Thermal comfort level in Chennai Metropolis under present and future climate scenarios

Abstract

Climate change poses unprecedented challenges to urban inhabitants. Thermal comfort is one of the major issues in cities and it is expected to change in future due to climate change. The change of climate parameters particularly, temperature and relative humidity will affect the thermal comfort environments of people. Discomfort levels are largely preventable and requires prior assessment. In this study, the observed and projected thermal comfort level of Chennai Metropolis are calculated using Thermo-Hygrometric Index (THI) under present and future climate scenarios. The observed climate data of Chennai Metropolis for the period 1951-2010 procured from IMD are used to find the long term changes in observed thermal comfort. Monthly trends of THI are calculated for different periods to understand the thermal comfort behaviour in recent decades. On long term observation, high discomfort level is noticed during May and June months followed by July, August, April and September months. While there is a sharp increase in THI during winter months of recent decades. There is a considerable increase in discomfort level notice in post-monsoon season especially in December and November months. Future THI is calculated using high-resolution future climate scenarios developed using PRECIS. The deviations of THI from baseline to mid-century (2041-2070) and end-century period (2071-2099) are calculated and geospatially mapped using ArcGIS. There would be 2.0°C increase of THI is expected during winter and post monsoon months in mid-century scenario. Changes in future THI warrants the need for better cooling requirements and city planning to adapt with the future trends of external environment. Thus the study urges urban planners to evolve climate smart adaptation strategies to provide the congenial climate for a better living.