Climate change is the defining public health challenge of the 21st century. Rising temperatures, extreme weather events, shifting disease patterns, air pollution, water insecurity, food system disruption, and forced displacement are already affecting human health on every continent, and the impacts will intensify in the decades during which you will be practicing healthcare. The World Health Organization estimates that climate change will cause approximately 250,000 additional deaths per year between 2030 and 2050 from malnutrition, malaria, diarrhea, and heat stress alone, and these estimates are widely regarded as conservative. As a future healthcare professional, understanding the health impacts of climate change prepares you to protect your patients, advocate for your communities, and contribute to a more sustainable healthcare system.
Direct Health Impacts
Extreme Heat: Rising global temperatures increase the frequency, duration, and severity of heat waves, which cause heat exhaustion, heat stroke, acute kidney injury, and cardiovascular events including heart attacks and strokes. Elderly individuals, outdoor workers, people without air conditioning, and those with chronic medical conditions are most vulnerable. Urban heat islands (cities are significantly hotter than surrounding rural areas due to concrete, asphalt, and reduced green space) concentrate heat exposure in densely populated areas. Clinicians in warmer regions are seeing increasing volumes of heat-related illness during summer months, and this trend is projected to worsen.
Extreme Weather Events: Hurricanes, floods, wildfires, droughts, and severe storms cause direct injury and death, displace populations, destroy healthcare infrastructure, contaminate water supplies, and create conditions for infectious disease outbreaks. The mental health consequences of extreme weather events (PTSD, depression, anxiety, substance use) persist long after the physical damage is repaired. Healthcare systems in disaster-prone regions must prepare for increasing frequency and severity of these events.
Air Quality: Climate change worsens air quality through increased wildfire smoke, higher ground-level ozone formation in hot weather, and continued reliance on fossil fuels. Poor air quality exacerbates asthma, COPD, and cardiovascular disease, and contributes to lung cancer and respiratory infections. Children, elderly individuals, and people with pre-existing respiratory or cardiovascular conditions are most vulnerable. Studies estimate that air pollution contributes to millions of premature deaths globally each year.
Indirect Health Impacts
Infectious Disease: Climate change is altering the geographic range of disease vectors (mosquitoes, ticks, fleas) and the pathogens they carry. Diseases like dengue, Zika, chikungunya, Lyme disease, and West Nile virus are expanding into regions where they were previously uncommon. Warmer temperatures extend the breeding season for mosquitoes and accelerate pathogen development within vectors. Healthcare professionals in newly affected regions need to add these diseases to their differential diagnoses.
Food and Water Security: Climate change threatens crop yields through drought, flooding, and extreme temperatures, contributing to food insecurity and malnutrition. Water scarcity, contamination from flooding, and saltwater intrusion into coastal freshwater supplies affect drinking water quality and availability. These impacts are most severe in low-income countries and communities, exacerbating existing health disparities. See our social determinants of health page and global health page.
Mental Health: The psychological impacts of climate change include eco-anxiety (chronic worry about the environment and climate future), grief related to environmental loss, PTSD from climate-related disasters, and the cumulative stress of living in communities affected by repeated extreme weather events. These mental health impacts are increasingly recognized as a significant component of the climate-health relationship. See our mental health and wellness page.
Healthcare’s Carbon Footprint
The healthcare sector itself is a significant contributor to climate change. In the United States, the healthcare system accounts for approximately 8 to 10 percent of national greenhouse gas emissions, making it one of the largest single-sector contributors to the very problem it is then tasked with treating and mitigating. Sources of healthcare emissions include energy use in hospitals and clinics, transportation (patient travel, ambulances, supply chain logistics), pharmaceutical manufacturing, medical device production, anesthetic gases, and medical waste. Efforts to decarbonize healthcare include transitioning to renewable energy, reducing unnecessary procedures and tests, minimizing waste, choosing lower-carbon anesthetic agents, and building sustainable supply chains.
What Healthcare Professionals Can Do
Clinical Preparedness: Learn to recognize climate-sensitive conditions (heat illness, vector-borne diseases, respiratory exacerbations from air quality, mental health impacts of disasters) and incorporate climate and environmental exposure questions into your clinical assessments. Patients with chronic conditions may need adjusted management plans during extreme heat or poor air quality events.
Community Advocacy: Healthcare professionals are among the most trusted voices in communities. Use that trust to advocate for climate policies that protect health: clean energy investments, air quality standards, heat action plans, green infrastructure in urban areas, and disaster preparedness programs. Medical and public health organizations (AMA, APHA, WHO) have all issued statements declaring climate change a health emergency and calling for healthcare sector engagement.
Sustainable Practice: Wherever you practice, look for opportunities to reduce the environmental impact of healthcare delivery. Support institutional sustainability initiatives, minimize unnecessary testing and prescribing, reduce waste in clinical settings, and choose lower-carbon options when clinically equivalent alternatives exist.
For related topics, see our global health page, health equity page, social determinants of health, and cross-cutting topics hub.
Vulnerable Populations: The health impacts of climate change are not distributed equally. Children, elderly individuals, pregnant women, outdoor workers, people with chronic medical conditions, low-income communities, communities of color, and indigenous populations bear disproportionate burdens from climate-related health threats. This inequity mirrors and amplifies existing health disparities: the communities least responsible for greenhouse gas emissions often experience the most severe climate-related health consequences. Climate adaptation and resilience planning must prioritize these vulnerable populations to avoid widening health inequity. See our health equity page and social determinants of health page.
Climate-Informed Clinical Practice: As climate change accelerates, clinicians will increasingly need to incorporate environmental and climate factors into their clinical reasoning. During heat waves, proactively contact vulnerable patients (elderly, those on medications that impair thermoregulation like anticholinergics and diuretics) to review heat safety plans. During wildfire smoke events, advise patients with asthma and COPD on indoor air quality measures and medication adjustment. When evaluating patients with novel symptom patterns, consider whether shifting disease vectors may be responsible (Lyme disease appearing in previously unaffected regions, for example). Climate-informed practice means thinking about the environment as a determinant of health, not just a backdrop.
Sustainable Healthcare Systems: Healthcare organizations around the world are beginning to measure and reduce their environmental footprint. The NHS in England committed to reaching net-zero emissions by 2040 for its direct activities. In the United States, Health Care Without Harm and Practice Greenhealth lead efforts to help hospitals and health systems reduce waste, transition to renewable energy, minimize unnecessary resource consumption, and choose sustainable products. Anesthesiology is a particularly active area of sustainability innovation because inhaled anesthetic agents are potent greenhouse gases, and substituting lower-impact agents or using regional anesthesia techniques can significantly reduce operating room emissions. As a future healthcare professional, you will have opportunities to participate in sustainability initiatives wherever you practice.
References
World Health Organization. “Climate Change and Health.” WHO, 2025. https://www.who.int/health-topics/climate-change. Accessed March 2026.
Lancet Countdown. “Tracking Progress on Health and Climate Change.” The Lancet, 2025. https://www.lancetcountdown.org/. Accessed March 2026.
Eckelman, M.J., and Sherman, J. “Environmental Impacts of the U.S. Health Care System and Effects on Public Health.” PLoS ONE, 11(6), e0157014, 2016.