Linked ocean circulation may have amplified Earth’s ice ages
Researchers have identified a possible connection between Earth’s opposite poles that could help explain the onset of ice ages.
As large ice sheets expanded across the Northern Hemisphere, they cooled waters in the Atlantic Ocean. Some of that colder water then traveled south toward Antarctica, where the cooling may have disrupted circulation in the Southern Ocean. A slower or altered circulation could have enabled the ocean to absorb and store more carbon dioxide from the atmosphere.
Because carbon dioxide is a greenhouse gas, its removal from the atmosphere through ocean uptake would reinforce cooling, creating a feedback in which ice-sheet growth led to broader ocean circulation changes and additional planetary cooling. The proposed mechanism offers a way to connect changes in one hemisphere with the climatic transitions seen in the other.
The researchers describe this ocean circulation response as one possible driver of ice-age development. Its role in past climate change would need further testing to establish how influential the feedback was compared with other mechanisms.