Regional impacts of heat stress on livestock in Brazil under climate change scenarios

Rising temperatures and humidity threaten global livestock production and food security. This study assesses the future impacts of heat stress in regions with high livestock production in Brazil by analyzing high-resolution (5 km) climate projections from the Eta Regional Climate Model under the RCP4.5 and RCP8.5 scenarios. Using the Temperature-Humidity Index (THI), we evaluated future heat stress conditions for dairy and beef cattle, goats, sheep, pigs, broilers, and layers. The results indicate a substantial increase in both the frequency and intensity of heat stress events across Brazil during the 21st century, especially under the RCP8.5 scenario. The number of days reaching extreme heat-stress levels (ndaysTHI) is projected to increase significantly, particularly in the western and central regions of the study area, and for more vulnerable species such as pigs and poultry. For instance, the number of extreme THI days for dairy cattle and goats is projected to increase by up to 244 days by the end of the century (long-term period compared to historical) under RCP8.5. This research provides essential data for developing effective and sustainable adaptation strategies to mitigate the effects of climate change on Brazil's livestock sector, offering insights applicable to other countries facing similar challenges. It addresses a significant knowledge gap by providing high-resolution, localized projections of future heat stress across Brazil's major production regions.