6.5 What is the likely human impact?

6.5.1 Who and where will the negative impacts affect most?

Negative impacts by 2050 will impact poor people more


Assuming no adaption
Easterling, et al. (2007)

Some major global crop and livestock producing regions will experience negative impacts on productivity.

Based on expert judgement from lead authors of the IPCC reports, in 2007, most of the negative agricultural impact up to 2050 will affect poorer regions. Developed countries, typically in northern hemispheres, are expected to experience some positive impact, at least in the earlier half of the twenty first century. However, from a global food production perspective, many of the staple foods (cereals, grains, etc.) that all populations rely on, and that are traded globally, are produced in areas that may experience negative impacts. Increased climatic variability may be more damaging than gradual changes in temperature, per se.

How these impacts affect food security will depend on socio-economic factors and on the policies put in place to adapt to climate change.

6.5.2 What are the likely nutritional impacts?

Probable reduction in nutritional quality – will vary for different crops but the general trend is negative


Myers, et al. (2014)

The study (whose results are shown above), tested changes in nutritional quality for a variety of crops, in field experiments, under conditions of increased atmospheric CO₂, finding reductions in nutrients in most cases. Some crops showed less negative (and in some cases, positive) changes, but the nutritional quality of key crops such as wheat, rice and legumes is expected to suffer as a result of climate change.

Nutritional impacts: high degree of uncertainty and complexity

Increased concentrations of CO₂ have been linked to reduced protein content in some crops (e.g. wheat) and decreases in zinc, sulphur, phosphorus, magnesium, and iron in wheat and barley.

But these relationships are very complex and uncertain, and are likely to vary by region, and by crop type.

6.5.3 What are the likely economic impacts on food security?

Supply and price volatility will impact food insecure regions and net food importers

Food security has been defined by the United Nations Food and Agriculture Organisation as follows:

“food security exists when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food which meets their dietary needs and food preferences for an active and healthy life.”

(see Chapter 7 for more on food security).

How might climatic change impact food security?

  • Countries who are net food importers are particularly vulnerable.
  • Low-income economies that are net food importers could experience significant losses in food access through a double negative effect on
    • reduced domestic agricultural production
    • increased food prices on global markets.
  • Any increases in climate extremes will exacerbate the vulnerability of all food-insecure people, including urban citizens and rural smallholders.
  • With greater food insecurity, people may prioritise securing enough calories over accessing nutrient dense foods – with negative consequences for micronutrient deficiencies and childhood stunting.

Impacts of price increases will impact poorer regions more significantly


Poor people spend more of their budget on food.

This means less for education and health, increasing overall vulnerability.

Economist (2013)

The proportion of income that is spent on food varies widely across countries and within populations, and is linked to inequality of incomes. Populations who spend a high proportion of their income on food are more vulnerable to supply and price changes in food, but additionally have less disposable income to spend on, for example, education and health. They can also be more vulnerable to sanitation risks, lack of safe drinking water and related illnesses. This poverty trap exacerbates health outcomes; poorer populations are more food insecure and more vulnerable to connected health problems. For more on the impacts of poverty on health, in relation to food and nutrition, see Chapter 7.

Higher food prices could be beneficial to net food producers but many of the world’s poorest farmers are actually net food purchasers.