Climate change translates into increased heat stress for humans, animals and crops.
“We studied which temperatures are desirable and harmful to humans, cattle, pigs, poultry and agricultural crops, and found that they are surprisingly similar,” said Sendolt Asseng, professor of digital agriculture at TUM in Germany. According to the study, the preferred temperature is between 17 and 24 degrees Celsius.
With high humidity, moderate heat stress for humans starts at about 23°C and low humidity at 27°C. “If people are exposed for long periods of time to temperatures above 32°C with high humidity or below 45°C with very low humidity, it can be dangerous,” says the professor. Asseng
“During extreme heat events with temperatures above 40 degrees Celsius, such as those currently seen on the Northwest Coast of the United States and Canada, people need technical support, for example, in the form of air-conditioned spaces.”
Asseng cites various strategies to mitigate the increase in heat stress, including increasing the natural shade of trees or increasing structural shade. Cities and buildings can become high temperature passive, for example by using roof and wall insulation or by using light, reflective colors to reduce heat stress.
How does high temperature affect livestock?
In cattle and pigs, heat stress occurs at 24°C with high humidity and 29°C with low humidity. Cows’ milk production decreases by 10 to 20 percent when exposed to heat stress, and pigs’ fattening performance decreases. A comfortable temperature range for birds is 15-20 degrees. Chickens experience moderate heat stress at 30°C. At 37°C and above, they experience severe heat stress and their spawning rate decreases.
In general, heat stress leads to reduced growth in dairy cows and cows, pigs, poultry and other livestock, meaning lower yields and reproductive performance. “There are examples of evolutionary adaptations to warm climates in terrestrial mammals. Transylvanian chickens are more heat tolerant than other chicken breeds because of a complex genetic mutation that suppresses feather growth. They are naturally temperate because they lack neck feathers,” says Asseng.
How Crops Respond to High Temperatures
“In crops, the ideal temperature zone and temperature ranges seem to be very different due to differences between species and varieties”, explains the expert.
Cold-weather crops such as wheat, for example, do best at low temperatures, while warm-weather crops such as corn are sensitive to frost but tolerate high temperatures. Strategies to reduce heat stress in agricultural production include shifting planting dates to avoid seasonal heat stress, irrigation (if possible), switching to more heat-tolerant crops, and breeding for heat tolerance.
How Climate Change Affects Life on Earth
“By the end of the century, 45 to 70 percent of the world’s land area could be affected by climate conditions where humans cannot survive without technological support such as air conditioning. Currently, it is 12 percent,” he said. This means that in the future, 44 to 75 percent of the human population will suffer from chronic heat stress. A similar increase in heat stress is expected for livestock, poultry, agricultural crops and other species.
“Genetic adaptation to a changing climate often takes several generations. The time available for many higher forms of life is very short. If current climate trends continue, many species may suffer severely due to temperature change or disappear completely from the Earth,” concludes Senthold Asseng.
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