Population Exposure Changes to Mean and Extreme Climate Events Over Pakistan and Associated Mechanisms.

The increasing prevalence of warmer trends and climate extremes exacerbate the population's exposure to urban settlements. This work investigated population exposure changes to mean and extreme climate events in different Agro‐Ecological Zones (AEZs) of Pakistan and associated mechanisms (1979−2020). Spatiotemporal trends in mean and extreme temperatures revealed significant warming mainly over northern, northeastern, and southern AEZs. In contrast, mean‐to‐extreme precipitation changes showed non‐uniform patterns with a significant increase in the northeast AEZs. Population exposure to mean (extreme) temperature and precipitation events increased two‐fold during 2000–2020. The AEZs in urban settlements (i.e., Indus Delta, Northern Irrigated Plain, and Barani/Rainfall) show a maximum exposure to extreme temperatures of about 70–100 × 106 (person‐days) in the reference period (1979−1999), which increases to 140–200 × 106 person‐days in the recent period (2000−2020). In addition, the highest exposure to extreme precipitation days also increases to 40–200 × 106 person‐days during 2000–2020 than 1979−1999 (20–100 × 106) person‐days. Relative changes in exposure are large (60%–90%) for the AEZs across northeast Pakistan, justifying the spatial population patterns over these zones. Overall, the observed changes in exposure are primarily attributed to the climate effect (50%) over most AEZs except Northern Irrigated Plain for R10 and R20 events, where the interaction effect takes the lead. The population exposure rapidly increased over major AEZs of Pakistan, which could be more vulnerable to extreme events due to rapid urbanization and population growth in the near future. Plain Language Summary: This study investigates the impact of climate change on population in different AEZs of Pakistan from 1979 to 2020. The findings depict widespread warming trends in northern, northeastern, and southern AEZs of Pakistan, whereas changes in precipitation patterns are non‐uniform, with a notable increase in the northeast zone. The study reveals that population exposure to temperature and precipitation events doubled between 2000 and 2020. Urban AEZs such as the Indus Delta, Northern Irrigated Plain, and Barani/Rainfall exhibit the largest exposure to extreme temperatures and precipitation, with exposure increasing over time. The northeast zones of Pakistan experience the highest relative changes in exposure, highlighting the vulnerability of these AEZs to climate events. Climate effect account for the majority of observed exposure changes in AEZs, except Northern Irrigated Plain, where interaction effect plays a key role. The findings suggest that as urbanization and population growth continue, major AEZs in Pakistan are becoming increasingly susceptible to extreme climate events in the future. Key Points: Spatiotemporal trends in mean to extreme temperature (precipitation) events reveal widespread warming across Agro‐Ecological ZonesPopulation exposure to mean (extreme) temperature and precipitation events increases two‐fold in recent climate periodObserved changes in population exposure are primarily attributed to the climate effect (50%) over major Agro‐Ecological Zones [ABSTRACT FROM AUTHOR]