The majority of Americans are aware of climate change and acknowledge it is happening, but unfortunately many do not know or understand the serious risks climate change poses to human health or the importance of taking action to protect themselves. The changing climate has already been responsible for death, disease, and the worsening of current health conditions in the U.S. — and the future outlook for how climate change will continue to impact human health appears increasingly dire unless we decrease fossil fuel use and take steps to protect people and communities. Understanding how the environment may be affecting your health and the health of your community is key to protecting against climate-related health risks.
In April 2016, the groundbreaking scientific report entitled: The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment was released. This timely publication is the current gold standard for the state of the science on climate and health issues; it describes the growing threats of climate change to the health and well-being of those living in the United States.
Likely the most important message reinforced by the assessment is that climate change is not only expected to affect human health in the future, rather it is a significant and dangerous threat right now affecting Americans. Health risks will multiply as the climate continues to change, exacerbating existing conditions and creating new public health challenges, and ultimately impacting substantially greater numbers of people in more locations throughout the country. While people in vulnerable groups are most at risk, in truth everyone is at risk.
Some of the most critical environmental threats to human health from climate change include the following:
Heat – Increases in both average and extreme temperatures result from increased concentrations of carbon pollutants, known as greenhouse gasses, in the atmosphere. The numbers of new cases of heat-related illnesses such as heat exhaustion, heatstroke, and hyperthermia are on the rise, and the number of yearly premature deaths caused by extreme summertime heat are projected to increase many-fold before the end of the century. Prolonged exposure to high temperatures is associated with increased hospital admissions for exacerbations of chronic conditions such as kidney, respiratory, metabolic, and cardiovascular diseases. Populations most vulnerable to illness and death caused by extreme heat include children, older adults, those suffering from chronic illness, and people who live in low-income communities.
Air pollution and allergies – Poor air quality can negatively affect heart and lung health. Shifts in weather patterns from climate change affect the levels and location of outdoor air pollutants, including fine particulate matter (such as wildfire smoke, dust, and pollen) and ground-level ozone, which is a dangerous lung irritant produced from the interaction of emissions from burning fossil fuels with heat and sunlight. Health effects include wheezing, coughing, and shortness of breath in people who have asthma or other lung conditions. Increased carbon dioxide emissions, especially coupled with increased temperatures, also result in longer pollen growing seasons and increased concentrations of airborne allergens (aeroallergens), leading to increasing allergic sensitization and asthma episodes. Air quality is not limited to the outdoors — pollutants and aeroallergens can also infiltrate schools, homes, workplaces, and other buildings.
Vector-borne diseases – Vectors, such as mosquitoes, ticks, and fleas, can transmit infective pathogens to humans in the form of viruses, bacteria, and protozoa. Shifts in precipitation and temperature patterns in some regions can significantly affect the prevalence of infections and/or introduce new diseases to areas previously unaffected. Rising average temperatures lengthen the vector breeding season, while increased rainfall, flooding, and humidity create breeding grounds for disease-carrying insects. Consequently, vector-borne diseases such as Lyme Disease, Dengue Fever, Chikungunya, and Zika are threatening additional populations and in greater numbers. The effect of climate change on vector-borne disease transmission is also influenced by other factors, including changes in ecosystems and land use, pathogen mutations and adaptations, changes in human populations and demographics in certain regions, human behavior and adaptive capacity. These complex interactions affect both short- and long-term projected outcomes.
Extreme weather events – The occurrence and severity of certain types of extreme weather events are projected to continually increase by the end of the century as a result of climate change. Related changes in frequency, intensity, and duration of extreme weather have already had costly impacts on some regions of the United States, in lives and property damage. Health risks include the exacerbation of underlying medical conditions, increased exposure to foodborne and waterborne illness, and life-threatening injuries. Extreme weather also threatens infrastructure, including power, water, transportation, and communication systems, all which are essential to safeguarding human health by maintaining access to healthcare, clean water, public services, and emergency response. Health impacts can occur before, during or long after an extreme weather event. The severity and resulting devastation depend on not only the physical impacts of the extreme events themselves but also the unique human, societal, and environmental circumstances at the time and place where weather events occur.
Mental Health and Well-Being – The social and environmental stressors associated with extreme weather events and other climate change impacts can deteriorate community stability, provoking interpersonal conflict and increased aggression and violence, as well as precipitate clinical disorders such as anxiety, depression, post-traumatic stress. Children are especially vulnerable in the aftermath of an extreme event, often leading to emotional and behavioral issues. Individuals with existing psychiatric conditions mental health disorders, such as dementia, Alzheimer’s disease, and other psychiatric conditions can exhibit impaired judgment and maladaptive behavioral responses when faced with crisis situations, therefore people with these conditions are placed at considerable risk.
Vulnerable populations – While climate change threatens the health and well-being of all Americans, some groups of people are disproportionately harmed more than others. Among the populations most vulnerable to climate change are young children, older adults, those living in poverty, and individuals whose health is already compromised by illness. Certain occupations can place some individuals at high risk, especially those requiring outdoor work. Pregnant women and their newborn babies are also highly susceptible to adverse health outcomes caused by environmental exposures associated with climate change.
Public Health Priorities and Lessons Learned
Future projections for the magnitude of health impacts from climate change threatens to undermine public health progress achieved in last 50 years. However, on a more positive note, we are learning that tackling climate change could possibly be the greatest public health opportunity of the 21st century. Reducing the use of fossil fuels will result in cleaner air and water, giving rise to immediate improvements in health. Continuing to invest in public health and climate change research will foster an improved understanding of how to adapt to climate change to ensure better health at the local and national levels, as well as aid in the development of effective strategies for mitigating climate change and preventing future health threats.
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Marybeth Montoro, MPH, CPH, is a health education researcher in the Program on Climate and Health at George Mason University; contact her at mmontoro@gmu.edu
Mona Sarfaty, MD, MPH., FAAFP, is the director of the Program on Climate and Health at George Mason University’s Center for Climate Change Communication; contact her at msarfaty@