India is expected to see its urban population explode in the coming decades, but its cities are already failing and climate change will make living conditions even tougher.

The metropolis of Mumbai, one of India’s largest, has grown in the past 30 years by around eight million people – roughly equivalent to all of New York City – to 20 million inhabitants, and forecasts are that another seven million will be added by 2035.

As in other Indian megacities, Mumbai’s infrastructure for housing, transport, water and waste management has not kept pace, with around 40 percent of people living in slums.

These crowded clusters of ramshackle buildings, side by side with some of India’s wealthiest neighborhoods, often lack regular water, electricity or adequate sanitation.

As the world population approaches eight billion, most of it in developing countries, this is a situation that is being repeated around the world.

Those living on the outskirts of Mumbai commute for hours to work, with many hanging out in the open air on crowded trains and others traveling by car or motorbike on congested, potholed roads that flood during the monsoons.

In the largest slum, Dharavi, known as the “Slumdog Millionaire”, where a million people live, Mohammed Sartaj Khan came from rural Uttar Pradesh as a teenager and works in a tannery.

“My childhood in the village was wonderful. It’s a peaceful environment unlike the crowds here,” Khan, now 35, told AFP in Dharavi’s maze of alleys.

“When I came here, I saw people running like ants,” he said. “The way ants keep going in their tracks despite the crowd… No one cares about others.”

But in his village, he added, “people don’t have any money”.

He started out earning 6,000 rupees ($70) a month in Mumbai, but now he operates one machine and makes four times that, most of which he sends back to his wife and children, whom he can rarely afford to visit.

The United Nations predicts that India’s population will increase from the current 1.4 billion to overtake China’s, peaking at 1.7 billion in the 2060s before rising to 1.5 billion by the start of the next century falls behind.

By 2040, 270 million more people will live in Indian cities, according to the International Energy Agency, driving up carbon emissions from power generation and transport, as well as from the production of steel and concrete for residential buildings.

Overpopulation, ailing infrastructure and severe air, water and noise pollution are part of everyday life in India’s megacities.

About 70 percent of the billions of liters of wastewater produced every day in urban centers go untreated, according to a government report last year.

Every winter, the capital New Delhi, home to 20 million people, is blanketed in toxic air pollution that caused nearly 17,500 premature deaths, according to a 2019 Lancet study.

Millions of people in Indian cities have no running water and depend on deliveries by truck or rail.

People in Delhi and elsewhere are digging deeper and deeper wells as the water table drops.

Chennai in south-east India ran out of water in the summer of 2019, a crisis blamed on both insufficient rainfall and urban sprawl on former wetlands.

At the same time, urban flooding is becoming more frequent.

The tech hub of Bengaluru – formerly Bangalore – has some of India’s worst traffic congestion and experienced flooding in September that was blamed on unauthorized construction.

It is predicted that natural disasters will cause more and more misery for India’s cities as the planet’s climate warms and the weather becomes more volatile.

Scientists believe that the annual monsoon rains are becoming more erratic and heavier, causing more flooding and also more droughts.

Rising temperatures are making Indian summers increasingly scorching, especially in urban areas full of concrete that seal in the heat. This year India experienced its hottest March on record.

And while Covid-19 hasn’t hit India’s slums as badly as some feared, overcrowding puts them at risk in future epidemics.

Poonam Muttreja of the Population Foundation of India said more investment in the rural economy could curb migration to cities, while new incentives could encourage people to move to smaller urban centres.

“Poor people, especially urban migrants, are most at risk from climate change, whether it’s from weather changes or flooding, jobs or lack of infrastructure,” Muttreja told AFP.

“In India, a paradigm shift needs to take place. And instead of whining, we have to start doing something.”