Protest chants boomed through downtown Denver on Friday, echoing between high rises and intertwining with the wafting scents of sage and patchouli. The thousands of voices were united in the name of saving the planet — and the loudest among them were the shouts of children.

Colorado students walked out of their classrooms as part of a global movement to bring attention to the need for action on climate change, and they were joined by supportive adults, environmental organizations, parents, families and the scorching September sun that reminded them why they were there.

“It’s still this hot — and it’s September,” said 14-year-old Piper Moss, a Denver School of the Arts student who marched from Union Station to the Capitol building along with thousands. “It’s outrageous.”

Friday’s Global Climate Strike inspired dozens of youth-led movements to spring up across the state from Salida to Colorado Springs to Breckenridge. The Colorado protests joined others across the country and the globe intended to raise awareness about sustaining the future of the planet.

Abi Horton, 16, took the 16th Street Mall Ride to Union Station with a group of her Denver School of the Arts classmates. In transit, the girls wondered how much of a future they’d have left to protect if the climate crisis wasn’t taken seriously.

“People keep saying we need to preserve the Earth for our children and their children and their grandchildren, and I’m thinking,’Is the Earth going to live that long?’ ” Horton said. “I’m semi-prepared for a future that’s post-apocalyptic. I know that’s sad, but it’s true.”

Streams of people — young, old, disabled, veteran activists, new conservationists and beyond — flooded the 16th Street Mall, eventually spilling onto the lawn of the state Capitol with their protest songs and signs leading the way.

Meet Josephine Kenney, 16, and Vivian Kenney, 14, of Denver School of the Arts. “I’m missing a full day of school for this. I value my education,” Josephine said. “I’m out here so that I can live past 30. Nothing’s being done.” pic.twitter.com/aCoxNRVcp2 — James Burky (@BamesJurky) September 20, 2019

Xanthia Borg, 14, came with her Jefferson County Open School classmates and carried a sign that read “our planet is getting hotter than my imaginary boyfriend.” Seventeen-year-old Sebastian Andrews from Denver School of the Arts held a sign bearing a picture of Bill Nye the Science Guy that pleaded, “Listen to this man.” Shreya Shrestha, 17, of Colorado Springs’ Pine Creek High School carried a sign reading, “Our oceans are rising and so are we.”

Shrestha and her friends drove to Denver from Colorado Springs on Friday morning, motivated to be among like-minded people and make their voices heard. Shrestha said her peers just started an environmental club at their school and plan on being louder about global warming.

“If we don’t do anything, my future won’t exist,” Shrestha said. “It’s heartbreaking and enraging.”

The protests were part of the Global Climate Strike initiative, coinciding with Monday’s UN Climate Action Summit in New York City. They are partly inspired by Greta Thunberg, a Swedish teenager who led weekly demonstrations called “Fridays for Future” for the past year, asking world leaders to step up their efforts against global warming.

A report released last year by a UN science panel concluded that there’s still a chance to meet the 2015 Paris climate accord’s goal of keeping global temperatures from rising more than 1.5 degrees Celsius — or 2.7 degrees Fahrenheit — by 2100 compared to pre-industrial times. But achieving this would require drastic measures, including ending the use of fossil fuels by mid-century.

“If we don’t try to make change, it’ll get worse,” said 12-year-old Riley Minogue-Rau.

Shreya Shrestha (right) is 17 & from Pine Creek HS in Co Springs. She and her friends just started an environmental club at their school. They drove here this morning from the Springs. “If we don’t do anything, my future won’t exist. It’s heartbreaking and enraging.” pic.twitter.com/mFiTTrLrhg — Elizabeth Hernandez (@ehernandez) September 20, 2019

Minogue-Rau was among a group of middle schoolers at Denver School of the Arts who held a protest on the edge of their school grounds because they weren’t allowed to leave their campus.

“I want to die of old age,” Minogue-Rau said. “Not because of climate change.”

Inside the school, 17-year-old Amelia Gorman oversaw a letter writing campaign to local lawmakers. “We’re just a small voice of thousands,” she said. “And I think it’s unfair that those in power aren’t listening.”

Will Jones, Denver Public Schools spokesman, said the district provided guidance to all school leaders about the walkout.

“The DPS Department of Safety has encouraged schools to provide activities that allow student voices to be heard on campus in an effort to minimize students traveling far distances off campus,” Jones said. “However, we know some students may choose to participate in the walkouts.”

When DPS students leave the building without parental or school permission, Jones said their absence is considered unexcused.

“To ensure students’ safety, we will require a school or district employee to accompany them off campus if possible,” Jones said. “This is not a sign that we support their protest; rather, that our students’ safety is our top priority. If students leave campus, we will notify parents as soon as possible.”

Some parents, like Monica Lockrem, joined their children in protest. Lockrem took her 13-year-old daughter Rowan and a group of her friends to the Denver march from their Lakewood school.

Rowan Lockrem decided to undertake a month of sustainable living in which she will eat as a vegetarian, participate in composting, find alternative ways to get to school instead of being driven, and pick up trash in her area.

“I feel like my generation missed the ball,” Monica Lockrem said. “That’s why I’m here. I’m here for these kids.”

Back at the Capitol, young people filled the steps leading into the building where laws are made, calling for those in power to hear them out and heed their warnings.

Hailey Hayes, a 17-year-old from South High School, said the mass turnout and unity gave her chills.

“It’s incredible,” Hayes said, looking at the crowd. “This shows that people aren’t willing to stand idly by and watch the planet burn.”

The Associated Press contributed to this report.