Changes in Hong Kong’s climatic factors that can be attributed to both global warming and localized urbanization include temperature rise in urban area, increasing number of very hot days and hot nights, reducing number of cold days, and rising sea level in the harbour. Some key findings include –

Temperature Rises Compared with the 1980-1999 average of 23.1ºC, the annual mean temperature in Hong Kong in the decade 2090-2099 is expected to rise by 4.8ºC. As for extreme weather, the study by Hong Kong Observatory shows that the annual number of hot nights (days with a minimum temperature of 28ºC or above) and very hot days (days with a maximum temperature of 33ºC or above) in summer will increase. On the other hand, the annual number of cold days in winter (days with a minimum temperature of 12ºC or below) will continue to drop.

The annual number of hot nights in summer is expected to increase from the average of 15 nights in 1980-1999 to 41 nights in 2090-2099. The annual number of very hot days in summer is expected to increase from the 1980-1999 average of 7 days to 15 days in 2090-2099. The average annual number of cold days in winter is expected to drop below one in the decade 2030-39. The average annual number of cold days at the end of the last century (1980-1999) was 14 days.

Sea Level Rises An analysis of the sea level records for more than 50 years of the Victoria Harbour show that the mean sea level in the Victoria Harbour has risen 0.13 m from 1954 to 2007, at an average rate of 2.4 mm per year. The trend was similar to that over the South China Sea as measured from satellites using remote sensing techniques from 1993 to 2005.