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The Lancet Planetary Health: Food, climate, greenhouse gas emissions and health

April 04, 2017

  • Feeding 1.64 billion by 2050: how small dietary changes could improve health, reduce water use and cut emissions
  • Small and medium farms are essential to sustain quality of global food supply
  • Drought in Western USA: study explores link between drought and harms to human health

Increasing temperatures, water scarcity, availability of agricultural land, biodiversity loss and climate change threaten to reverse health gains seen over the last century. Improved understanding of the links between health and environmental change, and potential adaption strategies will be important in order to safeguard human health and the health of the planet on which we depend.

By 2050, the world is estimated to need an increase of 70% in food availability. In the inaugural issue of The Lancet Planetary Health, two new studies look at the challenge of sustainable food production -- from healthy dietary changes to reduce water use and cut emissions, to global maps linking farm size and nutrient production.

A third study looks at the effect of drought on human health in western USA. Climate change is expected to increase the severity and frequency of droughts, but so far, little has been known about the direct effects on health.

The Lancet Planetary Health: Feeding 1.64 billion by 2050: how small dietary changes could improve health, reduce water use and cut emissions

Modifying diets by a few grams per day according to the composition of vegetables, fruit and meat could significantly reduce groundwater use in India, and help the country meet the challenge of feeding 1.64 billion people by 2050, according to a new study published in the first issue of The Lancet Planetary Health.

Overall, the changes to diets included reducing the consumption of wheat and poultry, increasing the consumption of vegetables and legumes, and switching to fruits like melon, oranges and papaya with lower water requirements in production. Not only could these changes help reduce groundwater use, they could also cut greenhouses gases and have a positive effect on health.

The multiple benefits -- across human and environmental health -- highlight the potential importance of dietary change as a means for tackling planetary health challenges.

In many parts of the world, freshwater sources are being depleted faster than they can be replenished and, under climate change, rainfall is likely to become increasingly unpredictable. As water availability declines and population increases, food systems around the world are put under significant pressure.

Previous studies have looked at the impact of diets, especially red meat, on greenhouse gases. But, the study published today demonstrates how diets could be optimised to improve both human and environmental health, and play an important part in developing resilient food systems.

The study looked specifically at India, where approximately half of the usable water is currently required for irrigation. The population of India is predicted to rise to 1.64 billion people by 2050, and in order to ensure enough freshwater is available, water use will need to be reduced by a third.

In this study, researchers looked at five typical dietary patterns in India and modelled how they could be optimised to reduce groundwater use, while meeting nutritional standards and maintaining overall energy intake. They also modelled the effect of these changes to human health and greenhouse gas emissions.

They found that modifying the average diet to increase fruit consumption by 51.5g per day and vegetable consumption by 17.5g per day, along with a reduction in the consumption of poultry of 6.8g per day could lead to a 30% reduction in freshwater use and a 13% reduction in dietary greenhouse gas emissions.

Dr James Milner, lead author from the London School of Hygiene & Tropical Medicine, UK, says: "Food systems worldwide are likely to face increasing pressure as populations increase and water availability declines. In India, the proportion of freshwater available for agricultural production may already be unsustainably high and water availability per person is likely to decline significantly over the coming decades. Our study is the first to investigate the potential of changing diets as a solution to decreasing freshwater availability and finds modest dietary changes could help meet the challenge of developing a resilient food system in the country." [1]

The study was funded by the Wellcome Trust.
[1] Quotes direct from author and cannot be found in the text of the Article

The Lancet Planetary Health: Small and medium farms are essential to sustain quality of global food supply

Small and medium farms produce more than half of the food globally, and produce the vast majority of food and nutrients in low income countries, according to a new study that maps global nutrient production from farms worldwide.

As the world moves towards large scale agriculture to meet the growing demands for food, the findings published in the first issue of The Lancet Planetary Health highlight the need for crop and livestock diversity, and investment in small and medium farm owners in low and middle income countries to sustain the quality and quantity of global food supplies.

Estimates suggest that by 2050, there will need to be a 70% increase in food availability to meet the demands of a growing population. But, the increase in volume alone will not guarantee human wellbeing. Food systems will need to produce food of high nutritional value and crops, livestock and fish must be diverse to ensure food security.

In this study, researchers estimate the relative contribution of small and large farms to the quantity and quality of food produced at a global scale. For the first time, they map how much calcium, folate, iron, protein, vitamin A, vitamin B12 and zinc is produced in farms of different sizes from 41 crops, 7 livestock products and 14 fish groups (see maps, figure 4).

Globally, more than half (51-77%) of the volume of major food groups (including cereals, livestock, fruits, pulses, roots and tubers and vegetable) are produced by small and medium farms, but there are regional differences. For instance, large farms (over 50 hectares) dominate food production in North and South America, Australia and New Zealand and produce 75-100% of all cereal, livestock and fruit in those regions. Small farms (under 20 ha) produce 75% of most food commodities in sub-Saharan Africa, South Asia, Southeast Asia and China. Areas with small and medium farms had greater agricultural diversity than areas with large farms. And, independently of farm size, areas with more diversity of production, also produce more nutrients.

Dr Mario Herrero, lead author from the Commonwealth Scientific and Industrial Research Organisation, Australia says: "Small and medium farms produce more than half of the food globally, and are particularly important in low income countries, where they produce the vast majority of food and nutrients. Large farms, in contrast, are less diverse but their sheer scale ensures tradable surpluses of nutrients available to parts of the world that need them most. A sustainable food system that meets the needs of a growing population means we must focus on quality as well as quantity, and it is vital that we protect and support small and medium farms and more diverse agriculture so as to ensure sustainable and nutritional food production." [1]


The study was funded by the Commonwealth Scientific and Industrial Research Organisation, Bill & Melinda Gates Foundation, CGIAR Research Programs on Climate Change, Agriculture and Food Security and on Agriculture for Nutrition and Health funded by the CGIAR Fund Council, Daniel and Nina Carasso Foundation, European Union, International Fund for Agricultural Development, Australian Research Council, National Science Foundation, Gordon and Betty Moore Foundation, and Joint Programming Initiative on Agriculture, Food Security and Climate Change Belmont Forum. Foundation, and Joint Programming Initiative on Agriculture, Food Security and Climate Change--Belmont Forum. [1] Quotes direct from author and cannot be found in the text of the Article.

The Lancet Planetary Health: Drought in Western USA: study explores link between drought and harms to human health

Unlike other extreme weather events such as heat waves or floods, the direct health effects of drought are poorly understood. Yet, in 2011-12, drought across western USA affected 150 million people, and climate change is expected to increase the severity and frequency of droughts.

In a new study published in the first issue of The Lancet Planetary Health, researchers looked at the link between drought in 618 counties in western USA and daily rates of hospital admissions for cardiovascular and respiratory illness and death among adults aged 65 and over during 2000-2013.

The classification of drought is complex -- it includes a gradual onset, is persistent, affects large geographical areas and it can be difficult to assess where one begins or ends. The researchers used data from the US Drought Monitor to identify periods of non-drought, periods of drought, and whether drought periods were worsening or improving. They further categorized worsening drought periods into low- or high-severity drought conditions.

Compared to non-drought periods, respiratory admissions were reduced during periods of drought, and there was no difference in rates of cardiovascular admissions or mortality between drought periods (over 150 days of consecutive drought) and non-drought periods.

The researchers then looked at periods of worsening drought and whether different regions were affected differently. They found that mortality was increased during periods of high-severity worsening drought and that the risk for both cardiovascular admissions and mortality was greatest in regions where drought was less frequent (eg. Upper Midwest or Washington, rather than California or the South West).

The increased risk was small, and because the study is observational it cannot confirm whether the link is causal or what the exact mechanism is. However, drought affects large populations and understanding the links between drought and human health is likely to become of increasing concern as climate change makes drought more common.

Dr Jesse Berman, lead author from Yale School of Forestry and Environmental Studies, USA, says: "Our study is one of the largest to explore the link between drought and human health and, as far as we know, the first to investigate cardiovascular and respiratory related admissions. Considering that drought is characterised by gradual onset and can last for extended periods of time, being aware of health risks could help authorities put preventative measures in place to protect people from the worse effects. But, much more research is now needed to explore these links." [1]


Study funded by the Yale Institute of Biospheric Studies, the National Institute of Environmental Health Sciences, the US Environmental Protection Agency.
[1] Quotes direct from author and cannot be found in the text of the Article

The Lancet

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