One of the outcomes of the heat island effect is the increase in the number of hot nights. The Hong Kong Observatory defines hot nights as the temperature exceeds 28 degrees celsius. The number of hot nights in Hong Kong have increased rapidly in the recent 50 years. From a number of 3 or 4 nights every year in the 19th century to a total of 38 nights in 2016. Figure 3.
1- Annual total number of hot nights observed at the Hong Kong Observatory since 1884 With the number of hot nights increasing in the past century, more and more people are ill because of the heat effect. A research paper by the Polytechnic and Chinese universities shows that there are more mortalities on hot summer days.The paper analysed data from 284,477 mortality records and the underlying causes of death from 2007 to 2014. They found out that mortality increases about 7 to 8 percent when consecutive “hot nights(nighttime above 28 degrees celsius)” and consecutive “very hot days”(at least one hour of temperature above 33 degrees celsius) occurs. They mainly died from cardiovascular or respiratory diseases that are more likely to occur in high temperatures. The danger of “hot nights” is that at night most people are staying indoors with poor air ventilation, especially in small apartments due to Hong Kong’s expensive house prices. People are also most likely to be sleeping, leaving them more vulnerable to the heat effect as they are unconscious about the high temperature.
Future projectionsAccording to projections by the Hong Kong Observatory, the number of “hot nights” would take up to a quarter of a whole year in Hong Kong if greenhouse gases emission continues to be at the same levels by the we reach 2050. The projection also stated that the numbers of very hot days and hot nights can reach about 89 days per year and 137 nights per year respectively in the decade of 2090–2099, which is almost 40% of the whole year. The consequences of consecutive hot nights will be deadly as they can cause a large amount of heat-related diseases in Hong Kong. The five hottest places in Hong Kong currently is Kwun Tong, Tsuen Wan, Sheung Wan, Mongkok and Causeway Bay where peak daytime temperature can be at least 3 degrees higher than the daily temperature recorded by the Hong Kong observatory.
By 2050 these areas could have become at least five degrees hotter.Solutions to reduce the urban heat island effectActions must be taken In order to relieve the urban heat island effect in Hong Kong. The environment Bureau in Hong Kong published an action plan that aims to be completed in 2030.Many strategies was discussed in the plan to lower the temperature of urban areas in Hong Kong.
One of the ways to reduce the heat island effect is to encourage urban forestry. It is the care and management in planting of trees in urban areas to improve the urban environment. The plans in urban forestry includes in focusing on greenery urban landscape designs on public sector infrastructures. For example, planting on rooftops and enhancing the amount of vegetation on roads in urban areas to create a urban forest. Green rooftops can help lowering urban temperatures in Hong Kong by lowering the urban heat island effect on the roof. Rooftop greeneries can also increase heat insulation and energy efficiency by reducing energy consumption on cooling systems. Another method is to implement air ventilation corridors in high compact areas to increase wind speed to cool down a densely populated area. They counters the problems of the “wall effect” and “canyon effect” in urban areas.
Since 2006 the government required all public infrastructure to have air ventilation assessment to increase the average wind speed. A good example of government’s urban planning is the implementation of wind corridors in the street of Kwun Tong. Revitalizing river channels in urban areas is also a strategy to reduce the urban heat effect.
According to the climate report 2015 of Hong Kong, the majority of river channels in Hong Kong were mainly channelised with concrete just for the sake of quick flood relief. The government now is working on revitalizing projects that rebuild concrete river channels. The new river channels focuses on environmental designs instead of efficiency.
Where wetlands is included to slow down the flow of the river and also attract ecology. The riverbeds and banks are designed to be covered with plantation, which is more give aesthetic pressure that will provide a relaxing and sustainable environment. ConclusionIt can be concluded that the difference in the temperature of rural and urban areas in Hong Kong Is caused by multiple human and physical factors. Firstly, it is the difference in the thermal masses of infrastructures in rural and urban areas. Secondly, the difference in the amount of concrete pavement and greenery. Finally, the poor air ventilation in urban areas due to high-rise buildings, and compacted building arrangements.
The secondary data included in this investigation also supported the conclusion drawn from the study of Whampoa and Shatin. In order to the relieve the urban heat island effect in Hong Kong, the environment Bureau have come up with different plans that aims to be completed by 2030. If the temperature in urban areas in Hong Kong continues rises at the same rate more and more issues will occur, such as heat related diseases and mortalities. The government of Hong Kong should take serious measures to counter this problem before further disastrous consequences occur. The methodology chosen in this essay can be improved by taking into account of other measurements such as wind speed and air pollution index. The measurement of wind speed can be used to explain the how better air ventilation can lead to a lower temperature which relates to the “Wall” effect and the “Urban Canyon” effect of high-rise buildings in urban areas.
Including the air pollution index in the areas investigated provides a sense of how much greenhouse gas emission there is in the area, which is a indicator of how much wasted heat is produced. In order to broaden the investigation more locations from urban and rural areas should be investigated, and errors and outliers can be eliminated by looking into more data from different locations.