The development of megacities has been championed by the World Bank and some environmentalists as the most efficient way to shepherd the Earth's resources as world population increases. However, a study in the March 2010 issue of the journal Nature Geoscience argues that the drivers of tropical deforestation have shifted in the early 21st century from subsistence agriculture to the growth of cities and globalized agricultural trade.
The report finds that tropical countries like Brazil, Indonesia, and Cambodia have been supplying increasing amounts of palm oil, soybeans, sugar, meat, and other processed products for export. Not all the products are used for food; palm oil and sugar in particular are also being converted into biofuels. As small farmers within tropical nations move away to become city dwellers, they may actually come to use more resources from the countryside. "Collectively, these results indicate a shift from state-run road building and colonization in the 1970s and 1980s to enterprise-driven deforestation," says the study.
Almost 60 percent of remaining forests occur in areas where net agricultural trade, percentage of products exported, and urban growth are all relatively low. But as demand for products grows, these areas are likely to see increased pressure, the study says. According to projections by the United Nations, nearly all population growth in the next 40 years will take place in cities, and some two-thirds of people will live there by 2050.
The report carries a strong message for those looking for solutions to deforestation. Most initiatives currently focus on getting small landowners to conserve forests—a popular mechanism among governments and nonprofits. That response ignores the real damage done by large-scale clearing, finds the report, meaning that governments need to look to policies that intensify yields on existing fields rather than clearing more land.