Where the rapid rise of megacities is unsustainable

With 10 billion people expected to cram into urban areas by mid-century, the world will add at least 14 new megacities — many of which are at risk of threats including food and water insecurity, conflict and high crime rates, as well as climate-change related disasters like flooding and drought.

These growing cities, each with populations surpassing 10 million by 2050, add to 33 existing megacities. But ecological threats and lack of societal resilience make their rise — and the rapid pace of urban expansion more generally — unsustainable, warns a report published Wednesday by the global think tank Institute for Economics and Peace.

Emerging Megacities
The world is expected to add at least 14 new megacities by mid-century, each with population surpassing 10 million.

The fastest-growing cities will be in sub-Saharan Africa, projected to be home to 2.1 billion people over the next three decades. The region includes five of the 20 most at-risk emerging and existing megacities, according to the report. Among the most unsustainable are Kinshasa in the Democratic Republic of Congo; Nairobi, Kenya; and Lagos, Nigeria, all of which could see their metro area populations grow by at least 80%.

All of the megacities in South Asia, meanwhile, will see their populations grow by at least 50%. At least eight are listed by the report as being among the most unsustainable, including Dhaka, Bangladesh; Lahore, Pakistan; and Kolkata and Delhi in India.

"Generally, they are in low-income, low-peace countries, meaning they simply don't have the financial capacity to be able to cope with the growth," says IEP's founder Steve Killelea. A lack of finances can block cities from improving critical infrastructure, reducing crime and supporting the local economy. Those with the largest population growth — mainly in sub-Saharan Africa and South Asia — will see resources stretch even thinner and confront the most sustainability challenges.

Food and Water Insecurity
Sub-Saharan Africa has the worst ecological threat report (ETR) score, which measures a country's population growth alongside its vulnerability to food insecurity, natural disasters and water stress, according to the report. Several cities also rank low or very low on IEP's Positive and Global Peace Indices, which quantify a country's level of peacefulness as it relates to social and economic resilience. 

That includes three rapidly emerging megacities: The Dar es Salaam, Tanzania, and Nairobi metro areas could see their current populations more than double to 16.4 million and 10.4 million, respectively, while the population in Luanda, Angola, will grow by 62% to 14.6 million people.

But while more than half of the region's population considers crime and violence as more urgent than climate change, the report emphasizes that ecological degradation, resilience and conflict are intertwined. "The lack of water is intimately related to lack of food and to high population growth in areas that are already in conflict and already unsustainable," Killelea says.

Shoppers and pedestrians walk past stalls at the Bhadra Fort market in Ahmedabad, India, on Oct. 22, 2020. Photographer: Sumit Dayal/Bloomberg

South Asia, which is home to the predicted megacity Ahmedabad in India, has the second-worst ETR score, according to the report. Cities like Ahmedabad will be increasingly exposed to extremely high levels of air pollution, water stress and catastrophic-weather disasters. Many who move to already-crowded city centers are seeking shelter, stability and refuge from climate catastrophes, putting stress on  infrastructure and the government's ability to provide jobs and services.

In Bangladesh, where the government predicts that one in every seven citizens will be displaced by climate change by 2050, Dhaka's population could grow from 22.6 million to 34.6 million, testing the city's housing infrastructure, among other things. "People tend to flow to areas that are simply the cheapest, and they're going to quite often the most overcrowded place where they can just simply survive," says Killelea. "So slums just seem to rise up naturally."

Dhaka's informal settlements — where sewage is inadequate, fresh water is lacking, and illegal gas lines and burners raise the risks of fires — have been expanding into hazardous, low-lying areas near water, putting residents at risk of dangerous flooding.

Time for Policy Changes
That's not to say that megacities in higher-income countries aren't without threat, even if they tend to have more resources to adapt. The  Chicago and London metro areas will both surpass 10 million residents in 2050. The New York metro area will see its population jump from 18.9 million to 22.8 million. These cities face rising threats of extreme heat and catastrophic flooding that will put pressure on aging storm-drain systems and pose particularly significant risks to underserved communities.

But Killelea says there's still time for cities to enact key policy changes to mitigate the sustainability risks. The report calls for interventions like multilateral cooperation between governments and the private sector, and budgetary restructuring to prioritize ecological adaptation (though it also emphasized the need to study how funding reallocation may impact different groups)

A key solution, he stressed, is the economic empowerment in low- and middle-income countries. Not only will that boost resilience through improving the workforce, studies have shown that empowering women in particular leads to smaller family sizes and better health policies in low- and middle-income countries.

The report also calls for cities to empower local communities to address challenges, as opposed to top-down interventions. Community-led approaches make better use of local knowledge and garner greater community buy-in, thereby reducing research and implementation costs.

Though the challenge is immense, Killelea added that he's optimistic. "I'm not underestimating the challenges," he says. "But if you don't look at the challenges and take in a somewhat optimistic approach, what hope is there?"

Linda Poon is a writer for CityLab in Washington, D.C., focused on climate change and urban life. She also writes the CityLab Daily newsletter.

Disclaimer: This article first appeared on Bloomberg, and is published by special syndication arrangement.