Speaker
Description
Keywords: Climate shocks, nutrient adequacy, double burden of malnutrition
Introduction: Climate change and food production are deeply intertwined. Roughly 25-30% of all greenhouse gas emissions stem from food systems (Poore & Nemecek, 2018). Simultaneously, climate change disrupts agricultural outputs through rising temperatures, shifting rainfall patterns, drought, storms, and more extreme weather events (Hansen et al, 2011; Fisher et al., 2015). These climate impacts cascade through agroecosystems, often destroying crops and altering pests, pathogens, and weed pressure on crops. Ongoing declines in pollinator populations, rising water scarcity, increasing ground-level ozone, and collapsing fisheries exemplify these complex dynamics (Altieri et al., 2015). The effects appear most severe in lower-income regions already facing food insecurity (IPCC, 2022). Numerous studies have traced sharp agricultural yield and food security drops to extreme weather events (Amare et al., 2018; Fanzo et al., 2018). However, research on subsequent impacts on nutrition security and potential mediating factors still needs to be conducted (McLaughlin et al., 2023). This knowledge gap is especially concerning for regions confronting the double burden of malnutrition. Closing it should be a top priority.
Objective: To assess how climate shocks alter diets - via macro- and micronutrient intake shifts - and investigate the drivers of these dietary changes.
Data and Methods: Our primary data source is the nationally representative Tanzania National Panel Survey (TNPS), spanning 2008-2019 across five waves. The survey comprises over 16,639 households and includes detailed modules on agriculture, livestock, community dynamics, and more. We supplement TNPS with food diaries from the Survey of Household Welfare and Labour to quantify consumption of various food groups and estimate intake levels of calories, macronutrients, and micronutrients. Households from the TNPS are linked with geospatial data on rainfall, temperature, and water scarcity to capture exposure to climate shocks.
Given its high double burden of malnutrition, rapidly growing urbanisation, diverse agro-ecological zones, and rainfed agricultural systems facing mounting climate risks, Tanzania provides an opportune setting. Much of the rural population relies on fisheries, also threatened by sedimentation and warming waters. Despite abundant water resources overall, spatiotemporal scarcity remains widespread.
We estimate the impact of climate shocks on macro- and micronutrient consumption via fixed effects regression, sequentially integrating covariates like socioeconomic status, agro-ecological zones, and explanatory mechanisms around yields, production, income, and livelihoods. Our approach controls for multiple hypothesis testing and cluster-robust standard errors. Robustness checks employ difference-in-difference models leveraging major weather events.
Findings: Our analysis reveals significant reductions in calorie intake and essential nutrient consumption for those exposed to climate shocks. However, the declines appear disproportionately concentrated in vitamins and minerals compared to calories and macronutrients. This implies households switch away from nutrient-dense foods like vegetables, fruits, and animal products towards calorie-dense staples in response to climate stresses. Investigating potential mechanisms, we find falling incomes, rising food prices, and reduced personal production primarily drive the changes in nutrient intake.
Crucially, it is important to note that our calculations likely underestimate the actual decline of nutrient levels in food. This is because increased levels of CO2 directly lead to a reduction in protein, iron, zinc, and other mineral concentrations in key crops such as wheat, rice, potatoes, and barley. Consequently, these staple foods may be less nutrient-dense than their current nutritional profiles suggest (Myers et al., 2014).
Conclusion: These findings carry important implications for regions like Tanzania confronting rising micronutrient deficiencies (Ameye, 2023) and nutrition-related non-communicable diseases (Bigna & Noubiap, 2019). Climate shocks not only reduce calories and macronutrients, but disproportionately diminish micronutrient intake through constrained access to produce, meats, fish and dairy. As fresh foods become costlier and less available, households increasingly rely on packaged and ultra-processed items. Such dynamics may further accelerate preferences for food-away-from-home (e.g., rapidly rising in Tanzania (Ignowski et al., (2023)), linked to higher saturated fat and sugar consumption plus escalating obesity and diabetes. Climate resilience and nutrition security demand integrated “double duty actions.” Alongside addressing hunger, solutions must encompass sustainable food systems, enhanced micronutrient density in staple crops, and reduced overconsumption - particularly of less healthy processed foods.
References:
Altieri, M.A., Nicholls, C.I., Henao, A. and Lana, M.A., 2015. Agroecology and the design of climate change-resilient farming systems. Agronomy for sustainable development, 35(3), pp.869-890.
Amare, M., Jensen, N. D., Shiferaw, B., & Cissé, J. D. (2018). Rainfall shocks and agricultural productivity: Implication for rural household consumption. Agricultural systems, 166, 79-89.
Ameye, H. (2023). Dietary quality in rural areas, secondary towns, and cities: Insights from Tanzania. Food Security, 15(6), 1563-1584.
Bigna, J. J., & Noubiap, J. J. (2019). The rising burden of non-communicable diseases in sub-Saharan Africa. The Lancet Global Health, 7(10), e1295-e1296.
Fanzo, J., Davis, C., McLaren, R., & Choufani, J. (2018). The effect of climate change across food systems: Implications for nutrition outcomes. Global food security, 18, 12-19.
Fisher, M., Abate, T., Lunduka, R. W., Asnake, W., Alemayehu, Y., & Madulu, R. B. (2015). Drought tolerant maize for farmer adaptation to drought in sub-Saharan Africa: Determinants of adoption in eastern and southern Africa. Climatic Change, 133, 283-299.
Hansen, J. W., Mason, S. J., Sun, L., & Tall, A. (2011). Review of seasonal climate forecasting for agriculture in sub-Saharan Africa. Experimental agriculture, 47(2), 205-240.
Ignowski, L., Belton, B., Tran, N., & Ameye, H. (2023). Dietary inadequacy in Tanzania is linked to the rising cost of nutritious foods and consumption of food-away-from-home. Global Food Security, 37, 100679.
IPCC (2022). Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. Cambridge University Press, Cambridge, UK and New York, NY, USA, 3056 pp.
McLaughlin, S. M., Bozzola, M., & Nugent, A. (2023). Changing Climate, Changing Food Consumption? Impact of Weather Shocks on Nutrition in Malawi. The Journal of Development Studies, 59(12), 1827-1848.
Myers, S. S., Zanobetti, A., Kloog, I., Huybers, P., Leakey, A. D., Bloom, A. J., ... & Usui, Y. (2014). Increasing CO2 threatens human nutrition. Nature, 510(7503), 139-142.
Poore, J., & Nemecek, T. (2018). Reducing food’s environmental impacts through producers and consumers. Science, 360(6392), 987-992.
