Blue Mountains high school students made their voices heard at the School Strike 4 Climate gathering in Sydney on Friday.
About 50 Katoomba High students from a newly-formed climate action group took part in the strike.
"Most of us don't want to bludge school, that's not why we are doing this," said student James Dawes.
"I feel like climate change is a looming shadow on our lives."
He attended the November students strike, and realised then that as a collective, they could make a difference.
Many of the students from Katoomba High wore Give a Dam shirts to the protest in Sydney in support of a campaign against the raising of the Warragamba Dam wall.
Environmental groups say parts of the Blue Mountains World Heritage Area will be inundated if the wall is raised.
"To see such a culturally and environmentally destructive dam proposal being pushed by the NSW government once again demonstrates how out of touch our leaders are with protecting the earth for future generations," said Katoomba High captain Arliah Varnel.
She said it was important that action be taken on climate change now.
"For me, striking for climate shows government and the world that even though youth aren’t able to vote, we have a voice, we have opinions and we will keep fighting for what is right. The question I ask myself every day is 'why are we sitting in classrooms to prepare us for our futures when there may not even be one if climate change continues at the rate it is today?' The oceans are rising and so are we.
"Today's [Friday's] climate strike was extremely powerful. Standing shoulder to shoulder with 30,000 of my fellow climate change activists was inspiring and brought us hope."
The movement calls for "all politicians to take urgent action to stop the climate crisis". They are against the Adani coal mine and new fossil fuel projects, and want Australia to be powered by 100 per cent renewable energy by 2030.
Thousands attended the strike in Sydney at Town Hall, and there were nearly 50 strikes held around Australia. More than 100 countries are taking part around the world, in a movement which began in Sweden by teen activist Greta Thunberg in 2018.