[Paper Review] Impact of the Ukrainian crisis on the global food security

Jean Cyrus de Gourcuff, David Makowski+2 more|arXiv (Cornell University)|Jan 24, 2023

Russia and Soviet political economy4 citations

TL;DR

This study uses a global wheat trade network model to quantify the cascading effects of a 50% reduction in Ukrainian wheat exports, estimating that 4.8 million additional people could fall below minimum dietary energy requirements. The model reveals that over 90% of the impact in the most affected countries results from indirect trade disruptions rather than direct export cuts.

ABSTRACT

Using global wheat trade data and a network model for shock propagation, we study the impact of the Ukrainian crisis on food security. Depending on the level of reduction in Ukrainian wheat exports, the number of additional individuals falling under the minimum dietary energy requirement varies from 1 to 9 millions, and reaches about 4.8 millions for a $50\%$ reduction in exports. In the most affected countries, supply reductions are mainly related to indirect trade restrictions.

Motivation & Objective

• To assess the global food security impact of a reduction in Ukrainian wheat exports due to the 2022 war.
• To quantify how trade shocks propagate through the global wheat trade network (GWTN) and amplify food insecurity.
• To distinguish between direct and indirect effects of export reductions on food availability in importing countries.
• To estimate the number of additional undernourished individuals resulting from supply chain disruptions under varying shock levels.
• To evaluate the structural resilience of the global wheat trade network under extreme export shocks.

Proposed method

• Constructed a Global Wheat Trade Network (GWTN) with 170 countries (nodes) and 4,950–5,690 directed, weighted edges representing annual wheat trade flows from 2010–2019 using FAO data.
• Classified countries into three types based on import behavior: direct importers, indirect importers via intermediaries, and mixed importers.
• Simulated a 50% export reduction from Ukraine using a recursive, proportional shock propagation mechanism through the network.
• Assumed inelastic wheat demand and no mitigation, redirecting all available wheat to domestic food supply in affected countries.
• Calculated total available calories per country using a conversion factor derived from national food balance sheets: $ C^{ ext{tot}}(t+dt) = C^{ ext{tot}}(t) + C^{ ext{cal}}(t) imes rac{1}{Q^{ ext{cal}}(t)} imes (I^{ ext{cal}}(t+dt) + P^{ ext{cal}}(t+dt) + ext{stocks} + ext{import error}) - C^{ ext{cal}}(t) $.
• Used a worst-case scenario assumption: if demand exceeds supply, all available wheat is allocated to domestic food supply, maximizing undernourishment estimates.

Experimental results

Research questions

• RQ1 What is the projected increase in undernourished individuals globally if Ukrainian wheat exports drop by 50%?
• RQ2 To what extent are food security impacts driven by direct export cuts versus indirect trade network propagation?
• RQ3 How does the structure of the global wheat trade network (e.g., number of importers, edge density, average trade volume) change under export shocks?
• RQ4 Which countries are most vulnerable to indirect supply chain disruptions from a Ukrainian export shock?
• RQ5 How does the magnitude of export reduction (from 10% to 100%) correlate with the number of additional undernourished individuals?

Key findings

• A 50% reduction in Ukrainian wheat exports leads to an estimated 4.8 million additional individuals falling below the minimum dietary energy requirement.
• Over 90% of the undernourishment impact in the most affected countries results from indirect trade disruptions rather than direct export cuts.
• The number of strictly importing countries increases from 39 to 100, and the average trade volume per relationship increases by 60% due to shock propagation.
• The global wheat trade network becomes structurally shallower, with more countries relying on fewer, direct trade links after the shock.
• The total number of undernourished individuals increases from 1 million (10% export drop) to 9 million (100% export drop), with a nonlinear relationship between shock size and impact.
• Countries like Yemen, Egypt, and Libya are highly vulnerable due to complex, multi-tiered import chains that amplify disruptions.