Heatwaves are a reminder to work up a sweat in the fight against climate change

(10 August 2022 SCMP)
Long-lasting heatwaves struck many parts of the world in July, with daytime temperatures hitting and even surpassing 40 degrees Celsius in some places.

Hong Kong is not far from reaching such sweltering temperatures. The city broke 11 weather records last month; there were 21 “very hot days” and 25 “hot nights” in July, making it the hottest month since records began 138 years ago. The heat forced many people to leave their poorly ventilated subdivided units to spend the night at one of the 18 temporary heat shelters provided by the government for those in need.

I was born and raised in Hong Kong, but I have never experienced such unbearable heat in the city before. Last summer, I didn’t turn on the air conditioner even once during the day while working from home occasionally.

Unfortunately, I wasn’t able to sustain my low-carbon practice last month; I found myself dripping with sweat if I didn’t switch on the air conditioner while working at home. Instead, I turned the air conditioner on for just a few hours with the thermostat set to 27 degrees, while pulling down my blinds to block out the burning sunshine whenever the external temperature rose above 33 degrees.

Continuous heatwaves are a sign that the effects of climate change are becoming a lot tougher for humanity to cope with. After global carbon dioxide emissions fell during the first year of the pandemic, they rebounded in 2021, with a sharp increase in the use of coal in electricity generation for commercial, industrial and domestic activities.

The rise in the number of private electric cars in Hong Kong and elsewhere means the world needs ever more electricity to power these so-called zero-emission vehicles. In Hong Kong, the electricity used to power such status-enhancing cars still mostly comes from coal or gas-fired power generation. And as for making a serious switch to renewable sources, we are told we must wait a few more years.

As nations worldwide apply strong, but not necessarily sustainable, stimulus to drive post-pandemic economic recovery, and with the price of natural gas rising steadily since July 2020, there has been an increase in the use of coal. As a result, coal accounted for over 40 per cent of the overall increase in global carbon dioxide emissions in 2021, according to the International Energy Agency.

We must work much harder and faster than in the past to reverse the demand for fossil fuels by accelerating the zero-carbon energy transition, improving energy efficiency and investing in carbon capture and other emerging technologies which are quickly becoming scalable. Shifting into reverse gear in the middle of the decarbonisation journey is not simply unwise, but absolutely misguided.

Back to Hong Kong: why is the city still so hot at night when the sun has gone down? We can attribute this phenomenon to the urban heat island effect, where dense concrete jungles act as enormous heat sinks, absorbing solar radiation during the day and releasing it into the environment at night.

High-rise buildings packed closely to each other inhibit the dispersion of heat to higher up in the atmosphere. The problem is further intensified by the lack of trees in urban districts that would otherwise absorb heat emitted by air conditioners, vehicles and construction equipment.

Increasing green, open spaces and planting vegetation is an effective means, as the government well knows, of absorbing ambient heat and lowering temperatures. Therefore, urban and country parks are essential for regulating climate, and must be conserved and enhanced.

Those working in cool or even downright cold air-conditioned offices might not be aware of the threats posed by record-breaking heat as they can continue business as usual shielded by artificial cooling systems which themselves require a lot of energy to run and which emit carbon dioxide and heat. This is a vicious cycle we must break by rethinking our wasteful habits.

Humanity should be prepared to face even hotter temperatures and more extreme climate threats in the near future if we refuse to sacrifice our comfort a little and continue to only practise sustainable development superficially.

Edwin Lau
Executive Director, The Green Earth