ding:
- Inadequate nutrition can permanently affect the physical and mental development of children. In the US, low iron levels are experienced by one of out of every five children for part of their childhood (Irwin and Jeffrey 2001).
- Low iron levels have been associated with decreased cognitive function (Jáuregui-Lobera 2014), reduced work capacity (Haas and Brownlie 2001), decreased quality of life, and reduced life expectancy (Shander et al. 2014).
- Reduced protein decreases muscle mass.
- Undernourished people have greater difficulty fighting infections.
- Severe zinc deficiency can cause diarrhea, weight loss, skin lesions, and decreased immunity (NCHS undated).
Climate Impacts on Food Availability and Nutrition
Food and nutrition concerns resulting from a warming world could outweigh all other human health impacts brought on by climate change (Springmann et al. 2016). Examples include:
- Elevated CO2 levels can reduce the protein and micronutrient concentration in grains, putting larger swaths of the global population at risk for malnutrition and anemia (Medek et al. 2017; Smith and Myers 2018; Uddling et al. 2018).
- Increased temperatures, both modest and extreme, can lower crop yields (Zhao et al. 2017; Vogel et al. 2019), as can drought (Lesk et al. 2016) and extreme weather events (Nelson et al. 2014).
- Increased food prices are an economic result of lower crop yields, making some foods less available to those who may already be undernourished. Increased food prices disproportionately affect lower income people (Lake et al. 2012).
- Montana has seen longer growing seasons, offset by summers becoming hotter and drier. Hence, it is hard to project whether local food production will increase.
Climate change can also lower the overall quantity of food produced, resulting in multiple impacts including to traditional sources for American Indians (Zhao et al. 2017; Gowda et al. 2018b; see Section 4 sidebar: Changes Rippling Through Our Lives and Waters). The salt content of underground water sources (aquifers) and coastal lands globally is increasing due to greater withdrawal of groundwater and sea-level rise, making these regions less productive or non-productive. Some pests and weeds that lower the productivity of food crops can thrive better in a CO2-enriched atmosphere (Deutsch et al. 2018; Ziska et al. 2019). Increasing extreme weather (e.g., flood and precipitation events), growing season drought, and increasing fire severity can also be a detriment to food production.
Food and nutrition concerns resulting from a warming world could outweigh all other human health impacts brought on by climate change (Springmann et al. 2016).
Livestock, not just plants, are impacted by climate change. Milk production decreases as dairy cows are exposed to increased heat (reviewed in Whitlock et al. 2017; Summer et al. 2018). Deaths in all animals, including livestock, increase with excessive heat, and animals with dark coats are more sensitive to extreme heat. Heat waves make livestock less fertile (Takahashi 2012). Extreme weather events, such as flash floods and drought, also lead to increased animal mortality.
Vectors—primarily arthropods such as ticks, mosquitoes and fleas—are organisms that transmit diseases from one host to another. Globally, vector-borne diseases include Zika, plague, dengue, malaria, yellow fever, Chagas disease, and Chikungunya, among others. In the US, Rocky Mountain spotted fever, Lyme disease, and anaplasmosis, all carried by ticks, and West Nile virus, transmitted by mosquitoes, are most prominent. Zika, dengue, Chikungunya, and Eastern Equine Encephalitis are also of concern.
Overall, climate change is expected to increase the range of vectors, primarily ticks and mosquitoes in the US, thereby increasing the number of people exposed to the diseases that these arthropods transmit (Beard et al. 2016; Sonenshine 2018). Recent work by Rosenberg et al. (2018) shows that the number of vector-borne diseases tripled in the US between 2004 and 2016, with over 100,000 cases reported in 2016. Whereas the