Editing IPCC:AR6/WGII/Chapter-16 (section)

===== 16.5.2.3.6 Risk to food security (RKR-F) =====

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Climate change affects food security primarily through impacts on food production, including crops, livestock and fisheries, as well as disruptions in food supply chains, linked to global warming, drought, flooding, precipitation variability and weather extremes ( [[#Myers--2017|Myers et al., 2017]] ; [[#FAO--2018|FAO et al., 2018]] ; [[#Mbow--2019|Mbow et al., 2019]] ). This RKR builds on Key Risks identified primarily in the Food, Fibre and Other Ecosystem Products Chapter, some sectoral (Health), and regional (Africa, Australasia, Central and South America, North America) chapters, as well as SR15, SRCCL and SROCC.

The severity of the risk to food security is defined here using a combination of criteria including the magnitude and likelihood of adverse consequences, affecting tens to hundreds of millions of people, timing of the risk and ability to respond to the risk. In this assessment, we use the number of undernourished people as a proxy outcome of these dimensions and their multiple interactions.

Climate change will pose severe risks in terms of increasing the number of undernourished people, affecting tens to hundreds of million people under High vulnerability and High warming, particularly among low-income populations in developing countries ( ''high confidence'' ). Extreme weather events will increase risks of undernutrition even on a regional scale, via spikes in food price and reduced income ( ''high confidence'' ) ( [[#FAO--2018|FAO et al., 2018]] , Hickey and Unwin, 2020; [[#Mbow--2019|Mbow et al., 2019]] ). The timing of these impacts and our ability to respond to them vary based on the level of GHG emissions and Shared Socioeconomic Pathways (SSP).. Under a low vulnerability development pathway (SSP1), climate change starts posing a moderate risk to food security above 1°C of global warming (i.e., impacts become detectable and attributable to climate-related factors), while beyond 2.5°C the risk becomes high (widespread impacts on larger numbers or proportion of population or area, but with the potential to adapt or recover) ( [[#Hurlbert--2019|Hurlbert et al., 2019]] ). Under high vulnerability–high warming scenario (i.e., SSP3-RCP6.0), up to 183 million additional people are projected to become undernourished in low-income countries owing to climate change by 2050 ( [[#Mbow--2019|Mbow et al., 2019]] ). Climate-related changes in food availability and diet quality are estimated to result in a crude mortality rate of about 54 deaths per million people with about 2°C warming by 2050 (SSP2, RCP8.5), most of them projected to occur in South and East Asia (67–231 deaths per million depending on the country) ( [[#Springmann--2016|Springmann et al., 2016]] ). In a medium vulnerability–high warming scenario (SSP2, RCP6.0), [[#Hasegawa--2018|Hasegawa et al. (2018)]] project that the number of undernourished people increases by 24 million in 2050, compared with outcomes without climate change and accounting for the CO 2 fertilisation effect. This number increases by around 78 million in a low-warming scenario (RCP2.6) accounting for the impacts of both climate change and mitigation policies. Caveats to these modelling studies are that most models (crop models in particular) are designed for long-term change in climate but not suited to project the impacts of short-term extreme events. The inclusion of adaptation measures into modelling estimates remains selective and partial.

Climate change risks of micronutrient deficiency will become severe in high-vulnerability development pathways and in the absence of societal adaptation, leading to hundreds of millions of additional people lacking key nutrients for atmospheric CO 2 levels above 500 ppm ( ''high confidence'' ) ( [[#Myers--2017|Myers et al., 2017]] ; [[#Nelson--2018|Nelson et al., 2018]] ; [[#Mbow--2019|Mbow et al., 2019]] ). For example, concentration of many micronutrients (e.g., phosphorus, potassium, calcium, sulphur, magnesium, iron, zinc, copper and manganese) can decrease by 5–10% under atmospheric CO 2 concentrations of 690 ppm (3.5°C warming). The decline in zinc content is projected to lead to an additional 150–220 million people affected by zinc deficiency with increases in existing deficiencies in more than 1 billion people ( [[#Myers--2017|Myers et al., 2017]] ). Similarly, decrease in protein and micronutrient content in rice due to a higher CO 2 concentration (568–590 ppm) can lead to 600 million people with rice as a staple at risk of micronutrient deficiency by 2050 ( [[#Zhu--2018|Zhu et al., 2018]] ). Additionally, the impact on protein content of increased CO 2 concentration (&gt;500 ppm) can lead an additional 150 million people with protein deficiency by 2050 (within the total of 1.4 billion people with protein deficiency) in comparison with the scenario without increased CO 2 concentration ( [[#Medek--2017|Medek et al., 2017]] ).

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