We all know that climate change is wreaking havoc on the global environment. It's affecting our ability to grow wine grapesmaking rice more toxicand making seafood more vulnerable to bacterial contamination, which can pass to you when you eat it. And now, it seems it's also threatening some of our favorite cheeses.

In November, the New York Times reported new data showing that milk production in Italian cows is sharply declining due to rising summer temperatures. It cited an analysis of government data by CLAL, a dairy industry research center based in Modena, which revealed that between 2022 and 2024, milk production dropped by an average of 17.2% during the summer months (March-September). However, this isn't the only data showing this drastic change, nor is Italy alone in this plight.

How heat hurts milk production

In July, researchers from Israel published their study on milk production and climate change in the journal Science Advances. According to their research, just one day of extreme heat can reduce milk production by up to 10%, and the effects of that weather can last for more than 10 days.

As Eyal Frank, an assistant professor at the Harris School of Public Policy and a coauthor of the study, explained, her team focused their work on the dairy industry in Israel as it has "an advanced dairy system" already in place. To reach their conclusion that heat affects dairy production, they tracked more than 130,000 cows over more than a decade and surveyed more than 300 dairy farmers to determine whether their cooling methods influenced outcomes.

"Climate change will have wide-ranging impacts on what we eat and drink, including that cold glass of milk," Frank bluntly shared in a statement. "Our study found that extreme heat leads to significant and lasting impacts on milk supply, and even the most high-tech, well-resourced farms are deploying adaptation strategies that may be an insufficient match to climate change."

Specifically, the researchers discovered that milk production dropped significantly when "wet-bulb" temperatures exceeded 78.8°F. That measurement, they explained, combines information on ambient air temperature and humidity, providing a "measure that better captures heat stress." In other words, it's not the heat, it's the humidity that gets you.

The researchers noted that when cows are exposed to this humid heat, it is called "steam bath" conditions, which, even if the cows experience this for just one day, can disrupt their milk production for more than a week before it returns to normal levels.

It's not just the volume of production that changes; the consistency does too. As Agro Review explained, cheesemakers have also noted that milk from cows experiencing heat-related stress curdles more slowly and takes longer to set, further complicating an already delicate process.

Adaptation can only go so far

Nearly all of the farmers surveyed in the Israeli study reported using cooling technologies such as misters and fans. But even with these measures, the impact was limited—offsetting only half the production losses on 68°F days and just 40% on hotter ones. “The hotter it gets, the less they help,” the researchers concluded.

"Dairy farmers are well aware of the negative impacts that heat stress has on their herds, and they use multiple forms of adaptation," Ayal Kimhi, associate professor at the Hebrew University of Jerusalem and vice president of the Shoresh Institution for Socioeconomic Research, and coauthor of the study, shared.

"Adaptation is costly, and farmers need to carefully balance the benefits they obtain versus the costs," Kimhi added. "This is why we see some investment in cooling measures, but not a complete insulation of cows from their environment, which would be far too costly to implement."

And, again, this is far from an isolated issue in Israel or Italy. Globally, without cooling methods, the top 10 milk-producing countries could see dairy milk output drop by 4%, with major producers like India, Pakistan, and Brazil facing even steeper declines.

America faces its own dairy decline

Think the United States is immune? Think again.

Think the U.S. is safe? Think again. In February, researchers from the University of Illinois at Urbana–Champaign published a study that found that 1% of total annual milk yield in the Midwestern and Eastern states is already lost to heat stress — equivalent to about 1.4 billion pounds of milk and $245 million in lost revenue over five years. By 2050, those losses are projected to rise by about 30% under various climate scenarios.

"Cows are mammals like us, and they experience heat stress just like we do. When cows are exposed to extreme heat, they can have a range of negative physical effects. There is an increased risk of infection, restlessness, and decreased appetite, which leads to a decline in milk yield. For dairy producers, the heat impact is a direct hit on their revenue," Marin Skidmore, assistant professor in the Department of Agricultural and Consumer Economics, shared.

As for a solution, Skidmore offered this: "There's interest in continuing to have a healthy and robust small dairy production presence in the U.S., that probably will require financial incentives to help farmers implement mitigation strategies, as well as investments in further research on how to manage the highest levels of heat stress."