Climate change is severely impacting human health worldwide, with heat-related deaths surging to an average of 546,000 annually. This alarming trend is part of a broader health crisis driven by global warming, according to leading medical and environmental experts. They warn that inaction on climate change is costing millions of lives each year and straining health systems globally.^[1][2][3] ### Global Health Threats Intensify The latest Lancet Countdown on Health and Climate Change report, released in collaboration with the World Health Organization (WHO), reveals that 12 of 20 key indicators tracking health threats have reached record levels.^[1][2] Extreme heat is a major concern. Adults over 65 and infants under 1 year now face twice as many heatwave days as they did between 1986 and 2005.^[4] In 2024, the average person experienced 16 days of dangerous heat that would not have occurred without human-caused global warming.^[1][2] Heat-related deaths among older adults were 167% higher in 2023 compared to 1990-1999.^[5] Dr. Jeremy Farrar, Assistant Director-General for Health Promotion and Disease Prevention and Care at the WHO, stated, "The climate crisis is a health crisis. Every fraction of a degree of warming costs lives and livelihoods."^[1] He emphasized that while climate inaction is currently deadly, climate action represents the greatest health opportunity of our time.^[1] Marina Romanello, Executive Director of the Lancet Countdown at University College London, underscored the urgency, saying, "The destruction to lives and livelihoods will continue to escalate until we end our fossil fuel addiction and dramatically up our game to adapt."^[2] ### Widespread Health Consequences Beyond heat, air pollution presents another critical threat. The combined effects of outdoor and household air pollution are linked to 7 million premature deaths each year globally.^[6] Burning fossil fuels alone contributes to 2.5 million deaths annually from air pollution.^[2] Wildfire smoke, intensified by climate change, was tied to a record 154,000 deaths last year.^[7][2] Dr. Maria Neira, Director for Environment, Climate Change and Health at the WHO, highlights the direct impact. "On other days it means reminding the world that 7 million premature deaths every year are due to air pollution," Neira said.^[8] She also stated that air pollution affects every organ in the body, damaging cognitive development and being associated with conditions like dementia and low birth weight.^[9] Climate change also expands the reach of infectious diseases. Altered temperature and precipitation patterns are accelerating the spread of vector-borne illnesses like malaria and dengue fever.^[10][7][11] Diseases transmitted by mosquitoes, ticks, and fleas tripled in the United States between 2004 and 2016.^[12] The WHO conservatively projects that between 2030 and 2050, climate change could lead to approximately 250,000 additional deaths per year from undernutrition, malaria, diarrhea, and heat stress alone.^[10][11] Food and water security are also under severe pressure. Climate stressors increase risks of waterborne and foodborne diseases.^[10][11] Droughts and heatwaves contributed to an additional 124 million people facing moderate or severe food insecurity in 2023.^[1][3] In 2020, 770 million people, primarily in Africa and Asia, experienced hunger.^[10] Globally, 2 billion people lack access to safe drinking water.^[10] The mental health toll of climate change is also growing. Experts note that extreme weather events, displacement, and disrupted social cohesion induce immediate issues like anxiety and post-traumatic stress, along with long-term disorders.^{[13][10][14][11][15]} ### Economic Burden and Urgent Solutions The economic costs of climate change on health are staggering. Direct health damage costs are estimated at US$2-4 billion per year by 2030.^[10] Heat exposure led to 640 billion potential labor hours lost in 2024, resulting in productivity losses of US$1.09 trillion.^[1] The costs of heat-related deaths among older adults reached US$261 billion.^[1] A World Economic Forum analysis projects that by 2050, climate change could cause an additional 14.5 million deaths and US$12.5 trillion in economic losses globally.^[15] Despite these dire warnings, government spending on fossil fuel subsidies remains high. Governments in 73 of 87 reviewed countries spent US$956 billion on fossil fuel subsidies in 2023. This amount is more than triple the annual funds pledged to support climate-vulnerable nations.^[1][3] Experts emphasize that many climate solutions are also health solutions. Dr. Jonathan Patz, Director of the Global Health Institute at the University of Wisconsin-Madison, stated, "The health benefits of a low-carbon economy are so enormous."^[16] He highlighted that strategies like reducing air pollution, eating less meat, and driving less offer significant health advantages.^[17][18] Dr. John Balbus, Director of the HHS Office of Climate Change and Health Equity, echoed this sentiment, saying, "Climate solutions are health solutions and vice versa."^[19] The health sector itself is taking steps, with health-related greenhouse gas emissions falling 16% globally between 2021 and 2022, even as care quality improved.^[1] Transitioning to clean energy is a powerful intervention, with a global shift away from coal preventing an estimated 160,000 premature deaths annually between 2010 and 2022.^[1][2][3] Policies promoting green spaces and walkable cities also offer dual benefits for both climate and public health.^[16] The urgency for action is clear. With 3.6 billion people already living in areas highly susceptible to climate change, experts call for health to be at the center of climate policy decisions to protect current and future generations.^[10][8]