Businesses in city 'must plan ahead' to limit damage from rising sea levels, experts say
How badly affected would Hong Kong be if sea levels rise as predicted? The city's rugged coastline and high sea walls offer some protection but government and businesses cannot be complacent from the threat of stronger typhoons and accompanying storm surges, say experts.
"The government has to have policies at all levels. When we think about the substantial cost associated with sea flooding versus taking early action to avoid damage, it is better to plan ahead," said Kalmond Ma, the head of climate programme at the World Wildlife Fund.
The most deadly surges would come from a southerly direction and combine typhoon-strength winds, spring tides and a low pressure system to devastating effect, said Mok Hing-yim, a senior scientific officer at the Hong Kong Observatory, the government agency in charge of monitoring storms.
Ma said elevated sea levels around Hong Kong would put at risk residential and commercial buildings in unprotected districts. They would also affect wildlife sanctuaries such as the Mai Po marshes near the border.
Buildings less than 10 metres above sea level were potentially in trouble, said Caspar Honegger, the head of flood perils at Swiss Re. For those 20 metres and above, surges were not a problem, he added.
Sea levels in Victoria Harbour had risen on average 29mm per decade since 1954, when records began, Mok said.
Referencing data from the UN Intergovernmental Panel on Climate Change, the Observatory estimates sea levels will rise between 17 and 38cm by 2065, and between 26 and 82cm by 2100.
At the same time, it expects typhoons to increase in number and severity. In the Observatory's worst-case scenario, a storm like Typhoon Hagupit in 2008, which whipped up waves up to 3.53 metres high in Victoria Harbour and caused flooding and power cuts, will no longer be a once in 50 years event.
By 2065, it will happen every five years, and by 2100, it will be an annual occurrence. By 2100, wave surges topping 4 metres would hit Hong Kong every decade under this scenario, said Mok.
Various government departments were now assessing the impact climate change might have on Hong Kong, said Paul Chu, a spokesman for the Civil Engineering and Development Department, and a report was expected by early next year.
In a 2012 report, the Hong Kong Business Environment Council, a corporate-sponsored think tank, recommended a "first response" towards climate change. The government, power sector, transport network operators and the construction industry, among others, all needed to develop strategies to adjust to a changing climate, it said.
There are no cost estimates of the potential damage of future storm surges to Hong Kong, or of the investment required to protect existing shorelines.
In a recent report assessing the impact of hurricanes and rising sea levels on New York, Swiss Re analysts estimated that annual losses will increase from US$1.7 billion today to US$4.4 billion by 2050.
Mok said contractors and civil engineers routinely quizzed him on climate change.
"Contractors consider their safety margin and expected impact from climate change, the cost effectiveness and the longevity of the project," he said.
Coastline infrastructure needed to be protected by 5-metre-high walls, and new developments should be sited away from high risk areas, he said.
Ma recommends the construction of curved sea walls as these would help absorb a wave's power. Straight walls like the ones protecting Victoria Harbour, only deflect the waves and cause a ricochet effect. Low-lying land could be rezoned as unsafe and critical infrastructure moved to higher ground, he said.