Weather is a key variable and normally crop losses in one region are compensated by another, helped along by storage and trading systems resilient to short term disruption.
However, it is now "doubtful whether the current system is resilient to more extreme climatic conditions," a report said in the journal Nature Climate Change.
A team from the International Institute for Applied Systems Analysis (IIASA) based in Austria said climate change not only resulted in higher temperatures but is also producing more severe climatic events such as drought, heatwaves and floods.
"Climatic shocks to agricultural production contribute to food price spikes and famine, with the potential to trigger other systemic risks, including political unrest and migration," IIASA lead author Franziska Gaupp said.
The IIASA study said climate and crop yield data from 1967 to 2012 showed "a significant increase in the probability of multiple global breadbasket failures for particularly wheat, maize, and soybeans."
One of the largest losses of soybean production was 7.2 million tons in 1988-89, it noted, adding that if all major growing regions were hit, the loss would "be at least 12.55 million tons."
A related report in the same journal warned that changes in the jet stream sharply increased the risk of heatwaves in regions responsible for up to a quarter of global food production -- Western North America, Western Europe, Western Russia and Ukraine.
"We found an under-explored vulnerability in the food system: when these global scale wind patterns are in place, we see a twenty-fold increase in the risk of simultaneous heatwaves in major crop producing regions," said Kai Kornhuber, a guest scientist at the Potsdam Institute for Climate Impact Research (PIK).
"We will see more and more heatwaves striking different areas at the same time and they will become even more severe," PIK co-author Jonathan Donges said.
"This can impact food availability not only in the regions directly affected. Even remoter regions may see scarcities and price spikes as a result."
Separately, an Economist Intelligence Unit survey of 113 countries for its Global Food Security Index (GFSI) showed food prices were rising worldwide.
Singapore was ranked first for overall food security, followed by Ireland and the United States in a report which "highlights (the) need for innovation and investment in food systems to adapt to climate threats," the EIU said.
"Smart choices today can protect the food sector from the most severe consequences of climate change and minimise the impact of agriculture on the environment," it added. - AFP