Reading passage
In 2008, humanity crossed a demographic threshold: for the first time in history, more than half of the global population lived in towns and cities rather than in the countryside. The United Nations projects that by 2050 nearly seven in ten people will be urban dwellers, and that most of this growth will be concentrated in Africa and Asia. At the apex of this transformation stand the megacities, urban agglomerations of more than ten million inhabitants, whose number has risen from just ten in 1990 to more than thirty today, with Tokyo, Delhi and Shanghai among the largest.
Although the financial crisis of 2008 briefly slowed migration to some booming cities, the underlying drift from countryside to town has resumed almost everywhere, apparently indifferent to short-term economic cycles. Historically, urbanisation has been inseparable from economic development. As agricultural productivity rises, fewer workers are needed on farms, and surplus labour migrates towards towns, where wages are higher. Cities today generate roughly 80 percent of global gross domestic product while occupying only around 3 percent of the Earth's land surface. Economists attribute this extraordinary concentration to agglomeration effects: firms benefit from proximity to suppliers and customers, while workers gain access to deeper labour markets in which their skills can be matched more precisely to employers' needs.
Yet researchers increasingly caution against assuming that urban growth automatically produces prosperity. Parts of sub-Saharan Africa have experienced what scholars call urbanisation without growth, in which cities have swollen even though industrial employment has stagnated. Deprived of formal jobs, many newcomers scrape a living in the informal economy, and nearly one billion of the world's urban residents now live in informal settlements, often without secure tenure, clean water or reliable sanitation. Kinshasa and Lagos, each expected to add tens of millions of residents this century, illustrate how urban expansion can run far ahead of the state's capacity to provide even basic services, leaving municipal governments to chase a moving target.
Infrastructure is another persistent bottleneck. In many rapidly growing cities, road building and public transport lag years behind population growth, and the resulting congestion imposes heavy economic costs. In Jakarta alone, traffic delays have been estimated to cost several billion dollars a year in lost productivity and wasted fuel. Housing presents an equally acute problem: where supply fails to keep pace with demand, prices climb beyond the reach of ordinary households, pushing the poor to the urban periphery and lengthening their commutes.
The environmental dimension is equally contested. Cities account for around 70 percent of global greenhouse gas emissions, and the urban heat island effect means that dense built-up areas experience higher temperatures than the surrounding countryside, sometimes by several degrees. Yet density can also be an environmental asset. Residents of compact cities such as New York emit far less carbon per person than the average American, largely because they drive less, live in smaller dwellings and share infrastructure more efficiently.
Governance may ultimately matter more than size. Many megacities are administered by dozens of overlapping municipal authorities, few of which possess the revenue or the mandate to plan at a metropolitan scale. Tokyo is frequently cited as an exception, having coordinated transport and land use across its vast conurbation for decades, while the Brazilian city of Curitiba demonstrated that even a mid-sized city with limited funds could pioneer low-cost innovations such as bus rapid transit. Advocates of so-called smart cities argue that networks of sensors can now fine-tune traffic, energy and waste systems, although critics warn that pervasive monitoring could erode privacy.
Looking ahead, demographers point out that the fastest urban growth is now taking place not in the celebrated megacities but in small and medium-sized cities, many of which lack professional planning departments altogether. How these secondary cities absorb their new residents may prove more consequential for global welfare than the fate of any single giant metropolis. The struggles of the twenty-first century, as one urban theorist famously concluded, will be won or lost in its cities, and the outcome remains very much undecided.