Rapid melting of the Greenland ice sheet could have ‘Day After Tomorrow-style’ consequences for Europe (Pictures: Getty/Twentieth Century Fox)
It may sound like something out of Hollywood, but Europe could be plunged into a ‘deep freeze’ centuries earlier than predicted as a key ocean current faces collapse.
If the current is ‘shut off’, temperatures across northwestern Europe could plunge by as much as 27C as Arctic ice spreads south and the world’s rainfall pattern is thrown into disarray.
It’s all down to the snazzily-named Atlantic Meridional Overturning Circulation (AMOC).
This huge conveyor belt moves warm and cold water around the ocean, and powers the Gulf Stream, which brings warm air from the Gulf of Mexico to the continent. The Gulf Stream is why New York has much colder winters than London, even though it is significantly further south.
However, the AMOC has been slowing in recent years, and a new study by Utrecht University suggests it could hit a ‘cliff-like’ tipping point much sooner than predicted.
If it does shut down, not only will Europe face Arctic temperatures, other parts of the world will heat up even more than already seen. Others will face droughts, while the overall chaotic weather could cause global food and water shortages.
The great ocean conveyor belt keeps the climate stable (Picture: IPCC)
‘We are moving closer [to the collapse], but we’re not sure how much closer,’ said lead author Dr Rene van Westen, a climate scientist and oceanographer at Utrecht University in the Netherlands. ‘We are heading towards a tipping point.’
When exactly it will happen is ‘the million dollar question’ he said, but added that it could happen in his lifetime. He is 30.
‘It also depends on the rate of climate change we are inducing as humanity,’ said Dr van Westen.
A study last year suggested the AMOC could shut down as soon as 2025, with a full or partial collapse ‘most likely’ to happen this century.
How does the AMOC work?
The AMOC drives warm water north, which evaporates and cools as it moves, becoming saltier and denser. This causes it to sink and head back south before it is pulled to the surface and warmed again, repeating the cycle.
It is just one current in the ‘great ocean conveyor belt’ that regulates the world’s climate.
However, as global warming leads to the melting of ice in the northern hemisphere, particularly from the Greenland ice sheet, the volume of freshwater in the Atlantic has increased. This dilutes the seawater, so it does not sink, ready to repeat the cycle.
The Atlantic Meridional Overturning Circulation, or AMOC (Picture: S Rahmstorf)
In addition, the end of the AMOC would increase the temperature in the tropics, because the heat would no longer be drawn north.
How do we know when it will collapse?
The latest prediction is based on new computer simulations considering multiple factors, including freshwater content and salt concentration in the top 1,000m of the ocean.
Although impossible to confirm until the current actually does switch off – at which point it is too late to act – other scientists have shared their support for the new study, published in the journal Science Advances.
Rapid melting of the Greenland ice sheet is disrupting the current (Picture: Getty)
University of Exeter climate scientist Tim Lenton told Phys.org that the effects of the AMOC collapse would be ‘so abrupt and severe that they would be near impossible to adapt to in some locations’.
Stefan Rahmstorf, head of Earth Systems Analysis at the Potsdam Institute for Climate Research in Germany, said: ‘The new study adds significantly to the rising concern about an AMOC collapse in the not too distant future.
Speaking to Phys.org, he added: ‘We will ignore this at our peril.’