Coastal city research steps up amid record super typhoons

Hong Kong has stepped up research into the impact of climate change and extreme weather events on coastal cities to help build urban resilience in Hong Kong, southern China and across the typhoon-prone region with the inauguration in December of a major new university-based China State Key Laboratory (SKL) of Climate Resilience for Coastal Cities.

The Hong Kong Observatory’s annual review released this month showed that 20 weather records were broken in the city in 2025, including the record for the highest average temperature for the second half of the year. Each of the 12 months of 2025 was warmer than those months in previous years.

Powerful storms battered Hong Kong and southern China last year, including Super Typhoon Wipha in July 2025 and Super Typhoon Ragasa from 23 to 25 September 2025 – the second most intense tropical typhoon worldwide last year. Storms classed as super typhoons pack sustained wind speeds of over 240 km per hour.

The two super typhoons twice led to the raising of a No 10 alert signal – the highest alert level in the city. It was the first time in 60 years that Hong Kong has seen a No 10 alert. Tropical cyclone warning signals were issued 14 times in 2025 – the highest number in a year in almost 80 years and more than double the long-term average of six warning signals per year.

Ragasa’s fierce winds triggered storm surges, landslides and overtopping waves, causing flooding in many parts of coastal Hong Kong. The China Meteorological Administration dubbed Ragasa the “King of Storms”, shutting down schools, businesses and transport systems in parts of the province. The Philippines, Taiwan and Vietnam were also affected.

Pointing to the increased frequency of extreme weather events, Charles Ng, professor in the Department of Civil and Environmental Engineering at Hong Kong University of Science and Technology (HKUST), said Hong Kong experienced five “500-year return period” rainstorms in just the last 30 years.

“Theoretically, these should happen only once in 500 years, not five times,” he told University World News, attributing the frequency to climate change.

“The Hong Kong government has been trying their best to improve the resilience of the city,” added Ng, co-director of the newly inaugurated China State Key Laboratory of Climate Resilience for Coastal Cities, jointly run by HKUST and Hong Kong Polytechnic University (HKPolyU).

New coastal cities lab

The new coastal cities lab will conduct research into strengthening climate-risk early-warning systems and emergency response capabilities and promoting sustainable development to address challenges posed by climate change.

“By pioneering solutions for urban disaster mitigation and infrastructure resilience, this laboratory represents a strategic national initiative,” HKUST President Nancy Ip said at the inauguration event held on 4 December 2025.

Ng at HKUST and co-director Professor Li Xiangdong at HKPolyU, noted in a joint statement that the various research initiatives “will significantly improve coastal cities’ future forecasting accuracy and response capabilities under severe weather conditions”.

New weather patterns are emerging, Ng notes. According to his own research over the past 30 years in collaboration with Hong Kong’s Civil Engineering Development Department (CEDD), total rainfall only increased by about 4 mm per year, but rainfall distribution has become more localised – heavy rain falls in one area of the city while just a few kilometres away, neighbourhoods remain dry.

“That’s very unusual,” Ng pointed out, adding this requires more detailed research and more granular area forecasts.
Hong Kong’s first university-owned satellite was launched by HKUST in August 2023 to collect more precise climate and carbon dioxide data. The civilian multispectral optical satellite aims to improve early warning systems for extreme weather events, potentially extending warning times from three to six hours and providing street-level precision down to one square kilometre for weather forecasts.

For example, the satellite’s data is helping to create a “digital twin” of Hong Kong’s thousands of slopes to map landslide hazards as the climate changes.

HKUST this month announced that its researchers had developed the world’s first AI-assisted weather model enabling four-hour advance rainstorm forecasts based on satellite data.

It is also 15% more accurate for areas of around 48 square kilometres than existing radar-based systems, according to the research team led by HKUST professor Su Hui, climate change and extreme weather direction lead of the new coastal cities SKL.

Conventional weather forecasts, which rely on numerical weather prediction models, are typically only accurate 20 minutes to two hours ahead of such sudden events, which does not meet the needs of emergency response, according to Hui.

The new system “can be applied to data from different satellites, expanding its coverage and enabling more countries and regions to respond effectively to rising climate risks,” she told a press conference on 28 January.

She added: “We are moving from simply observing weather to intelligently anticipating it, which is a fundamental shift for safety and sustainability in a warming world."

State key laboratory system

SKLs are prestigious centres of research excellence funded by China’s Ministry of Science and Technology (MOST).

Around 16 SKLs have been set up in Hong Kong since 2005, but the coastal cities laboratory is the first completely new SKL facility, set up after a review of Hong Kong SKLs was completed by MOST last year and a new competition launched for the city’s universities to host SKLs.

MOST “invited each university to come up with one team to compete for potentially new [SKL] slots”, including sustainability as a new category, explained Ng, who was vice-president at HKUST’s Guangzhou campus till August 2025. “Ours was the only new [category], so we came under stringent scrutiny – our proposal had to be world-leading,” he noted.

He added: “They measure quality by comparing with international standards.”

The SKL designation is very prestigious, he added. “It enhances opportunities for mainland research collaboration and student recruitment. Another important aspect is to be able to attract a high quality of students to join, including postdocs. That means we can strengthen the research.”

The SKL designation brings an additional HK$20 million (US$2.5 million) in annual funding from the Hong Kong government's Innovation and Technology Commission (ITC).

“Members of state key labs are able to apply for joint research grants on the mainland,” Ng said, noting that China has opened up some competitive research grants to applications from researchers in Hong Kong.

China is heavily prioritising climate change research and is now a global leader in both research output and investment in green technology.

China’s largest basic research funding body, the National Natural Science Foundation of China (NSFC), has emerged as a leading global funder of climate change science, supporting 8.3% of reported global research between 2000 and 2023, according to a 2025 report by Germany’s Max Planck Institute for the History of Science, Berlin.

Preparing for compound events

Hong Kong is not just a coastal city; it is densely populated and hilly with many high-rise buildings on its slopes. This contributes to landslide risk but also increases the speed of flooding and compound flooding, which can impact its vibrant economy.

Simon Lee Sui-po, a senior lecturer in accounting and finance at the Chinese University of Hong Kong’s Shenzhen campus, estimated total losses in Hong Kong from Ragasa at HK$2-3 billion (US$257-$386 million).

Seven typhoons from June to December 2025 also caused “direct economic losses” of CNY12.44 billion (U$1.7 billion) to China’s Southern Guangdong province neighbouring Hong Kong, according to statistics from China’s Ministry of Emergency Management.

Nonetheless, while Ragasa’s wind speeds were stronger than previous typhoons, flooding in Hong Kong was not as severe as it was with Super Typhoon Hato in 2017 and Super Typhoon Mankut in 2018.

With Ragasa, “the storm surge [mean sea level change] did not coincide with high tide or spring tide, unlike Hato and Mankut, which were superimposed with spring tides and caused a lot of flooding,” according to Wang Jinghua, assistant professor at HKPolyU, part of the new coastal cities SKL. “Hong Kong should plan for powerful storm surges caused by stronger typhoons occurring in the South China Sea and multiple events occurring concurrently.”

As global temperatures continue to rise, so does the risk of compound flooding – a dangerous convergence of heavy rainfall, storm surges and rising sea levels that can overwhelm drainage systems and natural defences, Wang, an expert in coastal engineering and storm surge modelling, told University World News.

In a recently published study, Wang simulates the impact of a concurrent storm-tide-tsunami event, with the tsunami generated by an earthquake in the Manila subduction zone, an active seismic area of the South China Sea.

“Tsunamis are very rare. Storm surge or typhoon events are more frequent and happen several times a year, and policymakers, when they think about early warning, usually look at the two events separately,” notes Wang.

Improving coastal infrastructure

In September 2023, torrential rain, Hong Kong’s heaviest in at least 139 years, associated with super typhoon Haikui, brought severe floods and landslides to many parts of the city, inundating shopping malls and metro stations. But it also led to government plans to upgrade seawalls, install demountable flood barriers, construct nine stormwater storage schemes and improve more than 50 km of drains by 2030.

In the past two years Hong Kong has more than doubled its annual spending on stormwater drainage to an estimated HK$3.17 billion, or US$407 million.

Wang said universities were important in providing the authorities with technical support.

Pointing to damage to Hong Kong waterfront businesses during Ragasa, Wang noted: “The seawall is definitely underdesigned – it cannot provide sufficient protection.”

The city authorities have floated the idea of increasing seawall height. “This is the easiest way but may not be the smartest way because people like to socialise and relax in that area. It would totally ruin the view.”

“You can easily change the shape of the seawall to be a bit curved. So, instead of the waves overtopping, they will be diverted back to the ocean,” he explained. This research is currently being discussed with engineering companies before being put to the Hong Kong government as a possible solution, he said.