What is it about?
Cities are expanding horizontally and vertically. This study assesses the environmental impacts across three dimensions: climate change (carbon emissions, CE), environmental pollution (PM2.5 concentrations, PM), and ecological equity (blue-green space exposure, BGS). Though the study focuses on data from China, the data are also relevant for other countries where the rate of urbanization is big and rapidly increasing.
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Why is it important?
Horizontal expansion and constructing more vertical structures are the result of urbanization, not only in China but also in many other countries. What this study found out is that an increase in vertical structures, although good from the perspective of compact cities, also has more significant environmental consequences. These vertical structures create more carbon emissions and have more environmental burdens than horizontal expansion.
Perspectives
How to look for extra space for cities can be difficult. One has to either expand the area of the city or invest in higher buildings on the same space. Both options have however positive and negative consequences. This study investigates the negative consequences in the form of carbon emissions and environmental pollution. The findings are surprising. While vertical expansion is preferable in view of saving surrounding spaces and land uses, it also has more negative environmental impacts. This study provides an interesting perspective on how to deal with urban growth and how to assess the environmental impacts of dealing with urban growth. From a land management perspective, it provides an insight in the effects of opting for horizontal expansion (usually at the expense of agricultural land or green areas) or vertical expansion (usually at the expense of damaging the environment). Finding a right balance, or looking for alternatives for urban expansion is thus required.
Professor Walter Timo de Vries
Technical University of Munich
Read the Original
This page is a summary of: Interpretable machine learning unveils greater environmental burden of vertical urban growth over horizontal sprawl in China, Sustainable Cities and Society, September 2025, Elsevier,
DOI: 10.1016/j.scs.2025.106787.
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