Climate change often refers to an increase in greenhouse gas emissions. It causes a long-term change in the average weather patterns: increased global average temperature, changes in rainfall patterns, and more frequent and intense flooding and droughts (Lieber, Chin-Hong, et al. 2020).
Climate change also affects human health in several different ways. A few of them are reduced crop production, increased heat strokes, changes in access to fresh water, violence in areas with reduced resources, and reduced aquatic ecosystem productivity.
By reducing crop production, climate change aggravates malnutrition, particularly undernutrition and micronutrient deficiencies that lead to underweight, wasting, and stunting. In 2000, climate change caused 154,000 deaths, half of which were due to malnutrition.
Since 2000, several studies have assessed the impact of climate change-aggravated malnutrition on children and adults in many parts of the world.
For example, Singh et al. 2006 found that 2003-drought in India caused 10% of childhood stunting, which was significantly more than 1.6%, the National Institute of Nutrition found, during a previous non-drought period (Singh, Fotedar, et al. 2006).
Four flood studies, as described in del Ninno & Lundberg 2005, found that decreases in rice production were partially responsible for increased levels of stunting among 4,433 Bangladeshi children following a devastating flood in the summer of 1998 (del Ninno and Lundberg 2005).
On average, children who experienced more rainfall had height-for-age z-scores that were 0.32-0.87 lower than children who experienced an average amount of rain during the rainy season found Skoufias & Vinha in 2012 (Skoufias and Vinha, 2012).
Drought caused a higher level of childhood mortality and undernutrition in rural areas and a higher prevalence of underweight among children in semi-urban areas (i.e., near towns) in sub-Saharan Africa (De Waal et al., 2006; Mason et al., 2005).
In Hossain et al. (2013), the prevalence of underweight among children in severely flood-affected regions of Pakistan (46-48%) was also higher than in moderately affected areas (39%−40%) (Hossain, Talat, et al. 2013).
In Islam et al. (2014), the underweight prevalence was 21.6% in the flood-affected areas of Assam, India, compared to 13.7% in non-flooded areas (Islam, Mahanta, et al. 2014).
In 2014, The World Health Organization (WHO) projected that malnutrition would be the most significant contributor to morbidity and mortality due to climate change (WHO 2014). Though childhood malnutrition has decreased over the past several decades globally, there has been an increase in global undernourishment since 2015, partly associated with climate and extreme events (FAO 2018).
In 2016, while investigating the relationship between climate variables and childhood malnutrition, Sorgho et al. found that malnutrition is a leading cause of death in children in low- and middle-income countries. Annually, 6.9 million deaths of children under 5 were attributable to malnutrition directly or indirectly (Sorgho, Franke, et al. 2016).
An important review examined the association between climate variability and childhood stunting and found that extreme weather events and fluctuations in temperature and precipitation were associated with childhood stunting (Phalkey, Aranda-Jan et al. 2015).
In another review, Lieber and co-authors, 2020, also found a strong positive relationship between climate change and malnutrition in children and adults (Lieber, Chin-Hong, et al. 2020).
Several factors are moderating the effects of climate and weather variability on malnutrition. Among children, those in the 1- to 2-year age group were found to be the most vulnerable to drought conditions.
Of these, changes in infancy feeding patterns during this period decreased crop production and an increased prevalence of infectious diseases such as HIV and malaria.
The mechanisms linking climate change and malnutrition have been explored in a recent study. The study finds that higher temperatures are an equal or even more significant contributor to child malnutrition and low-quality diets than poverty, inadequate sanitation, and poor education. The results were published online on 14 January 2021 in the journal Environmental Research Letters (Niles, Emery, et al. 2021).
The study, led by University of Vermont researchers, examines diet diversity and micronutrient intake among 107,000 children five and under in 19 countries in Asia, Africa, and South America.
Based on the intake of 10 types of foods:
1. Cereal grains.
2. White tubers and root foods.
3. Dark leafy greens.
4. Vitamin A-rich vegetable/tubers.
5. Vitamin A-rich fruits.
6. Other fruits and vegetables.
7. Meat and fish foods.
10. Milk and milk products,
The researchers made a 0 to 10 points scale. By counting the number of food groups eaten over a given period of the diet, the researchers calculated diet diversity.
They found that the children included in the study had eaten food from 3.2 food groups (out of 10)—including meat and fish, legumes, dark leafy greens, and cereal greens—in the previous 24 hours.
Five of the six regions examined–Asia; Central and South America; North, West, and Southeast Africa– had significant reductions in diet diversity associated with higher temperatures.
“A warming climate has the potential to undermine all the good that international development programs provide,” said co-author Taylor Ricketts, Director of UVM’s Gund Institute for Environment.
“In fact, that is something we find again and again in this global research: continued environmental degradation has the potential to undermine the impressive global health gains of the last 50 years.”