Climate change is pushing livestock systems to their limits, and new research shows that even the most technologically advanced dairy farms can only partially adapt to rising heat
Climate variability and climate change had significant effects on agriculture, including the dairy sector, with implications for income, nutrition, and food security at both local and global scales. While dairy science had long acknowledged milk production’s sensitivity to heat stress, most economic assessments of these impacts at the country level were lacking. Existing studies often relied on oversimplified assumptions about the relationship between temperature and milk yield, based on small, localized datasets, and rarely accounted for farmers’ short- or long-term adaptation strategies.
To address this gap, researchers in a BARD-funded study used exceptionally large, high-resolution datasets on milk production from Israel (over 30 million daily cow-level records annually). This was done along with newly collected survey data on coping strategies used by Israeli dairy farms. By applying advanced methods, including machine learning and causal inference techniques, the research generated more precise, flexible estimates of how temperature and humidity affected milk production and assessed the costs and benefits of various adaptation measures.
The study adapted recent innovations from environmental and agricultural economics to the dairy context and introduced new approaches for comparing results across different temporal scales. These tools were used to project how both current and future climate scenarios could impact milk production in Israel and the U.S., while systematically factoring in adaptation costs and effectiveness. Beyond informing dairy sector policy, the project’s unique data also enabled methodological advances, such as testing key assumptions about how weather impacts were modeled in the economics literature.
The case test
The team of researchers including Prof. Ram Fishman from Tel Aviv University , Prof. Ayal Kimhi from the Hebrew University and Prof. Eyal Frank and Dr. Claire Palandri from the University of Chicago analyzed more than 320 million daily milk yield records from 130,000 Israeli dairy cows over 12 years, paired with farm surveys on adaptation strategies. Israel’s dairy sector, renowned for its high productivity and near-universal use of cooling technologies, offered a rare opportunity to assess the upper bounds of heat adaptation potential.
Key findings: Extreme humid heat can cut milk yields by up to 10% on the hottest days, and the damage lingers for more than 10 days after exposure. Losses are worst when cows are at peak productivity, revealing a productivity–resilience trade-off: the highest-yielding cows are also the most heat-sensitive.
The study focused on wet-bulb temperature (Twb) – a combined measure of heat and humidity, as a more physiologically relevant indicator than the commonly used Temperature Humidity Index. When Twb exceeded 26°C, milk output fell sharply, with prolonged heat waves amplifying losses.
Cooling systems, such as fans, sprinklers, and evaporative units are widespread in Israel, yet the analysis found they reduced losses by less than half. On moderately hot days, cooling could eliminate heat impacts; but above 24°C Twb, it cut losses by only 40%, and above 26°C, even less. Other strategies, like shifting calving to cooler months or altering feeding schedules, showed small additional benefits.
Economic analysis
Economic modeling suggests that cooling equipment pays for itself in 1.4–1.5 years through avoided milk losses, making it a strong investment. Still, the limited mitigation at high temperatures raises concerns for regions facing more intense heat extremes.
Looking ahead, climate projections for mid-century under high-emission scenarios show many of the world’s top milk-producing countries could lose up to 4% of annual daily yield per cow due to heat stress—without accounting for fertility or mortality effects. While cooling offers the largest gains in hotter regions, it won’t fully offset losses, particularly as heat waves become more frequent and prolonged.
The findings underscore two major challenges. The first are physiological limits. Even with advanced cooling, cows’ thermoregulation can be overwhelmed in extreme conditions. The second is global vulnerability. The Israeli case likely represents a best-case scenario for adaptation, meaning many other dairy regions may face even greater losses.
Future steps to adapt to heat stress
Researchers caution against assuming that existing technology alone will protect dairy systems in a warming world. Alternatives such as more heat-resilient breeds, redesigned housing, and broader stress-reduction strategies may be needed. However, some high-tech solutions, like fully enclosed climate-controlled barns, may not be financially or socially viable everywhere; and could introduce new animal welfare concerns.
As the dairy sector grapples with rising demand and rising temperatures, the study highlights a sobering reality: adaptation helps, but has limits. Meeting future food needs will require not only technological improvements, but also systemic changes to reduce animals’ exposure and sensitivity to heat stress.
Read the publication: https://www.science.org/doi/10.1126/sciadv.adw4780
