Cities Are Growing Up Instead of Out, New Research Finds

Cities around the world are literally growing up. A new study shows that, as urban areas expand, they are doing so less by sprawling and more by reaching skyward.

While upwards expansion has historically been restricted to a handful of megacities like New York and Tokyo, global high-rise development has expanded considerably over the past few decades. Even so, prior analyses of city growth generally stuck to traditional 2D models that couldn’t account for the rise (heh) in the number of taller buildings.

To remedy this, a team of researchers gathered data on over 1,550 cities from satellite-based radar systems capable of measuring the height of physical objects. The team found that, as a general rule, the rate at which cities have been expanding outwards has slowed since the 1990s, while the speed at which they are growing vertically is speeding up. The findings were true across continents, though the trend was especially strong in Asia.

The trend toward vertical development has accelerated in cities with populations exceeding 5 million. In the 1990s, only 7% of land in these cities was occupied by tall buildings, a figure that increased to 28% in the 2010s.

The study, published in the journal Nature Cities, not only provides a fascinating glimpse into urban evolution but also offers valuable insights for enhancing urban life as more people make cities their home. More than 56% of all humans live in cities, a number the World Bank expects to grow to 70% by 2050. Taller buildings lead to denser populations, which significantly impacts urban planning for public services and the fight against climate change, among other challenges.

“Urban population has nearly doubled since 1990, with a need to increase transportation and infrastructure,” said Steve Frolking, a professor emeritus of Earth sciences at the University of New Hampshire, who led the research, in a press release. “How cities grow affects their greenhouse gas emissions, demand for specialized materials and even impacts urban climates creating micro-climates—local atmospheric conditions that differ from those in the surrounding areas.”

If the idea of towering residences blotting out the Sun brings to mind troubling visions of Judge Dredd-like post-apocalyptic Megacities, the notoriously mellow residents of Vancouver may have a better way.