In the 2004 film ‘The Day After Tomorrow’, the world is plunged into a new ice age after climate change leads to the collapse of the Gulf Stream.
That might have been considered science fiction 20 years ago, but scientists now warn that the film’s terrifying plot could be coming true.
In an open letter, 44 of the world’s leading climate scientists have warned that key Atlantic Ocean currents – including the Gulf Stream – are on the brink of failure.
The scientists caution that the collapse of the Atlantic Meridional Overturning Circulation (AMOC) could lead to ‘devastating and irreversible impacts’ which will affect ‘the entire world for centuries to come’.
While the disasters of The Day After Tomorrow are triggered by the Gulf Stream, that current is just one small part of AMOC’s massive system.
This giant ocean conveyor belt is critical for moving heat around the planet, but research suggests that it has been slowing down and could soon reach a tipping point.
Without urgent action, the scientists warn that AMOC could fail completely within the next few decades.
As warm water travels northwards from the tropics, it hits the sea ice around Greenland and the Nordic countries, cooling and becoming much saltier.
As the water cools it becomes denser, sinking rapidly towards the bottom of the ocean where it flows back southwards before once again warming and rising to the surface.
This process of ‘deep water formation’ is the engine for a vast global conveyor belt which pumps heat and water all around the Atlantic Ocean.
However, studies suggest that AMOC’s deep water engine has started to slow and is now showing worrying signs of breaking down altogether.
As global temperatures rise, melting ice pours fresh water back into oceans, diluting the denser salty water and preventing it from sinking.
If this process were to break down entirely, it would have catastrophic knock-on effects including the weakening of the Gulf Stream and the disruption of global weather patterns.
Encouragingly, the latest Intergovernmental Panel on Climate Change (IPCC) report states: ‘There is medium confidence that the Atlantic Meridional Overturning Circulation will not collapse abruptly before 2100.’
However, the authors of the open letter argue that this risk has been massively underestimated.
In their letter, the scientists write: ‘The passing of this tipping point is a serious possibility already in the next few decades.’
Research from the University of Copenhagen published earlier this year found that a collapse could occur any time from 2025 onwards.
By looking at ocean temperature data over the last 150 years, the researchers argued that such a scenario is ’95 per cent certain’ by the end of this century if current greenhouse gas emissions persist.
The open letter also argues that the severity of the risk warrants more concern even if there were only ‘medium confidence’ in a potential collapse.
‘The purpose of this letter is to draw attention to the fact that only “medium confidence” in the AMOC not collapsing is not reassuring, and clearly leaves open the possibility of an AMOC collapse during this century,’ say the authors.
‘Even with a medium likelihood of occurrence, given that the outcome would be catastrophic and impacting the entire world for centuries to come, we believe more needs to be done to minimize this risk.’
Should the AMOC collapse, the effects would be widespread, devastating, and extremely long-lasting.
Scientists believe that the last time AMOC completely collapsed was during the end of the last Ice Age around 12,000 years ago, when temperatures in western Europe plummeted by up to 10°C (18°F).
The collapse would lead to major cooling and ‘unprecedented extreme weather’, especially in Nordic countries.
This would enlarge and deepen the ‘cold blob’ of anomalously cold waters which has already developed over the eastern North Atlantic due to the slowdown of heat-carrying currents.
This would be particularly bad news for the UK which is kept warm by currents of warm water carried by AMOC northwards from the Gulf of Mexico.
Previous studies have suggested that this could lead to winter temperatures in Britain becoming 10°C to 15°C (18°F to 27°F) lower on average.
While the expert say more research is needed, they note that this could ‘potentially threaten the viability of agriculture in northwestern Europe’.
Around the world, the collapse of the AMOC currents would also have devastating consequences.
The tropical rainfall belt and monsoon regions could shift southwards, precipitating enormous disruptions to agriculture and water supplies in the region.
Such a shift could cause widespread drought and famine, and could lead to massive increases in the number of climate refugees and escalating geopolitical tensions.
In the US, the scientists say that a collapse of AMOC would create a ‘major additional sea-level rise’, potentially threatening vulnerable low-lying areas on the Atlantic coast such as New York and Miami.
Additionally, the authors argue that the resulting changes to weather patterns would cause an ‘upheaval of marine ecosystems and fisheries’.
In the face of these threats, the authors of the open letter are calling on the leaders of Nordic countries to seriously consider the risk of an AMOC collapse and put pressure on their global partners to stick to the aims of the Paris Agreement.
This post was originally published on here
