Eye on Earth: Satellite atlas shows changes

Africa
The population of Nairobi, Kenya, at independence in 1963 was 350,000. Since 1979, it has seen explosive growth, and the population is now well over 3 million, making it the largest African city between Johannesburg and Cairo.

Satellite images from 1979 and the present show how the city sprawled to new suburbs and slums north, east and west. The growth of development along the edge of Nairobi National Park and out to Jomo Kenyatta International Airport is also visible.

Asia-Pacific
Beijing, China’s capital, has undergone tremendous growth since the start of economic reforms in 1979, and its population now numbers some 13 million.

Satellite images show Beijing mushrooming from a small central area to one that has turned towns such as Ginghe and Fengtai into suburbs. The expansion is seen to have also gobbled up the forests to the west and the rice, winter wheat and vegetable plots that once surrounded the city.

A similar, huge expansion is seen for Delhi, India’s capital. In 1975, the city had a population of 4.4 million. By 2000, it had well over 12 million inhabitants. By 2010, it is set to rise to nearly 21 million. The latest satellite images show Delhi’s growth concentrated in the suburbs of Faridabad, Ghaziabad and Gurgaon.

Sydney is Australia’s largest city with over 4 million inhabitants. Its growth is seen spreading west toward the Blue Mountains. The urbanization is leading to more and more homes being built in the bush, making them vulnerable to summer fires.

Middle East
Riyadh, the capital of Saudi Arabia, has grown from 500,000 people in 1972 to more than 2 million as a result of migration from urban areas, a decrease in death rates and high birth rates.

The growth has been made possible by Saudi Arabia’s big investments in desalination plants that extract drinking water from seawater. Seen as a small dark and red patch in 1972, the city now shows up on satellite images as a grid-like network of blue lines that are roads, with a more than tripling of the urban area.

Europe
Turkey's Ataturk Dam, built on the Euphrates River in 1990, has had a dramatic impact on the landscape. Flooded areas appear as a large, jagged mass of black. South of the dam, around the town of Harran, the area has become green as a result of irrigation schemes made possible by the dam.

Bucharest, Romania, was a compact, well-defined city in the late 1970s. During the 1980s, villages on the outskirts were dismantled to make way for expansion and centrally planned projects. Today, partly as a result of the privatization of land, people are moving out of the center into new suburbs.

Latin America
Mexico City's population grew from 9 million in 1973 to 14 million in 1986 and is now more than 20 million. Satellite images show the city sprawling in all directions, causing significant deforestation in the mountains west and south.

Similar images reflect the doubling of the population to 5 million in Santiago, Chile.

North America
In the 1950s, Las Vegas was home to just over 24,000 people. Today, it tops 1 million, not including tourists, and may double by 2015.

Satellite images reveal how the city has spread in all directions, displacing the few vegetated lands and replacing natural desert with housing and irrigated golf courses.

The Fort Lauderdale-Miami area in Florida shows the conversion of farmland into cityscapes and the spread of Miami south and west toward the Everglades National Park.

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