Bracing for worse to come: city's typhoon defences need to evolve, experts say

During typhoons in Hong Kong, winds slam into skyscrapers with such force that buildings sway. Tidal surges turn Victoria Harbour into a cauldron of foaming waves. The roads of Central and Mong Kok become rivers of water. And residents lock themselves inside, listening to the echo of rain hammer on their outdoor air-conditioning units like furious pounding on typewriters.

Hong Kong has a protective system of defences to weather tropical cyclones. These defences continue to evolve, which is vitally important because experts predict the city will see even fiercer storms in the coming decades that will test engineering skills.

Rising sea levels and increasingly extreme weather present a challenge that could threaten the city's standing as an Asian financial centre and tourist hub.

The average temperature in Hong Kong is rising about 0.12 degrees Celsius every decade, with a mean 4.8 degrees rise predicted by 2100, according to the Hong Kong Observatory.

The blame, the observatory says, rests with growing levels of greenhouse gas emissions as well as the phenomenon of what's called the urban heat island - areas that are significantly warmer than their rural neighbours. Contributing factors are the city's crowded streets choked in excess motor vehicle emissions, poor ventilation between buildings and scarce vegetation.

The city's warming has triggered increased evaporation from the ocean and consequently more water in the atmosphere, Observatory forecasters say.