When Mike first saw the alternative projection in a magazine, his immediate response was to try to draw on it, to show how water moves around the globe – the great conveyor that transports heat, carbon and nutrients to all corners and back again.

This flow has many pathways, and Mike, with his Antarctic hat on, naturally thinks of the circulation around the White Continent as being the “central roundabout” in the system. But he taps the map in the North Atlantic: “This is the branch that’s getting all the attention right now.”

He’s referring to the Atlantic Meridional Overturning Circulation, or AMOC. It’s considered one of Earth’s climate tipping points – classified by the Intergovernmental Panel on Climate Change as “low risk, high impact”. Some climate models predict the circulation might decline or even slow dramatically in the future under certain warming conditions.