How close are we to dangerous North Atlantic tipping point? New £5m project to find out

Researchers are setting out to discover how close the North Atlantic Subpolar Gyre is to a tipping point which could lead to a cascade of catastrophic, irreversible changes to our climate.

An international team led by the University of Southampton and the National Oceanography Centre (NOC) has received £5m from the Advanced Research and Invention Agency (ARIA) to deploy autonomous profiling floats which will collect data on ocean mixing in the North Atlantic Subpolar Gyre - a key region influencing global ocean circulation and the climate.

POLEMIX is one of several projects funded by the £81m ARIA Forecasting Tipping Points programme , which aims to enhance our climate change response by developing an early warning system for tipping points.

The North Atlantic Subpolar Gyre, or SPG, is a massive system of rotating ocean currents in the North Atlantic. It transports heat from the tropics to the North Atlantic, helping to regulate temperatures in Europe and North America.

It also helps to power the Atlantic Meridional Overturning Circulation (AMOC)—a key part of the global ocean conveyor belt that moves heat and nutrients around the world.

Ocean mixing moves and blends waters through turbulence, winds, tides, and differences in temperature and salinity. As cold, salty surface water becomes dense enough to sink, new water moves in, reinforcing the gyre’s circulation through a process called deep water convection.

“If this mixing or convection weakens—for example, due to excess freshwater from melting Greenland ice - the SPG could slow down or even collapse, triggering disruptions in weather, sea level, and global ocean circulation,” says Doctor Bieito Fernandez Castro ,  a Lecturer in Physical Oceanography at the University of Southampton who is leading the POLEMIX project.

“The UK and northern Europe could experience much harsher winters, similar to parts of Canada, while the East coast of the USA could see dramatic sea level rises due to changes in ocean circulation.”

To better understand these crucial underlying processes, the team will deploy 12 to 15 autonomous profiling floats - robotic devices that move up and down through the ocean, continuously collecting data.

This data will then feed into advanced ocean and climate models, improving their accuracy and helping scientists refine predictions about whether, when, and how close we are to reaching the SPG’s tipping point.

Dr Alice Marzocchi, a co-investigator on the project from NOC added: “This is a unique opportunity to undertake a truly ambitious, innovative project delivering a leap forward in ocean observations and our understanding of the ocean and climate system.”

The project also involves Massachusetts Institute of Technology in the US, Laboratoire d'Océanographie de Villefranche-sûr-Mer in France, and Rockland Scientific in Canada.

This funding remains subject to final contract negotiation.