Animal thermal comfort index for the state of Paraíba, Brazil: trend, influencing factors, and mitigating measures

The present work had the objective to determine the tendency and the influence percentage of climatic variables on the Temperature and Humidity Index (THI) in the interannual, rainy, and dry seasons for the state of Paraíba. First, the occurrence or not of a trend on the THI was determined by the Mann-Kendall method in the periods under study. After normalizing all variables under study, it was possible to calculate the influence percentage of each variable and to identify which variables most contributed to the increase/decrease of the THI in the municipalities. Also, it was calculated the THI under conditions of future climate change scenarios (RCP4.5 and RCP8.5) and made a zoning for all States proposing mitigating measures to reduce the impacts on the thermal discomfort. Thus, the present work shows that there was an increase in the THI trend for all municipalities, except in Monteiro, which presented a reduction of −0.73 per decade. The air temperature was the variable which presented the highest contribution percentage, except in Patos during the rainy period because it had sunshine duration as the variable which most influenced the THI. The present work shows also that climatic variables that are not present in the THI calculation exert influences on it. Under conditions of climate change, more than half of Paraíba State will be in moderate stress for dairy cattle, taking as mitigation measure the planting of trees or through tiles, straw, or curtains, facilitating the maintenance of homeothermia and reducing the excess heat received by direct solar radiation.