The Eiffel Tower is buried part-way in snow. The London Eye has frozen shut. The ColosseumA vast stadium built by the Roman emperors Vespasian and Titus. It could seat between 50,000 and 80,000 spectators. It was used to hold gladiatorial contests and even mock sea battles. has become a skating rink. And Moscow has become so cold that the population has started living underground. We are in another Ice AgeA long period of time in which global temperatures are extremely cold..

This could be a montage from a science fiction film.¹ But, according to a research paper published at University College London (UCL), a frozen Europe is a real possibility. 

The research suggests that global warming could cause the collapse of the Gulf Stream. The UCL paper estimates 2050 as the most likely date of collapse, unless global carbon emissions are not seriously reduced. But it also contains the possibility that it could occur as soon as 2025.²

The Gulf Stream is a current of warm water that flows north from Florida along North America's East Coast, before crossing the Atlantic to Europe.

It releases heat energy into the atmosphere, warming Europe and maintaining the moderate temperatures the continent currently enjoys. According to UCL's Professor David Thornalley, the Gulf Stream is "equivalent to the energy from millions of power stations".³

The Gulf Stream is one part of the Atlantic Meridional Overturning Circulation (Amoc), a network of looping currents that pumps warm water around the world, from the Equator towards the North and South poles. A change in one of these loops can have a significant effect on the others.

As they move, these bodies of water partly evaporate. Salt levels in the remaining water are becoming more concentrated and this now-denser water sinks down, allowing warm water to rise up. And so the circulation continues.

As the Met Office explains: "This global process makes sure that the world's oceans are continually mixed, and that heat and energy are distributed to all parts of the Earth."

But now Greenland's freshwater ice cap is melting, making the seawater less salineA solution of salt in water, or salty water (such as seawater). and consequently less dense, and this has slowed down the Amoc system. It is currently at its weakest point in 1,600 years.⁴

Other studies have found that climate change is weakening the jet streams, fast-moving winds that, among other things, help to propel the ocean streams. This might further damage the Gulf Stream.

If the Gulf Stream does completely collapse, temperatures in Europe could fall between 10 and 15C. This would transform the continent completely. There would be harsh storms. Agriculture would no longer work the same way. Food would become scarcer. Winters might become difficult to survive.

Yet Europe would not be the only place to suffer. Environmental journalist Damien Carrington writes: "A collapse would have disastrous consequences around the world." 

The sea level would rise up to 10cm on the east coast of North America, possibly placing the houses and livelihoods of many Mexicans, Americans and Canadians at risk. It would disrupt the rains that allow India, west African and South America to farm food. And it would transform the seasons in the Amazon, the Earth's greatest absorber of carbon dioxide.

It is clear, however, that some people will be affected more than others. Climate change will fall more heavily on those in poorer countries, who have fewer tools to defend themselves against the change.⁵

As former UNUnited Nations. An intergovernmental organisation based in New York that aims to maintain international peace and security. Secretary-General Kofi Annan once said: "the whole of humanity stands to lose" because of climate change.

Will this affect all of us?

Yes: There is no doubt about it. Countries in Europe will be most directly affected, but the Gulf Stream is part of a network which stretches across the entire globe. Everywhere will face one consequence or another.

No: Most people will have to change their lives to accommodate newer, colder temperatures. But, as is often the case, some of the ultra-wealthy will find a way to escape the effects that everyone else will be left to suffer.

Or... Scientists have only kept records on Amoc since 1980. We should not accept predictions based on such a small sample. The circulation pattern might be stronger than we think.