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The Climate-Health Nexus

Environmental change has far-reaching implications that intersect with nearly every aspect of humankind including public health. Environmental change and associated impacts do not stop at geopolitical boundaries- the world is connected.

In the face of a public health catastrophe, COVID-19 offers a glimpse into the resilience and absorptive capacity of a place, but it also draws attention to the balancing act between the health sector and other internal and external socio-economic and political actors. Shared ecological surveillance, strong local to international partnerships, and political will for social protections can aid in addressing climate-health stressors (Ebi et al. 2013).

Since the Industrial Revolution, global temperatures have increased 1°C (2.5°F), a warming primarily driven by society’s fossil fuel addiction. In 2015, the Lancet sounded the alarm on climate change citing it as a medical emergency. Prolonged, more frequent heatwaves exacerbate pre-existing health conditions such as those pertaining to cardiovascular and respiratory disease. In a warmer world, evaporation increases and may modify water security risk. Toxic algae blooms and acidification of marine ecosystems threaten food security.

Climate change also shifts the distribution, range, and abundance of disease vectors such as the mosquito Aedes aegypti which can transmit West Nile, dengue, and yellow fever. While success has been made in reducing the impact of infectious disease, emerging and re-emerging diseases are not new, nor have they magically disappeared. Morens and Fauci (2013) suggest between 60-80% of these diseases originate in animals. New emerging and re-emerging diseases associated with landscape modification and habitat fragmentation heighten the probability for human-animal interactions (Patz et al. 2005).

Rapidly changing environmental conditions serve as a risk multiplier to public health. Contributing factors – microbial agents and pathogens, animal reservoirs, natural and social systems – highlight associated complexities of disease ecology. Additionally, environmental factors are dependent upon social determinants – economic stability, education and awareness, and the built environment. The Centers for Disease Control and Prevention (CDC) highlights a One Health framework that recognizes the connection between the health of people, animals, and the environment. In other words, a healthy individual and community depends on a healthy ecosystem.

Environmental change is presently impacting health in each of our project site locations. While these examples are geographically specific, other evidence exists with respect to the intertwined climate-health nexus.


Environmental stressors have impacted food security in Colombia. A decrease in the diurnal temperature range has optimized conditions for the development of a fungus which has contributed to a 31% decrease in coffee production (Avelino et al. 2015). Pests and diseases threaten the livelihood of 500,000 small-scale family farms. Crop management techniques are being developed in Colombia to safeguard not only the economic but also the cultural significance of these agricultural products. Elsewhere, Famine Early Warning Systems monitor and anticipate food insecurity issues.


In 2017, a resurgence of West Nile virus (WNV) was observed in southern Greece. The transmission occurred during mid-summer and early autumn when mosquitos are most active. While specific weather conditions influence the survival and reproductivity of the vector, future climate scenarios indicate these spatial-temporal domains will continue to shift, increasing strain on the Greek public health sector (Paz 2015). Epidemiological modelers should work with climate scientists to identify knowledge gaps and available datasets aimed to reduce the burden of past, present, and future risks associated with vector-borne diseases.

South Africa

In October 2019, as air temperatures approached 40°C (104°F) in parts of South Africa, Eskom Holdings SOC Ltd., the utility that generates 95% of South Africa’s energy, warned of more frequent rolling blackouts. A new Integrated Resource Plan was developed to identify necessary investments in the energy sector to meet forecasted demand. This partnership provides an example by which energy providers need to engage with emergency managers to reduce vulnerability associated with extreme heat and draws attention to the interconnectedness of health hazards beyond simply environmental conditions.

How Can We Absorb the Impacts of Climate Change?

Geospatial, environmental-related data can help inform decision makers about the absorptive and adaptive capacity of a place. Where are rapidly declining aquifers located? Why is faster deforestation taking place here but not there? How might sea level contribute to more flood events, or how will acidification modify vital marine ecosystems that many rely upon for food and economic way of life? Where might the next hotspot for emerging diseases be?

Remote sensing tools such as GRACE have aided our understanding of groundwater depletion, but this tool is just one piece of the Jenga puzzle. Recognizing that environmental factors are not the sole push factor for population displacement, working with other disciplines is essential. Through these partnerships, additional questions such as how does culture and traditional ecological knowledge (TEK) play a role? How many hospital beds are available? How much strain is placed on the energy grid? What type of medical services are available, and are these services equitable, safe, and accessible? What policies exist or should exist to improve absorptive capacity before, during, and after an environmental catastrophe?

Throughout this project, we expect to explore more of these questions in order to understand how climate stressors impact communities responding to any number of socio-economic or environmental crises.


· AT Editor (21 October 2019) Ramaphosa speaks out on Eskom power cuts as heat wave arrives. African Times

· Avelino, J., Cristancho, M., Georgiou, S., Imbach, P., Aguilar, L., Bornemann, G., ... & Morales, C. (2015). The coffee rust crises in Colombia and Central America (2008–2013): impacts, plausible causes and proposed solutions. Food Security, 7(2), 303-321.

· Centers for Disease Control and Prevention (2020) One Health. U.S. Department of Health and Human Services

· Ebi, K. L., Lindgren, E., Suk, J. E., & Semenza, J. C. (2013). Adaptation to the infectious disease impacts of climate change. Climatic Change, 118(2), 355-365.

· Ebi, K.L., J.M. Balbus, G. Luber, A. Bole, A. Crimmins, G. Glass, S. Saha, M.M. Shimamoto, J. Trtanj, and J.L. White-Newsome, 2018: Human Health. In Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II [Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, pp. 539–571. doi: 10.7930/NCA4.2018.CH14

· Gray, Ellen (31 March 2020) NASA, University of Nebraska Release New Global Groundwater Maps and U.S. Drought Forecasts.

· Integrated Resource Plan (October 2019) South Africa Department of Mineral Resources and Energy.

· Lindsey, R., Dahlman, L. (2020) Climate Change: Global Temperature. National Oceanic and Atmospheric Administration.

· Morens, D. M., & Fauci, A. S. (2013). Emerging infectious diseases: threats to human health and global stability. PLoS Pathog, 9(7), e1003467.

· Office of Disease Prevention and Health Promotion (2020) Social Determinants of Health

· Patz, J. A., Confalonieri, U. E. C., Amerasinghe, F. P., Chua, K. B., Daszak, P., Hyatt, A. D., ... & Vasconcelos, P. (2005). Human health: ecosystem regulation of infectious diseases. Ecosystems and Human Well-Being: Current State and Trends: Findings of the Condition and Trends Working Group of the Millennium Ecosystem Assessment, 391-415.

· Paz, S. (2015). Climate change impacts on West Nile virus transmission in a global context. Philosophical Transactions of the Royal Society B: Biological Sciences, 370(1665), 20130561.

· Watts, N., Adger, W. N., Agnolucci, P., Blackstock, J., Byass, P., Cai, W., ... & Cox, P. M. (2015). Health and climate change: policy responses to protect public health. The Lancet, 386(10006), 1861-1914.

· Wight, Andrew (15 July 2018) Colombia’s coffee is in danger. These scientists are fighting to save it. NBC News

· World Bank; CIAT; CATIE. 2014. Supplementary material to Climate-Smart Agriculture in Colombia. CSA Country Profiles for Latin America Series. Washington D.C.: The World Bank Group.

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