Gulf Stream collapse explained

Climate experts are warning of “catastrophic consequences” after a new study found that a key part of the Gulf Stream is weakening and may be approaching irreversible collapse, leading to disastrous changes in worldwide weather patterns.

Some reports have suggested that the apocalyptic scenes depicted in the 2004 film The Day After Tomorrow, which purported to show the effect of a sudden change in ocean currents, could become reality.

Here is what we know.

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What is the Gulf Stream?

The Gulf Stream is one of the planet’s major heat distributors, which works a bit like a conveyor belt. It is a large system of ocean currents that transports warm water from the tropics northwestwards into the North Atlantic.

It is critical to the global climate because it has a moderating effect on temperatures on the Atlantic coasts of North America, Europe and northwestern Africa.

What is changing?

The Atlantic meridional overturning circulation (AMOC), which is part of the Gulf Stream, is believed to be in serious decline because its underlying system “has become destabilised”, says the Daily Mail.

The currents are already at their slowest point in at least 1,600 years, and the new study, which was published in the peer-reviewed British journal Nature Climate Change, shows they may be nearing a shutdown.

Climatologist Tim Palmer of Oxford University told the BBC that while the Gulf Stream will not grind to a halt, it is likely to move “a little further south than where it is now and that will end up cooling the North Atlantic and probably parts of Europe including the UK”.

What might this mean?

The effect could be profound. Analysts say the end of the AMOC would be “one of the planet’s main potential tipping points”, The Guardian reports. It could lead to “catastrophic consequences”, including severe disruption of the rains that “billions of people depend on for food in India, South America and West Africa”. Parts of Africa could return to quasi-permanent droughts, similar to those that captured global attention in the 1980s.

Al Jazeera says other outcomes would include “extreme cold” in Europe, where temperatures could drop by an average of 8C. According to modelling published last year, UK temperatures would drop by 3.4C and “rainfall during the growing season is expected to drop by 123mm”, says Ars Technica, causing “a big hit to the UK’s agricultural productivity”.

Sea levels would rise in parts of the US, and secondary effects could further endanger the Amazon rainforest and Antarctic ice sheets, exacerbating the climate disaster.

David Alexander, professor of risk and disaster reduction at University College London, who was not involved in the research, said the UK is particularly unprepared for the disastrous scenarios that could follow. “Britain does not have a proper civil protection system,” he told the Daily Mail. “There is a failure to learn from other countries’ good practices.”

What can be done to stop it happening?

Niklas Boers, from the Potsdam Institute for Climate Impact Research in Germany, who led the study, said climate change is responsible for the effects on ocean currents.

“The only thing to do is keep emissions as low as possible,” he said. “The likelihood of this extremely high-impact event happening increases with every gram of CO2 that we put into the atmosphere.”