The temperature in the inner urban areas of Honk Kong, China, is predicted to rise by two to three degrees Celsius in the next 30 years, according to researchers at the Department of Land Surveying and Geo-Informatics (LSGI) of the Hong Kong Polytechnic University (PolyU).
The scientists used remote sensing technology as well as satellite images to map the distribution of temperatures for daytime and nighttime over Hong Kong. Taking into consideration the temperature change due to greenhouse-induced warming as well as the impact of urbanization, known as the Urban Heat Island (UHI) effect, these maps model the temperature changes for the next 30 years.
The urban area of Hong Kong is significantly warmer than its rural surroundings, and the temperature difference is larger at night and in winter. These increases are caused by high-rise buildings that block thermal radiation at night, materials with thermal bulk properties, like asphalt and concrete, and the lack of vegetation.
Urbanization is an additional factor in causing the temperature rise, and if current trends continue, temperatures could increase much faster in the future, states Janet Nichol, lead author. The annual temperature in Hong Kong could rise by 3.0 to 6.0 degrees Celsius by 2100, given that there will be no further urbanization. However, within the same period with a constant urbanization rate as before, the temperature rise is predicted to rise by 3.7 to 6.8 Celsius degrees within the same period.
The study also suggests that in the next three decades, nighttime temperatures in the center of Kowloon are expected to rise by at least two degrees Celsius, reaching 31.5˚C at night, making most urban districts in the city “uncomfortable” at night by 2039.