Title Cities used to sprawl. Now they’re growing taller ✅

The Economist Menu My Economist Graphic detail |Above, not beyond Cities used to sprawl. Now they're growing taller Large-scale high-rise developnment is becoming the norm across the world Aug 16th 2024 Saved Share Give T HERE ISA specialthrill to landing in anew city.The view youget before the plane touches down reveals alot about aplace.You can tell whether locals live packed together in tall towers or spread out in low buildings. You can gauge whether there is adense centre or a sparse urban sprawl. A new study revealsthat low-rise cityscapes may, one day, be athing ofthe past.Increasingly,cities are growing upwards rather than outwards.
Allgrown up Direction of urban growth in megacities,estimated using satellite images +More outwards More upwards 1990s Beijing 2010s 1990s Delhi 2010s 20km 10 km 1990s Ho ChiMinh City 2010s 1990s Cairo 2010s 20km 20km Sources: "Global urbanstructural growth shows a profound shift from spreading out to building up", by S.Frolking et al., Nature Cities, 2024; The Economist Cities expand asbusinesses thrive, jobs are created and peoplepour in. This happens in three ways.There is a process of"infilling",whereby pockets ofvacant land within a city are built on.There is lateral development,where buildings spread out onto land outside theurban centre. And there is upward development,where low-rise buildings are replaced by taller ones. A new paper, published in Nature Cities by Steve Frolking and colleagues based in America andGermany, used satellite data to measure theworld's cities in three dimensions. Previous research has used satellite images to assess infilling and lateral growth,but the authors ofthis study added a clever technique to gauge upward development too. They applied their method to morethan 1,550 cities from around 1993 to 2020.

The pace at which urban areas are expanding also differs dramatically across the world (see chart 2).InAfrica,which includes some ofthe world's poorest and least developed cities,upward growthwas slow in the 1990s and 2000s,but has accelerated in the past decade. In more developed emerging markets, like China and the Middle East,upward growthspurts began in the 2000s. Perhaps unsurprisingly,urban growth in the most developed regions Europe and North America--has been relatively slow in both directionsover the past 30years. Allthismatters forpeople and the planet. Dense cities tend to have higher productivity and produce more innovations than dispersed urban areas do. Residents have shorter commutes and better access to entertainment and public vices. Tall cities also tend to have lower carbon emissions per person,as locals make fewer journeys by car. And growingupwards instead of outwards means that green space surrounding the city can remain untouched. But there are downsides, too. High-rise housing tends to be more expensive to build,which can increase inequality,and inner-city congestion means higher levels ofpollution.That provides plenty to think about next time you gazeout ofan aeroplane window at a towering metropolis.