Climate change affects everyone on the planet, but its consequences fall hardest on people who have the least resources to cope. About 3.6 billion people already live in areas highly susceptible to climate change, and in vulnerable regions, the death rate from extreme weather events over the last decade was 15 times higher than in less vulnerable areas. The gap between who causes climate change and who suffers most from it is stark: low-income countries and small island developing states contribute minimally to global emissions yet endure the harshest impacts.
Low-Income Countries and Communities
The countries most vulnerable to climate change are overwhelmingly low-income. The Notre Dame Global Adaptation Initiative ranks Chad, Niger, Solomon Islands, Somalia, Sudan, and Eritrea among the most climate-vulnerable nations on Earth. Every country in the top ten most vulnerable spots falls into either the low-income or lower-middle-income category. These nations face a compounding problem: fragile healthcare systems, limited infrastructure, and fewer financial reserves to recover from floods, droughts, or crop failures.
Within wealthier nations, poverty still determines who suffers most. In major U.S. cities, people living below the poverty line experience urban heat island effects nearly 1°C more intense than people earning above twice the poverty line. That difference sounds small, but it compounds over weeks-long heat waves and in neighborhoods with less tree cover, fewer parks, and older buildings without air conditioning. Climate change could push an additional 62 to 99 million people worldwide into extreme poverty by 2030 compared to a scenario without it.
Children, Pregnant Women, and Older Adults
Age is one of the strongest predictors of climate vulnerability. Infants, young children, pregnant women, and older adults share physiological traits that make heat especially dangerous: difficulty regulating body temperature, greater susceptibility to dehydration, and weaker immune responses.
For pregnant women, high temperatures are linked to preterm birth, stillbirth, gestational diabetes, and pregnancy-related hypertension. Each additional 1°C in minimum daily temperature above roughly 24°C has been shown to increase the risk of infant mortality by as much as 22%. Preterm birth, already the leading cause of childhood deaths globally, spikes during heat waves.
Children and adolescents face cognitive effects too. Heat waves impair concentration and learning, which means rising temperatures don’t just threaten physical health but also educational outcomes. On the other end of the age spectrum, older adults are more likely to suffer heart attacks and respiratory distress during extreme heat events, particularly those with pre-existing heart or lung conditions.
Women and Girls in Developing Nations
Climate change intensifies pre-existing gender inequalities. Women who are young, poor, less educated, or living in rural areas face the greatest difficulty accessing healthcare when climate-related crises hit. In many low- and middle-income countries, water scarcity forces women and girls to walk long distances to collect water, a task that causes physical injuries and pulls girls out of school. Adults in these households lose time they would otherwise spend earning income, deepening financial instability in already marginalized families.
Droughts reduce food availability and alter household diets, raising the risk of malnutrition. For pregnant women, this translates into higher rates of premature birth and low birth weight. The combination of extreme heat, food insecurity, and limited healthcare access creates layered risks that fall disproportionately on women in the regions least equipped to respond.
Outdoor and Manual Workers
Rising temperatures are an occupational hazard for millions of people who work outside or in environments without climate control. Farmers, construction workers, firefighters, miners, soldiers, and manufacturing workers in non-air-conditioned facilities all face elevated risk of heat-related illness. Agriculture ranks among the industries with the highest rates of heat illness and injury.
Between 2003 and 2008, construction workers accounted for 36% of all heat-related workplace deaths recorded in the U.S. Underground miners face compounding heat from rock at depth, while firefighters wearing heavy protective gear lose the ability to dissipate body heat effectively. The risk is highest in tropical regions and low- to middle-income countries, where labor protections and workplace cooling are often minimal or absent entirely.
Coastal Populations and Climate Migrants
Sea level rise and intensifying storms put coastal communities at growing risk. In the United States alone, roughly 2.5 million people in 1.4 million homes live in areas projected to face a severe coastal flood by 2050, even under scenarios where nations meet their current pledged emissions reductions. Globally, the numbers are far larger, with hundreds of millions of people living in low-lying coastal zones across South and Southeast Asia, West Africa, and the Pacific Islands.
When the land people live on becomes uninhabitable, whether from flooding, drought, or failing crops, migration follows. The World Bank estimates that climate change could force 216 million people to migrate within their own countries by 2050. Sub-Saharan Africa faces the largest projected displacement at 86 million internal climate migrants, followed by East Asia and the Pacific (49 million), South Asia (40 million), North Africa (19 million), Latin America (17 million), and Eastern Europe and Central Asia (5 million). These are not people crossing international borders. They are people moving from rural areas to cities, from coastlines to inland regions, within their own countries.
Indigenous Communities
Indigenous peoples face climate threats that go beyond physical safety and economic loss. Many Indigenous communities depend directly on local ecosystems for food, medicine, and cultural practices. When temperatures shift, rainfall patterns change, or species migrate, these tightly connected ways of life are disrupted in ways that standard climate models often miss. Most climate forecasting for agriculture focuses on globally traded cereal crops like wheat, maize, and rice, overlooking the locally important crops that are central to food sovereignty, economic security, and cultural identity in Indigenous food systems.
Indigenous communities report widespread, ongoing impacts on the social and ecological systems they depend on. Because these communities often occupy land that is ecologically sensitive, from Arctic tundra to tropical forests to low-lying Pacific islands, they experience the earliest and most visible effects of a changing climate while holding the least political and economic power to influence emissions policy.
Racial and Ethnic Minorities
Within wealthy nations, climate change does not affect all racial and ethnic groups equally. In U.S. cities, people of color experience significantly higher urban heat island intensity than non-Hispanic white residents, a pattern that holds across every climate zone studied. This disparity reflects decades of housing policy, zoning decisions, and unequal investment in green infrastructure. Neighborhoods with more pavement, fewer trees, and denser housing absorb and retain more heat.
These temperature differences layer onto existing health disparities. Communities already facing higher rates of asthma, cardiovascular disease, and limited access to healthcare are the same ones experiencing the most extreme heat exposure. Ethnic minorities, migrants, and displaced persons are consistently identified among the groups facing the most disproportionate climate-related health risks worldwide.