- Hong Kong Observatory says cooler temperatures are exhibiting a significant long-term rising trend as the number of cold days has decreased
- Local experts warn low-income populations are at risk due to lack of air conditioning in many homes; those working outdoors also a concern
Hong Kong’s winters getting shorter while the summers are getting longer. Photo: ShutterstockAs the winter sets in over Hong Kong, have you been feeling the chill? If you haven’t, it’s not just you – the number of cold winter days has decreased, while hot days in the summer have been continually increasing. Unfortunately, according to local experts, this is only the beginning.
According to the Hong Kong Observatory, against the backdrop of climate warming, winter temperatures in the city are exhibiting a significant long-term rising trend.
Xiaoming Shi, assistant professor of environment and sustainability at the Hong Kong University of Science and Technology (HKUST), says this is no coincidence. “Global warming is making the hot season longer and the cold season shorter,” he said.
According to Hang Wai Tong, a scientific officer at the Observatory, the worst is yet to come. “Looking into the future, if greenhouse gas emissions continue unabated, the annual numbers of hot nights and very hot days are projected to increase significantly while the annual number of cold days is projected to further decrease,” he said.
The issue is more than just meteorological – class plays a significant role in how intensely people are affected. “For the middle class and upper class, people already have good AC in their homes, so we have already gotten kind of used to hot weather. But for low-income populations … that’s a more vulnerable population,” said Shi.
“In Hong Kong, we have some people who live in small flats or subdivided flats [which] do not have good AC,” he said. “Even if they have it, sometimes they worry about the electricity bills.” This social gap leads to harm, both physical and psychological, for these less affluent people.
Dr Lawrence Delina, an assistant professor also at HKUST, highlighted another demographic that is hit particularly hard: “Those who are working outside … [such as] construction workers [and] labourers are exposed to intense heat during those hotter days, are also the most vulnerable,” he said.
Apart from income, age is also a risk factor, said Delina. Contrary to popular belief, it’s not just the elderly, either. “Children [and] small babies are also in danger from hotter days and hotter nights, especially since they are moving most of the day.”
According to Shi, the situation is exacerbated by a particular weather phenomenon – extratropical cyclones. These cyclones “can transport heat from the low latitudes to high latitudes,” he said, making annual temperatures at higher latitudes less cold.
Research from the UK’s National Research Council says that baroclinic instability, which is the existence of different temperatures in the atmosphere, influences the development of such cyclones. “Global warming … can enhance that instability and therefore make the extratropical cyclones stronger,” said Shi. The mixing of temperatures caused by these cyclones results in more moderate temperature lows in the winter.
For Hong Kong residents, this could have grim consequences. “That extra heat creates heatwaves, which can melt ice and glaciers, which raise sea levels,” said Delina, who added that since Hong Kong is a coastal city, rising sea levels would affect our food and water sources.
“Hong Kong is an important global city, and it’s one of the most dense … the issue of urban overheating is really crucial in the years to come.”
Hong Kong needs to invest in preparing itself for a warmer climate, said Delina. “We have to ensure that we have the infrastructure in Hong Kong ready for those weather extremes … and provide a lot of spaces for cooling during the summer,” he said.
On an individual level, Tong stressed lifestyle choices as a way to contribute to the alleviation of the problem. “We must all work together to save energy, reduce carbon emissions and adopt greener lifestyles to achieve carbon neutrality as soon as possible.”