Quantifying global and regional food crises through cascade modeling of supply fragmentation

Food supply shocks, characterized by sharp declines in food availability, threaten global food security, particularly as supply chains become increasingly interdependent. While globally integrated trade networks in food, fertilizers, and agricultural inputs can buffer localized shortages from natural hazards, this interconnectedness creates structural vulnerabilities: when key trading partners withdraw or critical supply routes close due to conflict, political instability, or infrastructure collapse, dependent countries face abrupt supply disruptions with limited alternatives. Rising geopolitical tensions - from armed conflicts to trade wars and the formation of political blocs - are progressively fragmenting global food trade networks. Countries are increasingly restricting exports to secure domestic supplies, impairing trade infrastructure, and imposing trade barriers, creating compounding and cascading disruptions that extend far beyond direct conflict zones.
 
This study employs a global three-stage cascade network model to quantify food security vulnerabilities for eleven critical staple crops across countries and political-military-economic blocs. We model sequential disruptions in natural gas trade, the key pre-cursor for nitrogen fertilizer production, trade in fertilizer which in turn reduces crop production capacity, and trade in food products. Using spatially explicit shock response coefficients, we calculate production losses at each cascade stage and aggregate results by country and defined blocs.
 
Our findings reveal pronounced regional disparities in agronomic supply chain dependency and vulnerability. The Persian Gulf region depends almost exclusively on crop imports, while the Global South relies on crops and potassium fertilizers. The EU and G7 face primary vulnerability to natural gas supply disruptions, whereas Latin America is critically dependent on nitrogen fertilizer imports. African nations are exposed to both direct food import disruptions and potassium fertilizer scarcity. Simulated trade disruptions project regional crop availability losses ranging from 0 to 70 percent, with severe humanitarian implications. We find that in a fragmented world, countries are generally better off participating in alliances where trade supposedly persists and where there is more support from other members in case of an emergency. Critically, no country is immune to food security collapse regardless of development status; already vulnerable countries with existing food insecurities will be disproportionately affected, creating humanitarian emergencies requiring coordinated anticipatory response with long-term consequences for global stability.