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Climate change refers to the effects of accumulated greenhouse gases (GHGs) in the atmosphere on long-term weather patterns. Anthropogenic emissions—in particular from the burning of fossil fuels and land conversion—have increased mean global temperatures by approximately 1° Celsius above preindustrial levels. Extreme weather events, including heatwaves and natural disasters (e.g., wildfires, droughts, and floods), are becoming more frequent and lead to resource scarcity (including access to safe drinking water and food), increased environmental pollution and degradation, violent conflict, and precarious migration. The climate crisis thus has direct consequences for human health, the practice of medicine, and the stability of health care systems and as such represents a health emergency. See Chap. 125 for an overview of climate science.


The World Health Organization predicts that between 2030 and 2050, there will be an additional 250,000 deaths per year globally from climate-sensitive diseases. These include deaths from infectious diseases (Chap. 125); respiratory, cardiovascular, and renal disease; heat-related illness, injury, and trauma; mental illness; and malnutrition (Fig. 475-1). As with much of the global burden of disease, this increase in mortality will be disproportionately borne by low- and middle-income countries (LMICs) whose health infrastructures have been weakened by neocolonialism and structural adjustment. Within wealthier countries such as the United States, climate change will amplify existing health disparities between white people and black, indigenous, and Latinx populations.

FIGURE 475-1

Climate change impacts a wide range of health outcomes. This slide illustrates the most significant climate change impacts (rising temperatures, more extreme weather, rising sea levels, and increasing carbon dioxide levels), their effect on exposures, and the subsequent health outcomes that can result from these changes in exposures. (Source:


Asthma and Other Respiratory Ailments

Climate change exacerbates the negative health effects of harmful air pollutants (e.g., particulate matter, ozone, sulfur dioxide, and nitrogen dioxide). While increases in fine particulate matter (<2.5 microns—PM2.5) are a function of wildfires and the burning of fossil fuels, the latter is the predominate driver of anthropogenic climate change. In 2016, exposure to ambient air pollution and/or household air pollution was estimated to cause 7.1 million premature deaths worldwide per year, making it the largest global environmental risk factor for reversible death and disability (see Chap. 289 for an overview).

By increasing ground-level ozone and/or particulate matter concentrations in some regions, the higher temperatures associated with climate change will directly increase the global burden and severity of asthma (Chap. 287), the respiratory effects of allergies (Chap. 352), rhinosinusitis, chronic obstructive pulmonary disease (COPD), respiratory tract infections, interstitial lung disease, and lung cancer, resulting in increased hospital admissions and premature death. ...

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