The growing importance of global trade in agricultural commodities has increased the risks of disruption at key transport "chokepoints", potentially triggering food price surges.
The Panama Canal and the Strait of Malacca are among 14 of the world's critical junctures through which significant amounts of grains and soyabeans trade pass, according to a report from Chatham House.
"A serious interruption at one or more of these chokepoints could conceivably lead to supply shortfalls and price spikes, with systemic consequences that could reach beyond food markets," warns the report.
The dangers of food price volatility were highlighted in the 2007-08 food crisis, which resulted in protests and riots in almost 100 countries. The grain export bans in the Black Sea region in 2010-11 contributed to unrest in north Africa as well as the Arab Spring.
Global food security depends on trade in four staple crops — corn, wheat, rice and soyabeans — output of which is concentrated in a handful of exporting "breadbasket" countries including the US, Brazil and the Black Sea region.
With global trade in food commodities expanding 127 per cent to 2.2bn tonnes between 2000 and 2015, and rates of growth projected to continue to rise, the dependency on the chokepoint transit routes was likely to increase for the foreseeable future, according to Chatham House.
Laura Wellesley, one of the report's authors, said the risks and vulnerabilities of key physical "chokepoints" in the global food trade had previously been ignored. "The oil industry has been mapping this sort of risk for years but it has been woefully overlooked in discussions of food security," she said.
The 14 food trade chokepoints include shipping and overland trade routes as well as inland waterways. A large share of global grains trade passes through one or several of these chokepoints. Around a fifth of global soyabean exports and a sixth of global corn exports transit the Panama Canal each year, while a fifth of global wheat exports and a sixth of global corn exports pass through the Turkish Straits.
Of the areas and countries that are vulnerable, the Middle East and North Africa (MENA) region is the most food-import dependent in the world, according to Chatham House. Encircled by maritime chokepoints including the Strait of Hormuz and the Strait of Bab al-Mandab, it depends heavily on wheat imports from the Black Sea region which come via the Turkish Straits.
Just over a third of all grain imports to the MENA region pass through at least one maritime chokepoint for which there is no viable alternative. "The risk of disruption, given the political situation in the region, is high," said the report.
China is also a major importer — particularly of soyabean — but has done the most to mitigate its exposure to "chokepoint risk" by investing in port infrastructure around the world.
The disruptive hazards which present potential threats include climate change and extreme weather events, war, political instability and terrorism. Climate change is likely to make things worse by increasing the frequency of extreme weather events, fuelling conflict and damaging already-weakened infrastructure, the report said.
Ms Wellesley said governments needed to diversify production and inventories and invest in climate-resilient infrastructure. She said: "There have been constant and repeated disruptions at these critical chokepoints over the last 15 years. That none of these events has led to a crisis does not mean that the risk can be discounted."