In recent years, Hong Kong has faced a series of extreme weather events, indicating the influence of global climate change. The Chinese University of Hong Kong's (CUHK) School of Architecture, in collaboration with the University of Hong Kong (HKU) and the Hong Kong University of Science and Technology (HKUST), conducted a study on the impacts of extreme weather events on the built environment in Hong Kong.
Using a combination of a mesoscale Weather Research and Forecasting (WRF) Model and local urban environmental data, the research team projected the future trends and effects of extreme weather events in Hong Kong. Their findings indicate an increase in the average number of hot nights, defined as nights with temperatures not falling below 28 degrees Celsius. The 10-year average number of hot nights is expected to rise by 50%, from 32 days to approximately 48 days, by the 2040s. The longest consecutive number of hot nights is also projected to increase from eight to around 10, with a maximum of 15 consecutive hot nights. Previous studies have highlighted a greater threat to public health posed by hot nights compared to hot days.
Considering Hong Kong's high-density urban morphology and the urban heat island effect, the research team assessed the variations in heat stress by district based on the longest consecutive number of hot nights. The areas heavily affected by hot nights in the projected future include Sha Tin, Tuen Mun, Kowloon, the northern and southern parts of Hong Kong Island, and the airport region.
Furthermore, climate model projections indicate that Hong Kong is expected to experience its highest hourly rainfall of 230mm in the 2040s, which is over 40% higher than the record set during a recent black rainstorm. The research team warns that more intense and frequent extreme rainfall events will increase the risk of landslides and severe flooding, posing significant threats to public safety and urban infrastructure.
Professor Edward Ng, the project leader and Yao Ling Sun Professor of Architecture at CUHK, stresses the importance of raising public awareness about the severity and potential impacts of these extreme weather events. The new normal of extreme weather requires individuals to prioritize personal safety by staying indoors during heavy rain, avoiding flooded areas and slopes.
Professor Jimmy Fung, Chair Professor in the Department of Mathematics and the Division of Environment and Sustainability at HKUST, highlights the destructive nature of heavy rainfall. Its sudden onset and the challenges of accurate prediction will test the government's disaster preparedness and emergency response capabilities.
Dr Chao Ren, Associate Professor in the Faculty of Architecture at HKU, emphasizes the vulnerability of the elderly and individuals with chronic illnesses to heatstroke and cardiovascular diseases during prolonged extreme heat. She calls for effective allocation of medical resources and enhanced community services based on the varying degrees of heatwave impact in different districts.
The research team supports the measures proposed in the 2023 Policy Address regarding extreme weather and believes that their findings can provide scientific data for the government's decision-making process. They urge the government to adopt a proactive approach in addressing extreme weather crises by formulating protocols, implementing permanent support measures, and adjusting infrastructure management plans. Effective coordination among different government departments is crucial for issuing forecasts and implementing response measures. The community at large should also enhance disaster preparedness training and ensure the availability of emergency evacuation supplies. Reducing carbon emissions is deemed more urgent than ever, and the research team calls for collective efforts from businesses and citizens to address the challenges of climate change.
