Climate change is the greatest threat to human health, with one of its direct effects being global warming and its impact on health. Currently, the world is experiencing an increase in the mean global temperature, but this increase affects different populations to different degrees. This is due to the fact that individual, demographic, geographical and social factors influence vulnerability and the capacity to adapt. Adaptation is the process of adjusting to the current or envisaged climate and its effects, with the aim of mitigating harm and taking advantage of the beneficial opportunities. There are different ways of measuring the effectiveness of adaptation, and the most representative indicator is via the time trend in the temperature-mortality relationship. Despite the rise in the number of studies that have examined the temperature-mortality relationship in recent years, there are very few that have analysed whether a particular population has or has not adapted to heat. We conducted a scoping review that met the following criteria, namely: including all persons; considering the heat adaptation concept; and covering the context of the impact of global warming on health and mortality. A total of 23 studies were selected. This review found very few studies targeting adaptation to heat in the human population and a limited number of countries carrying out research in this field, something that highlights the lack of research in this area. It is therefore crucial for political decision-makers to support studies that serve to enhance our comprehension of long-term adaptation to heat and its impact on the health of the human population.