Cascading Risk Propagation in Global Sulfur Trade Networks: A Directed Weighted Complex Network Model for Systemic Risk Management

Globalized production and trade have knitted national economies into a tightly coupled interdependent network, in which a localized shock can propagate through dependency links and escalate into a systemic event. Sulfur underpins phosphate fertilizer and the clean-energy transition, yet the global sulfur trade network is concentrated, heavily import-dependent, and exposed to geopolitical chokepoints. Based on the global sulfur trade data from UN Comtrade from 2015 to 2024, we construct a directed weighted complex network and introduce the cascading failure model to systematically explore the topological evolution laws of the sulfur trade network and the dynamic propagation mechanism of supply risks. Three results emerge: First, although the total trade volume grew by 129%, the network contracted sharply after 2022, indicating a rising concentration of trade relations and, potentially, higher systemic exposure. Second, avalanche sizes follow a heavy-tailed distribution in which Russia is the dominant systemic risk source, and Turkey is a secondary amplifier, while the largest exporter—the United Arab Emirates—transmits risk mainly through indirect contraction. Third, the model is calibrated against the 2022 Russia–Ukraine shock (R2 = 0.8928). The framework offers a quantitative tool for identifying systemically important nodes and for scenario-based preparedness planning in commodity trade networks.