Dairy production is set to come under increasing threat from the rising frequency and severity of heatwaves, according to a new study.
Analysing data from over 130,000 dairy cows across a 12-year period, researchers found that extreme heat can reduce milk yields by as much as 10%. Just a single hour of exposure to a wet-bulb temperature — a combined measure of heat and humidity — exceeding 26°C is enough to lower a cow’s daily milk output by 0.5%. The impact is not limited to the day of the heat event: milk production remains below average for up to ten days afterwards.
Using climate projections for the year 2050, the study estimates that average daily milk yields could fall by 4% due to increased heat stress. Researchers from the Universities of Jerusalem, Tel Aviv, and Chicago warn that this decline will be especially significant for the 150 million households around the world that depend on dairy production.
The effects will be felt most acutely in South Asia, a region expected to account for more than half of global growth in milk production over the next decade. Continued fossil fuel use and rising greenhouse gas emissions are likely to intensify the risk of extreme heat events in the region, further undermining dairy yields.
Cattle are also a major contributor to climate change, responsible for roughly one-third of anthropogenic methane emissions — a potent greenhouse gas that, like carbon dioxide, accelerates global warming.
Farmers are already adopting measures to help cattle cope with rising temperatures. In Israel, where the study was conducted, virtually all dairy farms use some form of heat mitigation, including shade provision, ventilation, and sprinkler systems to cool the animals directly.
However, the researchers found that on days when temperatures exceeded 24°C, these strategies were only able to offset around 40% of the heat-related decline in milk production — highlighting the limits of current adaptation methods in the face of escalating climate pressures.
Claire Palandri, the lead author of the study published in the journal Science Advances, has urged policymakers to “look into more strategies to not only cool cows but reduce stressors, like confinement and calf separation. Stressors make cows more sensitive to heat and less resilient.”
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