Get on with it - global warning is real

The science of predicting global warming has its sceptics, among them vested interests like big industry. An update on rising sea levels by the United Nations climate panel, which forecasts up to a metre's rise by 2100, may not win new converts.

But a graphic presentation of how coastal flooding could gut the economic assets of low-lying cities should persuade laggard governments that taking timely preventive measures is not a matter of choice. Climate doubters can challenge the science, but not the visceral evidence of extreme weather phenomena. This is why a new climate study, which places 13 of the 20 most vulnerable cities in Asia alone, should concentrate minds.

Singapore is spared the dubious distinction, but its planners will want to evaluate the impact on the economy of flood damage to Guangzhou and Shenzhen in China, and Mumbai and Kolkata in India - besides Jakarta, Bangkok and Ho Chi Minh City. Shanghai, Tianjin and Xiamen are also at risk.

These are cities Singapore does business with. The study, published in the journal Nature Climate Change, calculates that flood damage to the 139 coastal cities assessed worldwide could reach US$1 trillion (S$1.27 trillion) annually by mid-century if mitigating steps are not taken.

Building and strengthening defences like levees and storm barriers go beyond preparing for an apocalyptic event by the end of the century, when island chains in the Pacific could vanish. Coastal flooding as a result of storm surges, land subsidence from groundwater depletion and urban growth will wreak havoc on an ascending scale well before sea levels rise.

Flood defences are not a recent invention.

Tokyo has had them going back 400 years. But with typical technological acuity, the authorities are building an underground reservoir carved into rock to receive excess runoff.

San Francisco is mulling a massive flood wall near the Golden Gate Bridge to save the bay area's multi-billion dollar technology economy from going underwater.

New York worries about its logistical operations.

Singapore has had the benefit of advice from the Dutch - reassuring as countless studies credit Holland with having the world's best flood defences.

But the frequency of inner-city flooding would have alerted the authorities to the adequacy of its primary defences - stone embankments, the Marina Barrage and a requirement that new reclamations be raised in elevation.

These are periodic infrastructural works which governments plan for and execute as a matter of course. The "scientific" notion of countering the effects of climate change through treaty- mandated reductions in carbon emissions is on the other hand fraught with problems. It is clear what governments should focus on.

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