
Join the community:
Create a free account
Support DU (and get rid of ads!):
Become a Star Member
Latest Breaking News
Editorials & Other Articles
General Discussion
The DU Lounge
All Forums
Issue Forums
Culture Forums
Alliance Forums
Region Forums
Support Forums
Help & Search
Expansion of Antarctic Bottom Water contributed to the End of the Last Ice Age
https://www.geomar.de/news/article?tx_news_pi1%5baction%5d=detail&tx_news_pi1%5bcontroller%5d=News&tx_news_pi1%5bactbackPid%5d=12123&tx_news_pi1%5bbackPid%5d=12123&tx_news_pi1%5bnews%5d=10097New study highlights the key role of the Southern Ocean in the Earth’s climate system
01 December 2025 / Kiel. A study by an international team involving the GEOMAR Helmholtz Centre for Ocean Research Kiel shows that the expansion of Antarctic Bottom Water during a major warming phase around 12,000 years ago displaced a carbon-rich mass of deep-water in the Atlantic sector of the Southern Ocean. This process released carbon dioxide that had been stored in the deep ocean, thereby contributing to the end of the last Ice Age. The study provides important insights into how the ocean may respond as Antarctica continues to warm today. The findings are published today in Nature Geoscience.
…
During the last Ice Age, the extremely cold, dense deep water that forms around Antarctica today was substantially retracted. Instead, large parts of the deep Southern Ocean were filled with carbon-rich water masses originating from the Pacific – a glacial precursor to today’s Circumpolar Deep Water (CDW). The CDW is described as carbon-rich in the study because it circulates in the deep ocean for long periods with limited ventilation. Consequently, more dissolved carbon remained stored in the ocean, keeping atmospheric CO₂ concentrations low.
As the planet warmed and the ice sheets melted between about 18,000 and 10,000 years ago, the volume of Antarctic Bottom Water expanded in two distinct phases. These phases coincided with known warming events in Antarctica. As vertical mixing in the Southern Ocean increased, the carbon that had been stored in the deep ocean was able to return to the atmosphere.
“The expansion of the AABW is linked to several processes,” explains Gutjahr. “Warming around Antarctica reduced sea-ice cover, resulting in more meltwater entering the Southern Ocean. The Antarctic Bottom Water formed during this transitional climate period had a lower density due to reduced salinity. This late-glacial AABW was able to spread further through the Southern Ocean, destabilising the existing water-mass structure and enhancing exchanges between deep and surface waters.”
…
Huang, H., Gutjahr, M., Hu, Y. et al. Expansion of Antarctic Bottom Water driven by Antarctic warming in the last deglaciation. Nat. Geosci. (2025). https://doi.org/10.1038/s41561-025-01853-7
01 December 2025 / Kiel. A study by an international team involving the GEOMAR Helmholtz Centre for Ocean Research Kiel shows that the expansion of Antarctic Bottom Water during a major warming phase around 12,000 years ago displaced a carbon-rich mass of deep-water in the Atlantic sector of the Southern Ocean. This process released carbon dioxide that had been stored in the deep ocean, thereby contributing to the end of the last Ice Age. The study provides important insights into how the ocean may respond as Antarctica continues to warm today. The findings are published today in Nature Geoscience.
…
During the last Ice Age, the extremely cold, dense deep water that forms around Antarctica today was substantially retracted. Instead, large parts of the deep Southern Ocean were filled with carbon-rich water masses originating from the Pacific – a glacial precursor to today’s Circumpolar Deep Water (CDW). The CDW is described as carbon-rich in the study because it circulates in the deep ocean for long periods with limited ventilation. Consequently, more dissolved carbon remained stored in the ocean, keeping atmospheric CO₂ concentrations low.
As the planet warmed and the ice sheets melted between about 18,000 and 10,000 years ago, the volume of Antarctic Bottom Water expanded in two distinct phases. These phases coincided with known warming events in Antarctica. As vertical mixing in the Southern Ocean increased, the carbon that had been stored in the deep ocean was able to return to the atmosphere.
“The expansion of the AABW is linked to several processes,” explains Gutjahr. “Warming around Antarctica reduced sea-ice cover, resulting in more meltwater entering the Southern Ocean. The Antarctic Bottom Water formed during this transitional climate period had a lower density due to reduced salinity. This late-glacial AABW was able to spread further through the Southern Ocean, destabilising the existing water-mass structure and enhancing exchanges between deep and surface waters.”
…