Lesson 13 min 20 XP
Climate Change and Health
How climate change is emerging as the greatest threat to global health in the 21st century, from heat deaths and vector-borne diseases to food insecurity and mental health.
Ask about this lesson
For the complete documentation index, see llms.txt.Skip to main content
How climate change is emerging as the greatest threat to global health in the 21st century, from heat deaths and vector-borne diseases to food insecurity and mental health.
The WHO has called climate change the greatest threat to health in the 21st century. The pathways from climate change to health harm are numerous. Rising temperatures increase heat-related mortality: the 2023 European heatwave caused an estimated 60,000 excess deaths. Changing rainfall patterns expand the range of mosquito-borne diseases like malaria and dengue into previously unaffected regions. Air pollution from wildfires, intensified by climate change, causes respiratory disease. Food insecurity, driven by drought and crop failure, threatens nutrition for hundreds of millions.
The Lancet Countdown, an annual assessment of health and climate change, tracks multiple indicators. It has documented increasing heat exposure for vulnerable populations, expanding suitability for disease vectors, declining crop yield potential, and growing economic losses from extreme weather. The health impacts are disproportionately felt by populations that contributed least to emissions: subsistence farmers in the Sahel, slum dwellers in South Asian cities, and indigenous communities worldwide.
Health systems must adapt to climate change. Hospitals need to prepare for increased demand during heatwaves and extreme weather events. Disease surveillance systems must track the geographic expansion of vector-borne diseases. Water, sanitation, and hygiene (WASH) infrastructure must be climate-proofed against flooding and drought. Health workforce training must include climate health competencies.
At the same time, the health sector itself contributes to climate change. If the global health care sector were a country, it would be the fifth-largest emitter on the planet. Health facility energy use, medical supply chains, pharmaceutical manufacturing, and health care waste all generate significant emissions. Decarbonizing health care, through renewable energy, sustainable procurement, and reduced waste, is both a climate mitigation strategy and a matter of the sector living its own values.