From evictions and skyrocketing rents to substandard infrastructure and services, many residents in cities across the global south face acute housing challenges. And the problem is growing. According to estimates, one-in-three people in cities are unable to access affordable and secure housing, leading to burgeoning slums in many fast-growing cities.

Sheela Patel, chair of Slum/Shack Dwellers International (SDI), recently sat down with WRI to discuss the latest installment of the World Resources Report, “Confronting the Urban Housing Crisis in the Global South: Adequate, Secure and Affordable Housing.”

For decades, Patel has been a champion for the needs of the urban poor. In 1984, she founded the Society for the Promotion of Area Resource Centres, an Indian NGO that partners with communities to expand access to housing and basic services for the urban poor. Today, she is well known across India, Africa and Latin America for her work with SDI extending lines of micro-credit, stopping evictions, and helping organize networks of urban poor to better advocate for their own concerns.

Here, we share three of her key messages.

The Scale of the Problem

The global housing gap is enormous and it’s not getting better, Patel says. Currently, 330 million households in cities around the world, equivalent to 1.2 billion people, do not have access to affordable and secure housing. By 2025, this number is estimated to grow by 30 percent, to 1.6 billion people.

All this growth means that decisions made now will have a significant impact on housing for decades to come. As urbanization intensifies in Asia and Africa, the challenge will get worse without a change in approach.

“We are at a very critical point at which we have to make decisions not only to address the challenges of the deficits today,” Patel says, “but that that process will help us deal with the increase that cities will face [in the future].”

There’s No One Size-Fits-All Answer

Patel echoes a key finding of WRI’s research: there’s no one size-fits-all solution. Instead, practitioners should explore a range of approaches that have proved promising in cities around the world.

“One of them, which is very close to our heart, is the one that looks at upgrading existing informal settlements,” she says. Participatory slum “upgrading” provides residents secure tenure and basic services in the places they already live, rather than relocating them to locations devoid of economic opportunity, and includes their input in the process.

Much of Patel’s work around the world has been focused on upgrading slums in a way that is resident-driven. This model has been demonstrated in several contexts, including India and Thailand, but runs counter to the approach in many cities of simply displacing or relocating slum residents to the urban periphery to make way for new construction within the city. WRI’s research suggests this only exacerbates the growth of slums and inequality in cities.

Looking at the Bigger Picture

Finally, Patel notes that the housing gap is not only a problem for the poor but affects the proper functioning and development of entire cities. “The city is like the human body; you can’t just take care of one part and expect everything else to function,” she says.

Indeed, the report notes that the housing problem is so severe, it threatens the traditional view of cities as reliable drivers of economic growth. At a global level, even as the proportion of urban residents in poverty has declined in recent decades, their absolute number has increased.

“When two-thirds of a city are living in a situation where its garbage is not picked up, its residents are being evicted, they don’t have access to clean water, they don’t have access to safe sanitation, you are creating a situation that jeopardizes the health and well-being of the whole city,” Patel says.

A primary goal of the World Resources Report is to examine whether meeting the needs of the urban under-served can achieve more economically prosperous, environmentally sustainable and socially equitable cities for all. Good housing, Patel and the working paper argue, is fundamental to people’s physical and financial security, economic productivity, and health. Rethinking housing policy then is a truly transformative intervention for cites; it must be viewed as part of a holistic approach to development and planning and not simply another special project.

For more from Sheela Patel on the urban housing crisis, watch a full-length interview here.

“Confronting the Urban Housing Crisis in the Global South: Adequate, Secure and Affordable Housing” is the latest working paper in WRI’s flagship World Resources Report, “Towards a More Equal City.”

Alex Rogala is a former editor of TheCityFix and currently a master’s student in urban planning at the Harvard Graduate School of Design.