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DENVER – Climate activist Greta Thunberg and thousands of other climate activists came together in Civic Center Park for a climate strike Friday.

“This is a movement with millions upon millions of people telling world leaders to act,” Thunberg told the crowd. “We are demanding a safe future for everyone and that is not something you can continue to ignore.”

The Swedish teenager has become famous worldwide for her climate strikes and taking on the climate change issue.

“We, as young people, are tired of being betrayed by people who are supposed to be for our greater good,” Thunberg said.

350 Colorado was one of the organizers of the event. The group describes itself as an organization dedicated to addressing climate change and transitioning to a clean energy future.

350 Colorado says Thunberg visited to support the work of youth organizers leading climate strike efforts, including the Sept. 20 climate strike in Denver, which organizers say had more than 7,500 participants.

“Colorado’s youth organizers are calling to end all fossil fuel expansion, a rapid and equitable transition to 100% renewable energy, and for fossil fuel companies to be held responsible for the damage they have caused,” the release stated.

In addition to 350 Colorado, event organizers include International Indigenous Youth Council, Fridays for Future, Earth Guardians, Sunrise Colorado, Youth Climate Strikes U.S., Greenpeace, Extinction Rebellion Denver, 350.org and others.

Friday’s event was attended by no Republican lawmakers — even most major Democratic politicians in Colorado did not attend.

Sage Nauman, a spokesman for the Colorado Senate GOP, said while the energy of the group is impressive, their demands are costly.

“If you look on their website and see what there proposals are, we are talking about ending 75 percent of energy production in Colorado,” Naumann said. “How are we supposed to maintain our quality of life?”