A recently published study suggesting that the Gulf Stream’s Atlantic Meridional Overturning Circulation (AMOC) could collapse by the end of the century is coming under scrutiny.

The Gulf Stream is one of the largest and fastest ocean currents on our planet: It transports warm water from the Gulf of Mexico along the east coast of the U.S. and continues via the North Atlantic Current, part of the AMOC, towards Europe into the Arctic Ocean.

Driven mainly by the westerly winds on the North Atlantic, these powerful currents supply large parts of Europe with gigantic amounts of thermal energy, equivalent to the output of 1 million power plants.

Without the Gulf Stream, winters in Europe would be much colder and large parts of the Baltic Sea would freeze over in winter.

In July, a study published by scientists at the University of Copenhagen suggested that the AMOC, thus including the North Atlantic Current, may collapse by the mid-century and by 2095 at the latest. This immediately sparked controversy in the scientific community.

Dr. Levke Caesar, ocean researcher at the University of Bremen says, “Future climate model simulations all show a weakening of the AMOC over the course of the 21st century, with the extent of the weakening also depending on the amount of future carbon dioxide emissions and ranging from about 30 to 45 percent by 2100.

“There are very, very few models that simulate a collapse of the AMOC before 2100. So, we're relatively confident that the probability of that is low.”

A collapse of the Gulf Stream is considered one of the tipping points in the climate system, causing a lasting and irreversible regional change in the climate. But even a weakening would have a huge impact on the climate in Europe.

Many studies suggest that a weaker North Atlantic Current could change weather patterns near Greenland and on the North Atlantic. This would have major implications for our climate.

Storm depressions would change their track and thus the distribution of precipitation. Possibly resulting in less rainfall in Central Europe as a result. Another study, led by the University of Southampton, assumes that a weakening North Atlantic Current could favour heat waves in Europe.

A rise in temperature sets off a chain of reactions that ultimately lead to a weakening of the AMOC. Freshwater input to the North Atlantic plays a primary role in this process.

This occurs through the melting of ice and glaciers in Greenland, but also through precipitation increasing due to generally warmer seawater. The salty water is 'diluted', and no longer sinks as much due to its lower density. Weakening the circulation.

However, direct measurements of the North Atlantic circulation have only been available since 2004, and this period is still too short to make a reliable statement on climate-related changes.