Antarctica drives a global network of ocean currents called the “overturning circulation” that redistributes heat, carbon and nutrients around the globe.
The overturning is crucial to keeping the earth’s climate stable.
It’s also the main way oxygen reaches the deep ocean.
Recent measurements show the overturning circulation has slowed by almost a third (30%) and deep ocean oxygen levels are declining.
This is happening even earlier than climate models predicted.
As the flow of bottom water slows, the supply of oxygen to the deep ocean declines.
The shrinking oxygen-rich bottom water layer is then replaced by warmer waters that are lower in oxygen, further reducing oxygen levels.
Ocean animals, large and small, respond to even small changes in oxygen.
Deep-ocean animals are adapted to low oxygen conditions but still have to breathe.
Losses of oxygen may cause them to seek refuge in other regions or adapt their behaviour.