Extreme heat, particularly when combined with periods of high humidity, can reduce dairy milk production by up to 10%, a study by the Hebrew University of Jerusalem and the University of Chicago has found.
The study, which examined the effects of climate change on more than 130,000 dairy cows in Israel over a 12-year period, found that one day of extreme heat can cut milk production by up to 10%, with the effects lasting for several days – milk output remains below normal for more than 10 days following an extreme heat event.
‘Wide-ranging impacts’
“Climate change will have wide-ranging impacts on what we eat and drink, including that cold glass of milk,” commented Eyal Frank, a co-author of the study and an assistant professor at the Harris School of Public Policy.
“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.”
The study, which was published in Science Advances, also surveyed more than 300 dairy farmers to see how much cooling technologies have helped alleviate periods of high temperature when it comes to dairy production.
As it found, despite the rollout of ventilation and spraying systems to cool herds, these adaptations only offset part of the heat-related losses.
On cooler days, when temperatures are around 20°C, cooling systems reduce losses by approximately 50%. On hotter days, when temperatures rise to 24°C and above, the mitigation drops to about 40%.
At the same time, the study noted that installing these technologies represents an economically viable option, with return on investment in around a year and a half.
“Dairy farmers are well aware of the negative impacts that heat stress has on their herds, and they use multiple forms of adaptation,” said co-author Ayal Kimhi, associate professor at the Hebrew University of Jerusalem and vice president of the Shoresh Institution for Socioeconomic Research.
“Adaptation is costly, and farmers need to carefully balance the benefits they obtain versus the costs. 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.”
Global impact
Based on their findings, the researchers also projected the global impact of climate change on milk supply, noting that by the mid part of the century, daily milk production in the world’s top 10 producer countries could decline by an average of 4% per cow per day, if cooling systems are not employed.
“Our research underscores the value and the limitations of cooling technologies and other efforts taken by dairy farmers to adapt to climate change,” added lead-author Claire Palandri, postdoctoral scholar at the Harris School of Public Policy.
“Policymakers should 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.” Read more here.
