periods of abnormally warm ocean temperatures - may have negative health effects on children who live in coastal communities in low- or middle-income countries, according to a study led by researchers at Penn State and the University of North Carolina at Chapel Hill.
The study - recently published in the Proceedings of the National Academy of Sciences of the United States of America - found that exposure to marine heat waves is associated with an increased risk of children experiencing acute malnutrition; thinness; chronic malnutrition, as indicated by low height for their age; and mortality.
Study co-author Brian Thiede, professor of rural sociology, of sociology and of demography in Penn State's College of Agricultural Sciences and director of the University's Population Research Institute, said this may be because fish are an important source of protein and micronutrients among many coastal populations, and marine heatwaves have the potential to hurt fish supply through changes in the range, nutrient quality and mortality among fish populations.
"Such disruptions can have direct impacts on food supplies and also may have secondary impacts by affecting income among fishers and food prices for consumers," he said. "These factors may shape households' ability to purchase food or to have the economic resources needed to access other critical services, such as healthcare."
Thiede added that the findings emphasize that climate change is affecting many Earth systems critical to human health and survival, including coastal communities that depend on the ocean for food or financial support.
"Researchers and practitioners should place renewed focus on coastal populations and better differentiate between the sources of vulnerability faced by coastal and inland populations," he said. "Coastal populations face unique climate-related risks due to their environment and livelihoods."
Marine heatwaves are increasing in both frequency and severity as global weather shifts with climate change, according to the researchers. These heatwaves can trigger many additional ecological changes, including those that directly affect human society, with coastal populations in low- and middle-income countries being particularly vulnerable.
Thiede said attention to the human health impacts of these marine heat waves is important for several reasons, including the fact that, globally, human populations tend to be concentrated in and around coastal environments.
"Ocean temperatures are warming rapidly, making these heat waves more common and severe," he said. "Additionally, poor health has widespread and multidimensional consequences, from the immediate human costs of illness and death to adverse impacts on education and employment that can slow economic growth in poor countries."
For the study, the researchers linked nationally representative data on children's and women's health and survival from more than 9,800 coastal sites in 36 low- and middle-income countries to global data on sea surface temperatures.
Next, they identified marine heat waves that occurred in ocean waters near individuals in the months and years prior to when their health was measured. The team then applied statistical techniques to isolate the relationship between marine heat wave exposure and health and survival outcomes.
The team found that a standard-deviation increase in the number of heatwaves over the two-year period increased the odds of child mortality by 5.4%, child wasting - or being too thin for their height - by 6.5% and child stunting - or being too short for their age - by 8.8%.
The researchers also found that these impacts are largest in countries dependent on small-scale fishing - versus more industrialized, commercial sectors - and in urban areas.
"While the impacts in urban areas may be somewhat unexpected, it is consistent with fairly widespread evidence that city-dwelling populations can be quite vulnerable to environmental change," Thiede said. "Their populations may be less involved in agriculture and aquaculture than rural populations, but they may still be vulnerable to shocks through market mechanisms, such as increases in fish prices."
The researchers said the findings suggest the need to target populations affected by marine heatwaves with nutrition-improving interventions or other safety net programs. Practitioners might also use marine temperature forecasts in their early-warning systems to anticipate where resources will need to be allocated. They added that more research focusing on the links between climate change and health in coastal areas also is needed.
Clark Gray, Sally Dowd, Noah Shaul and Janet Nye, all of the University of North Carolina at Chapel Hill, co-authored the paper.
This research was supported by the National Institutes of Health's (NIH) Eunice Kennedy Shriver National Institute of Child Health and Human Development under grant number R03HD101859 and benefited from infrastructure support from Penn State's NIH-funded Population Research Institute. This content is solely the responsibility of the authors and does not necessarily represent the official views of the funders.
