Dear Colleagues and Students,
Earth Day will be observed worldwide on Monday April 22nd, and while we don’t know the full extent of the impending effects of climate change on public health, it is clear that change is upon us. From droughts to floods to wildfires and extreme weather, climate change is impacting lives around the globe. Given the critical connections between the environment and public health, there are myriad ways that climate change is influencing health outcomes. In addition to injury and illness from extreme weather, shifting distributions of disease vectors, and challenges for food security and air quality, there are a number of ways that climate change influences water resources, which will have subsequent effects on health. A few examples are outlined here.
Warming air temperatures result in increased surface water temperatures, which can degrade water quality by enhancing the growth and survival of waterborne pathogens. Cholera cases (caused by the bacterium Vibrio cholerae), for example, have been observed to increase with warmer sea surface temperatures, and a study by MacFadden et al. (2018; Nature Climate Change 8) found that warmer local temperatures and increased population density are associated with a greater prevalence of antibiotic resistant infections in the United States. There is concern that additional water-related infectious diseases – such as Legionnaires disease and infection with Naegleria fowleri, the “brain-eating amoeba” – will increase with a warming climate.
Increases in rainfall intensity and flooding are concerns not only due to risks related to physical injury. Flood water and stormwater runoff can also contain contaminants such as sewage and toxic chemicals from households, industry, agricultural areas, and sites contaminated with hazardous materials (e.g., superfund sites and brownfields). Flood waters can pollute nearby water resources and deposit contaminants on urban surfaces. When floodwaters recede, there are risks of exposure to mold due to damp building materials, especially in warm climates.
Increased stormwater runoff and water temperature have also led to the observed increase in harmful algae blooms. Harmful algae, such as cyanobacteria, produce and release toxins that include microcystin, an irritant and hepatotoxin that is also associated with gastrointestinal illness. This and other climate change-induced alterations to surface water chemistry are providing new challenges for water utilities that use impacted surface waters as drinking water resources.
Drought-induced reductions in water quantity can also be detrimental for public health, given the minimum volumes of water required for drinking, personal hygiene, economic activity and growing food. Extreme droughts or floods can also result in human displacement. These effects are particularly worrying, given that that food insecurity and mass human migration can lead to conflict. In fact, a nice review paper by Carleton and Hsiang (2016; Science 353) highlighted how climate anomalies influence social and economic outcomes, including human aggression and conflict.
It was an honor to speak about these topics at the Planetary Health Forum hosted by GPH on April 4th. For those who may have missed it, please see the post-event coverage here.
Andrea Silverman, PhD, MS
Assistant Professor of Civil and Urban Engineering
1. Lipp, E. K., Huq, A. & Colwell, R. R. Effects of global climate on infectious disease: the cholera model. Clin. Microbiol. Rev. 15, 757–770 (2002).
2. MacFadden, D. R., McGough, S. F., Fisman, D., Santillana, M. & Brownstein, J. S. Antibiotic resistance increases with local temperature. Nature Climate Change 8, 510 (2018).
3. Walker, J. The influence of climate change on waterborne disease and Legionella: a review. Perspect. Pub. Health 138, 282–286 (2018).
4. Kemble, S. K. et al. Fatal Naegleria fowleri infection acquired in Minnesota: possible expanded range of a deadly thermophilic organism. Clin. Infect. Dis. 54, 805–809 (2012).
5. US CDC. Floodwater After a Disaster or Emergency(2018). Available at: https://www.cdc.gov/disasters/floods/floodsafety.html
6. Brandt, M. et al. Mold prevention strategies and possible health effects in the aftermath of hurricanes and major floods. Morbidity and Mortality Weekly Report: Recommendations and Reports 55, 1-CE-4 (2006).
7. World Health Organization. Cyanobacterial toxins: Microcystin-LR in Drinking-water. in Guidelines for Drinking-water Quality (World Health Organization, 2003).
8. Carleton, T. A. & Hsiang, S. M. Social and economic impacts of climate. Science 353 (2016).