Assessing impacts to maritime shipping from marine chokepoint closures

Global supply chain disruptions caused by the six-day blockage of the Suez Canal in March 2021 and the reduction in shipping through the Bosporus Strait since the onset of the Ukraine War in February 2022 are recent demonstrations of the critical importance of marine chokepoints to international trade and thus global economic security. To better understand and anticipate effects of a chokepoint closure on global trade, we combine GIS data of international shipping lanes with 2019 bilateral trade data to estimate how the closure of each of eleven chokepoints could change trade flows through other chokepoints and between countries. Estimates from the closure scenarios reveal alternate-shipping route linkages between seven chokepoints whereby if one were closed for an extended period, trade through one or more of the others would change significantly. The estimates also underscore the economic importance of the Danish Straits, the Bosporus Strait, the Strait of Hormuz, and the South China Sea and East China Sea to those countries that must rely on these chokepoints for access to maritime trade. Moreover, the estimates project delays and shifts in coastal seaport activity that could lead to knock-on effects that disrupt global supply chains long after a chokepoint blockage is cleared.