Gulf Stream

[Michael de Groot]

Dramatic temperature shifts have happened in the past, driven partly by changes in a major ocean currents.

A "great ocean conveyor" helps transport heat around the globe via surface and deep-sea movements of water.

Scientists are exploring whether global warming might slow or shut it down - a scenario considered "low probability, high impact".

This could disrupt mostly wind-driven surface currents such as the Gulf Stream, which helps to bring milder weather to Northern Europe.