While estimates of the size of the Climate Strike in Australia vary, one thing is certain: many generations want real action to deal with climate change — and they want it now.

According to School Strike 4 Climate organisers, more than 300,000 people protested in more than 110 towns and cities across the country on September 20.

Former Greens leader Bob Brown said there were more people at the Hobart strike than during the height of the Franklin Dam protests; other seasoned protesters say at least 10% of the city joined in.

In Melbourne and Sydney, where bigger protests are more common, many were still blown away by the size: 100,000 and 80,000 respectively.

According to organisers, the turnout in Brisbane was 30,000, in Adelaide 20,000, in Canberra 15,000 and in Perth 10,000.

Reports sent to Green Left Weekly said there were 10,000 in the coal town of Newcastle, 500 in Moruya, 1500 in Port Macquarie (all in NSW), 1500 in Cairns (Queensland) and 1000 in Bairnsdale (Victoria).

Trade union contingents came out, as did parents and grandparents. In some cases, teachers bought entire classes.

A new generation is leading this powerful movement for climate action. They are doing so with a clear set of demands: no new fossil fuels, 100% renewables, and funding for a just transition to sustainable jobs for all workers and communities reliant on the fossil fuel industry.

First Nations peoples led many of the strikes because, as organisers said: “They are and have always been at the forefront of the fight to protect land, water, air and Country”.

Popular chants included: “The seas are rising, no more compromising”, “The youth are rising, no more compromising” and “What do we want? Climate action. When do we want it? Now!”

The stark reality of inheriting a world in which catastrophic climate events has become the norm is motivating young climate organisers. They are not afraid to point out the hypocrisy and doublespeak on climate change from politicians.

You could feel that a mighty movement was being born as primary and secondary school students talked about why they were there and how powerful it was to be with so many others.

“System change, not climate change” summed up the overall mood. A generation is being radicalised by Australia's climate denying governments.

But what happens next will be critical. As the Iraq war mobilisations in 2003 showed, one huge protest is not enough. To make the climate safe, we have little time left to lay down the framework to rapidly decarbonise the atmosphere over the next decade.

We are already beginning to experience what catastrophic climate change looks like. The students are right to be angry: the climate emergency is already here and whether we can rise to the challenge of defying the deniers and forcing a change is a question we all face.

The students have shown their willingness to have a go and organise a global strike. Next time we have to back them up better.

While the Australian Council of Trade Unions put out a statement of support, and many unions did mobilise contingents, a safe climate must become front and centre of union business.

This is the only way to ensure the Climate Strike is a game changer.