Several 2020 Democrats expressed support for students participating in the second “Global Climate Strike” on Friday and reaffirmed that the time has come for world leaders to tackle climate change in the run-up to the United Nations Youth Climate Summit.

“Young people have already demonstrated they can take on powerful fossil fuel companies and force politicians to answer their call to action. To the millions of young people and allies worldwide who are striking today to demand climate justice: I stand with you,” White House hopeful Sen. Bernie Sanders (I-VT) wrote on Twitter along with a video promoting the international demonstration.

Fellow presidential candidate Sen. Elizabeth Warren (D-MA) not only praised the march but pointed to Amazon Employees For Climate Justice, a group of Amazon employees who say it is their “responsibility to ensure our business models don’t contribute to the climate crisis,” as a model for how large corporations can help combat so-called global warming.

“Climate change is an existential threat—and we are already facing the effects. The youth-led #ClimateStrike and the solidarity strikes from groups like @AMZNforClimate show that our country is ready to fight for the big, structural change we’ll need to tackle the climate crisis,” tweeted Warren.

Sen. Kamala Harris (D-CA) wrote of the global walk-out: “There is nothing more powerful than our nation’s youth marching together, demanding action be taken to protect our planet — and their future. It’s time our leaders listened.”

Julián Castro, former San Antonio mayor and Obama-era HUD secretary, announced he will join striking students in Cedar Rapids, Iowa, on Friday and urged his nearly 390,000 Twitter followers to search for local #ClimateStrike events to partake in.

Spiritual guru Marianne Williamson said her campaign is “proud” to participate in the strike, calling it an “uprising of consciousness” in which “WW2-level mass mobilization” is required to “repair” the earth from the effects of climate change.

Tens of thousands of people around the world skipped school Friday as part of a coordinated global strike, one of the largest environmental protests in history.

More than 2,500 strikes and other activities are planned in 156 countries for Friday and September 27th as part of the Global Climate Strike — a show of opposition toward what organizers say is government inaction in fighting climate change.

Major American cities including Washington, D.C., Boston, Seattle, Minneapolis, Miami, Los Angeles, and Denver will hold events — but the largest is expected to take place in New York City, where the United Nations Climate Action Summit is set for Monday. The high-level summit will evaluate plans to reduce greenhouse gas emissions under the Paris climate agreement.

An estimated 1.1 million students were allowed to skip school after the city announced they wouldn’t be penalized for missing school if they attended the strike.

The strikes are an offshoot of the Fridays for the Future movement, which was started by now-famous 16-year-old Swedish climate activist Greta Thunberg. Students worldwide participated in strikes from school every Friday to demand their governments solve the climate crisis.

Greta sailed to the United States on a racing sailboat. She and other young activists will speak at 12 p.m. EDT Friday. Thunberg is also scheduled to speak at the U.N. summit Monday.

She testified in Congress earlier this week and will lead a demonstration at New York City’s Foley Square on Friday afternoon before attending Monday’s climate summit.

“I don’t want you to listen to me. I want you to listen to the scientists and I want you to unite behind the science,” she told lawmakers Wednesday at a joint session of the House climate crisis committee and House foreign affairs subcommittee. “And then I want you to take real action.”

The UPI contributed to this report.