GoKawiilUrbanization is usually judged by what is built, but it should also be evaluated according to what it hollows out. Around the world, increasing numbers of people are moving to cities — 67% of the global population is projected to live in urban areas by 20501. But this trend is about more than people relocating.
The rural regions that migrants leave behind are being steadily dismantled. Globally, up to 400 million hectares of land have been abandoned since the 1950s2 and up to half of the world’s rangelands (large expanses used as grazing land for livestock) are considered degraded3. Meanwhile, growing urban demand for food, water and biomass is intensifying the extraction of resources beyond city boundaries. The effects of these pressures are already evident in Europe’s emptying interiors, East Asia’s vanishing towns and Latin America’s swelling informal settlements.
How buildings and cities can be aligned with life
These diverse cases expose a common policy oversight: a tendency to treat urban greening and nature-based solutions as an environmental cure-all. But cities depend on their hinterlands for survival — these areas provide food, deliver water and sequester carbon. Yet, the creation of urban green space doesn’t prevent working countryside from losing its human stewards, its fertile topsoil and the capacity to sustain ecosystem services.
Addressing this crisis requires managing urban and rural domains as a single entity. Here, we outline an approach that combines geospatial monitoring, landscape engineering and watershed planning to optimize ecological productivity and livelihoods in the countryside.
One-way flow of resources
Rural decline is driven by three kinds of flow: demographic, land and ecosystem. Demographic flows begin when working-age populations migrate to cities to find better-paid jobs and more affluent lifestyles. With fewer workers left in rural areas, infrastructure and services diminish. Many remaining families are then forced to relocate, eroding both the tax base and local memory. Land flows refer to changes in land use driven by urban demand, whereas ecosystem flows describe transfers of water, biomass and ecosystem services from rural areas to cities.
Globally, thousands of small towns and villages face severe declines in population (see ‘Growing cities, lost countryside’). In Spain alone, some 4,000 of around 8,000 municipalities have fewer than 13 residents per square kilometre4; the Iberian Highlands in the centre and east of the country have roughly two residents per square kilometre (see go.nature.com/4agrer).
Sources: Top: go.nature.com/4cevar; Bottom: Analysis by Y. Liu et al.
Meanwhile, a 2024 report classed 744 of 1,729 Japanese municipalities as being at risk of severe population decline5 — defined as a fall of at least 50% in the number of women aged 20–39 between 2020 and 2050. Nanmoku in Gunma Prefecture illustrates this pattern: its population fell by 73% between 1980 and 2020 (see go.nature.com/4y5lpnc); by 2024, roughly two-thirds of its remaining residents were aged 65 or older.
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