What will rising sea levels do to the world's megacities?

How major cities will be affected by rising sea levels. Image: Statista/CityMetric.

So you know how sometimes people are like, “this is a good news, bad news kind of a thing”? This isn't one of those times. It's bad news that comes with more bad news behind it. It's a bad news sandwich.

This infographic, made for us by the nice people at Statista using Climate Central data, how sea level rises are going to affect a selection of the world's cities. We've focused on the megacities – that is, those with populations of 10m or more – partly because these are where people are mostly likely to be affected in large numbers, and partly just to manage the size of the map.

The bubbles, and the numbers attached to them, represent the share of the cities' 2010 populations that would be below sea level in the event of particular increases in global temperature. The size of the light red bubble represents the percentage of the urban population that could be submerged in the event of a 2°C increase in global temperature (a degree of increase which feels pretty much inevitable); the dark red one is how much people will be affected by a 4°C increase in global temperature (which we could probably still avoid if we tried, but let's be honest, we probably won't try).

The first bit of bad news is that these figures are very obviously awful. London gets off pretty lightly – but a 4°C increase in global temperature would still put 13 per cent of its population under water. In New York, which is bigger, a full quarter of its population lives in areas that may well be underwater.

But these numbers are as nothing towards some of those Asian cities. In Mumbai and Calcutta it's half; in Shanghai, a city of 23m people, it's more than three-quarters.

In 2010, Dhaka, the capital of Bangladesh, contained an estimated 32m people; in the event of the sort of sea level rise that's expected to follow a 4°C increase in global temperature, 38 per cent of them will be underwater.

In other words, what this map shows is that tens of millions of homes are very possibly going to be underwater at some point before the century is out.

Now you may be thinking, well, could be worse. Okay, Asia's in real trouble here (sorry Asia) but much of the rest of the world is getting off relatively lightly.

Ha. No. Remember, this graphic only shows cities of 10m or more. Some of the world's megacities are relatively safe from sea level rises – Moscow and Kinshasa are both well in-land; Sao Paulo isn't, but it is a long way above sea level.

But a lot of other large cities are excluded because they're not quite big enough to make the cut. A 4°C increase in global temperature would put 26 per cent of San Francisco's population under water. In Tampa, Florida, it's 40 per cent. Barisal, a Bangladeshi city of 7m people, would see 88 per cent of its population submerged by the same increase in temperature.

Perhaps the most terrifying of all, though, are the figures that relate to the Netherlands, a name which literally means “lower countries”. In the event of that 4°C increase in temperatures, 98 per cent of the populations of Amsterdam and the Hague will be below sea level.

Now – below sea level doesn't mean “inevitably underwater”, of course. There are mitigation measures cities can take.

But one of the most important mitigation measures is almost certain to be “moving a lot of people to somewhere else”.

We're in trouble, is basically what we're saying here.


Barnet council has decided a name for its new mainline station. Exciting!

Artist's impression of the new Brent Cross. Image: Hammerson.

I’ve ranted before about the horror of naming stations after the lines that they’re served by (screw you, City Thameslink). So, keeping things in perspective as ever, I’ve been quietly dreading the opening of the proposed new station in north London which has been going by the name of Brent Cross Thameslink.

I’ve been cheered, then, by the news that station wouldn’t be called that at all, but will instead go by the much better name Brent Cross West. It’s hardly the cancellation of Brexit, I’ll grant, but in 2017 I’ll take my relief wherever I can find it.

Some background on this. When the Brent Cross shopping centre opened besides the A406 North Circular Road in 1976, it was only the third large shopping mall to arrive in Britain, and the first in London. (The Elephant & Castle one was earlier, but smaller.) Four decades later, though, it’s decidedly titchy compared to newer, shinier malls such as those thrown up by Westfield – so for some years now, its owners, Hammerson, have wanted to extend the place.

That, through the vagaries of the planning process, got folded into a much bigger regeneration scheme, known as Brent Cross Cricklewood (because, basically, it extends that far). A new bigger shopping centre will be connected, via a green bridge over the A406, to another site to the south. There you’ll find a whole new town centre, 200 more shops, four parks, 4m square feet of offices space and 7,500 homes.

This is all obviously tremendously exciting, if you’re into shops and homes and offices and not into depressing, car-based industrial wastelands, which is what the area largely consists of at the moment.

The Brent Cross site. Image: Google.

One element of the new development is the new station, which’ll sit between Hendon and Cricklewood on the Thameslink route. New stations are almost as exciting as new shops/homes/offices, so on balance I'm pro.

What I’ve not been pro is the name. For a long time, the proposed station has been colloquially referred to as Brent Cross Thameslink, which annoys me for two reasons:

1) Route names make rubbish modifiers because what if the route name changes? And:

2) It’s confusing, because it’s nearly a mile from Brent Cross tube station. West Hampstead Thameslink (euch), by contrast, is right next to West Hampstead tube.

Various other names have been proposed for the station. In one newsletter, it was Brent Cross Parkway; on Wikipedia, it’s currently Brent Cross South, apparently through confusion about the name of the new town centre development.

This week, though, Barnet council quietly confirmed it’d be Brent Cross West:

Whilst the marketing and branding of BXS needs to be developed further, all parties agree that the station name should build upon the Brent Cross identity already established. Given the station is located to the west of Brent Cross, it is considered that the station should be named Brent Cross West. Network Rail have confirmed that this name is acceptable for operational purposes. Consequently, the Committee is asked to approve that the new station be named Brent Cross West.

Where the new station will appear on the map, marked by a silly red arrow. Image: TfL.

That will introduce another irritating anomaly to the map, giving the impression that the existing Brent Cross station is somehow more central than the new one, when in fact they’re either side of the development. And so:

Consideration has also been given as to whether to pursue a name change for the tube station from “Brent Cross” to “Brent Cross East”.

Which would sort of make sense, wouldn’t it? But alas:

However owing to the very high cost of changing maps and signage London-wide this is not currently being pursued.

This is probably for the best. Only a handful of tube stations have been renamed since 1950: the last was Shepherd’s Bush Market, which was until 2008 was simply Shepherd's Bush, despite being quite a long way from the Shepherd's Bush station on the Central line. That, to me, suggests that one of the two Bethnal Green stations might be a more plausible candidate for an early rename.

At any rate: it seems unlikely that TfL will be renaming its Brent Cross station to encourage more people to use the new national rail one any time soon. But at least it won’t be Brent Cross Thameslink.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and also has a Facebook page now for some reason. 

Want more of this stuff? Follow CityMetric on Twitter or Facebook