Rising temperatures threaten global milk supply chains as per Israeli study

Milk, a staple in diets across the globe, is now facing a growing and underappreciated threat in the form of climate change. While much of the focus remains on melting ice caps and rising seas, a quieter but deeply troubling crisis is playing out on dairy farms — where rising temperatures are increasingly disrupting milk production.

Heat stress in cows is not a new phenomenon as farmers have long observed a seasonal dip in milk yield during hotter months. What once were occasional hurdles have now become recurring and intensifying challenges, fuelled by accelerating climate shifts. Scientists warn that if this trend continues, the impact on global milk production could become severe and potentially irreversible, jeopardizing food supplies and rural livelihoods alike.

A recent in-depth study sheds light on the gravity of the problem, finding that extreme humid heat can slash milk yields by as much as 10%, even with advanced cooling systems in place. The findings have been studied in an article published on Earth and reveal a troubling limit to how much current technologies can offset nature’s growing extremes.

The study, which analyzed over 320 million daily records from Israeli dairy farms over 12 years, concluded that wet-bulb temperatures above 26°C — which account for both heat and humidity — trigger significant drops in milk yield. Even after heatwaves end, cows take more than 10 days to fully recover, underscoring the lingering effects of heat stress. “Climate change will have wide-ranging impacts on what we eat and drink — including that cold glass of milk,” said Eyal Frank, assistant professor at the Harris School of Public Policy.

Israel’s dairy sector is among the most technologically advanced in the world, operating under a system of government-regulated milk prices. Researchers collected data from more than 130,000 cows and surveyed over 300 farmers on their strategies for mitigating heat, such as using sprinklers, fans, and shade structures.

“The dairy industry in Israel serves as a valuable testbed because its farms span a range of climate conditions that mirror those in many of the world’s leading milk-producing countries,” explained Ram Fishman, associate professor at Tel Aviv University.

Limits of cooling technology

Cooling systems were found to cut milk losses in half during moderately hot days, and farms typically recoup installation costs within 1.5 years — making them a sound but incomplete solution. On hotter days, however, these systems become less effective, especially when humidity is high.

“Dairy farmers are well aware of the negative impacts that heat stress has on their herds, and they use multiple forms of adaptation,” said Ayal Kimhi, associate professor at the Hebrew University of Jerusalem. Despite these efforts, losses persist, especially during prolonged heat events.

The study also revealed that the longer the heat persists, the more severe the production drop. Ten consecutive days of extreme humid heat can result in yield losses of up to 26%. This suggests that heat stress has a cumulative effect on cows, making it harder for them to bounce back once temperatures return to normal.

Some farmers have responded by shifting calving periods or adjusting feeding schedules to cooler parts of the day. These approaches offered marginal improvements in resilience but fell short of providing comprehensive protection against escalating heatwaves.

Troubling forecast for global milk supplies

Looking ahead, the researchers modeled the effects of rising heat on key milk-producing nations. Without widespread adoption of cooling systems, countries like India, Pakistan, and Brazil could see annual milk production fall by up to 4% by mid-century. Even nations with more temperate climates — including the United States and China — aren’t immune, as cooling systems alone may not fully offset future losses.

Perhaps most alarming, the study identified a key vulnerability in high-output dairy systems: the very cows that produce the most milk are also the most sensitive to heat stress. Early lactation stages and older, high-yield cows were hit hardest by heat-related declines, suggesting a fundamental trade-off between productivity and resilience.

While full indoor housing might offer more temperature control, it introduces welfare concerns like stress from confinement. The researchers urge lawmakers that new strategies must be developed to balance productivity with sustainability, potentially including reduced confinement and more natural behaviour allowances for cows.

By Nazrin Sadigova