The global effect of extreme weather events on nutrient supply: a superposed epoch analysis

Caro S Park,Elisabeth Vogel,Leila M Larson,Samuel S Myers,Mark Daniel,Beverley-Ann Biggs

doi:10.1016/s2542-5196(19)30193-7

Abstract

To date, the effects of extreme weather events on nutrient supply within the population have not been quantified. In this study, we investigated micronutrient, macronutrient, and fibre supply changes during 175 extreme weather events within 87 countries in the year that a major extreme weather event occurred, with a targeted focus on low-income settings. We collected data from the International Disasters Database and the Global Expanded Nutrient Supply model for the period 1961-2010, and applied superposed epoch analysis to calculate the percentage change in nutrient supply during the year of an extreme weather event relative to its historical context. We composited globally and by subgroup (EU, landlocked developing countries, least developed countries, low-income food deficit countries, and net food-importing developing countries). Lastly, we reported nutrient supply changes in terms of recommended dietary allowance for children aged 1-3 years. Globally, all micronutrient supplies had a modest negative percentage change during the year of an extreme weather event; of these effects, those that reached an α=0·05 significance level included calcium, folate, thiamin, vitamin B6, and vitamin C, with nutrient supply changes ranging from -0·40 to -1·73% of the average supply. The effect of an extreme weather event was especially magnified among landlocked developing countries and low-income food deficit countries, with significant nutrient supply changes ranging from -1·61 to -7·57% of the average supply. Furthermore, the observed nutrient supply deficits in landlocked developing countries constituted a large percentage (ranging from 1·95 to 39·19%) of what a healthy child's sufficient average dietary intake should be. The global effects of extreme weather events on nutrient supply found in this study are modest in isolation; however, in the context of nutrient needs for healthy child development in low-income settings, the effects observed are substantial. Australian-American Fulbright Commission.

Highlights

Extreme weather events are defined as especially severe or unseasonal weather phenomena at the extremes of the historical distribution and rare for a particular place or time.[1]
Many studies have referred to extreme weather events threatening food security, in developing countries,[10,11,12] no study has yet quantified the global impact of extreme weather events on total nutrient supply
By further framing the nutrient supply reductions in terms of child recommended dietary allowances, we provided a practical, relevant, and important context for interpreting the results of this superposed epoch analysis

Summary

Introduction

Extreme weather events are defined as especially severe or unseasonal weather phenomena at the extremes of the historical distribution and rare for a particular place or time.[1]. Understanding historical nutrient supply fluctuations caused by extreme weather events will inform future estimates of nutritional impacts in the aftermath of such events. To this end, it is necessary to acknowledge the socioeconomic factors—such as human geography, economic development, and governance structure— that modulate a nation’s response to extreme weather events.[17,18,19,20,21,22] Recovery is difficult in low-income settings, where infrastructure maintenance and equitable food distribution are challenges even in fair weather. A vast majority of the world’s 821 million undernourished people and 50·5 million children under 5 affected by wasting (low weight for height) reside in low-income countries, and they stand to lose the most from further nutrient supply fluctuations.[23]

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