The record-high rainfall and serious flooding that hit Hong Kong on Thursday night were a reminder that “climate change is really here,” former Observatory director Lam Chiu-ying has said, as he called on the government to enhance the city’s resilience in face of natural disasters.
The torrential rain, which brought severe flooding and landslides to multiple districts across Hong Kong would have been “unimaginable” half a century ago, retired meteorologist Lam told HKFP on Friday after the city was largely paralysed by the extreme weather event.
Images of people struggling to make their way along submerged streets and through flooded MTR stations and shopping centres circulated widely online in the early hours of Friday, shortly after the Hong Kong Observatory issued the first Black rainstorm signal of the year at 11 pm on Thursday. At least two people died during the rainstorm, one of which was being treated as a suicide, and 115 others were injured as a result of the downpour.
An hourly rainfall of 158.1 millimetres was recorded in the hour after the Black rain warning was hoisted, the highest since records began in 1884. It was 12.6 mm more than the 145.5 mm in 2008, the previous record.
“The flood reminds us that climate change is really here,” Lam, who led the Hong Kong Observatory between 2003 and 2009, said in a Cantonese phone interview with HKFP.
Extreme weather scientist Professor Chu Jung-eun of the City University of Hong Kong told HKFP on Friday that the heavy downpours were a result of the meeting of air movements steered by powerful typhoons Saola and Haikui.
The Observatory issued the top-level Hurricane Signal No. 10 last Friday as Saola hit Hong Kong as a super typhoon, bringing serious flooding, fallen trees and blown out solar panels. Chu said while the tropical cyclone moved away from the city, it still had indirect effects on the city by a southwesterly monsoon flow.
The air movements formed by the two typhoons met in Hong Kong on Thursday evening and resulted in very strong and heavy localised precipitation, the CityU scientist said. Both typhoons also showed rapid intensification, she added, meaning their intensity increased more than 50 km per hour within 24 hours.
Chu said based on the climate simulations she conducted and consensus shared by academics in the field, typhoons are expected to become stronger with heavier precipitation under the effects of climate change.
“Climate change will definitely influence the intensity of typhoons,” she said, adding that typhoons also received more energy from warmer oceans as a result of the El Niño effect, which is a natural phenomenon that raises the sea surface temperature regardless of human activities.
Professor Jed Kaplan of the University of Calgary, Canada told HKFP on Friday that the world has seen record-high ocean surface temperatures, including in the northern portion of the South China Sea offshore of Hong Kong. Such warm ocean temperatures led to more humidity in the air, which could fall as rain under the right meteorological conditions.
Hong Kong is experiencing climate change not only through tropical cyclones, but also through extremely hot days and nights, said Kaplan, who conducted research at the Department of Earth Sciences at The University of Hong Kong from March 2019 until he left the university earlier this month.
“All of these meteorological phenomena lead to conditions that can be difficult for people to handle: increased incidences of heatstroke and other heat related illnesses, damage to infrastructure from rain and flooding, hurricane-force winds, and landslides all contribute to economic damage and costly investments in repair and mitigation of future risks,” he said.
To cope with more extreme weather conditions, the Hong Kong authorities should review past disaster preparation measures and take into account new data when evaluating the efficiency of its systems for preventing slope failure and flooding, former Observatory chief Lam suggested.
“Climate change is here. Extremes will become normal… there is a need to enhance the climate resilience of our city,” he said.
Improving Hong Kong’s resilience meant ensuring the city’s infrastructure could withstand extreme weather conditions, and post-disaster recovery must be well-planned, too, Lam said.
The city should also broaden the scope of its disaster preparation to include measures for handling “secondary disasters,” such as the collapse of mobile network during a storm.
Lam also reminded Hongkongers to step up their disaster awareness and be aware of the “vulnerabilities” of a city.
“There is a lack of disaster awareness. People think that houses in Hong Kong are very well-built and the government is doing a good job and they do not have to worry because they assume someone would protect them. But when a disaster comes, you can only save yourself,” he said.
This should be ‘a learning experience’
A man who gave his name as Liu, 30, spoke to an HKFP reporter in Wong Tai Sin, where floods remained on Friday afternoon. He said he had been at a friend’s home in Ho Man Tin when the warning was hoisted on Thursday night, and had to take a detour to find his way back to his home in Wong Tai Sin.
He said he did not have enough time to take proper safety precautions at home.
“If the government is able to predict that the emergency conditions will have to be in place hours in advance, shouldn’t it also be able to send the [initial] warning much earlier?” he asked. “They should take this as a learning experience.”
Additional reporting: James Lee
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