Walkability under the influence of extreme temperatures: the impact of climate change on outdoor thermal discomfort in Saudi Arabia

Abstract

• A significant increase is projected in discomfort days across Saudi Arabia, with coastal areas seeing the worst impacts. • Major cities, like Jeddah, Dammam, and Madinah, are expected to face the highest levels of discomfort by 2100. • Findings highlight the need for adaptive planning to make outdoor spaces comfortable for pedestrians in a changing climate. Summer is ideal for outdoor activities like walking; however, as extreme heat rises, these pleasant walks may gradually be overtaken by heat stress, compromising pedestrians’ comfort and safety at risk. This study investigates the implications of climate change on pedestrian thermal comfort by estimating future changes in thermal discomfort days and their potential impacts on walkability across Saudi Arabia and its major cities. The study uses the outputs of 27 bias-corrected high-resolution models from NASA’s NEX-GDDP-CMIP6 program to estimate projected changes in discomfort days with different thermal stress ranges during the near-future (2021–2040), mid-future (2041–2060), and far-future (2081–2100) periods under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios. The study also estimates future urban population exposure to discomfort days in Saudi Arabia under the selected SSP scenarios. Future projections under various SSPs indicate a significant increase in very uncomfortable days across most parts of Saudi Arabia, with impacts intensifying inland by the end of the 21st century. Coastal regions, though expected to experience fewer uncomfortable days, will see an increase in days falling into higher discomfort ranges. Under the SSP5-8.5 scenario, the projected rise in extremely uncomfortable days, particularly across coastal and inland areas of Saudi Arabia, is predicted to substantially affect walkability and limit outdoor activity. In terms of urban environments, Jeddah, Dammam, and Madinah are projected to experience the highest levels of discomfort, reaching up to 35 °C under the SSP5-8.5 scenario by 2100. The projected urban population exposure is likely to be 1–8 million people-days in Saudi Arabia, with coastal cities experiencing the highest exposure in the future periods, particularly under high-emission scenarios. Our findings emphasize the critical need for adaptive urban planning to ensure outdoor spaces remain accessible and comfortable for pedestrians in a warming climate.

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