With climate change’s impacts on global health increasingly being recognized and experienced around the world, U.S. agencies are taking note. According to the U.S. Agency for International Development’s (USAID) recently released 2022-2030 Climate Strategy, “climate change negatively affects life-long physical and mental health, mortality, food security, and access to essential services, such as health care; water, sanitation and hygiene; and education.” The strategy seeks to address the widespread implications of climate change on global health and tackle both urgent challenges and long-term system changes needed to benefit people around the world.

The implications of climate change for global health are impossible to deny, with climate change not only exacerbating existing health threats but also creating new public health challenges.

• It is estimated that climate change could lead to 250,000 excess deaths per year due to heat, undernutrition, malaria, and diarrheal disease by 2050. Africa is projected to account for more than half of that excess mortality.
• 5 million people across the World Health Organization’s (WHO) Western Pacific Region die each year from avoidable environmental causes such as air pollution, extreme weather, or waterborne disease. Moreover, every 14 seconds, a person dies from air pollution in the region.

While the nexus between climate change and global health is complex, their overlap can be most clearly seen in: 1) clean water and nutritious food; 2) rising heat, the spread of disease, and air pollution; and 3) extreme weather and displacement.

Clean Water and Nutritious Food

Clean water and nutritious food are essential for human health, and climate change is increasingly putting these fundamental resources at risk. While people are only able to survive about three days without any water, rising global temperatures can lead to deadly pathogens in freshwater sources, impeding access to clean water. Contaminated water puts human health at risk and poses a particularly large threat to children’s lives. While access to nutritious food is also critical for health, malnutrition leads to stunting and wasting, threatening lives around the world. And despite overall agricultural productivity increasing, climate change has slowed agricultural growth over the past 50 years globally.

• Roughly half the world’s population currently faces severe water scarcity at least part of the year, including 450 million children who are in areas without enough water to meet their everyday needs. Additionally, average rainfall has reached new record lows over the last three decades.
• Every 48 seconds, a person is estimated to be dying of starvation in Ethiopia, Somalia, and Kenya, according to a new report by Oxfam and Save the Children.
• Global heating is contributing to the decline in global yield potential for major crops, which has fallen from 7.4% to 5.6% since 1981. This abatement, combined with the impacts of extreme weather and soil depletion, is interfering with efforts to combat undernutrition.

Rising Heat, the Spread of Disease, and Air Pollution

Over the past twenty years, the earth’s temperature has increased at unprecedented rates. While the planet’s temperature has risen by 0.14 degrees Fahrenheit per decade since 1880, the rate of warming over the past 40 years is twice that, rising 0.32 degrees Fahrenheit per decade since 1981. This increase in temperatures is accompanied by the spreading of mosquitoes carrying diseases like malaria and dengue into new areas. As rising temperatures both allow and force animals to leave their native habitats, this movement and the subsequent novel encounters between animals leads to an increased risk of transmission of pathogens from wild animals to humans. Additionally, a new report from the University of Chicago’s Energy Institute found that air pollution is “deeply intertwined” with climate change, with roughly 97% of the world’s population living in places where pollution exceeds the recommended level.

• The 10 warmest years on record have occurred since 2005, and, in the past 20 years, heat-related mortality among people over 65 years of age has increased by more than 50%. An article in the New England Journal of Medicine found that higher temperatures have resulted in tropical infections, dermatological malignancies, pregnancy complications, cardiovascular and pulmonary morbidity and mortality, and much more.
• While the WHO estimates that there were an estimated 241 million cases of malaria worldwide in 2020, climate change is likely to expand malaria transmission in eastern and southern Africa due to warmer temperatures. Projected increases put an additional 76 million people at risk of malaria exposure for 10-12 months a year by the 2080s.
• The meeting of new species for the first time will create at least 15,000 new instances of viruses jumping between animals by 2070. There are currently at least 10,000 viruses “circulating silently” among wild mammals that have the capacity to cross over into humans, mostly in the depths of tropical forests.
• Around 9 million people have died due to environmental contamination per year since 2015. Seven of the 10 countries with the most pollution-related deaths are in Africa.

Extreme Weather and Displacement

As a result of climate change, extreme weather events like droughts, floods, and heat waves have become more frequent and intense around the world. A recent study warns that as these events become more frequent, it will become increasingly difficult to predict the effects of extreme weather on infection rates and disease outcomes due to varying background temperatures and unknown consequences of changing host-pathogen interactions. Moreover, extreme weather events often render places inhabitable, forcing people to flee their homes, with people in low-income countries often disproportionately impacted.

• Between 2010 and 2020, droughts, floods, and storms killed 15 times as many people in highly vulnerable countries than in the wealthiest countries.
• The Global Report on International Displacement 2022 found that extreme weather displaced almost 24 million people in 2021, disproportionately impacting people in low-income countries. What’s more, the impacts of climate that “are approaching irreversibility” could result in at least 1 billion people at risk of losing their homes to storms fueled by rising seas alone by 2050.
• Approximately 80% of people struggling with hunger live in regions that are susceptible to climate extremes, which can then impact food production, availability, and accessibility.
• In the Americas, 67% of health facilities are in areas at risk of disasters. In the last decade, 24 million people were left without access to health care for months because of damaged infrastructure.

What’s It Worth?

In September 2021, over 200 medical journals warned in an unprecedented statement of the grave threat the rapidly warming climate is to global public health. Moreover, in their 2022 report, the Intergovernmental Panel on Climate Change (IPCC), the main authoritative source on climate change, highlighted the overwhelming connection between climate change and global health.

The evidence is clear: It is in the United States’ interest to lead globally on strategies that address climate change’s impact on global health. What’s at stake? America’s health and safety, as well as the health and safety of people around the world.