By 2030, Nearly 100,000 Additional Child Deaths From Undernutrition Will Occur Due to Climate Change

Most public discussion has been slow to connect the dots between climate change, food and health.

Photo Credit: Riccardo Mayer/Shutterstock

The following excerpt is from Climate Change and the Health of Nations: Famines, Fevers, and the Fate of Populations, by Anthony J. McMichael with Alistair Woodward and Cameron Muir. Copyright © 2017 by Oxford University Press and published by Oxford University Press. All rights reserved.

Food shortages, undernutrition, and starvation have been the great killers throughout agrarian history—literally the grim reaper. Many of those crises and famines were triggered or amplified by natural climatic changes. Yields of food and flows of freshwater are highly dependent on temperature, rainfall, and other climatic conditions, and irrigation systems and water-flow management are crucial to food security in many parts of the world. Much of sub-Saharan Africa, where most agriculture still depends on rainfall, is already prone to sporadic food shortages and hence to illnesses, deaths, and civil conflict. That region’s general vulnerability to future climate change is therefore very high.

But the causal chain gets more complex. Since food yields are affected by many other factors, including soil degradation, groundwater shortage, pest infestations, and the diversion of harvests into biofuel production, estimating what proportion of an observed change in food yield is due to regional climate change can only be approximate, even though the fact of that change occurring is of crucial importance to human health, social stability, and geopolitical security. As world food prices escalated during 2008, the World Food Program drew attention to the likely contribution of recent adverse climatic influences on food yields. Subsequently, there has been a growing recognition that climate change and extreme weather events are affecting food yields in some regions and that this threatens nutritional sufficiency, child development, general health and vitality, and, in the extreme, survival. Yet most public discussion has been slow to connect the dots between climate change, food yields, and human health. Many economists, politicians, and food corporations still view agricultural production primarily as an economic entity rather than as something that humans must find or produce to ensure their health and survival. “Food” has become increasingly marketized.

The general connection between climate-related changes in regional or local food availability and human nutritional needs and health outcomes is understood generically, but quantifying it—especially in relation to future circumstances—is a challenge. The work of one research group, at the London School of Hygiene and Tropical Medicine, illustrates how we might grasp this nettle. Using a multistep linked model, they estimate that for a medium greenhouse warming scenario there would be an additional 95,000 child deaths from undernutrition in 2030, compared to a world in which there was no climate change. All such modeling must take account of the known or likely nonlinear relationships that characterize how plants and livestock respond to climate, many relationships being of “Goldilocks” form. Assumptions of straight-line relationships are often inappropriate. For example, when rainfall is either too low or too high, the concentration of trace elements and other minerals in soil tends to be low and plant growth is impaired. Dry soils cannot dissolve minerals from rocky formations, and very wet soils leach out much of the mineral content. With these cautions noted, studies such as the assessment by the London School nevertheless provide policy-useful estimates of where trends and risks are heading—a cut above reliance on soothsayers or techno- triumphalist reassurances.

An impaired food supply follows upon reduced water sufficiency and quality. Freshwater is essential to health and survival, for many reasons beyond its fundamental influence on food yields. Water is essential for safe drinking, basic personal hygiene, sanitation, and wastewater management. Water in excess, as with flooding, will often contaminate local drinking water and vegetable gardens and exacerbate outbreaks of cholera, dysentery, and other diarrheal diseases, especially in poorer communities. Diarrheal diseases are ready targets of climate change, since currently a little over half of all diarrheal deaths are due to lack of adequate drinking water, sanitation, and hygiene.

On a larger scale, cross-border tensions are likely if river flows recede as regional rainfall or mountain snowpack declines and if upstream water diversion reduces downstream supply. These adversarial situations can easily translate into hunger, conflict, displacement, and their many health consequences. In South Asia and Southeast Asia, many of the great rivers that flow off the northern slopes of the Himalayas are destined to have lower flows as mountain glaciers melt. As national water shortages escalate, these rivers are liable to be dammed as they flow off the Tibetan plateau, disrupting downstream irrigation, river ecosystems, and fish yields. The long-standing seasonal rhythm in the Mekong River flow is crucial to the two-way inflow and outflow hydraulics and ecology of the remarkable Tonle Sap lake system in Cambodia, the main source of the nation’s freshwater fish catch.

Finally, the influence of climate on cholera has a further, intriguing dimension. Outbreaks in coastal Bangladeshi communities often occur during episodes of warming of coastal water. The warmer water and its nutrient eutrophication by nitrogen- and phosphorus-enriched agricultural and wastewater runoff stimulate algal blooms. Algae serve as hosts for quiescent cholera bacteria in the natural watery ecosystem, and during algal blooms those bacteria are ingested by algae-feeding fish. As the cholera bacteria pass up the food chain, the larger infected fish then become hazardous food for coastal communities.

From CLIMATE CHANGE AND THE HEALTH OF NATIONS: Famines, Fevers, and the Fate of Populations by Anthony J. McMichael with Alistair Woodward and Cameron Muir. Copyright © 2017 by Oxford University Press and published by Oxford University Press. All rights reserved.


Anthony John McMichael (1942-2014) was an Australian epidemiologist who retired from the Australian National University in 2012.

Alistair Woodward is Head of Epidemiology and Biostatistics at the University of Auckland. He was Head of the School of Population Health at Auckland from 2004-2012 and previously he led departments of public health at the University of Otago Wellington and the University of Adelaide. He co-led the writing of the health section of the 5th assessment report for the Intergovernmental Panel on Climate Change.

Cameron Muir is an environmental historian. He maintains the Australian & New Zealand Environmental History Network and the Centre for Environmental History websites.

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