By Vaudine England
BBC News, Hong Kong
A leading Hong Kong think-tank has released the first study examining the likely impact of climate change on Hong Kong and the Pearl River delta.
Extreme weather caused flooding in southern China in 2005
The Civic Exchange study concludes that even small water-level rises combined with extreme weather could cause flooding across the low-lying delta.
The Pearl River delta is southern China's manufacturing and trade centre.
The knock-on effects of such flooding could be felt globally, the report suggests.
The study looks at long-term changes in water levels and what can happen within a decade or two when small water-level rises combine with typhoons.
The report suggests that flooding in the region would quickly lead to a shutdown in key industries and trade across the delta and in Hong Kong.
Given the importance of this region to world trade, the effects could be widely felt.
Key infrastructure such as ports, power lines and drainage systems will fail to function.
Lead author Alexandra Tracy said policy makers need to start considering how to improve coastal defences.
She said scientists' predictions of a 30-cm rise in sea level within about 20 years suggest a greater risk of water surges caused by typhoons and heavy rain.
"While that happens the economy of the delta is severely compromised - factories can't run, raw materials can't come in, power can't be reconnected," she said.
"Finished goods can't go out of the ports and airports because everything has been disrupted."
Several heavy storms this year have already flooded parts of southern China and the damage can only get worse, the report warned.