Climate change will affect health by impacting on water availability and food production

The increased prevalence and intensity of extreme weather events due to climate change is likely to increase the morbidity and mortality associated with these events. The changing patterns of infectious and zoonotic diseases will put millions of people at risk of new illnesses. Likewise, the negative effects of climate change on agricultural productivity and water availability will have drastic health implications across the globe.

Water scarcity

Glaciers provide fresh water for approximately 1.2 billion people. Global warming is causing nearly all of the world’s 60,000 glaciers to retreat. It is predicted that within the next 40 years around a quarter of those glaciers will be gone and by 2030 nearly half of the world’s population will be living in regions of water stress. The World Resources Institute has created global maps that illustrate the geographical spread and severity of water stress. The projected water risk in 2040 under the “business as usual” scenario as defined by the Intergovernmental Panel on Climate Change’s 5th assessment report is shown below.

Projected water stress in 2040 under “business as usual” scenario. Major food producing regions around the world are projected to experience extremely high water scarcity.

It is evident that the major food producing regions in all continents are at an extremely high risk of water stress. Currently, approximately 700 million people lack access to safe and affordable drinking water and more than 2 billion people lack adequate sanitation. This statistic is only likely to worsen with reduced water availability.

The projected water stress is likely to exacerbate the occurrence of prolonged droughts in many of the world’s great agricultural civilisations like Bangladesh, Vietnam, Egypt, and Iraq. Increased water stress in these regions will have myriad health risks from deprivation, displacement, and conflict that results from shortages of water. Insufficient access to clean water coupled with food insecurity as crop yields decline are likely to increase the burden of undernutrition, particularly among children.

Given that the early life environment affects health and social outcomes later in life, inadequate childhood nutrition will have lasting effects on educational attainment and labour productivity, trapping people in a cycle of transgenerational poverty and ill health. A positive relationship between rising temperatures and declining rainfall and childhood stunting has already been observed in Kenya since 1975, indicating that as projected warming and drying continue to occur, food yields and health of people will suffer.

Women carry jerry cans of water from shallow wells dug from the sand along the Shabelle River bed, which is dry due to drought in Somalia's Shabelle region
Women carry jerry cans of water from shallow wells dug from the sand along the Shabelle River bed in Somalia’s Shabelle region (2016) [Feisal Omar/Reuters; taken from]
Arjano Adoni, 30, was admitted to hospital after she started vomiting. The dry season is set to continue into April and there are warnings that if the rains fail, Somalia will be plunged into famine [Karel Prinsloo/UNICEF; taken from]
Reduced crop yields

One third of our land is projected to dry out by the end of this century. The United States of America, which produces 25% of the world’s grain supply, could experience up to a 50% loss in crop productivity by 2080. This would not only have dire consequences for food security in the USA, it would have serious implications for food availability around the globe. A systemic review of more than a thousand studies concluded that climate change is a threat to crop productivity in areas that are already food insecure. A relative increase in severe stunting of 31 – 55% across regions of sub-Saharan Africa and 61% in South Asia is projected to occur as a result of undernourishment; approximately 25 million children are expected to suffer undernutrition. Already, nations like China, Korea, and the middle-eastern oil producing countries are insuring their future by seeking investment opportunities for land and food in eastern Africa and other poorer regions of the world, which in turn is driving undernutrition and poverty in those regions.



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Lloyd SJ, Kovats RS, Chalabi Z. Climate change, crop yields, and malnutrition: development of a model to quantify the impact of climate scenarios on child malnutrition. Environ Health Perspect. 2011; 119(12): 1817-1823.

Nellemann C, MacDevette M, Manders T, Eickhout B, Svihus B, Prins AG et al (Eds). The environmental food crisis – The environment’s role in averting future food crises. A UNEP rapid response assessment [Internet]. United Nations Environment Programme, GRID-Arendal [cited 2017 Feb 19]. Available from:

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Smith KR, Woodward A, Campbell-Lendrum D,  Chadee DD, Honda Y, Liu Q et al. Human health: impacts, adaptation, and co-benefits. In: Field CB, Barros VR, Dokken DJ, Mach KJ, Mastrandrea MD, Bilir TE et al., editors. Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press; 2014, pp. 709-754.


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