Key ocean system regulating climate on course for ‘tipping point’

large and vital system of ocean currents that helps maintain the world’s climate may already be on course to a tipping point, according to scientists.

Known as the Atlantic Meridional Overturning Circulation (Amoc), this network of deep and surface currents help keep temperatures milder in the UK and Western Europe compared to other regions at similar latitudes – such as parts of eastern Canada as well as Siberia.

Scientists say a breakdown of this system could potentially plunge the UK and large parts of the Northern Hemisphere into a new ice age, an outcome dramatised in the 2004 Hollywood blockbuster, The Day After Tomorrow.

It would also disrupt rainfall that billions rely on for agriculture, cause sea levels to rise in many parts of the world and lead to changes in weather patterns with significant impacts on ecosystems and human societies. Dr Rene van Westen, a postdoctoral researcher in climate physics at Utrecht University in the Netherlands, said: “Cooler temperatures over Europe may seem positive, but the repercussions are farreaching, with other regions experiencing accelerated warming and altered precipitation patterns.

“Additionally, a 100cm rise in European sea levels is projected due to the abrupt ocean circulation collapse.”

Dr Van Westen, along with a team of researchers at Utrecht University, designed a simulation where they gradually introduced surface freshwater over the course of 2,200 model years.

The findings showed a gradual decline of the Amoc over 1700 model years, followed by an abrupt tipping event beginning around the year 1758 and lasting for about a century.

Simulations showed that du ra ing this time, the European climate cooled by about 1C per decade, with regions experiencing over 3 C cooling per decade.

The researchers said that comparing these figures to the current global warming rate of 0.2C per decade underscores the devastating impact an Amoc tipping event could have on the planet. They said that while current observational records are too short to make a reliable estimation, there are early warning indicators suggesting “we are moving in the direction of the tipping point”.