On September 20, 2019, millions of people around the world joined in perhaps the largest global mass mobilization in history, demanding urgent action on climate change. Taking place in 156 countries, the Global Climate Strike was inspired in part by sixteen-year-old Swedish activist Greta Thunberg's "School Strike for Climate" and "Fridays for Future" movement. Students throughout Colorado walked out of class, kicking off a week of climate action events. In Denver, indigenous youth led some 7,500 people on a march that started at Union Station and ended with a rally at the State Capitol. All of these global actions were planned in advance of the U.N. Climate Action Summit, which begins on September 23.