Global warming may increase undernutrition through the effects of heat exposure on people, according to a new study published this week in PLOS Medicine by Yuming Guo of Monash University, Australia, and colleagues.
It has been well documented that global warming will indirectly result in more undernourished people through threatening crop production in the long term. In the new study, researchers analyzed daily hospitalization data that covers nearly 80% of the population of Brazil, spanning the years 2000 through 2015. They studied the link between daily mean temperatures and hospitalization for undernutrition.
For every 1°C increase in daily mean temperature during the hot season, there was a 2.5% increase in undernutrition hospitalization (OR=1.025, 95% CI 1.020–1.030, p<0.001). People under age 19 years or over age 80 years with undernutrition were the most vulnerable to heat exposure. Overall, heat exposure was estimated to be responsible for 15.6% (95% CI 9.0–21.4) of undernutrition hospitalization during the study period. That fraction increased from 14.1% to 17.5% over the study period, during which time the mean temperature increased by 1.1°C.
"The possible pathways of this direct impact of heat might include reducing undernourished people's food intake, impairing their digestion and absorption function, and causing fluid and electrolyte disturbances," the authors say. "Global strategies addressing the syndemic of climate change and undernutrition should not only focus on food supply but also the prevention of heat exposure especially among the young and elderly people."
Xu, R. et al. (2019) The association between heat exposure and hospitalization for undernutrition in Brazil during 2000−2015: A nationwide case-crossover study. PLOS Medicine. doi.org/10.1371/journal.pmed.1002950