Increasing temperature extremes and thermal discomfort over Southern India: concerns for human health

The paper analyses trends in temperature extremes such as hot days, very hot days and extremely hot days over southern India during summer season for the period 1969 to 2015. Tendencies in human thermal discomfort have also been worked out for the same time period. Linear regression and Mann-Kendall test were applied for time series analysis. Human thermal discomfort was investigated using Heat Index (HI) and Wet Bulb Globe temperature (WBGT) indices. It was observed that hot days and very hot days have increased during the study period over southern half of the study area. The rate of change is higher and significant over west coast. Consequently an increase in discomfort was observed over west coast during all summer months, which are March, April and May. During April and May even the east coast stations revealed significant upward trend in discomfort. Even some inland stations have registered rising tendencies in discomfort. It reveals that the heat stress is rising in the southern India, which is a major health concern for the population living in this area. There is a need to develop a warning system of heat stress, which will help in preventing casualties due to heat stress.