Both are possible. Houston’s sprawl no doubt made Hurricane Harvey’s impact far more severe than had the city a more efficient and dense design.
But there’s another reason for making our future cities dense and green: Rapid urbanization in developing economies could lead to unsustainable levels of greenhouse emissions unless cities adopt more efficient and dense urban designs, says a recent report from the Energy Transitions Commission (ETC).
Cities contribute fewer greenhouse-gas emissions per person than more rural areas (though extensive suburbs can wipe out the climate benefits, according to a UC Berkeley study.) The average carbon footprint of households in the center of large, population-dense cities is about 50% below average, while households in distant suburbs have up to twice the average.
Unfortunately, urban density is moving in the opposite direction. Urban population is increasing around the world, not just in Houston but also in Lagos, Nigeria, or Mumbai, India — where recent monsoon flooding has devastated the city and region. But urban land area is expanding at a higher rate; the urban population of developing countries could double by 2030, while the area covered by cites could triple.
How to counter unchecked urban sprawl — and the resulting increase in greenhouse gas emissions — while making sure cities are better able to withstand the hazards of our climate-challenged world? Low-carbon transport systems are key, the ETC report says, making it possible to grow economically without expanding energy consumption.
We might also take a look at this Somali plan, with an initial focus on Mogadishu, that calls for long-term investment in urban livelihoods, services and infrastructure as a way to become more resilient in the face of recurring natural disasters.
“We simply can’t go on with haphazard urbanization — it hits the poor very badly,” said Rohinton Emmanuel, professor of sustainable design and construction at Glasgow Caledonian University. “Saying that we can’t afford to have space for greenery and parks is very short-sighted… no one has looked at the whole life cost of these things: how much does the flood event cost?”