Deep beneath the ocean’s surface surrounding Antarctica, a channel of cold, dense water known as Antarctic Bottom Water flows northward, playing a crucial role in the global climate system by transporting heat and carbon across the oceans. This water forms one of the key components of the “global ocean conveyor belt,” known to scientists as the Atlantic Meridional Overturning Circulation, which influences weather patterns, sea levels, and heat distribution across the globe. Scientists discovered significant warming and slowing in the Antarctic Bottom Water during a comprehensive investigation into ocean observations. NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML) researchers Tiago Biló, Renellys Perez, and Shenfu Dong worked on this project with a team of researchers in contribution to an initiative to support innovative ocean dataset analysis.
The results, published in Nature Geoscience, reveal that the northward transport of Antarctic Bottom Water has decreased by about 12% between 2000 and 2020, a trend which appears linked to the formation of this water layer itself near Antarctica in the Southern Ocean. The North Atlantic has seen a rise in temperature and sea level at the same time, suggesting that changes in the Southern Ocean are having an immediate effect on the system as a whole. This finding has far-reaching significance, underscoring our planet’s interconnected systems and highlighting an urgent need for global monitoring and adaptation strategies as our ocean systems evolve with climate change. The authors advocate for continued, detailed observation of these trends to aid in better understanding and predicting future changes in global ocean circulation. This work is funded by a partnership between CPO’s Climate Observations and Monitoring (COM) Program, Climate Variability and Predictability (CVP) Program, and NOAA’s Global Ocean Monitoring and Observing (GOMO) Program to support NOAA’s observing and modeling communities.
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Image credit: Nicole Bozkurt, University of Miami