Impact of Climate Change on Outdoor Thermal Comfort in a Tropical Humid City
Keywords:climatic change, heat stress, thermal comfort, urbanization
This study examined the impact of rising air temperatures resulting from global warming and urbanization on the outdoor thermal comfort of the residents of the tropical humid city of Owerri in southeastern Nigeria. The bioclimatic indices adopted to evaluate the outdoor thermal comfort based on the thermal physiological balance of the human body are Thom’s Discomfort Index (DI) and the Humidity Index (Humidex) of the Canadian Center for Occupational Health and Safety. The study period spanned from 1988 to 2020. Results indicated the discomfort level deteriorated over the years of the study period. The results showed a 33-year increase in mean annual temperature of 0.45oC and in mean annual relative humidity of 0.27%. Over the 33-year study period, the DI increased from 23 to 26, while the Humidex increased from 37 to 41; suggesting that about 50% of the population felt some noticeable discomfort at the beginning of the study, but by the end of the study period, over 50% of the population felt great discomfort. Over any given time period, over 50% of the population felt intense discomfort during the dry season. At current temperature and relative humidity levels, over 50% of the population of the city feels some noticeable discomfort throughout the year. This knowledge is of immense benefit to health and tourism officials, building designers and organizers of outdoor activities. In view of the rising global temperatures, the study recommends provision of shady trees and use of cool pavements and cool roofs in city constructions to checkmate current discomfort trends from continuing. Ongoing commitments by nations to reduce greenhouse gas emissions should be fulfilled.