Cattle, whether grazing in small herds along the roadside or lowing singly from a nearby field, are an emblematic sight for much of Africa, as characteristic of the continent as the yoked oxen of southeast Asia or the gray squirrels of American suburbs. Yet large swathes of the continent may be stripped of the creatures as early as 2045 due to climate change-induced heat stress, according to a pair of recent studies by a team of scientists led by Philip Thornton, a principal scientist at the International Livestock Research Institute (ILRI).
The two studies investigated the impact of low and high climate change scenarios on livestock worldwide. The first, published in Global Change Biology, investigated the number of extreme heat stress days that can be expected for cattle, sheep, goats, poultry and pigs. It found that by 2050 as many as 370 million cattle could suffer from one or more days of extreme heat, as could some six billion chickens.
Cows are especially prone to heat stress, which occurs when they take in more heat than they can easily get rid of by respiration, sweating or wind blowing on them. It can negatively affect liveweight gain, milk yield, fertility and behaviour
The second study, published in Lancet Planetary Health, examined the potential economic costs of heat stress in the future. It found that by the end of this century livestock farmers may face financial losses between $15 and $40 billion annually, with most of that loss happening in poor, tropical countries of South America, Asia and Africa.