As anyone who has seen ‘The Day After Tomorrow’ can attest, the world would look dramatically different if the Gulf Stream gave way.
In the 2004 blockbuster film starring Jake Gyllenhaal, an enormous ‘superstorm’ triggered by the collapse of the Gulf Stream sets off catastrophic natural disasters.
Around the world, people are frozen under layers of snow, drowned in massive tsunamis and dramatically crushed under vehicles thrown by tornados.
Now, scientists at the Met Office warn that Earth’s system of ocean currents is ‘weakening’, although it is unlikely to collapse this century.
The Gulf Stream is only a small part of a much wider system of currents, officially called the Atlantic Meridional Overturning Circulation or AMOC.
Described as ‘the conveyor belt of the ocean’, it transports warm water near the ocean’s surface northwards from the tropics up to the northern hemisphere, keeping Europe, the UK and the US east coast temperate.
Lead author Dr Jonathan Baker, a senior scientist at the Met Office, said: ‘The AMOC has a crucial role in regulating our climate; without it, northwest Europe’s temperatures would be much cooler.
‘Although our study shows that collapse over the next 75 years is unlikely, the AMOC is very likely to weaken, which will present climate challenges for Europe and beyond.’
In the 2004 blockbuster film starring Jake Gyllenhaal , an enormous ‘superstorm’ triggered by the collapse of the Gulf Stream sets off catastrophic natural disasters
Characters are frozen under layers of snow, drowned in massive tsunamis and dramatically crushed under vehicles thrown by tornados
‘If the AMOC were to collapse, it could also lead to significant cooling in northwest Europe and chaotic weather patterns worldwide, affecting crops yields and ecosystems,’ Dr Baker said.
The academic stress that his study found the AMOC is unlikely to collapse this century, but a weakened AMOC poses ‘serious climate challenges’.
‘A weaker AMOC could alter global rainfall patterns, disrupt marine ecosystems, reduce the ocean’s ability to store carbon, and accelerate sea level rise along the US east coast,’ he said.
Professor David Thornalley, a climate scientist at University College London who was not involved with the study, said temperatures would plummet if the AMOC collapsed.
‘An AMOC collapse could cause more weather extremes, so as well as overall colder-than-average conditions, we also expect that there would be more winter storms caused by stronger westerly winds,’ he told MailOnline.
‘Unfortunately people would die due to stronger winter storms and flooding, and many old and young would be vulnerable to the very cold winter temperatures.’
However, in the UK, the effects would be ‘minor’ compared with elsewhere around the world, Professor Thornalley added.
‘A collapse in AMOC would cause a shift in the tropical rainfall belt which would massively disrupt agriculture and water supplies across huge swathes of the globe,’ he said.
The Gulf Stream is only a small part of a much wider system of currents, officially called the Atlantic Meridional Overturning Circulation (AMOC). This map indicates surface currents (solid curves) and deep currents (dashed curves) that form a portion of the AMOC. Colours of curves indicate approximate temperatures
In the Hollywood blockbuster The Day After Tomorrow (pictured), ocean currents around the world stop as a result of global warming, triggering a new ice age on Earth
‘Many millions would be affected and suffer from drought, famine and flooding, in countries that are already struggling to deal with these issues. There would be huge numbers of climate refugees, geopolitical tensions would rise.’
Jonathan Bamber, a professor of Earth observation at the University of Bristol, agreed that if the AMOC were to collapse, the climate of northwest Europe would be ‘unrecognisable compared to what it is today’.
‘It would be several degrees cooler so that winters would be more typical of Arctic Canada and precipitation would decrease also,’ he told MailOnline. ‘Very harsh, cold winters would certainly be a threat to life.’
In ‘The Day After Tomorrow’, a collapse of the AMOC takes place over a matter of days and the fictional weather immediately switches to extreme cold.
Thankfully, such a rapid transition will not happen in real life, said Penny Holliday, head of marine physics and ocean circulation at the National Oceanography Centre in Southampton.
‘If the AMOC does reach a tipping point it will happen over several decades at least,’ she told MailOnline.
‘However a slowdown of the AMOC, whether it is fast-acting or takes place over many decades, will lead to the generation of more extreme and violent weather systems that have the potential to cause deaths and major damage.’
Already, researchers have suggested that AMOC will weaken or collapse at some point in the 21st century as greenhouse gas emissions increase.
This illustration from the new Nature study depicts the AMOC’s upwelling pathways – where deep, cold water rises toward the surface – in the present day
Formally known as the Atlantic Meridional Overturning Circulation (AMOC), it powers the Gulf Stream that brings warm water from the Gulf of Mexico to the northeastern US coast
However, the extent of AMOC weakening is uncertain with wide variation across climate models, according to the researchers at the Met Office.
To find out more, the team, led by Dr Jonathan Baker, used 34 computer models to assess the AMOC’s response to extreme changes in greenhouse gas concentrations and rising sea levels.
Their findings, published in the journal Nature, reveal the AMOC would weaken, but is likely to withstand future global warming and won’t collapse this century.
This is because strong Southern Ocean winds act like a powerful pump, continuously pulling deep water to the surface, keeping the system running even under extreme climate change.
Met Office says that the effect of a weaker AMOC is included when making projections of future climate change for the UK.
Interestingly, a weaker AMOC will bring less warm water northwards, and this will partly offset the warming effect of the greenhouse gases over western Europe.
For the gradual weakening that is likely over the 21st century, but the overall effect is still a warming.
Professor Rowan Sutton, director of the Met Office Hadley Centre who was not involved with the study, said it brings ‘important new insights’ into AMOC’s future.
‘The Day After Tomorrow’ is based on the 1999 book The Coming Global Superstorm by Art Bell and Whitley Strieber
Professor Rowan Sutton, director of the Met Office Hadley Centre who was not involved with the study, said it brings ‘important new insights’ into AMOC’s future.
‘It shows that aspects of the AMOC may be more robust to a changing climate than some previous research has suggested,’ he said.
‘However, it doesn’t change our expectation that the AMOC will weaken over the twenty first century, and that this weakening will have important impacts on climate.’
But study author Geoff Vallis, climate scientist at the University of Exeter, said it does ‘not in any way mean that global warming is not a severe problem for society and our planet’.
‘I think it very unlikely that my house will burn down in the coming years; however, I still buy insurance to guard against that risk,’ Professor Vallis said.
