The lessons learned from two super typhoons in the past two years highlight an urgent need for Hong Kong to protect coastal areas from extreme weather, academics, business leaders and policymakers warned at a climate change conference in the city on Monday.
When the next monster storm hit, the results could be much worse, they cautioned.
The three-day event, which ended on Monday, was hosted by the Hong Kong University of Science and Technology. More than 500 speakers, stakeholders and experts gathered for the conference.
It came two weeks after the UN-backed Intergovernmental Panel on Climate Change (IPCC) produced a special report on global warming outlining the impacts of global temperatures rising 1.5 degrees Celsius instead of 2 degrees. The panel said “rapid and far-reaching” societal changes would be needed.
More severe weather extremes are in store and Hong Kong would have to design policies and infrastructure to withstand the onslaught, experts said at the conference.
“With Typhoon Mangkhut we realised there are still some gaps, it’s about continuous learning,” said event chairwoman Christine Loh Kung-wai, a former Hong Kong environment undersecretary. “Our defence was good but we noticed there were new lessons to learn.”
Mangkhut hit in September and was the strongest storm on record to lash the city.
Ocean-related challenges have been identified as major hurdles for Hong Kong. Heavier rainstorms affecting larger areas were expected as seas warmed, conference speakers said.
Hong Kong Observatory director Shun Chi-ming said sea level rises were one of the most important challenges and the city had to plan for the worst.
While Mangkhut broke many records, Hong Kong enjoyed a lucky escape from its worst excesses as the storm was barely a fully fledged super typhoon as it closed in and did not make direct landfall over the city, Shun said.
Had the storm not weakened over Luzon in the northern Philippines, the story could have been different, he added.
“Our modelling assessments at the time were really shocking – some of our worst figures were 5 metres of storm surge in Victoria Harbour. For Tolo Harbour, Sha Tin and Tai Po we obtained a number of 7 metres,” he said.
The actual figures were eventually 3.9 metres in Victoria Harbour and 4.7 at Tolo Harbour.
Zhang Limin, a geotechnical engineering professor at HKUST, said governments would have to consider different strategies to adapt – including moving inhabitants away from coastlines, elevating properties, or building protection in the form of higher sea walls or structures that could float.
“What’s enough now might not be good enough in the future, so we need a little bit more action. For example, raising public awareness, natural disaster and emergency preparedness, and cross-disciplinary cooperation,” Zhang said.
“Resilience should be central to infrastructure design.”
Zhang Xuebin of Australia’s Commonwealth Scientific and Industrial Research Organisation said the effects of ocean warming would become harder to reverse than those of air temperature increases.
“Even if we undertake lots of mitigation work this century, it is guaranteed the seas will continue to warm until 2100,” he said.
Other problems include ocean acidification as a result of increased carbon dioxide intake, and eutrophication – an excess of nutrients in the water that can lead to ecologically disastrous algal blooms.
According to some studies, every 1 degree rise in sea surface temperatures will lead to a 2 per cent decrease in oxygen levels in the water.
These “dead zones” where oceans become depleted of oxygen – a phenomenon known as hypoxia – are growing in and around Hong Kong and Macau waters, according to researchers with HKUST’s Ocean-HK programme.
