Green divides

Abstract

Urbanization invariably leads to direct vegetation loss when land is covered by built infrastructure. But the growth of remaining vegetation can also be affected by urbanization through planting and irrigation, and through processes such as the extension of growing seasons through urban heat retention or the enhancement of fertilization through higher carbon dioxide levels. Writing in Nature Sustainability, Chen et al. use satellite datasets of impervious surfaces and vegetation greenness to explore the direct and indirect effects of urbanization on vegetation dynamics. Across 4,718 cities worldwide, they find that the average fraction of impervious surfaces increased from 0.46 to 0.62 between 2000 and 2019; cities located in East and South Asia, the Pacific and sub-Saharan Africa underwent the highest rates of change. In many of these rapidly developing cities, the vegetation index showed browning trends, but 45% of cities worldwide — mostly Europe, North America and northeast Asia — actually greened over this period. Overall, positive indirect effects of urbanization on vegetation mitigated 79% of the negative direct effects in cities of the Global North, but only 38% in cities of the Global South. Urbanization-driven enhancement of vegetation growth was positively correlated with more-rapid urbanization, earlier urbanization, colder regions and gross domestic product. The authors’ modelling of urban vegetation changes to 2040 under three Shared Socioeconomic Pathways shows these disparate trends continuing, which will exacerbate inequality in city residents’ exposure to green spaces in different regions of the world.

Original reference: Nat. Sustain. https://doi.org/10.1038/s41893-025-01520-0 (2025)