Thousands of school students, parents and activists have gathered in Sydney's Town Hall Square to demand action on climate change as part of the global Strike 4 Climate Action movement.
The students - many wearing their uniforms - held signs on Friday with slogans such as "The climate is changing, why aren't we?" and "Make earth cool again".
The Sydney lunchtime demonstration is one of 50 simultaneous rallies across Australia.
Young people, including university students, are taking part in a worldwide event with more than 90 countries hosting protests.
Nine-year-old Eli Cunio Scarborough, from Bondi Beach Public School, attended the strike with his mother Stephanie Cunio.
Eli told AAP he was at the rally because "we need to help and scream out loud" that governments were making wrong decisions.
"If there's too much coal it will ruin and kill the animals and kill the planet ... and we can die too because coal is bad," he said.
The nine-year-old's message to governments was: "Listen to us kids. All the time."
