World milk production is now faced with an unprecedented climate challenge. While heat waves become more frequent and more intense under the effect of global warming, their consequences on cattle farms worry scientific and professional. Two recent studies sound the alarm on world dairy production, one carried out by the universities of Jerusalem, Tel Aviv and Chicago, published in Science Advances; The other conducted by the University of Illinois and published in Food Policy.
The thermometer climbs, the cows are struggling to produce milk
When temperature and humidity get carried away, dairy cattle enter a physiological vulnerability area which directly impacts their yield. According to the study coordinated by the universities of Jerusalem, Tel Aviv and Chicago, it is enough that the humidity temperature index (Thi) exceeds 26 ° C to trigger thermal stress in cows. This index combines air temperature and humidity to assess the difficulty of animals to evacuate heat. Beyond this threshold, cows are struggling to regulate their body temperature. They eat less, drink more and produce less milk.
In just one hour under these conditions, their daily production of milk decreases by 0.5 %. The effect does not stop with the return to milder temperatures. He lasts several days, animals needing time to regain their metabolic balance. As a result, a scorching episode can lead to a drop in yield of 10 %, a particularly critical proportion for already weakened farms.
Claire Palandri, author of the second study, insists on the extent of the phenomenon. “” By 2050, global average production could fall by 4 % if no adaptation measure is implemented ». This potential loss takes on a major social dimension when it is recalled that 150 million households worldwide depend directly on milk for their income and food.
The tropical and subtropical areas are the first concerned. South Asia is expected to concentrate more than 50 % of the growth of dairy production over the next decade. However, the increased frequency of heat waves combined with rapid urbanization and demographic pressure makes the sector even more vulnerable. These convergent factors place the dairy sector in the face of an unprecedented climate challenge.
Are all operations exposed in the same way?
To find out, the study published in Food Policy was interested in the impact of thermal stress on dairy production by analyzing 56 million data from 18,000 farms in the Midwest. Result: annual yield losses due to heat amount to an average of 1 %, or around 616 million liters of milk over five years, equivalent to $ 245 million. But the figure hides strong disparities. Small farms, those with less than 100 cows, have higher proportional losses (1.6 % of annual yield) than large farms. The latter are better equipped to amortize the effects of hot days. These modest farms represent only 20 % of the production studied, but concentrate 27 % of economic damage.
Skidmore underlines that ” Small farms rarely have capital necessary to invest in advanced cooling infrastructure ». The available solutions (ventilation, misty, design of open buildings) make it possible to limit damage during moderately hot days. But they lose their effectiveness during extreme episodes. Jared Hutchins, co-author, specifies that ” Even the best strategies reach their limits when humidity and prolonged heat prevent cows from regulating their temperature ». The study warns that with the expected multiplication of the days of intense heat by 2050, the differences between small and large farms are likely to widen more, whether in the USA or elsewhere in the world. Which threatens the viability of dairy systems on a human scale.
Adaptation strategies that do not follow the rate of the climate
To try to counter the effects of thermal stress, many farms experience adaptation measures. In Israel, where data from the study of Science Advances have been collected out of 130,000 cows over twelve years, almost all farms are already using a combination of umbridies, mechanical ventilation and water sprinkling. However, as Claire Palandri explains, ” These systems manage to reduce only 40 % of the impact of temperatures exceeding 24 ° C ». The reason? When temperatures and humidity remain high for several days, the physiology of cattle is saturated and their natural thermal regulation mechanisms become insufficient.
Other tracks are explored, such as adjusting the calving periods to avoid the hottest months. Some also evoke genetic improvement to select more tolerant heat breeds. But these approaches take challenges: increased health risks, significant deadlines for observing effects, and often prohibitive costs for small structures. Without public support, these technologies will remain inaccessible to a large part of breeders, especially in developing countries.
Milk production becomes a global issue for food and the economy
The medium -term projections suggest a worrying situation. By 2050, the study of Science Advances Anticipates a 4 % drop in world dairy production, a loss that would prioritize the most populated and milk dependent regions as a source of protein. This situation is likely to exacerbate food insecurity in already vulnerable areas.
The economic dimension is just as crucial. Dairy farming is a pillar for millions of households, especially in rural areas of Asia, Africa and Latin America. “” If no adaptation policy is implemented, these losses could cause waves of bankruptcy among small farms and upset the world markets Skidmore warns in the Guardian. The paradox is striking. The dairy sector, a highly methane transmitter – a powerful greenhouse gas – now undergoes the consequences of global warming which it contributes to aggravate.
Faced with this observation, reflections are underway to reduce emissions from the sector. They include food changes aimed at limiting enteric fermentation, improving effluents management and selecting less emitting cattle breeds. However, these solutions remain complex to generalize, especially in developing countries. Researchers therefore call for a global response and increased support to small producers. Without this, the reduction in milk production could become a sustainable marker of a sector unable to adapt to an overheating world.
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
