Overview
- Long-term observations from 1972 to 2021 show that precipitation and meltwater have freshened the surface, strengthening density stratification that separates surface and deep waters.
- This reinforced barrier has so far blocked the wind-driven upwelling of CO2‑rich deep waters that models anticipated, sustaining a region that holds roughly 40% of the ocean’s anthropogenic CO2.
- The upper boundary of deep water has risen by about 40 meters since the 1990s, bringing the system closer to conditions where mixing could expose stored carbon.
- Researchers have not confirmed any recent increase in deep‑ocean CO2 release and plan expanded year‑round measurements, including winter sampling, through the Antarctica InSync program.
- In related work, a modeling study suggests the Southern Ocean could release a burst of stored heat in a future cooling world with net‑negative emissions, with relatively little CO2 outgassing.