If all the ice on Earth melted, humanity would be in big trouble.
It’s been estimated that the disappearance of all the frozen water at the poles or on mountaintops would cause sea-levels to surge by 62 metres – a fifth higher than Nelson’s Column.
Cities like London and New York would be underwater as flooding transforms coastlines across the world so drastically that today’s maps would be almost meaningless.
Meanwhile, billions of refugees would jostle for space on reduced landmasses whilst battling to survive the climate chaos caused by and hotter temperatures.
There would inevitably be starvation on an epic scale, followed by war and pestilence as our once lovely blue planet descends into hell.
Thankfully, this nightmare scenario is thought to be 5,000 years away. But until catastrophe hits, some scientists believe we’re going to see small but potentially accelerating rises in sea level every year unless human society suddenly manages to pull back from the brink.
The oceans are already growing due to the melting of ice at the poles, which is caused by the increased temperatures prompted by carbon pumped out by human civilisation.
It’s happening slowly right now but is expected to become faster if we pass ‘tipping points’ like the melting of Greenland or Antarctic ice sheets.
As part of our Future of Everything series, we decided to find out what could happen as the sea levels rise:
What would happen if sea levels rose by 3mm?
Sea level is rising by about 3mm every year right now, according to Nasa stats.
This tiny amount might not seem particularly concerning, but a recent analysis from the US space agency suggested the pace of sea level rise is actually increasing at a dramatic rate.
It found that the oceans used to grow at the rate of about 2.5 millimetres per year in the 1990s but is now swelling at 3.4mm.
This is already producing larger storm surges, which is the name for inundations of water during typhoons, hurricanes or other storms.
It’s been estimated that surges today are roughly 20cm higher than they would have been in 1900, meaning they are more destructive and cause worse flooding.
What would happen if sea levels rose by two metres?
The melting of the Greenland, West Antarctic and East Antarctic ice sheets could increase sea levels by two metres between now and 2100, causing devastation around the world, the Fifth Assessment Report of the Intergovernmental Panel on Climate Change found.
Lead author Professor Jonathan Bamber from the University of Bristol’s School of Geographical Sciences said this would have ‘profound consequences for humanity’, resulting in the loss of land loss of 1.79million km2 of land ‘including critical regions of food production’ and the potential displacement of up to 187 million people.
It’s highly likely movement on people on this scale would spark wars over water and other resources.
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Climate events have a history of causing conflict. Some experts believe the collapse of the Bronze Age in the 13th and 12th century BC may have been driven in part by migration of people whose homes had been devastated by a climate event.
Severe drought created famine and sociopolitical unrest at a similar time to earthquakes and invasion by nomadic tribes. It plunged Europe into a Dark Age.
Moving back to modern times, once the ice caps begin to melt, they are likely to melt faster and faster, meaning sea levels could swell at an increased pace too.
Coastal communities and low-lying cities could be inundated with water due to increased storm sturges, although richer nations will be able to build better defences, meaning poorer countries will bear the brunt of the devastation.
What would happen if sea levels rose by 10 metres?
This is where things start to look apocalyptic.
A report by Climate Central said that a temperature increase of about 4 degrees celsius would result in sea levels swelling by almost nine metres.
Here in the UK alone, that would ruin the lives of six million people.
Globally, the soaring seas could submerge land home to 627 million people.
It’s unlikely London could survive in its current form if the oceans rose by 10 metres.
In 1928, a storm in the UK’s capital caused relatively small 1.2 metre-high floods but still drowned 14 people.
Right now, the city is guarded by the Thames Barrier but this is only believed to offer sufficient protection until 2070 at the latest.
Then we’re going to have to spend billions building a bigger one – or start thinking about moving to higher ground.
What if sea levels rose by 62 metres?
The current estimate for how much sea levels would rise if all the ice caps melted vary between 62 and 70 metres.
This would turn the San Francisco hills into a group of islands, the Netherlands would have long been submerged and all of London would be underwater.
Africa would actually fare best but, with the temperature increases needed for the melting ice caps, would be broadly uninhabitable because of the heat.
The tricky thing is knowing when this might happen.
Meteorologist Eric Holthouse says coastal cities could be submerged by 2100 and the last time the Arctic was this warm is believed to be as long as 120,000 years ago
The even trickier thing is not talking about it in a way that reports on this path as a ‘definite’.
It is how authorities deal with these problems this century that will define if we’re talking about 3mm, 3m or 30m in centuries to come.
The Future Of Everything
This piece is part of Metro.co.uk’s series The Future Of Everything.
From OBEs to CEOs, professors to futurologists, economists to social theorists, politicians to multi-award winning academics, we think we’ve got the future covered, away from the doom mongering or easy Minority Report references.
Every weekday, we’re explaining what’s likely (or not likely) to happen.
Talk to us using the hashtag #futureofeverything If you think you can predict the future better than we can or you think there’s something we should cover we might have missed, get in touch: [email protected] or [email protected]
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