Heat impacts during days and nights under climate overshoot: a single hazard multi-impact approach

Heat stress is a significant threat to human health and well-being, particularly in urban areas, and is expected to worsen in the future due to climate change. This study investigates the impacts of heat stress on human health in Lisbon, Portugal, during both days and nights under climate overshoot scenarios. The study employs a single hazard multi-impact approach to assess the health impacts of heat stress, considering both acute and long-term effects. The results show that the impacts of heat stress on human health are unequally distributed across the population, with some parishes being more affected than others. The study also finds that the impacts of heat stress will increase dramatically under current climate policies. In the daytime, heat stress is primarily driven by heat waves and maximum temperatures, leading to acute effects on human health, such as mortality. These effects are most pronounced in certain parishes and are expected to increase significantly even by 2040. Behavioural adaptation strategies such as adapting working hours have some potential to reduce heat impacts in certain settings. At night, heat stress is primarily driven by minimum daily temperatures, leading to sleep loss and long-term effects on health. Adaptation options for mitigating these impacts might require infrastructure investments. These findings highlight the need for targeted adaptation strategies to address the unequal distribution of heat stress impacts even under climate overshoot.