New horizons in adaptive capacity and heat-related health in older people: integrating frailty, energy insecurity and social resources

Extreme heat is a major environmental threat to healthy ageing, with older people experiencing the highest rates of heat-related morbidity and mortality. Although age-related physiological changes, multimorbidity and frailty remain key determinants of heat susceptibility, climate change, social inequalities and energy insecurity are reshaping the conditions in which older people experience and respond to thermal stress. This narrative New Horizons review integrates evidence identified through a structured, non-systematic search of peer-reviewed literature and relevant institutional reports across geriatric medicine, environmental health and climate science. It examines how frailty, intrinsic capacity, housing, energy affordability and social frailty influence the ability of older people to recognise risk, access protection and respond effectively to extreme heat. Particular attention is given to energy insecurity and summer cooling poverty, through which limited access to affordable household energy may undermine resilience. Ageing models primarily characterise individual vulnerability and functioning within the environment, whereas climate vulnerability models organise risk around exposure, sensitivity and adaptation; we use adaptive capacity to connect these perspectives by asking whether personal and contextual resources can be mobilised for protection. It may provide a conceptual basis for developing and subsequently validating a heat-adapted comprehensive geriatric assessment and for informing targeted prevention and climate adaptation policies for ageing populations.