Mercator Research Institute on Global Commons and Climate Change, 10829 Berlin, Germany.
Department Economics of Climate Change, Technische Universität Berlin, 10623 Berlin, Germany.
Proc Natl Acad Sci U S A. 2017 Aug 22;114(34):8939-8944. doi: 10.1073/pnas.1606036114. Epub 2016 Dec 27.
Urban expansion often occurs on croplands. However, there is little scientific understanding of how global patterns of future urban expansion will affect the world's cultivated areas. Here, we combine spatially explicit projections of urban expansion with datasets on global croplands and crop yields. Our results show that urban expansion will result in a 1.8-2.4% loss of global croplands by 2030, with substantial regional disparities. About 80% of global cropland loss from urban expansion will take place in Asia and Africa. In both Asia and Africa, much of the cropland that will be lost is more than twice as productive as national averages. Asia will experience the highest absolute loss in cropland, whereas African countries will experience the highest percentage loss of cropland. Globally, the croplands that are likely to be lost were responsible for 3-4% of worldwide crop production in 2000. Urban expansion is expected to take place on cropland that is 1.77 times more productive than the global average. The loss of cropland is likely to be accompanied by other sustainability risks and threatens livelihoods, with diverging characteristics for different megaurban regions. Governance of urban area expansion thus emerges as a key area for securing livelihoods in the agrarian economies of the Global South.
城市扩张通常发生在农田上。然而，人们对于未来全球城市扩张模式将如何影响世界耕地面积，知之甚少。在这里，我们将城市扩张的空间明确预测与全球耕地和作物产量数据相结合。研究结果表明，到 2030 年，城市扩张将导致全球耕地减少 1.8%至 2.4%，且存在显著的区域差异。大约 80%的全球耕地因城市扩张而流失将发生在亚洲和非洲。在亚洲和非洲，大部分将流失的耕地的生产力是全国平均水平的两倍多。亚洲将经历耕地绝对数量的最大损失，而非洲国家的耕地损失百分比将最高。在全球范围内，2000 年可能流失的耕地占全球作物产量的 3%至 4%。预计城市扩张将发生在比全球平均水平高出 1.77 倍的生产力的耕地上。耕地的流失可能伴随着其他可持续性风险，并威胁到生计，不同的特大城市地区具有不同的特征。因此，城市区域扩张的治理成为确保全球南方农业经济中生计的关键领域。
