Weather defences are vital in dense, built-up Hong Kong

Last week, Hong Kong experienced one of the hottest days so far this summer. Higher temperatures seem to be on the horizon. At the same time, we are encountering more frequent storms and even freak weather, such as the black rainstorm in March that saw hailstones hammering parts of Kowloon and the New Territories. The need to develop resilience against climate change is becoming more pressing.

The fifth assessment report of the Intergovernmental Panel on Climate Change, which was published earlier this year, cites evidence that human influence has been the dominant cause of observed global warming since 1950.

For the utility companies charged with making sure cities all over the world keep running, this is thought-provoking news. Professional engineers can construct bigger drains to accommodate more run-off water from storms and facilities managers can crank up the air-conditioning controls to deal with hotter days, but conventional engineering wisdom is being stretched to its limits in resolving the problems and risks that climate uncertainty brings.

This is largely because cities have become more compact and dense, not to mention vertical. As cities become sleek urban centres accommodating more and more people, the infrastructure to support this move is ageing and struggling to catch up, let alone deal with sudden weather surges.

Take energy and water, for example, which are essential for urban development. Constantly upgrading and protecting the systems that provide these two services will go a long way towards embedding climate resilience.

Equally, when shoring up a city's climate defences, human safety and business continuity are vitally important. In the event of severe weather disasters, people must be shepherded to safe places for shelter and protection.

Transport networks must be weather-proofed for this purpose, as well as affording access for emergency services. Clean water must be available for sanitation needs and avoidance of disease.

For an important financial centre like Hong Kong, business continuity is crucial, not just for the financial sector but for all other supporting industries in this vibrant city. Keeping the lights and computers on is not just a matter of making sure the city still functions but also vital in preserving global confidence.

Power and water are not the only concerns; we also depend on connectivity. Our vulnerability here is rapidly exposed once servers and telecom exchanges go down, with the result that our mobile phones and laptops malfunction.

Thankfully, we have put some measures in place. Building codes are being applied to make buildings more energy-efficient to cut down air-conditioning excesses, and the planting of green roofs to eliminate heat islands is being encouraged.

The use of building information modelling, which involves generating a digital representation of physical buildings, and introducing more advanced building materials further help architects and engineers shock-proof building structures.

Along stretches of key rail and road infrastructure, sea walls have been or are about to be erected to cope with sea level rises, and the possible use of green infrastructure like mangrove beds is being explored as an excellent example of nature's own defence systems. In the future, housing our utilities in protective rock caverns will be another elegant way of harnessing nature's resources.

Given our compactness, land use is an additional factor to be considered in building resilience. For instance, should we be developing on land areas that are visibly at risk? Many coastal cities elsewhere are contemplating whether it is more economic to withdraw further inland and abandon areas in the flood plain instead of erecting costly sea walls.

With Hong Kong's precarious land situation, would this be a viable option? Market as well as climate forces will no doubt come into play in this debate. Will the Central business district retreat up to Mid-Levels should the sea wish to reclaim what we took during the harbour reclamation projects of the 1980s and 1990s?

A key attribute of resilient cities is the ability to bounce back. New Yorkers were back on their feet within days of Hurricane Sandy. Even typhoon-stricken communities in Southeast Asia have made enormous strides in recovery over the years, although rebuilding still takes months and possibly years.

Disasters are not just climate-related. In 2003, Hong Kong's showed great character to come back from the impact of the outbreak of severe acute respiratory syndrome, which underlines the city's ability to get things done when properly mobilised. But it is best that we do not wait for a disaster to occur in order to react. It is far better to plan now and equip ourselves for a future shock.

For this to happen, we need leadership vision that percolates to the rank and file. Hong Kong needs a comprehensive integrated climate plan that engages the public and cuts across government agencies with cross-jurisdictional mechanisms so that we can coordinate with mainland resources.

Hurricane Sandy proved to be a sobering lesson for New Yorkers when lives were tragically lost and the power lines went down. Let's hope Hong Kong doesn't have to experience a Sandy episode to start rethinking climate defences.

Dr Thomas S. K. Tang is director of corporate sustainability, Asia, at Aecom