Since December, teenagers across Germany inspired by the 16-year-old Thunberg's climate fight have been marching weekly instead of sitting in classes. (AFP)
Thousands of German youths went on strike from school on Friday, joining Swedish teen activist Greta Thunberg who has taken her protest against climate change to Berlin.
Armed with homemade posters bearing slogans like "It's getting hot in here" or "Our house is on fire" or "You're never too small to make a difference", the teenagers packed into a park in central Berlin to sound the alarm about global warming.
From the park in front of the economy ministry, they were to march to Brandenburg Gate, where Thunberg is due to address the crowd.
Police said they have dispatched 300 officers to the protest which is expected to draw around 15,000 people.
"We're going to continue skipping classes every Friday because we can't keep going like that with the climate. We have to pull the emergency brakes," vowed Franziska Wessel, one of the organisers of the protests in Berlin.
Since December, teenagers across Germany inspired by the 16-year-old Thunberg's climate fight have been marching weekly instead of sitting in classes.
With the protests coming at a time when a government commission recommended that coal be phased out by 2038, the youths have seized on the theme to demand a halt to the polluting fuel by 2030.
The youth engagement has left politicians divided on how to react.
Economy Minister Peter Altmaier has urged students not to skip school saying that demonstrations are not less effective outside class hours.
But Chancellor Angela Merkel has welcomed their fight.