Study: HK to see more hot days, heavier rainfall

The study found that from 2020 to 2049, the 10-year average annual number of hot nights, with a minimum temperature of 28 degrees Celsius and above could go up 50 per cent to 48 days.


A resident enjoys the sunny weather at Clear Water Bay beach in Sai Kung on July 12, 2023. PHOTO: CHINA DAILY

November 28, 2023

HONG KONG – Hong Kong will see more hot nights and black-rainstorm signals amid worsening extreme weather up to 2049, a study revealed on Monday.

The scholars suggested the city adopt multipronged measures, including devising a sound response mechanism and adjusting the management of new infrastructure, to cope with the extreme weather and reduce carbon emissions.

The study — jointly conducted by the Chinese University of Hong Kong’s School of Architecture, the University of Hong Kong, and the Hong Kong University of Science and Technology (HKUST) — found that from 2020 to 2049, the 10-year average annual number of hot nights with a minimum temperature of 28 degrees Celsius and above in Hong Kong is expected to go up 50 percent to 48 days. The prediction was made by a mesoscale weather research and forecasting model with local urban environmental data.

The 10-year annual average of the longest duration of consecutive hot nights will rise from eight days in the 2011-20 period to 10 days by 2049, with the maximum number of consecutive hot nights reaching 15 days. Areas that are expected to be heavily affected by the hot nights by the 2040s include Sha Tin, Tuen Mun, Kowloon, the northern part of Hong Kong, the southern part of Hong Kong Island, and the airport region.

Ren Chao, associate professor in the Faculty of Architecture at HKU, who participated in the research, said that five consecutive days of intense heat will increase the risk of death by 6.66 percent.

Ren said that currently, the temporary night heat shelters in Hong Kong are insufficient in terms of number and location distribution, and experts say the government needs to pay attention the situation to effectively allocate medical resources and enhance community services.

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The report also predicted that the city is expected to have a record of hourly 230-millimeter rainfall in the 2040s, 40 percent higher than the current record of 158. The 158.1 mm of rain recorded in one hour in September was an unprecedented, once-in-a-century rainstorm. The heavy rain wreaked havoc in the city, with buildings, roads and tunnels inundated.

Jimmy Fung Chi-hung, chair professor in HKUST’s Department of Mathematics and the Division of Environment and Sustainability, said that the chance of landslides and severe flooding will significantly increase, as the extreme rainfall becomes more intense and frequent. The situation will also further test the disaster preparedness and emergency-response capabilities of the government and residents.

Apart from concerns of extreme rainfall, which have been addressed in the government’s latest Policy Address, the research team suggested heightened attention be given to hot weather, which also will have a significant impact on livelihoods and public health.

To tackle various extreme weather conditions, the study recommended that the government regularly review and update standards for extreme weather based on the latest scientific knowledge.

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Protocols for dealing with extreme weather, such as flood prevention measures in flood-prone areas, should also be developed in advance. To deal with the “new normal”, permanent support measures and services needs to be implemented, such as adding heat shelters. As for the new urban planning, particularly in the Northern Metropolis and the Kau Yi Chau Artificial Islands, the government should take into account the potential impact of extreme weather. Various government departments and all sectors of the society should also collaborate on training and the stockpiling of material to deal with weather-related disasters.

The city aims to achieve carbon neutrality by 2050, according to the Hong Kong Climate Action Plan 2050. Experts said the government should update its action plan with the latest study to update its road map to zero carbon emission.

Meanwhile, the city should work harder to reduce carbon emissions, which require more energy-saving efforts from every resident and company in their daily activities. The study suggests using green transport, reducing waste, and increasing recycling.

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