We study human geography as a sociologist at Mississippi State University and a computer scientist at Oak Ridge National Laboratory in the United States. Using newly available data from Oak Ridge that combines census results, satellite images and data science techniques, we were able to track growth patterns of coastal populations around the world.

The results show a striking pattern: The largest number of people by far, about 10 percent of the global population, live within 5 kilometers of the coast, and another 5 percent of the world’s people live between 5 and 10 km from the coast. In the rings beyond 10 km, the population declines swiftly.

The United Nations estimates that Earth’s population passed 8 billion people in 2022, an increase of 1 billion in just over a decade.

We found that over 2 billion of those people, 29 percent of the total global population, lived within 50 km of shore in 2018, based on Oak Ridge Laboratory’s publicly available dataset. About half of those inhabitants, over 1 billion people, or about 15 percent of the global population, lived within 10 km of the water.

If you picture the globe, that means 15 percent of the world’s population is living on 4 percent of the Earth’s entire inhabitable landmass.

People are drawn to coastal areas for many reasons. Coastal cities are often economic hubs, meaning job opportunities, access to trade and exposure to bustling communities. These areas also offer access to nature, including fisheries and recreation.

We found that between 2000 and 2018, the global population living within 10 km of the water increased by about 233 million inhabitants, roughly 28 percent. That’s equivalent to adding 23 new megacities with 10 million inhabitants each, about twice the size of the Miami, Florida, the US, metro area, right near the water’s edge.

Human settlement patterns have profound consequences for people’s exposure to risk, particularly near the coasts.

Rising sea levels contribute to high-tide flooding, more extreme storm surge during hurricanes and erosion in regions around the world. In some areas, particularly Southeast Asia and the Pacific Islands, rising saltwater has infiltrated farm fields and freshwater sources. Hurricanes and typhoons, which gain strength over warm water, have intensified as temperatures have risen.

Coastal ecosystems, including fragile mangroves, wetlands and coral reefs, are also sensitive to the expanding coastal populations and to the infrastructure and pollution accompanying human settlement.

Despite the importance of understanding these population patterns in coastal regions, a global picture of the growth has been hazy at best. The LandScan Global project at Oak Ridge National Laboratory is changing that by starting to allow public access to annual high-resolution population data. We can use that data to estimate the magnitude and growth patterns of coastal populations on an annual basis.

Coastal growth is happening across the globe, but we found the strongest growth patterns on two continents: Asia and Africa.

Currently, Asia has four of the five most populated countries: China, India, Indonesia and Pakistan. It also has 60 percent of the Earth’s coastal population. In comparison, Africa has about 12 percent, Europe has 11 percent, North America has 9 percent and South America has 7 percent.

But Africa has the fastest-growing population. Between 2000 and 2018, Africa’s coastal population grew 61 percent, with 58 million more people living within 10 km of the oceans. Asia added 125 million more inhabitants within 10 km of the coast, a more modest 25 percent increase.

On all of these continents, human population growth along the coast followed a similar pattern: The highest concentrations of inhabitants are in the bands closest to shore, decreasing rapidly as they move inland. Given the great differences among the cultures, economies and histories of the continents, it is remarkable to find consistent human population patterns.

Coastal regions are hubs of economic activity and infrastructure development, often playing critical roles in national and global economies. However, rapid population growth is accelerating human and environmental risks.

Understanding these coastal population growth patterns is fundamental to addressing this global challenge.

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Arthur Cosby is a professor of sociology at Mississippi State University, the US. Viswadeep Lebakula is a research scientist in human geography at Oak Ridge National Laboratory, Tennessee, the US. The article is republished under Creative Commons license.