Neon signs advertising the “MING COURT HOTEL,” “RUBY TUESDAY” and “THE STUDIO” hang over the streets of central Hong Kong and Tsim Sha Tsui, lighting up the city’s night sky, but also polluting it with carbon emissions.
In 2013, University of Hong Kong’s physics professor Jason Pun made headlines when he said the night sky near the space museum in Tsim Sha Tsui was 1,000 times brighter than the international standard of a dark sky.
The International Astronomical Union set up this dark sky standard in 1979, measuring night sky brightness levels in its bid to protect dark moonless skies from the light pollution emitted by artificial lighting.
Residential outdoor lighting in the United States alone pumps 15 million tonnes of carbon into the atmosphere every year, according to the Arizona-based International Dark-Sky Association (IDA). To offset that amount of emissions, humans would need to plant 600 millions trees a year, the association says.
While no research has been done in Hong Kong about the carbon cost of light pollution, Pun says the amount of energy used for lighting the city is similar to that used in the United States.
“About 10 percent to 15 percent of all electricity generated is used for lighting. But we haven’t really done [research about] how much energy is wasted and so on,” says Pun, who has spent ten years researching the lights in Hong Kong’s night sky.
The need to look at city lighting comes amid increasing concern over climate change. When humans burn fossil fuels they are emitting greenhouse gases, wrapping a blanket of carbon pollution around the earth. This traps heat in the atmosphere which causes heavier rain, stronger typhoons and raises sea levels, a series of Intergovernmental Panel on Climate Change reports show.
This is why Hong Kong’s leader Carrie Lam said in her 2020 policy address she would like the city to be carbon neutral by 2050. Working out how much light a city consumes, and whether it should be limited, will be key steps to reaching this target, particularly when the city’s light levels are so much brighter than a standard night sky.
Hong Kong’s total greenhouse gas emissions in 2017 amounted to 40.7 million tonnes. Electricity generation was the major source of these emissions, amounting to 26.6 million tonnes, or 65.4 percent of the total.
Hong Kong’s Task Force on External Lighting submitted a report in April 2015, drawing attention to the nuisance and energy wastage of outside lights. The report noted that there was much wastage due to intense light, inefficient installations and long operating hours.
There are no laws in Hong Kong to regulate excessive lighting, and in light of the report the government urged all its departments to switch off outside lighting with decorative, promotional or advertising purposes at 11 p.m. It also encouraged private businesses to turn off lights.
And indeed at 11 p.m. in Tsim Sha Tsui on May 19 most shops had turned off their lights after the closing time. Some 24-hour stores, restaurants, and clubs still had their lights on. A small number of stores kept the lights on to light up billboards even after the closing hour.
“I can understand why shop owners want to keep lights so bright. Stores in Hong Kong are so dense that everyone wants customers to notice his or her own store,” said Ma, a 28-year-old working in a milk tea shop in Tsim Sha Tsui who only wanted his last name used. “That’s why they use lights to catch people’s eyes.”
A store was keeping the lights on after closing at 11:18 p.m.
The Hong Kong lighting task force urged in its 2015 report that the public be educated about the problems of outdoor lighting.
International Astronomical Union (IAU) member Exodus CL Sit has spent the past few years educating people about the importance of having a dark sky and encouraging them to reduce outdoor lighting.
Sit updates his Facebook page every one or two weeks with events that promote the dark sky. Countries and regions like Japan and Taiwan have “dark sky regions” protected by law to remain dark. But Hong Kong is such a high-density city that it may be hard to operate an individual dark sky region.
The assistant curator of the Hong Kong Space Museum, Frances Leung Wing Yan said that because of the pandemic, they actually saw fewer lights being turned on as people went out less often, especially during the night.
But Leung worries this may be temporary. “When we go back to our normal life, the businesses will act as usual, and all the lights will be turned on and polluting the sky again,” he said.
The night scene in Tsim Sha Tsui at 8 p.m.
Besides turning off lights and limiting the time they are on, there are a number of other solutions, experts say. The IDA for one urges people to use energy-efficient lights.
The Hong Kong government wrote in its Climate Action Plan 2030+ that the airport community had already replaced over 100,000 traditional lights with LEDs, leading to significant carbon reductions and cost savings because the lights last longer.
The government has also encouraged the Highway Department and the Leisure and Cultural Services Department to use LED lights to save energy and slash emissions.
The LED light is currently the most energy-efficient light type in the world, said John Barentine, director of public policy at the IDA. But it still takes effort to switch to LED from an older technology like sodium lighting, which is still dominant in large parts of the world. The LED lights require new equipment and it takes time to cover costs.
The IDA team have also looked at how much light is lost to the night sky through unshielded or poorly-aimed outdoor lighting. Barentine says 20 to 50 percent of outdoor light is lost to the night sky. Shielded lights direct light to the ground where it is needed and thus saves energy.
As light pollution is still a niche concept to most people, Barentine said the onus must not be just on education, but also on solutions. “Our task is not only to make people aware of the problem. But convince them that they want a solution.”
Video: Dr. Barentine talks about how we can reduce light pollution
as well as keeping Hong Kong’s unique “light city” identity.
