Mechanisms underlying food insecurity in the aftermath of climate-related shocks: a systematic review

Food insecurity is prevalent, affecting 1·2 billion people globally in 2021. However, the effects of food insecurity are unequally distributed across populations and climate-related shocks threaten to exacerbate food insecurity and associated health consequences. The mechanisms underlying this exacerbation at the household level are largely unknown. We aimed to synthesise the available evidence on the mechanisms connecting extreme climate events to household-level food insecurity and highlight the research gaps that must be addressed to inform better food security and health policy. For this systematic review, a comprehensive literature search was done by a medical librarian in February, 2021 for articles about food security and climate-related shocks. Relevant publications were identified by searching the following databases with a combination of standardised index terms and keywords: MEDLINE, Embase, CINAHL, GreenFILE, Environment Complete, Web of Science Core Collection, and Global Health. Searches were limited to human studies published in English. Included studies measured food security outcomes using indicators developed by the UN Food and Agricultural Organization (ie, consumption patterns, livelihood change, malnutrition, and mortality) and explained the mechanism behind the household-level or population-level food insecurity. Purely theoretical, modelling, and review studies were excluded. Quality assessment was conducted using the appropriate Joanna Briggs Institute Critical Appraisal Tool. Data were analysed using thematic analysis of the categories of mechanism (interpreted using internationally accepted frameworks), risk and resilience factors, and author policy recommendations. We found a paucity of data with only 18 studies meeting criteria for inclusion out of 337 studies identified for full-text review. All the studies that were included in our analysis showed worse food security outcomes after climate-related shocks. Food availability was the most common mechanism cited (17 studies), although most studies addressed at least one additional mechanism (15 studies). Studies were of mixed methodologies with nuanced discussions of risk and resilience factors, and of policy recommendations. This systematic review shows that there is an incomplete assessment of food security at the household and community level after climate-related shocks in the literature and finds that food availability is the primary mechanism studied. The low number of studies on this topic limits subgroup analysis and generalisability; however, the good quality of the studies allows for important policy recommendations around improving resilience to climate shocks and suggestions for future research including the need for a more granular understanding of mechanisms and feasible adaptation solutions.