The study, published , indicates that globally, more than 1 billion cows will be exposed to heat stress by the year 2100 in a scenario where climate change worsens.
While a multifaceted approach is required from people, industries, sectors and countries to slow or reverse climate change - including reducing use of fossil fuels - consumers can do their bit by reducing demand for cattle products like cutting back on beef in their diets, researchers from the universities of KwaZulu-Natal, Cape Town and Chicago suggest.
Dr Michelle North, veterinarian and climate change researcher at the University of KwaZulu-Natal, explains:
With livestock farming being a substantial source of emissions, actions that reduce growth in this sector will make a difference. In many parts of the world there is a culture of excess intake of red meat - in parts of South Africa too - and in these regions consumers could benefit their own health as well as potentially contributing to a more sustainable livestock industry by reducing their intake of red meat to healthier levels, and complementing animal-based proteins with protein from other sources, such as plants. This would be a benefit for both human health and the climate.
Cutting back emissions that cause climate change and higher environmental protections, such as keeping cattle production close to current levels, could see heat stress in cattle reduced by at least 84% in Africa, 50% in Asia and 63% in South America, the paper indicated.
Currently, 80% of cattle globally are exposed to climate conditions associated with heat stress for at least 30 days per year. With very high emissions in future - nine out of 10 cows around the world will experience 30 or more days of heat stress per year, and at least three in 10 will experience it all year round.
Exposure to heat stress impacts fertility, milk produced, the growth rates of calves and makes cattle more susceptible to disease and death. This is apart from considering changes to water availability.
Challenges facing the South Africa livestock industry
"What this means is that cattle farming will become less and less viable in many parts of the world," North said.
Another author of the report, Dr Christopher Trisos, ecologist and climate change researcher at University of Cape Town, noted that expanding cattle production by cutting down or burning tropical forests is unsustainable. "…It worsens climate change and will undermine the welfare of hundreds of millions more cattle that will be exposed to severe, year-round heat stress," Trisos added. "Reducing the amount of cattle products in diets can help limit future expansion of cattle farming, creating opportunities to protect and restore forests that can help limit future global warming."
The study indicates that cattle farming is expected to expand the most in tropical regions like the Amazon, the Congo and India – heat stress is also projected to increase the most in these regions. This means livestock farming in these areas will become harder.
Farmers will have to adapt to changing climate conditions. Farmers could take steps to provide more shade or use fans and air conditioning to improve the environment for cattle. Some of these measures may be expensive and not viable in some places. Other options include changing feeding times or the type of feed to minimise heat produced when cattle digest food or switching to more heat-tolerant cattle breeds or other livestock species like goats.
"At the same time, farmers and governments need to carefully consider whether it makes sense to expand cattle production in regions that are projected to become too hot for cattle," said North.
Similar findings have emerged in other studies looking at heat stress in livestock. A 2021 study shows that human-caused climate change impacts livestock – this includes increasing heat stress. The study also projects that by the end of the century, extreme heat stress will increase for all livestock species in many tropical regions – and this also poses risks to the viability of livestock farming.
North said that such research is important given that livestock contributes to food security and supports the livelihoods of many people, including poor subsistence farmers.
