Dr Jamnern Woraratchaiphan told mayors and town planners that Phuket could have as little as five years before worsening pollution triggered irreversible damage.
Dr Jamnern of Brace - Building Climate-Resilient Asian Cities - gave his warning at a meeting at Phuket City council offices yesterday.
''About 1995, Phuket began trying to cope with growing numbers of tourists,'' he said. ''In 2005, after the tsunami, growth really accellerated and by 2009, problems with overly rapid development began to emerge.''
Garbage, bad water and unplanned development could not be dealt with unless there was a cohesive strategy involving every aspect of Phuket, across government and private fields, he said.
''Polluted water is allowed to flow into canals and into the sea,'' he said. ''Inevitably, this means tourists will contract skin complaints and infections.
''The forests are being cleared for resorts or condos, or rubber plantations. But water can't find its way through a 'concrete forest,' so Phuket inevitably has flooding and landslips.''
With growth now at five or six percent a year, Dr Jamnern gave Phuket just five more years before the problems would prove insurmountable.
''Chaotic, uncontrolled development without a plan means that Phuket's carrying capacity will be exceeded.
''Infrastructure is already behind and if it sinks further behind, Phuket will not remain an attractive place to visit.''
He said the local culture was also threatened as ''international culture'' took a hold.
''Knowledge has to be passed on to children at schools and the local councils have to support Phuket culture in every possible way,'' he said.
A long-term strategy to make sure there were green public spaces was the only option. Phuket needed decisions made on the island.
The more self-reliant Phuket could become, the better the outcome was likely to be, he said.