Deforestation driven by urban population growth and agricultural trade in the twenty-first century

Reducing atmospheric carbon emissions from tropical deforestation is at present considered a cost-effective option for mitigating climate change. However, the forces associated with tropical forest loss are uncertain1. Here we use satellite-based estimates of forest loss for 2000 to 2005 (ref. 2) to assess economic, agricultural and demographic correlates across 41 countries in the humid tropics. Two methods of analysis— linear regression and regression tree—show that forest loss is positively correlated with urban population growth and exports of agricultural products for this time period. Rural population growth is not associated with forest loss, indicating the importance of urban-based and international demands for agricultural products as drivers of deforestation. The strong trend in movement of people to cities in the tropics is, counterintuitively, likely to be associated with greater pressures for clearing tropical forests. We therefore suggest that policies to reduce deforestation among local, rural populations will not address the main cause of deforestation in the future. Rather, efforts need to focus on reducing deforestation for industrial-scale, export-oriented agricultural production, concomitant with efforts to increase yields in non-forested lands to satisfy demands for agricultural products. Maintaining carbon stocks in tropical forests is widely recognized as a relatively low-cost option formitigating climate change3,4 with ancillary benefits for biodiversity, regulating precipitation and a host of other ecosystem services5. The United Nations framework convention on climate change is considering whether reduced emissions from avoided deforestation and degradation (REDD) will be included as an allowable reduction strategy during the second, post-2012 commitment period. Voluntary carbon markets are also developing standards for incorporating REDD activities6. These initiatives will be effective in reducing deforestation only if they address the factors that promote forest loss. Yet demographic and economic factors associated with deforestation remain poorly understood, partly because these complex factors vary throughout the tropics and over time7, and partly because consistent and reliable data have not been available for cross-country analyses1. Major demographic and economic shifts are sweeping across many places in the tropics (Fig. 1). Population growth rates are slowing overall, but urban growth is vastly outpacing rural growth8. In the next 20 years, 22 of the 41 countries included in this analysis are projected to have fewer rural inhabitants than they do today, whereas all of the countries have increasing urban populations. In nine of the countries, urban populations are projected to more than double in the next 20 years9. Many countries throughout the tropics are also on a trajectory of increasing agricultural exports. The question we address in this study is the likely impact of