BY CLAIRE CHANG
The International Panel on Climate Change predicts that the global mean surface air temperature in 2016 to 2035 will be between 1 and 1.5°C warmer than the global mean temperature in 1850 to 1900.1 As one of this century’s biggest environmental threats, climate change influences both social and environmental determinants of human health. It is widely agreed by scientists that the effects of climate change on human health will be overwhelmingly negative.2 Scientists and public health organizations seek to understand the many ways that climate change has already, and will continue to, affect human wellbeing.
Climate change has many direct effects on human health. With mean global temperatures on the rise, extreme heat events are expected to increase.3 These heat waves not only lead to heat exhaustion, heat stroke, and death, but also can exacerbate preexisting diseases.4 Hurricanes and floods will occur more frequently; therefore, casualties from these events will rise. Climate change also increases cancer risk. The depletion of the ozone layer increases exposure to UV radiation, a substantial risk factor for skin cancer and cataracts. Furthermore, climate change has many direct effects on air quality. Rising concentrations of dust, fine particles, pollen, mold spores, and ground level ozone can raise the incidence of respiratory problems, as well as exacerbate preexisting respiratory conditions.2
Moreover, the indirect impacts of climate change on human health are even more numerous than the direct impacts. Since precipitation patterns and temperature changes determine the breeding zones, maturation rates, and feeding patterns of vectors like mosquitoes and ticks, climate change is likely to affect the distribution and seasonal transmission of vector-borne diseases. In some areas, changes in climate may reduce the distribution of vector-borne diseases like malaria, Chagas disease, and helminth infections. Other previously unaffected regions may also experience the emergence of these diseases.5 In addition, the climate change driven displacement of both human and animal populations could give rise to new diseases and infections. Droughts associated with climate change will likely cause food shortages, and the nutritional content of staple foods may fall as carbon dioxide levels rise in the atmosphere.6 Also, as ocean surface temperatures rise, toxic algal blooms may occur more frequently, and changes in ocean biochemical properties may lead to the contamination of fisheries.2 In addition, more frequent extreme rainfall events may contribute to a rise in water-borne diseases.7
Even when the human health effects of climate change are considered in isolation, climate change is an undeniable problem that must be addressed. It is important to remember that climate change is not only an environmental threat, but also poses serious human health risks. Carbon reduction policies have the “co-benefit” of improving human wellbeing.8 Unfortunately, social, economic, and political barriers make it difficult to reduce global greenhouse gas emissions through policy and individual lifestyle changes.
In September of 2014, Dr. Maria Neira, the director of the World Health Organization’s Department of Public Health and the Environment, offered specific recommendations about how to translate the scientific community’s increasing knowledge on the impacts of climate change into action. One of her recommendations is to maximize the “twin benefits” of efforts to mitigate climate change and improve human health.9 These “twin benefits” are vital justification for calls to reduce greenhouse gas emissions immediately.
Carbon reduction policies and behaviors can be designed to not only mitigate the human health risks associated with climate change in the long-term, but also provide immediate benefits to human health. The use of low-emission household cook stoves, for example, would both reduce emissions of air pollutants and greenhouse gases as well as significantly improve indoor air quality, which is a main cause of illness in many developing nations.10 A study in the United Kingdom found that interventions to improve the energy efficiency of households, such as changes in construction materials, fuel use, and ventilation, not only reduced carbon emissions, but also reduced disability adjusted life years in the population.11 Furthermore, many studies have demonstrated that establishing improved public transportation systems and promoting urban walking and cycling would both improve cardiovascular fitness and reduce emissions from vehicles.8
The impacts of climate change on human health vary by geographic region, and some populations are more vulnerable than others. The elderly, infants, and socioeconomically disadvantaged populations are particularly vulnerable to the adverse health effects of temperature extremes.2 People who live in areas with poor infrastructure are less able to access healthcare during floods or other extreme weather events. In places that already experience food insecurity and high rates of chronic and infections diseases, the physical stress associated with climate change may have more acute effects on health.
Nevertheless, global climate change poses health risks for everyone across the globe. Atmospheric carbon dioxide levels continue to rise and climate change is becoming increasingly irreversible. Global greenhouse gas emissions must be reduced as soon as possible. The potential for climate change mitigation efforts to minimize serious health risks must serve as an impetus for more drastic policy and behavior changes.
Claire Chang is a sophomore in Pierson College. Claire is an Environmental Studies major. She can be contacted at firstname.lastname@example.org.
- Stocker, T. F., Qin, D., Plattner, G. K., Tignor, M., Allen, S. K., & Boschung, J. (2013). Summary for Policymakers in Climate Change 2013: The Physical Science Basis, Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change.
- A human health perspective on climate change: a report outlining the research needs on the human health effects of climate change. (2010). A Human Health Perspective On Climate Change: A Report Outlining the Research Needs on the Human Health Effects of Climate Change. Environmental Health Perspectives (EHP); National Institute of Environmental Health Sciences.
- Meehl, G. A., & Tebaldi, C. (2004). More intense, more frequent, and longer lasting heat waves in the 21st century. Science, 305(5686), 994-997.
- Kovats, R. S., & Hajat, S. (2008). Heat stress and public health: a critical review. Annual Review Public Health, 29, 41-55.
- Parham, P. E., Waldock, J., Christophides, G. K., Hemming, D., Agusto, F., Evans, K. J., … & Michael, E. (2015). Climate, Environmental and Socio-Economic Change: Weighing up the Balance in Vector-Borne Disease Transmission. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 370(1665), 20130551.
- Myers, S. S., Zanobetti, A., Kloog, I., Huybers, P., Leakey, A. D., Bloom, A. J., … & Usui, Y. (2014). Increasing CO2 Threatens Human Nutrition. Nature, 510(7503), 139-142.
- Tirado, M. C., Clarke, R., Jaykus, L. A., McQuatters-Gollop, A., & Frank, J. M. (2010). Climate Change and Food Safety: A Review. Food Research International, 43(7), 1745-1765.
- Patz, J. A., Frumkin, H., Holloway, T., Vimont, D. J., & Haines, A. (2014). Climate Change: Challenges and Opportunities for Global Health. JAMA, 312(15), 1565-1580. doi:10.1001/jama.2014.13186.
- Neira, M. (2014, September 30). Commentaries. World Health Organization. Retrieved from http://www.who.int/mediacentre/commentaries/en/.
- Household Air Pollution and Health. (n.d.). World Health Organization. Retrieved from http://www.who.int/mediacentre/factsheets/fs292/en/.
- Wilkinson, P., Smith, K. R., Davies, M., Adair, H., Armstrong, B. G., Barrett, M., … & Chalabi, Z. (2009). Public Health Benefits of Strategies to Reduce Greenhouse-Gas Emissions: Household Energy. The Lancet, 374(9705), 1917-1929.