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Recently, there has been growing interest in epidemiology - the study of disease - and its applications to predict the effects of climate change on human health. Various institutions such as the National Institute of Health, the World Health Organization (WHO), Yale School of Medicine, and others have established direct correlations between climate change and public health issues.
Many of the health consequences of climate change will be heat related. According to the WHO, heat-related deaths among those over 65 have risen by 70% in the past two decades, and this trend is projected to continue. Warmer average temperatures caused by climate change will lead to hotter days and more frequent heat waves, which can lead to heat stroke and dehydration as well as cardiovascular, respiratory, and cerebrovascular disease. These factors have led the Environmental Protection Agency (EPA) to predict that there could be as many as thousands to tens of thousands of additional deaths each year during the summer by the end of the century.
Worsening air pollution also poses a significant threat to human health. Warmer temperatures will contribute to an increase in ground-level ozone, which is associated with damaged lung tissue, reduced lung function, and inflamed airways. Additionally, warmer temperatures will lead to more wildfires, resulting in more particulate matter in the air. Particulate matter are small particles and liquid droplets suspended in air, which can cause lung cancer, chronic obstructive pulmonary disease, and cardiovascular disease. These drastic changes in air quality threaten to mostly affect densely-populated urban areas.
Climate change will also magnify the transmission of vector-borne diseases. Vectors are agents that transmit diseases, such as mosquitoes, ticks, and fleas. According to the EPA, “The geographic range of ticks that carry Lyme disease is limited by temperature. As air temperatures rise, ticks are likely to become active earlier in the season, and their range is likely to continue to expand northward.” As temperatures rise, so will occurrences of Lyme disease. This pattern also applies to mosquitoes, causing climate change to likely result in more cases of Zika virus.
Along with physical health effects, climate change is also poised to have significant mental health effects. Researchers have linked climate change to increases in post-traumatic stress disorder (PTSD) and suicide. Studies have shown that victims of climate-related natural disasters are at high risk of developing PTSD, and some studies of survivors of wildfires in California show that they had rates of PTSD similar to war veterans. Other studies show that the economic impacts of droughts lead to increases in suicide, particularly among farmers, and that warmer temperatures could lead to as many as 40,000 additional suicides in the United States and Mexico by 2050.
These health consequences will likely disproportionally affect disadvantaged communities that have contributed the least to the crisis. People living in developing countries that do not have adequate healthcare infrastructure and access to treatment will suffer the most from climate-sensitive diseases. Additionally, homeless people and low-income households are the least likely to have access to air-conditioning, increasing their risk of suffering heat-related conditions.
Examining the effects of climate change as it pertains to human health is a stark reminder that climate change is at its core a human issue. It threatens to not only directly affect human health but also exacerbate existing inequalities and harm vulnerable communities. Raising awareness among healthcare professionals on climate change-related health issues and creating climate-resilient infrastructure is the first step towards mitigating the consequences of climate change.
Citations:
Climate epidemiology. (n.d.). Climate, Health, and Environment Nexus (CHEN) Lab. https://medicine.yale.edu/lab/kaichen/research/climate-epidemiology/
Climate impacts on human health | Climate Change impacts | US EPA. (n.d.). https://climatechange.chicago.gov/climate-impacts/climate-impacts-human-health#ref1
Novotney, A. (2023, April 21). How does climate change affect mental health? https://www.apa.org. https://www.apa.org/topics/climate-change/mental-health-effects
Padhy, S. K., Sarkar, S., Panigrahi, M., & Paul, S. (2015). Mental health effects of climate change. Indian Journal of Occupational and Environmental Medicine, 19(1), 3. https://doi.org/10.4103/0019-5278.156997
World Health Organization: WHO. (2023, October 12). Climate change. https://www.who.int/news-room/fact-sheets/detail/climate-change-and-health#:~:text=Climate%20change%20is%20impacting%20health,diseases%2C%20and%20mental%20health%20issues.