Global Arable Land Is Shifting Toward the Tropics and Drylands Under Urbanization

Arable land has been expanding since the advent of agriculture, and now sustains over eight billion people by supplying food, fiber, and fuel. However, the rapid expansion of built-up areas is increasingly displacing arable land across diverse regions, raising concerns about the long-term sustainability of global food systems. Addressing these concerns requires a fundamental understanding of global arable-land dynamics, which remains largely unknown. Using our newly developed high-quality arable-land product—integrated with global settlement layers, Köppen–Geiger climate classifications, and historical land-use reconstructions—we show that competition between arable land and urban systems for favorable climate fundamentally shapes global arable-land dynamics. Globally, urbanization in the Northern Hemisphere is displacing arable land from climatically favorable regions toward more marginal tropical and arid environments. In North America, Europe, and Asia, early co-development of arable land and urbanization has transitioned into intensified urban encroachment, pushing cultivation into adjacent arid zones. By contrast, low-latitude tropical regions continue to expand both systems at the expense of natural ecosystems, driven in part by agricultural investment from Northern Hemisphere countries. This framework not only offers a new perspective for synthesizing existing regional arable-land dynamics but is also closely linked to ongoing dryland greening, tropical deforestation, and groundwater depletion in drylands. Reconciling agricultural production with rapid urban growth is therefore essential to safeguarding sustainable land resources, forest health, water security, and global food security under accelerating demographic pressures.