Resilient cities - Hong Kong report: extreme heat

Effects of extreme heat



The loss in productivity negatively impacts the gross domestic product in nations across the globe. 29 In Hong Kong, the Guidelines on Site Safety Measures for Working in Hot Weather published by the Construction Industry Council sets out recommended measures and procedures that different personnel should follow during hot weather. According to the guidelines, when the UV Index is “high” as designated by the HKO, the weather is humid and “very hot” weather warning is issued, employers are advised to reschedule works to cooler periods or places, reduce the physical demands on workers and allow workers to take regular breaks in order to cool down. Such adjustments may reduce efficiency and productivity, thereby leading to economic loss. Hong Kong is well-known as a regional aviation hub. The Hong Kong International Airport (“HKIA”) is one of the busiest airports and has consistently been ranked as one of the best airports in the world. Due to the vast land surface with little vegetation, air temperature over the HKIA can be very high, especially in summer. According to the HKO, there is an increasing trend in the number of “very hot” days at the HKIA over the past two decades. 30

For an aircraft to take off, the lift has to be greater than its total weight. As temperatures increase, air density decreases, which results in less lift and makes it more difficult for aircrafts to take off. To address this issue, airlines may sometimes have to reduce airplane weight by loading fewer passengers and less fuel or cargo in order to take off. 31 If temperatures continue to increase, the cost of air travel may potentially increase as a result of the reduction in loading capacity of aircrafts. Extreme heat also leads to extra air- conditioning costs. Air-conditioning units can be found almost everywhere in Hong Kong, from small residential units to large-scale shopping malls, and from public facilities to commercial buildings. Statistics show that air-conditioning accounts for about 30% of all electricity consumption in Hong Kong, by far the largest end-use. 32 While air-conditioning units keeps people within the air- conditioned space cool, it exacerbates the problem of extreme heat because air- conditioning units often have a heating effect on the surrounding environment. More importantly, air-conditioning units are powered by electricity and electricity generation produces significant greenhouse gas emissions. Therefore, in the long run, air-conditioning has to be replaced by more sustainable methods of cooling which, however, can be costly to develop.

Climate change will affect infrastructure, transportation systems, energy, food, water supplies and public health. The consequences are felt by all strata of society but may be particularly serious for the poor and vulnerable. Government departments need to be well- coordinated to deal with climate change, and we must also collaborate with the community as a whole to face a variety of socio-economic challenges with a positive attitude. Other potential financial expenses that may be incurred as a result of climate change includemoney spent onmitigation investment, or adaptation measures to make existing infrastructure resilient to the effects of climate change or to minimise its impacts on human health and the economy.

Rising temperatures may also have a negative impact on mental health. A study conducted by Red Cross Hong Kong on the consequence of heat on the low-income and elderly population shows that extreme heat affects people’s everyday life. It often reduces the time they can spend outdoors and makes them feel lonely. 26 Another recent study led by the University of Hong Kong revealed a link between higher temperatures and the rate of suicide among senior citizens aged 65 or above. 27 The increase in heat not only affects the health and well-being of people in Hong Kong, but also brings about potential economic loss. A number of research papers have been published on the relationship between climate and productivity. According to a 2015 study published in the journal Nature, human productivity is the highest at around 13°C and “declines strongly” at higher temperatures. 28 Another study in 2016 suggested that people simply get tired more easily and accomplish less the hotter it gets. 3. ECONOMIC LOSS

−− Carrie Lam, Chief Executive of Hong Kong SAR 33 (2015)

26 27 suicide-among 28 Burke, Hsiang & Miguel, Global non-linear effect of temperature on economic production, Nature, 21 October 2015. Available at 29 workers-are-becoming-less-productive/ 30

31 32 33 This quote was given in the Hong Kong Climate Change Report 2015 published by the Environment Bureau. Carrie Lam was then Chief Secretary of Administration. The report is available at

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