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The climate change threat to nutrition

However, an area that does not attract much attention in the media or in public debates is the threat to nutrition security that is posed by climate change.

Published: 14th December 2019 04:00 AM  |   Last Updated: 14th December 2019 01:23 AM   |  A+A-

amit bandre

As the climate change debate heats up globally, thanks to the sharp jabs to humanity’s conscience by the accusatory advocacy of young people like Greta Thunberg (may her voice ring ever sharper), several health hazards associated with global warming also form a part of the voiced concerns. Severe heat effects, dangers to life posed by extreme weather events, spikes in vector-borne and water-borne diseases, a variety of chronic diseases and mental health disorders are listed in the catalogue of threats to human health that climate change will visit on a culpable humanity that has flagrantly violated the boundaries of environmental stability.

However, an area that does not attract much attention in the media or in public debates is the threat to nutrition security that is posed by climate change. Often buried behind the outrage and anxiety over melting glaciers, forest fires and flash floods, health effects do not receive much attention. Even when they do, the impact on agriculture and food systems, and further downstream impact on human nutrition is not adequately highlighted. Yet, that remains an imminent threat that we can scarcely ignore.

As we advance to 2050, the global demand for food will rise due to several factors. A growing global population will have more mouths to feed. The changing demographic profile will see less children and more adults and elderly, who require more food per capita than a young child. Longer life expectancy also means more years that they will need food.

Urbanisation, which is usually accompanied by increased food consumption, will be a progressive feature of this century. Rising incomes, with higher purchasing capacity, will also raise the demand for food as poverty diminishes with economic growth. Due to these multiple drivers, the demand for food is expected to increase by 60% to feed the anticipated global population of 9 billion in 2050. 

On the other hand, the availability of food will fall, mainly due to climate change, which affects both the quantity and quality of food produced and marketed. It has been estimated that the demand for food will grow by 10% per decade while its production will fall by 2% per decade. Even tech innovations that markedly boosted agricultural productivity per unit of land in the past half-century will yield diminishing returns.

Climate change acts through the impact of heat stress and water stress on crops, while offering a suitable temperature for pests. Many crops are heat sensitive, with low yields at high temperatures and are also water stressed when climate change affects rainfall and availability of water for irrigation. Both staples and non-staples are affected by climate change.

Even at present, rice and wheat are being grown at the upper limits of heat tolerance in many parts of South Asia. It has been predicted that a one degree further rise in temperature can lead up to 10% yield loss. Due to the effect of heat alone, yield losses predicted for rice and wheat are 6.6% and 9.1% respectively. The additional effect of increased pest-induced loss in hotter climates will be 2% and 1.6% for rice and wheat respectively. Non-cereal crops would suffer too. Fruits would ripen and rot early in excess heat. 

Many nutrient crops would have 3-17% lower concentrations of protein, iron and zinc. It has been projected that by 2050, India would experience a 2.9% increase in zinc deficient population (with 49.6 million new zinc deficient people) and a 2.2% rise in protein deficient population (with 38.2 million new protein deficient people). About 106.1 million children and 396 million women would become iron deficient.

Increased water scarcity and warming will also affect nutrition security. As water stress adds to heat stress to reduce the quantity and quality of land crops, even aquatic life will be affected. Since 1996, marine fish catch has fallen at an annual rate of 1.22 metric tonnes around India’s 7,000 km coastline. Ocean warming is predicted to impact fish diversity, distribution, abundance and phenology. Salinity of fresh water rises with the warmed seas to mix with the feeding rivers to impede agriculture. Increased salinity is affecting paddy farming and fishing in the Sunderbans, leading to climate refugees.

Agriculture and food systems also contribute to climate change, through methane-emitting livestock, deforestation and excessive water use. Globally, food systems are responsible for 29% of total greenhouse gas emissions; agriculture accounts for 70% of the world’s water use and 80% of global deforestation. Agriculturally motivated Amazon forest fires are a glaring example. We need to move from meat-based diets to plant-based diets and adopt farming methods that yield more nutrient crops per unit investment of land, water and energy. 

Apart from striving to stall or slow down climate change (mitigation), we also need to diversify farming in favour of more climate resilient crops. A recent report from the Data Science Institute at Columbia University estimates that replacing rice (a water intensive crop) with nutrient-rich but less-water-intensive crops like millets and sorghum would make India’s food supply more nutritious while reducing irrigation demand, energy use and greenhouse gas emissions. The study concludes that such crop diversification would also enhance India’s climate resilience without reducing calorie production or requiring more land use. 

Even though India’s per capita contribution to global warming is not high, we will undoubtedly be among the worst victims of climate change. This will be especially threatening to the nutrition security of our large population, with negative consequences for our economic growth and social stability. We must adapt our agriculture and food systems to recognise that reality and adopt climate smart diversification.

K Srinath Reddy
President, Public Health Foundation of India, and author of Make in India: Reaching a Billion Plus. Views expressed are personal Email: ksrinath.reddy@phfi.org



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