A wave of climate change protests swept the globe Friday, with hundreds of thousands of young people, including those in Denver and Colorado Springs, sending a message to leaders headed for a U.N. summit: The warming world can’t wait for action.

The Colorado chapter of Global Climate Strikes is launching what it calls a “Week of Escalated Actions” from Sept. 21-29. The week was preceded Friday with strikes in Denver, Colorado Springs, Boulder, Golden, Longmont and other cities.

Elsewhere, marches, rallies and demonstrations were held from Canberra to Kabul and Cape Town to New York. German police reported that more than 100,000 turned out in Berlin.

A young activist named Greta Thunberg helped rally the events by writing an opinion-editorial for the Guardian in May with 46 of her peers.

“Politicians have known about climate change for decades,” Thunberg and others wrote. “They have willingly handed over their responsibility for our future to profiteers whose search for quick cash threatens our very existence. We have learned that if we don’t start acting for our future, nobody else will make the first move. We are the ones we’ve been waiting for.”

The Week of Action aims to inspire Coloradans into action.

“Every aspect of our life in Colorado is affected by these environmental changes, from our mountains and wildlife, to our food and water supply,” the event page reads. “Our house is on fire and it’s time we acted like it.”

The Associated Press contributed to this report.