Tens of thousands of people attended a protest in a central Sydney park, holding up homemade signs with slogans such as “You’re Burning our Future” and “There Is No Planet B.” In Berlin, demonstrators gathered by the landmark Brandenburg Gate, just a few steps from where Chancellor Angela Merkel’s government hammered out a comprehensive climate- protection package.

Thousands are expected to march in Paris, London, Brussels and Warsaw, with similar protests planned in New York, Toronto and elsewhere in North America.

“This is about the future of our planet,” said Laura Lazzarin, an Italian national living in Berlin who joined demonstrators near the Brandenburg Gate. “We can’t go on like this, and politicians must realize that.”

Protesters joining the Global Climate Strike movement want governments to treat global warming as an emergency, slash subsidies for fossil fuels, and switch economies to 100% renewable energy as soon as possible. They’re part of a worldwide series of demonstrations that organizers say will take place in 150 countries on Friday and on Sept. 27.

“As we deal with devastating climate breakdown and hurtle towards dangerous tipping points, young people are calling on millions of us across the planet to disrupt business as usual by joining the global climate strikes,” according to a statement on the Global Climate Strike website.

The movement has taken hold in Europe, where climate has been catapulted to the top of the political agenda. The European Union should walk away from fossil fuels, the bloc’s energy chief told Bloomberg TV this week after a record spike in oil prices. A total of 93% of Europeans see global warming as a serious problem, according to a recent survey by the European Commission.

In front of the Brandenburg Gate, three protesters dressed in black stood on top of melting ice blocks with nooses around their necks as hundreds of people gathered around them, carrying home-made placards, blowing whistles and chanting “We are here, we are loud, because you’re stealing our future.”

In Poland, home of 33 of the EU’s 50 most polluted cities, more than 60 climate protests were held Friday. At the biggest gathering in Warsaw, more than a thousand demonstrators called for the government to curb its dependence on coal, which is burned to produce more than 80% of the country’s electricity.

“The government is doing too little and this needs to be changed,” said Dionizy Debski, a high school student from Warsaw.

The movement — inspired by the braided Swedish teenager Thunberg who started weekly school walkouts last year — has gone global, drawing parallels with other protests like the Civil Rights struggle and anti-apartheid demonstrations.

Friday’s protests are timed ahead of United Nations events, including the first Youth Climate Summit on Saturday and the Climate Action Summit of government, corporate and other leaders on Sept. 23 in New York. Thunberg, who founded the “Fridays for Future” protest group, captured media attention by sailing across the Atlantic to address the youth event, rather than traveling by plane — doing her bit to cap emissions.

The climate campaign has spurred some companies into action. Germany’s Volkswagen AG, the world’s biggest automaker, pledged to make more electric cars and become climate-neutral by 2050. Amazon.com Inc. Chief Executive Officer Jeff Bezos vowed Thursday to wean his company off fossil fuels by 2030. He also announced the formation of a new organization — the Climate Pledge — amid a steady drumbeat of criticism from activists and his own employees over Amazon’s dependence on fossil fuels.

On the same day, Alphabet Inc. Chief Executive Officer Sundar Pichai said Google had agreed to buy 1.6 gigawatts of wind and solar power, a record purchase of renewable energy by a single company.

More than 1,500 Amazon employees are scheduled to take part in Friday’s walkout. Workers from Google and Microsoft Corp. also plan to join protests.

In Australia, the campaign has the backing of high-profile business leaders such as the billionaire co-founder of enterprise software company Atlassian Corp., Mike Cannon-Brookes. Atlassian was among hundreds of Australian employers, including law firm Slater & Gordon Ltd. and real-estate portal Domain Holdings Australia Ltd., that allowed workers to take time off to attend the rallies.

The call to action has resonated across Europe, which has suffered from increasing bouts of drought and wildfires, and in Australia — the world’s driest inhabited continent that derives the bulk of its energy from burning coal.

For all the support the campaign is deriving, however, there are pockets of opposition. In Germany, the far-right AfD party on Friday vowed to oppose any new government measures on climate protection, citing escalating costs. Merkel’s government is “ruining Germany,” the AfD’s Joerg Meuthen said in a statement.

More must-read stories from Fortune:

—China is the world’s biggest coal user. Can it break the habit?
—How the energy industry is using data to decarbonize itself
—Why solar execs say the game is already over for non-renewable energy
—BP’s CEO says he’ll sell oil projects to meet Paris climate accord goals
—Listen to our audio briefing, Fortune 500 Daily
Subscribe to The Loop, a weekly look at the revolutions in energy, tech, and sustainability.