OPINION - The London Question: What happens if climate change gets out of control?
When you think about climate change, you probably imagine our world getting hotter. Ice melting, sea levels rising, miserable looking polar bears on lonely ice floes — you know the drill. For climate scientists like me that is likely where we're heading — but there's also a world in which the opposite happens and London actually gets colder… much colder. According to recent studies that's something that could happen in many of our lifetimes. In fact, even as early as 2025. Given that is literally this year, it's worth considering seriously.
I know it seems strange to speak of London getting colder when January felt like a Siberian winter and February very much picked up where that left off. London's cold, what's new? Fair question. To explain what I'm talking about we need to go on a quick jaunt around the Atlantic.
This is all about a giant, invisible, ocean current in the Atlantic Ocean. If we could see it, it would look like a huge piece of spaghetti draped from the northern to southern hemispheres and back again. It's called the AMOC (Atlantic Meridional Overturning Circulation) and it works like our planet's central heating system. It circulates water from north to south and back again in a long cycle within the Atlantic Ocean.
Its primary job is to move heat around the world, pushing 17 million cubic meters of water northwards every second. It makes sure the climate of Western Europe is much warmer than it would otherwise be. London is about the same distance from the equator as the cold regions of Canada, yet enjoys a much warmer climate because of this system.
But there's a problem — the AMOC is slowing down, stopping it doing all that stuff well. It's actually in its weakest state in nearly 2,000 years. How do we know this? Well there's a really big cold blob (no, seriously, it even has its own Wikipedia page) in the North Atlantic that we can actually see. It's the only place on Earth to have cooled in the past 20 years — indicating that heat transfer magic I mentioned before isn't doing what it should be doing. Some scientists have taken this a step further and think AMOC may even collapse.
The Day After Tomorrow was based on this exact event. Is the day after tomorrow, actually now tomorrow, or next week?
This big, old, invisible ocean current is a tricky customer because no one can quite agree on when that might be or how quickly it's slowing. We haven't been measuring it long enough to get actual estimates and instead have to rely on ice sheet data from 60,000 years ago. Depending on which scientist you speak to, you get dates as early as 2025, others offer up something around the 2050s and the official line from the IPCC (the fun people at the UN's climate team) is 'sometime before 2100' — not very helpful.
Reading between the lines and on the balance of probability, most, if not all, climate scientists seem to suggest we're looking at a case of when — and not if — here. I'll say right now, I'm pretty confident it's not going to be this year (don't cancel the in-laws at Christmas just yet) but it could very feasibly be something that happens in the mid-century and that makes it a very real problem, and a problem some of us will witness.
Remember the film in 2004, The Day After Tomorrow, the one that gave us early Jake Gyllenhaal? Well, that film was based on this exact event — an AMOC collapse.
Is that where we're heading? Is the day after tomorrow, actually now tomorrow, or next week?
It would leave London looking like northern Canada, with temperatures falling to -20C
All of that is a lot to digest, sorry. You're going about your day, already worried about climate change and I've just told you a giant invisible thing you can't see, and that maybe you hadn't even heard of, is suddenly going to plunge us into a deeper ice age.
Well, let's start with the good news: the events in that film happen over the course of a Hollywood two weeks. Even if the AMOC went belly up tomorrow, we wouldn't begin to feel the effects for several decades. So in that respect the film is just that: fiction. At some point though, things would eventually kick in…
While a snow day might sound fun, it would present dire consequences for agriculture, leaving us unable to grow many crops
A full-scale collapse would be nothing short of a planetary disaster: London and the rest of England could see temperatures drop by up to 10 degrees celsius. London would start looking like northern Canada (where winters regularly go below minus 20 degrees celsius).
While a snow day might sound fun, it would present dire consequences for agriculture, leaving us unable to grow many crops; it'd be like trying to grow potatoes in Norway. Not happening.
Land suitable for arable farming could plunge by a quarter, reducing crop value by £346 billion a year. There'd be a big increase in winter storms, because while we get cooler, the southern hemisphere gets warmer. Plus, there rainfall would reduce substantially — by 123mm during the growing season of crops. The sea level in the Atlantic Ocean would also rise as much as 70cm, submerging pretty much every borough along the Thames.
So there we go, maybe the day after tomorrow isn't actually tomorrow, but it may come sooner than you think. This system is as delicate as it is powerful, as fragile as it is strong and the scales are so finely balanced.
Much like so many other things on Planet Earth, the AMOC joins the long list of those we urgently need to take care of, and in my view has to be near, or even at the top of that list.
James Stewart is a broadcaster and climate scientist
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a day ago
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Scientists mapped what happens if a crucial system of ocean currents collapses. The weather impact would be extreme
The collapse of a crucial network of Atlantic Ocean currents could push parts of the world into a deep freeze, with winter temperatures plunging to around minus 55 degrees Fahrenheit in some cities, bringing 'profound climate and societal impacts,' according to a new study. There is increasing concern about the future of the Atlantic Meridional Overturning Circulation — known as the AMOC — a system of currents that works like a giant conveyor belt, pulling warm water from the Southern Hemisphere and tropics to the Northern Hemisphere, where it cools, sinks and flows back south. Multiple studies suggest the AMOC is weakening with some projecting it could even collapse this century as global warming disrupts the balance of heat and salinity that keeps it moving. This would usher in huge global weather and climate shifts — including plunging temperatures in Europe, which relies on the AMOC for its mild climate. What's less clear, however, is how these impacts will unfold in a world heated up by humans burning fossil fuels. 'What if the AMOC collapses and we have climate change? Does the cooling win or does the warming win?' asked René van Westen, a marine and atmospheric researcher at Utrecht University in the Netherlands and co-author of the paper published Wednesday in the Geophysical Research Letters journal. This new study is the first to use a modern, complex climate model to answer the question, he told CNN. The researchers looked at a scenario where the AMOC weakens by 80% and the Earth is around 2 degrees Celsius warmer than the period before humans began burning large amounts of fossil fuels. The planet is currently at 1.2 degrees of warming. They focused on what would happen as the climate stabilized post-collapse, multiple decades into the future. Even in this hotter world, they found 'substantial cooling' over Europe with sharp drops in average winter temperatures and more intense cold extremes — a very different picture than the United States, where the study found temperatures would continue to increase even with an AMOC collapse. Sea ice would spread southward as far as Scandinavia, parts of the United Kingdom and the Netherlands, the research found. This would have a huge impact on cold extremes as the white surface of the ice reflects the sun's energy back into space, amplifying cooling. The scientists have created an interactive map to visualize the impacts of an AMOC collapse across the globe. London, for example, could see winter cold extremes of minus 2.2 Fahrenheit , while Oslo could see temperatures as low as minus 55 Fahrenheit and endure maximum temperatures below 32 Fahrenheit for 46% of the year. Parts of Europe will also become stormier, the study found. The increased temperature difference between northern and southern Europe will strengthen the jet stream and increase storm intensity over northwestern Europe. It 'completely shifts the narrative, right?' van Westen said. 'Because now policy is planning for a warmer future, but maybe instead, we need to also prepare for a colder future.' While cooling on an ever-hotter planet may sound like good news, van Westen warns it's anything but. Society in many parts of the Northern Hemisphere 'is not built for these kind of cold extremes,' he said. Crops would die, threatening food security, and infrastructure could buckle. What's more, the impacts of an AMOC collapse would mostly be felt in Europe's winter; it would still endure increasingly deadly heat waves in the summer as the climate crisis intensifies. The Southern Hemisphere, meanwhile, is projected to experience increased warming. The scientists also looked at the impacts of an AMOC collapse in an even hotter world. If global temperatures reach around 4 degrees Celsius above pre-industrial levels, the heat outweighs the cooling impact of an AMOC collapse in Europe , van Westen said. 'The warming signal actually wins.' But, he added, an AMOC collapse won't only affect temperatures. Other impacts include increased sea level rise, which will particularly affect the US, where a weaker AMOC is already driving significantly increased flooding on the northeastern coast, according to recent research. Stefan Rahmstorf, a physical oceanographer at Potsdam University in Germany who was not involved in the latest research, said the study confirms 'an AMOC collapse would have massive impacts on European climate.' The research uses only one climate model; others will rely on different models and will likely come up with a variety of scenarios, he told CNN. What ultimately happens will depend on the how the two opposing trends play out: AMOC-induced cooling and climate change-induced heating. A 'large uncertainty' remains, he said. The study is 'by no means the last word' especially as huge questions remain over whether the AMOC could be on course to collapse, said Richard Allen, a climate science professor at the University of Reading, also not involved in the research. 'But even the mere possibility of this dire storyline unfolding over coming centuries underscores the need to forensically monitor what is happening in our oceans,' he said. What is crystal clear is that an AMOC collapse would be very bad for society, van Westen said. 'We want to avoid it at all costs.'
CNN
a day ago
- CNN
Scientists mapped what happens if a crucial system of ocean currents collapses. The weather impact would be extreme
Climate changeFacebookTweetLink Follow The collapse of a crucial network of Atlantic Ocean currents could push parts of the world into a deep freeze, with winter temperatures plunging to around minus 55 degrees Fahrenheit in some cities, bringing 'profound climate and societal impacts,' according to a new study. There is increasing concern about the future of the Atlantic Meridional Overturning Circulation — known as the AMOC — a system of currents that works like a giant conveyor belt, pulling warm water from the Southern Hemisphere and tropics to the Northern Hemisphere, where it cools, sinks and flows back south. Multiple studies suggest the AMOC is weakening with some projecting it could even collapse this century as global warming disrupts the balance of heat and salinity that keeps it moving. This would usher in huge global weather and climate shifts — including plunging temperatures in Europe, which relies on the AMOC for its mild climate. What's less clear, however, is how these impacts will unfold in a world heated up by humans burning fossil fuels. 'What if the AMOC collapses and we have climate change? Does the cooling win or does the warming win?' asked René van Westen, a marine and atmospheric researcher at Utrecht University in the Netherlands and co-author of the paper published Wednesday in the Geophysical Research Letters journal. This new study is the first to use a modern, complex climate model to answer the question, he told CNN. The researchers looked at a scenario where the AMOC weakens by 80% and the Earth is around 2 degrees Celsius warmer than the period before humans began burning large amounts of fossil fuels. The planet is currently at 1.2 degrees of warming. They focused on what would happen as the climate stabilized post-collapse, multiple decades into the future. Even in this hotter world, they found 'substantial cooling' over Europe with sharp drops in average winter temperatures and more intense cold extremes — a very different picture than the United States, where the study found temperatures would continue to increase even with an AMOC collapse. Sea ice would spread southward as far as Scandinavia, parts of the United Kingdom and the Netherlands, the research found. This would have a huge impact on cold extremes as the white surface of the ice reflects the sun's energy back into space, amplifying cooling. The scientists have created an interactive map to visualize the impacts of an AMOC collapse across the globe. London, for example, could see winter cold extremes of minus 2.2 Fahrenheit , while Oslo could see temperatures as low as minus 55 Fahrenheit and endure maximum temperatures below 32 Fahrenheit for 46% of the year. Parts of Europe will also become stormier, the study found. The increased temperature difference between northern and southern Europe will strengthen the jet stream and increase storm intensity over northwestern Europe. It 'completely shifts the narrative, right?' van Westen said. 'Because now policy is planning for a warmer future, but maybe instead, we need to also prepare for a colder future.' While cooling on an ever-hotter planet may sound like good news, van Westen warns it's anything but. Society in many parts of the Northern Hemisphere 'is not built for these kind of cold extremes,' he said. Crops would die, threatening food security, and infrastructure could buckle. What's more, the impacts of an AMOC collapse would mostly be felt in Europe's winter; it would still endure increasingly deadly heat waves in the summer as the climate crisis intensifies. The Southern Hemisphere, meanwhile, is projected to experience increased warming. The scientists also looked at the impacts of an AMOC collapse in an even hotter world. If global temperatures reach around 4 degrees Celsius above pre-industrial levels, the heat outweighs the cooling impact of an AMOC collapse in Europe, van Westen said. 'The warming signal actually wins.' But, he added, an AMOC collapse won't only affect temperatures. Other impacts include increased sea level rise, which will particularly affect the US, where a weaker AMOC is already driving significantly increased flooding on the northeastern coast, according to recent research. Stefan Rahmstorf, a physical oceanographer at Potsdam University in Germany who was not involved in the latest research, said the study confirms 'an AMOC collapse would have massive impacts on European climate.' The research uses only one climate model; others will rely on different models and will likely come up with a variety of scenarios, he told CNN. What ultimately happens will depend on the how the two opposing trends play out: AMOC-induced cooling and climate change-induced heating. A 'large uncertainty' remains, he said. The study is 'by no means the last word' especially as huge questions remain over whether the AMOC could be on course to collapse, said Richard Allen, a climate science professor at the University of Reading, also not involved in the research. 'But even the mere possibility of this dire storyline unfolding over coming centuries underscores the need to forensically monitor what is happening in our oceans,' he said. What is crystal clear is that an AMOC collapse would be very bad for society, van Westen said. 'We want to avoid it at all costs.'
CNN
a day ago
- CNN
Scientists mapped what happens if a crucial system of ocean currents collapses. The weather impact would be extreme
Climate changeFacebookTweetLink Follow The collapse of a crucial network of Atlantic Ocean currents could push parts of the world into a deep freeze, with winter temperatures plunging to around minus 55 degrees Fahrenheit in some cities, bringing 'profound climate and societal impacts,' according to a new study. There is increasing concern about the future of the Atlantic Meridional Overturning Circulation — known as the AMOC — a system of currents that works like a giant conveyor belt, pulling warm water from the Southern Hemisphere and tropics to the Northern Hemisphere, where it cools, sinks and flows back south. Multiple studies suggest the AMOC is weakening with some projecting it could even collapse this century as global warming disrupts the balance of heat and salinity that keeps it moving. This would usher in huge global weather and climate shifts — including plunging temperatures in Europe, which relies on the AMOC for its mild climate. What's less clear, however, is how these impacts will unfold in a world heated up by humans burning fossil fuels. 'What if the AMOC collapses and we have climate change? Does the cooling win or does the warming win?' asked René van Westen, a marine and atmospheric researcher at Utrecht University in the Netherlands and co-author of the paper published Wednesday in the Geophysical Research Letters journal. This new study is the first to use a modern, complex climate model to answer the question, he told CNN. The researchers looked at a scenario where the AMOC weakens by 80% and the Earth is around 2 degrees Celsius warmer than the period before humans began burning large amounts of fossil fuels. The planet is currently at 1.2 degrees of warming. They focused on what would happen as the climate stabilized post-collapse, multiple decades into the future. Even in this hotter world, they found 'substantial cooling' over Europe with sharp drops in average winter temperatures and more intense cold extremes — a very different picture than the United States, where the study found temperatures would continue to increase even with an AMOC collapse. Sea ice would spread southward as far as Scandinavia, parts of the United Kingdom and the Netherlands, the research found. This would have a huge impact on cold extremes as the white surface of the ice reflects the sun's energy back into space, amplifying cooling. The scientists have created an interactive map to visualize the impacts of an AMOC collapse across the globe. London, for example, could see winter cold extremes of minus 2.2 Fahrenheit , while Oslo could see temperatures as low as minus 55 Fahrenheit and endure maximum temperatures below 32 Fahrenheit for 46% of the year. Parts of Europe will also become stormier, the study found. The increased temperature difference between northern and southern Europe will strengthen the jet stream and increase storm intensity over northwestern Europe. It 'completely shifts the narrative, right?' van Westen said. 'Because now policy is planning for a warmer future, but maybe instead, we need to also prepare for a colder future.' While cooling on an ever-hotter planet may sound like good news, van Westen warns it's anything but. Society in many parts of the Northern Hemisphere 'is not built for these kind of cold extremes,' he said. Crops would die, threatening food security, and infrastructure could buckle. What's more, the impacts of an AMOC collapse would mostly be felt in Europe's winter; it would still endure increasingly deadly heat waves in the summer as the climate crisis intensifies. The Southern Hemisphere, meanwhile, is projected to experience increased warming. The scientists also looked at the impacts of an AMOC collapse in an even hotter world. If global temperatures reach around 4 degrees Celsius above pre-industrial levels, the heat outweighs the cooling impact of an AMOC collapse in Europe, van Westen said. 'The warming signal actually wins.' But, he added, an AMOC collapse won't only affect temperatures. Other impacts include increased sea level rise, which will particularly affect the US, where a weaker AMOC is already driving significantly increased flooding on the northeastern coast, according to recent research. Stefan Rahmstorf, a physical oceanographer at Potsdam University in Germany who was not involved in the latest research, said the study confirms 'an AMOC collapse would have massive impacts on European climate.' The research uses only one climate model; others will rely on different models and will likely come up with a variety of scenarios, he told CNN. What ultimately happens will depend on the how the two opposing trends play out: AMOC-induced cooling and climate change-induced heating. A 'large uncertainty' remains, he said. The study is 'by no means the last word' especially as huge questions remain over whether the AMOC could be on course to collapse, said Richard Allen, a climate science professor at the University of Reading, also not involved in the research. 'But even the mere possibility of this dire storyline unfolding over coming centuries underscores the need to forensically monitor what is happening in our oceans,' he said. What is crystal clear is that an AMOC collapse would be very bad for society, van Westen said. 'We want to avoid it at all costs.'
