At least seven protests are planned on the final day of the G20 summit, including a mock arrest of Prime Minister Tony Abbott for failing to act on climate change.
Police in Brisbane are hoping the protests will be as peaceful as the more than 20 events that played out on Saturday, when there were only a handful of arrests.
The Abbott impersonator known as Bad Tony will be "arrested" by a band of children for recklessly endangering their futures and sentencing the Great Barrier Reef to death.
The protest comes after US President Barack Obama used a landmark speech at the University of Queensland to demand climate change action by countries including Australia.
The president made particular mention of the reef, saying he wanted it to be there for his children and grandchildren to see.
Climate action campaigners from the group Generation Alpha say Mr Abbott is facing pressure on all fronts and must act now.
"Tony Abbott is doing everything he can to avoid real action on climate change at G20. This threatens the future of our children and they have every right to take him away for serious questioning," the group said in a statement.
Police have warned of more disruptions on the summit's final day, particularly at the end of the day as most world leaders depart.
"Until the last leader leaves, the job's not done. While they are here they remain our responsibility," Deputy Commissioner Ross Barnett has told reporters.
Assistant Commissioner Katarina Carroll said it was a huge logistical challenge getting so many protected people out of the city around the same time and delays can be expected, particularly on roads to the airport.
Once the leaders have left, the huge task of returning the city to normal will begin, with barricades along roads and hotels to be taken down, roads reopened and security cordons lifted.
Public transport will be running to normal timetables from Monday.
