Forests in protected areas worldwide face increased thermal pressure from urbanization

Protected areas (PAs), thermal refuges for biodiversity, are increasingly under pressure from urbanization. Gaps remain in how urbanization worldwide influences the thermal environment of PAs. Here, we quantify urban pressure on protected forests as a distance-weighted built-up intensity. The thermal impacts of urban pressure are assessed by comparing satellite-derived mean land surface temperature (LST) and thermal extremes inferred by the 90th-percentile maximum LST of protected forests within and beyond a 5-km buffer zone outside urban boundaries. We show that the global mean distance between urban areas and PAs has decreased by over one-third (12.82 km) since 1990, increasing urban pressure on protected forests by about 2.56%. Urbanization alters thermal environments by elevating LST, and the frequency and intensity of thermal extremes, with the highest impact on annual mean daily LST (0.63 °C) and intensity of thermal extremes (0.81 °C) in tropical protected forests. We highlight the need to integrate urban development and conservation planning to support biodiversity conservation and sustainable development.