Urbanization is transforming landscapes, climate, and ecosystems worldwide, with most people now living in cities and more expected to move to urban areas in coming decades. Research shows that urban growth concentrates people, infrastructure, and economic activity, intensifying demands for energy, water, land, and materials. This concentration accelerates resource extraction and waste generation and reshapes local and regional environments.

One central impact is the urban heat island effect. Cities, dominated by asphalt, concrete, and dark roofs, absorb and retain more solar energy than surrounding rural areas. Daytime temperatures in cities are typically higher, and nighttime cooling is reduced. This effect interacts with global warming, increasing heat stress, energy use for cooling, and health risks, especially during heatwaves. Dense high rise districts and limited vegetation further amplify heat.

Urbanization also changes surface properties and atmospheric conditions. Replacing vegetation with built surfaces alters evapotranspiration, runoff, and humidity. Air pollution from vehicles, industry, and heating systems adds aerosols and greenhouse gases to the atmosphere, influencing air quality and potentially regional climate patterns. Studies indicate that expanding urban areas can alter local rainfall distribution and timing, in part due to heat and aerosol effects.

Biodiversity is reduced as habitats are fragmented or replaced, although some species adapt to urban environments. At the same time, higher density living can, in principle, reduce per capita land use and emissions compared with dispersed settlement, if supported by efficient infrastructure, public transit, and green design. Current research emphasizes that the trajectory of urbanization will strongly influence future climate, resource use, and ecosystem health.