A 60% AMOC collapse would cut global cereal yields 5.3% and spike prices 40%

A new study warns that a 60% collapse in the Atlantic Meridional Overturning Circulation (AMOC) would cut global cereal yields by 5.3% within 50 years and could push average food prices 17% to 40% higher. The research, posted July 7 on the website of the nonprofit Alliance to Feed the Earth in Disasters (ALLFED), is not yet peer-reviewed, but it models a scenario that climate scientists say is already underway: the AMOC is the weakest it has been in more than 1,000 years, having lost 10% to 20% of its strength.

The global average hides severe regional damage. Germany and Ukraine would lose up to 19% of cereal yields from sudden cooling, Canada 12%, while the model shows a "very nasty brown splodge" of reduced precipitation over India, Pakistan, and big parts of China, plus severe rainfall declines in already water-stressed Iran, Sudan, and Eritrea. Study co-author Michael Hinge, a senior economist at ALLFED, told Live Science that "lots of these effects manifest earlier, so it's a moving target."

The study, which has not been peer-reviewed, is a proof of concept rather than a precise forecast. Hinge and his colleagues ran three crop models for the most common varieties of wheat, maize, and rice, layering them on top of AMOC simulations. They modeled 100 years of change assuming 3.6 degrees Fahrenheit (2 degrees Celsius) of warming above preindustrial levels, forcing an AMOC slowdown over the first 50 years in one simulation and leaving circulation unmodified in a second. The model reproduced broad Northern Hemisphere cooling and a southward shift of the equatorial rain belt, effects that previous studies found irreversible on human timescales.

The 5.3% global yield decline is an average, so it conceals year-to-year volatility. Hinge said there may be years when global cereal losses reach 10% or more, which would bump up food prices in part because countries might stockpile crops instead of trading them. The model also suggests average food prices worldwide could rise 17% to 40%, depending on how governments respond and whether agriculture can be sustainably expanded in places like the African Sahel and Brazil.

The United States would not be spared. The model indicated the country could see crop losses of about 3% for domestic wheat and corn, and Hinge said that loss would likely impact other foods that rely on cereal inputs, like meat. "The variety of foods available in the stores may well diminish for periods," he added.

The findings build on prior research led by Paul Ritchie, a climate scientist at the University of Exeter, whose 2020 study explored AMOC collapse effects on agriculture in Great Britain. Ritchie, who was not involved in the new work, told Live Science the study is "valuable in showing the potential scale and geographic distribution of the initial agricultural shock," but cautioned that what it would ultimately mean for food production and security is more uncertain because farmers, markets, and governments can respond in many ways. He said the regional predictions may be more informative than the 5.3% global average.

Hinge warned that maladaptation is a major worry: "You're preparing and setting up for much hotter temperatures or trying to develop areas for these temperatures and the trends you're seeing, and suddenly you see something different." That could cause a larger compounding effect on agriculture. He also predicted that governments might restrict exports and start stockpiling food, as they did during the 2008 financial crisis and the COVID-19 pandemic, which would "massively magnify the effects of AMOC."

For executives, the study is a reminder that climate risk is not just a warming problem. A sudden cooling shock in key breadbaskets could disrupt commodity markets, raise input costs for food and meat producers, and trigger protectionist trade policies. Hinge's bottom line: "There are no easy answers here; an AMOC collapse would be deeply catastrophic." The researchers hope their modeling pipeline can help decision-makers act swiftly if the warning light starts flashing, because right now, as Hinge put it, "if that warning light starts flashing, we're not sure what to do with it."