AAP: THE whole objective of an emissions trading scheme (ETS) is to change people’s behaviour and it should apply to as many sectors as possible, including transport and fuel, the head of the former government’s emissions task group says. But Peter Shergold, former secretary of the Department of Prime Minister and Cabinet, said even a carbon price of $20 or $30 a tonne would have a relatively modest impact on fuel prices, compared with price hikes so far this year. Speaking ahead …