Thousands of Portland high school and middle school students walked out of class today to protest climate change.

The walkout is part of a national day of action of young people demanding the reduction and reversal of global warming.

Jaden Winn, a Portland Public Schools student and founder of the organization Youth Igniting Change, says, "We are just one of the thousands of youth-led climate strikes putting pressure on government officials to take steps to reduce greenhouse gas emissions, thus ensuring a habitable planet and a sustainable future for generations to come."

Video of the walkout shows students marching along the waterfront and across the steel bridge, signs that read "There's No Planet B," and "We're Missing Our Lessons So We Can Teach You One," in hand.

Chants of "Climate Strike" and "Climate Justice" echoed through the large mass of students as they made their way downtown.

At the district office, student speakers gathered to protest a lack of climate change education in curriculum.

"Why are we here?" one student shouted through a megaphone. "We are here to finally teach PPS a lesson. We cannot let this madness go on any longer."

The protest in Portland is matched by demonstrations around the world—including ones in San Francisco, New York and Lisbon, Portugal.

Here's a look at how Portland students responded: