CLIMATE change is fast turning out or a big challenge for mega cities.While experts list coastal megacities like Chennai,Mumbai,Bangkok,Manila,Chittagong and Tokyo as among the most vulnerable to climate change, they feel that Asian cities could lead a fight back by turning in to ‘low – carbon cities,’ on the lines of Hong Kong and Singapore, Where the cities have not just cut down on on the usage of fossil fule, but have also developed an effective road and rail- based mass transit system.