A/70/287 number of diseases worldwide). Heavy rainfall ma y also be linked to lower quality of crops owing to fungal infections. Over time, climate change is set to reduce food quality, decrease water availability and aggravate the prevalence of infectious vector-borne diseases and chronic intestinal infections, while food storage will also become problematic owing to warmer weather. It is estimated that 50 -60 per cent of the world population will be exposed to dengue fever by 2085, further degrading their nutritional status. 10 17. Moreover, childhood undernutrition and stunting will increase, provoking a rise in nutrition-related deaths in children in developing countries. Calorie availability in 2050 is likely to decline throughout the developing world, resulting in an additional 24 million undernourished children. It is expected that health losses will occur mainly in areas that are already food insecure. Climate change exacerbates undernutrition and undermines efforts to reduce poverty and resilience, particularly in sub-Saharan Africa. A recent drought-triggered famine in Somalia spurred food crises in neighbouring countries, illustrating the possible consequences of more frequent extreme weather events. 11 18. Adaptation and mitigation strategies should address these challenges. So far, no broadly accepted and comprehensive analytical frameworks have been developed that analyse the impacts of climate change on food security and nutrition. Sustainability 19. While not specifically enunciated in general comment No. 12 (1999), sustainability is linked to hunger-reduction strategies and policies as it places emphasis on the principles of participation, non-discrimination, transparency and empowerment. 20. Sustainability is defined in connection with the notion of adequate food or food security, implying that food will be accessible for both present and future generations. Food sustainability and security are also dependent on an adequate diet, clean water, sanitation and health care, to reach a state of nutritional well -being where all physiological needs are met. 12 21. The Intergovernmental Panel on Climate Change predicts with medium confidence that droughts will intensify in the twenty-first century, owing to reduced precipitation and/or increased evapotranspiration. Water is crucial to food security, as it is necessary for food production, preparation and processing, as well as the absorption of nutrients within the human body. 22. Freshwater sources include rainwater, surface water and groundwater, all of which are crucial to food security. When rainfall is insuffi cient, agriculture relies on irrigation. As some 40 per cent of all irrigation relies on groundwater sources, 13 __________________ 10 11 12 13 6/25 Partnership for Maternal, Newborn and Child Health, “Protecting women and children’s health from a changing climate”, Knowledge Summaries, No. 32 (April 2015). Available from www.who.int/pmnch/knowledge/publications/summaries/ks32.pdf?ua=1. M. C. Tirado and others, “Climate change and nutrition in Africa”, Journal of Hunger and Environmental Nutrition, vol. 10, No. 1 (March 2015). FAO, “Food security”, FAO Policy Briefs, No. 2 (June 2006). Available from www.fao.org/ forestry/13128-0e6f36f27e0091055bec28ebe830f46b3.pdf. Ibid. 15-10041