The world’s food supplies are in danger as climate change and the increasing reliance on global trade threaten to create shortages and sudden, dramatic increases in prices, according to a new report by the leading think tank Chatham House.

The report’s authors warned of a “growing risk … to human security” with the potential for “systemic disruption” and so-called Black Swan events – major unexpected changes.

They called for an international “emergency response mechanism” to be created to help deal with crises as they arise and an increase in emergency food stocks.

Urgent action should also be taken to improve “weak and ageing” infrastructure in major crop-producing regions such as Russia, Ukraine and the US, the report added.

Global warming is expected to produce more violent storms and increased flooding in some areas, which could damage roads, railways and ports. And, as the temperature and rainfall change, this could also affect crop yields.

The report, called Chokepoints and Vulnerabilities in Global Food Trade, said international trade had enabled certain areas to specialise in certain types of food production, which had maximised productivity and reduced prices, but warned this food system was now “coming under increasing strain”.

“While market forces have largely adjusted adequately until now, the capacity of international trade to correct for supply disruptions in a climate-changed world is less certain,” the report said.

“Climate change will suppress growth in crop yields and make harvests more variable.

“It will threaten the reliability and integrity of the infrastructure on which international trade depends.

“In addition to more regular and more severe weather-induced damage to roads, railways, ports and inland waterways, climate change will have a multiplying effect on security and political hazards affecting the infrastructural backbone of international trade.”

Experts highlighted 14 chokepoints around the world – such as the Panama and Suez canals, the US rail network and its inland waterways, Brazil’s roads and the Turkish Straits – that are vitally important to the continued flow of food.

Just three regions, the US, Brazil and the Black Sea area, account for 53 per cent of global exports of wheat, rice, maize and soybean. The first three crops make up 60 per cent of the food we eat, while soybean is 65 per cent of animals’ protein feed.

The report said the chokepoints were the “potential epicentres of systemic disruption”.

“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,” it said.

“In an increasingly unpredictable world, ensuring the resilience of populations and critical infrastructure to compound and cascading supply chain disruptions, and to ‘black swan’ events, will become increasingly vital yet ever more challenging.

“Without significant investment in new approaches … food trade chokepoints will pose a material and growing risk to systemic stability and to human security, chiefly in the world’s most food-insecure and politically volatile regions.”

The report found 10 per cent of global trade in cereals, soybeans and fertilisers passed through a maritime chokepoint for which there was “no viable alternative”.

“Over the past 15 years, all but one of the 14 critical chokepoints has been subject to closure or to restrictions on traffic,” it added.

The rapid melting of ice the Arctic is opening up new shipping routes between the northern Atlantic and Pacific but the authors said this was “unlikely to relieve pressure on existing shipping routes before the second half of the century”.

One of the authors, Laura Wellesley, said the oil industry had been “mapping this sort of risk for years but it has been woefully overlooked in discussions of food security”.

“Past events, including floods in Brazil and the Southern US, and the export bans on wheat from the Black Sea countries that contributed in part to the Arab Spring, give us a flavour of the sort of disruptions that can occur when chokepoints are closed,” she said.

She said governments had a tendency to make decisions in their own “short-term, national interests in mind”.

But these could “exacerbate the global problem, and undermine systemic resilience”.

“We need a new, collaborative approach to mapping and mitigating the growing threat we all face,” Ms Wellesley said.

Robin Willoughby, Oxfam head of food and climate policy and campaigns, said climate change was "the single greatest threat to our chances of winning the fight against hunger".

And he added: "The global food system is woefully unprepared to cope with its savage impacts.

“Small-scale farmers and poor urban consumers are on the front lines of increased weather and food price volatility.

“They need major new support to adapt to the changing climate – from improved irrigation schemes, crop insurance and agricultural research and development to stronger social protection.