Population age structures and changes over time have a significant influence on vulnerability to the impacts of weather and climate. Older adults  are disproportionately vulnerable to the health impacts associated with climate change and weather extremes, including a greater risk of succumbing to waterborne pathogens due to poorer functioning thermoregulatory mechanisms, greater sensitivity to dehydration, changes in their immune systems and greater likelihood of having pre- existing chronic illnesses such as diabetes or respiratory, cardiovascular and pulmonary illnesses . Older adults may be less prompt in seeking medical attention when suffering from GI illnesses, which can lead to dehydration . Åström et al.  anticipate heat-related mortality among the elderly in Europe to rise in the 2050s under RCP4.5 and RCP8.5 in the absence of significant preventative measures. In a study of the combined effects of warming temperatures and an aging population in Korea, Lee and Kim  projected a four- to six-fold increase in heat-related mortality by the 2090s when accounting for temperature and age structure.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report