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.


Here’s how Henry Ford and IKEA could provide the key to solving the housing crisis

A flatpack house designed by architectural firm Rogers Stirk Harbour and Partners, on display at the Royal Academy, London, in 2013. Image: Getty.

For many people, the housing market is not a welcoming place. The rungs of the property ladder seem to get further and further out of reach. There are loud calls to build hundreds of thousands of new homes (and equally loud demands that they’re not built in anyone’s back yard).

If there was ever a time to introduce mass-produced affordable housing, surely that time is now.

The benefits of mass production have been well known since Henry Ford’s car factories made the Model T back in 1908. It was only made in one colour, black, for economic reasons. Not because it was the cheapest colour of paint, but because it was the colour that dried the quickest.

This allowed the production line to operate at faster, more cost effective, speeds. And ultimately, it meant the product could be sold at a more attractive cost to the customer.

This approach, where processes are tested to achieve increasingly efficient production costs, is yet to filter properly into the construction of houses. This makes sense in a way, as not everybody wants exactly the same type of house.

Historically, affordable mass-produced housing removed a large amount of customisations, to ensure final costs were controlled. But there is another way. Builders and architects have the ability to create housing that allows a level of flexibility and customisation, yet also achieves the goal of affordability.

Back in 2006, the “BoKlok” approach to affordable housing was launched to great acclaim in the UK. Literally translated from Swedish, the term means “live smart”. Originally created from a collaboration between flat-pack favourite IKEA and Swedish construction giant Skanska, the BoKlok housing approach was to allow for selected customisation to maximise individuality and choice for the customers. But at the same time, it ensured that larger house building components were duplicated or mass-produced, to bring down the overall costs.

Standard elements – wall panels, doors, windows – were made in large numbers to bring the elemental costs down. This approach ensured the costs were controlled from the initial sketch ideas through to the final design choices offered to the customers. The kitchens and bathrooms were designed to be flexible in terms of adding additional units. Draw and cupboard fronts interchangeable. Small options that provided flexibility, but did not impact on overall affordability.

It’s a simple approach that has worked very well. More than 10,000 BoKlok houses have now been built, mainly in Norway, Sweden and Denmark, with a small number in the UK.

But it is only part of the architectural equation. The affordable housing market is vital, but the cost of making these homes more adaptable is rarely considered.

Flexibility is key. The needs of a house’s inhabitants change. Families can grow (and shrink) and require more room, so the costs of moving house reappear. One clever response to this, in BoKlok homes, has been to allow “built in” flexibility.

Loft living

This flexibility could include a loft space that already has flooring and a built in cupboard on a lower floor which can be simply dismantled and replaced with a “flat-pack style” staircase that can be purchased and installed with minimal disruption to the existing fabric.

Weeks of builders removing walls, plastering and upheaval are replaced by a trip to the IKEA store to purchase the staircase and the booking of a subcontractor to fit it. The original design accounted for this “future option” and is built into the core of the house.

The best approach to new affordable housing should consider combinations of factors that look at design, materials and processes that have yet to be widely used in the affordable housing market.

And the construction sector needs to look over its shoulder at other market places – especially the one that Henry Ford dominated over a century ago. Today’s car manufacturers offer customised options in everything from colour to wheel size, interior gadgets to different kinds of headlamp. These options have all been accounted for in the construction and costing of each model.

The ConversationThey share a similar design “platform”, and by doing so, considerably reduce the overall cost of the base model. The benefit is quicker production with the added benefit of a cost model that allows for customisation to be included. It is a method the construction sector should adopt to produce housing where quality and affordability live happily together.

David Morton, Associate Professor in Architecture and Built Environment, Northumbria University, Newcastle.

This article was originally published on The Conversation. Read the original article.