Climate change’s health impact pathways divide into **direct impacts** (high temperatures/heatwaves, direct casualties from extreme weather events like floods and storms) and **indirect impacts** (health effects through ecosystem, infrastructure, and socioeconomic system changes). WHO estimates climate change will cause approximately 250,000 additional deaths annually between 2030-2050 (including malaria, diarrhea, malnutrition, and heatwave deaths), though this estimate is considered conservative, not fully capturing extreme weather, air pollution, and mental health effects.
## Climate-Driven Infectious Disease Distribution
**Geographic expansion of vector-borne diseases**: mosquitoes (vectors for malaria, dengue fever, Zika virus, Japanese encephalitis) expand their survival range to higher latitudes and elevations as temperatures rise. Dengue fever cases have increased 30-fold over the past 50 years; southern Chinese provinces (previously not dengue endemic areas) have seen local transmission cases in recent years. Tick distributions (vectors for Lyme disease, tick-borne encephalitis) are also rapidly expanding northward. **Waterborne diseases**: floods increase drinking water contamination risk (E. coli, Vibrio cholerae); rising temperatures accelerate pathogen reproduction (Vibrio species rapidly multiply in warmer coastal waters); post-extreme rainfall cyanobacteria blooms (algal blooms) contaminate water sources.
## Health Burden from Air Quality Deterioration
Climate change affects air quality through multiple pathways: high temperatures accelerate ground-level ozone (O₃) formation (ozone is a dangerous respiratory irritant); wildfires increase widespread fine particulate matter (PM2.5) pollution; extended pollen seasons (rising temperatures cause plants to flower earlier with longer pollen periods) exacerbate allergic diseases (allergic rhinitis, asthma). Against the backdrop of global warming, major cities will experience significantly more summer ozone pollution days, with particularly serious lung function harm to children and the elderly.
## Climate Anxiety and Mental Health
“Eco-anxiety” or “Climate Anxiety” is defined by the American Psychological Association as a chronic fear directed at environmental catastrophe from climate change. Especially among younger generations (Gen Z and millennials), significant associations exist between climate change information exposure and high levels of anxiety, depression, and helplessness. Psychology research-recommended coping strategies: convert concern into concrete action (rather than passive information exposure); build community support networks with shared concerns; focus on locally controllable positive changes rather than global systemic problems.
See [Heatwaves and Urban Heat Islands](https://sunqi.org/heatwave-urban-heat-island-en/), [The Scientific Basis of Global Warming](https://sunqi.org/climate-change-science-basics-en/), and [WHO Climate and Health Report](https://www.who.int/news-room/fact-sheets/detail/climate-change-and-health).
