As shown in the Groundswell report, climate change is becoming an emergent economic, social, and existential threat to human beings worldwide. Natural variations in the earth's climate have been accompanying man's environment since his origins, and it is believed that catastrophic climate changes could have played an important role on his evolution. A climate change can be regarded as a critical shift challenging both complex civilized and developing societies, with paramount effects, such as social disruption and political collapse. 1 The assessment of possible future ecologically critical climate conditions requires the study of current and past climate changes from the specific point of view of human adaptation. 2 Genetic evolutionary properties and behavioral adaptations allow species to go on living in their ecological and geographical contexts, with genetic mutations, phenotypic plasticity, or epigenetic mechanisms being established in order to avoid negative or catastrophic impacts due to environmental changes. Both genotype and phenotype respond to gradients of climatic properties and can be considered as evolutionary shelters. Populations are spreading, concentrating, and migrating from one territory to another in an effort to adapt in different geographical areas. Migration may be an attempt at dealing with climate changes: when living beings perceive they are losing fitness and health, they are forced to move to other ecosystems. Human mind is a highly integrated, coherent, sentient, and proactive information system. Doubtless, it provides an evolutionary advantage in complex and sometimes rapidly shifting environments. The adaptive capacity of individuals, communities, and health systems can manage the increase in frequency and intensity of extreme weather and climate events, and mitigate the burden of climate-sensitive health consequences. This adaptive plasticity and coping ability may function differently or be altered when a drastic environmental change occurs, as if a tipping point were reached. Vulnerability and resilience to climate changes are broad, flexible, and complex phenomena with internal factors related to environmental, physical, economic, and social aspects. At the group level, there are populations exhibiting a degree of vulnerability due to their geographical position (eg, those on the coasts, those subjected to hurricane activity, those living in areas subjected to heat waves). Other populations can carry out climate-sensitive activities like agriculture, aquaculture, fishing, pasture, or relay on natural resources and ecosystems as their livelihood. Groups linked to vulnerable conditions include demographic subpopulations such as women, children, and elderly, as well as people with pre-existing medical conditions, disabled individuals, migrants and refugees, minorities, occupational groups with direct exposure to climate changes or disasters (eg, field workers, emergency first responders), 3 people with mental illness, and the homeless category. Poverty in general is an important...