Sydney's five-week heat wave could be the cause of a spike in mass brawls as Australians drink more, becoming increasingly intolerant and hot-headed, says a leading emergency surgeon. In the early hours of Sunday morning an argument between two people escalated into what was thought to be Sydney's largest street brawl in a decade. Though initial reports said the brawl involved about 200 people, New South Wales police later said 30 people were actually involved.Meanwhile in Melbourne more than 100 people were involved in a fight apparently instigated by a local gang.The temperature in Sydney exceeded 28°C on Saturday, the 37th consecutive day of unusually hot and humid weather."Almost certainly the heat makes people crankier and hot-headed like on Sunday when two taxis crashed into each other, one ending up against a pole trying to get to the same fare first," said Gordian Fulde, head of the casualty department at Sydney's St Vincent's hospital. ..