Hong Kong: mega cities, mega heat.
Hong Kong is heating up. According to the Hong Kong Observatory, the city is seeing a significant long-term warming trend, which data from 2017 and 2018 confirm: 2017 was warmer than usual, with 41 hot nights [above 28°C] and 29 very hot days [above 33°C], ranking the highest and the sixth highest on record respectively. The 2018 ‘warm season’ opened with the hottest May on record since 1885 – with temperatures hitting 36.7°C.
Is this all down to climate change? We asked Lee Sai-ming, senior scientific officer for the Hong Kong Observatory to explain.
“When we talk about climate change, we look at the big picture,” he says. “We look at how the climate changes over long periods of time, not at specific years. But if put in the context of climate change, this year’s heatwaves in Hong Kong, and the many heatwaves going on around the world, show that it is increasingly likely to have very hot summers”.
Temperatures in Hong Kong are indeed rising – at a rate of 1.2 degrees per century, though data show that the rate of increase is becoming faster in the last decades.
Here and now: who is paying the price?
“Hot temperatures are dangerous for elderly people,” explains Irene Lui Sau-lan, manager of the Local Emergency Service of the Hong Kong Red Cross. “Many of them live alone and cannot count on the support of family. Often this situation is made worse when they live with chronic illnesses. Heat also affects their everyday life, reduces the time they can spend outdoor and makes them feel lonely”.
The effects that hotter temperatures have on vulnerable people can be seen in Kwun Tong, Hong Kong’s hottest district and home to the city’s highest proportion of low-income and elderly people. A large number of people here are very vulnerable to heat, but have little means to protect themselves.
“I go to the park early in the morning,” says Shuk-man Wong, an 82-year-old widow who lives alone in an apartment building of the Tsui Ping Estate in Kwun Tong. “I cannot do that during the day when it gets hot, so I come here at 5 or 6 am. I can exercise, talk with other people, but especially I can play my Erhu [a two-stringed bowed instrument]. My house gets too hot during the day and I can only play for a little while because I must keep my door wide open to let air circulate. But then the neighbours complain and I must stop.”
It’s even too hot to cook inside the apartment. “I cook here in the hallway,” she says. “I must bring my rice cooker out here. And I eat here every day. Because it is cooler here, I am suffocating inside”.
In Shuk-man’s tiny 8m2 flat, the only (small) window is blocked by her belongings — after all, she has little room to choose where to stacks her things. Originally from Fujian, China, Shuk-man has been living in Hong Kong for over 30 years: “Yes, Hong Kong is getting hotter,” she explains, adding that on some days, it keeps her from doing much of anything. The worst was the day they call ‘the great heat’ when it reached over 35 degrees “For the day of the ‘great heat’, on 23 July 2018, I did not dare to go out, but then I felt lonely. So I finally went to the elderly community centre”.
Catherine Wong Kuk-ching, senior manager of the True Light Villa District Elderly Community Centre knows situations like Shuk-man’s very well. “Elderly people, especially when leaving alone, can suffer badly from the consequences of heat. To protect themselves, they must stay at home, but this is risky as they can start to feel very isolated, and in the worse cases, develop depression. Also, many people do not use air conditioning because it is too expensive for them. So community centres can become people’s (second) homes. They come here to talk with their friends, and for the programmes we have. But of course, they also like to cool down in the air conditioning we have at the centre.”
Are cities making it worse?
But as cities get larger and larger, do they also play a role in pushing temperatures on the streets even higher?
According to studies conducted by the Hong Kong Observatory, urbanization contributes to about 50 percent of the warming in cities like Hong Kong. First of all, tall buildings block air circulation and reduce wind speed, limiting the sea breeze that the city would naturally enjoy. In addition, buildings made of dense materials such as concrete and steel trap and retain heat longer than wooden structures used in suburban and rural areas. At night, buildings release the heat they absorb during the day, but that heat cannot easily escape the narrow spaces between the lower floors. This means the city is less able to cool down at night, compared to rural areas. Studies show that temperature differences between countryside and cityscape can be very high. Some cases, have been recorded in which minimum temperatures in urban and rural areas differ by as much as 10 degrees.
There are other elements too. “Emissions of traffic and transportation contribute to the formation of rain-bearing clouds, so urban areas can get more rainfall than rural areas,” explains the Observatory’s Sai-ming. “A study we conducted shows that the increase of rainfall in Hong Kong is higher than in rural areas. A possible cause of this is high urban activity. So because of urban activities and hotter temperatures, the intensity and frequency of precipitation are also increasing in Hong Kong. Hot weather causes more evaporation from the oceans and the warmer atmosphere can hold more moisture. So when it rains, the chance of extreme rainfall increases”.
What can be done in response to a trend that seems irreversible? In short, the city needs to adapt. “We can increase greening in the city,“ suggests Sai-ming. “Planting more trees and vegetation can help cool the city without increasing carbon emissions. We can use heat-proof materials to reduce the amount of heat absorbed by buildings, and use reflective materials on the top of structures, to reflect more solar radiation back to space.”
Hong Kong Red Cross is also working on helping people adapt to hotter temperatures: “We help elderly single people,” says Irene Lui Sau-lan. “During home visits our volunteers talk about health risks and what steps people can make to keep cool when it’s very hot. Volunteers check that cooling equipment works well and there’s no risk of fire. It is simple things. But it can help.”
For Shuk-man, the visits were a welcome relief. “The volunteers cared about me very much,” she says. “They reminded me to use the ‘Call and Care Service’ to get help if I am unwell. They gave me a whistle to draw attention in case of fire. They also noticed my 10-year-old electronic fan. The fan had no cover but I did not want to throw it away. They helped replace it and now I have a better one”.