The world could see its first city with a population of 100 million by the end of this century. That is the conclusion of new research into the speed of urbanization in many fast-growing countries in Africa and Asia, which suggests even small cities could balloon into huge metropolises in the coming decades.

By the end of the century, the world’s population is forecast to reach up to 14 billion. Eighty percent of those people will be living in cities, according to new research from the Ontario Institute of Technology. 

“We are now seeing the urbanization wave headed through China, it is toward the latter part of its urbanization. And now it is headed for India, and then we will see it culminate in the big cities of sub-Saharan Africa,” co-author and professor Daniel Hoornweg told VOA via Skype.

That could mean the first 100-million population city, and the top candidate is Lagos, Nigeria.

WATCH: Africa Could See World’s First 100 Million City by Century’s End

Africa and cities

Today its population is 20 million, not the largest, as that accolade belongs to Tokyo with about 38 million people, but one of the fastest growing. In two generations, Lagos has grown a hundredfold. By 2100 it is projected to be home to more people than the state of California.

“Lagos, Dar Es Salaam, Kinshasa: These are the cities that are looking at four- to five-fold increases in population. By the end of the century, the lion’s share of large cities, the top 20 if you will, most of those will be in Africa,” Hoornweg said.

Lagos sprawls across 1,000 square kilometers, an urban jungle of skyscrapers, shanty towns and everything in between. Its population grows by 900 people per day.

The poorest residents, often migrant communities, live in slums by the lagoon. Amnesty International has warned of ruthless forced evictions to make way for new developments, which have left more than 30,000 people homeless and 11 dead.

Oladipupo Aiveomiye lives in the Ilaje-Bariga shantytown.

“The threat of being evicted, the threat of being chased away overnight has gripped people to the extent that they cannot even work or operate in this area,” he said.

Young continent

Across Africa the median age is younger than 20 and the fertility rate is 4.4 births per woman. Even small cities are forecast to balloon in size. Niamey in Niger could grow from less than 1 million today to 46 million by the end of the century; Blantyre in Malawi from 1 million to 40 million.

Asia, too, will witness huge urban growth, with Kabul in Afghanistan projected to hit 50 million people.

Hoornweg says despite the associated problems of slums, poor sanitation and pollution, increasing urbanization can be a good thing.

“Cities, by their nature, because of a more compact lifestyle, can provide a quality of life higher than anywhere else with less energy per unit of GDP,” he said. “So, cities actually provide a really important opportunity. We will not get to global sustainability without big cities.”

Many cities in the West are predicted to plateau or decline in size. By the end of the century, only 14 of the biggest 100 are forecast to be in North America or Europe.