New research uncovers how winter sea ice in the Southern Ocean boosts the ocean’s ability to absorb atmospheric CO2 — a vital defense against climate change hiding in plain sight.
Key Points at a Glance
- Southern Ocean absorbs ~40% of global oceanic CO2 uptake
- Longer-lasting winter sea ice boosts CO2 absorption by up to 20%
- Sea ice blocks wind-driven mixing that releases carbon-rich deep waters
- Year-round observations from the Antarctic Peninsula were key
Deep in the frozen wilderness surrounding Antarctica, a delicate balance unfolds each winter — one that could have global consequences. According to a groundbreaking study led by the University of East Anglia, the duration of sea ice during the Southern Hemisphere’s winter significantly shapes how much carbon dioxide the Southern Ocean can absorb from the atmosphere.
Long considered Earth’s most powerful oceanic carbon sink, the Southern Ocean is responsible for nearly 40% of the planet’s oceanic CO2 absorption. But scientists have long puzzled over its dramatic year-to-year variability. Now, thanks to a decade of observations from the west Antarctic Peninsula, researchers have found a surprising player in this carbon game: sea ice.
“In years with more persistent winter sea ice, the Southern Ocean absorbed up to 20% more CO2,” explains Dr. Elise Droste, lead author of the study. “This is because sea ice acts like a shield, preventing powerful winds from mixing surface waters with the carbon-rich layers below.”
This mixing process typically brings centuries-old carbon to the surface, where it can escape into the atmosphere. But when sea ice lingers through winter, it blocks this exchange, tipping the balance toward net carbon absorption rather than release.
The study analyzed data from 2010 to 2020, collected at Ryder Bay near the UK’s Rothera Research Station. Scientists braved the Antarctic winter to gather samples using boats and sledges on sea ice, building one of the only year-round datasets in the region. These hard-won measurements revealed the pivotal role of seasonal ice in regulating oceanic carbon flows.
“Most of our models and predictions about climate change overlook this dynamic,” says Prof. Dorothee Bakker of UEA. “But understanding when and how sea ice forms — and how long it lasts — could be critical for forecasting the ocean’s capacity to mitigate climate change.”
The findings also highlight the urgent need for more wintertime data from the Southern Ocean, a region notoriously difficult to access. New autonomous technologies could help bridge that gap, offering a clearer picture of Earth’s evolving climate system.
As climate change reshapes polar regions and alters sea ice patterns, this research sounds an alarm: the seemingly static, frozen surfaces of Earth’s southernmost waters are anything but passive. They are active regulators of our planet’s breath — and their seasonal rhythms matter more than we ever imagined.
Source: University of East Anglia
Enjoying our articles?
We don’t show ads — so you can focus entirely on the story, without pop-ups or distractions. We don’t do sponsored content either, because we want to stay objective and only write about what truly fascinates us. If you’d like to help us keep going — buy us a coffee. It’s a small gesture that means a lot. Click here – Thank You!
