In San Francisco on Friday, two high school leaders in the world of Jewish activism helped spearhead one of the city’s largest youth-led protests ever, joining millions of kids around the world who skipped school to urge action on climate change, the defining issue of their generation.

Isha Clarke, a senior at MetWest High School in Oakland, and Sam Saxe-Taller, a junior at Berkeley High, are active with Youth vs. Apocalypse, a group instrumental in leading the San Francisco march and directing the culminating rally at Embarcadero Plaza.

Among the group’s demands are a a “safe, healthy, and just planet,” “justice and asylum for people displaced by climate change” and “policy based on science.”

Clarke, 16, emceed the rally that began in the heat of the day, around 1 p.m. A dancer in her spare time, she entertained a sea of people as hip-hop blasted over the P.A. system. The crowd roared, danced, laughed, sang and chanted.

Behind her were signs reading “Stop denying our earth is dying,” “I need you to panic” and “The water is almost as high as me.”

In one of the largest global protests since the first Women’s March in 2017, an estimated 4 million kids and adult allies took to the streets in Cape Town, Nairobi, Tokyo, Bucharest, Tel Aviv, every major U.S. city and all 50 states (including in the tiny fishing village of Kodiak, Alaska, where protesters gathered outside the post office).

“A lot of young people are really scared,” Clarke said. “We feel the weight of the world on our shoulders.”

The protest began around 10 a.m. in front of the San Francisco Federal Building. From there thousands paraded down Market Street.

Rachel Gelman, director of programs at Jewish Youth for Community Action (JYCA), a progressive Bay Area organization that bases its activism on the values of tikkun olam (repairing the world) and tzedakah (charity), helped lead a contingent of Jewish activists. Their day began with the blowing of the shofar outside the Federal Building, some Jewish chanting and a short talk on tikkun olam.

Gelman, 29, who jokingly called herself one of the group’s elders, said her job was to support the idealism of the teenagers under her charge.

“I think we have so much to learn from young people,” she said.

Avery Krantz-Fire, 17, a student at Kehillah Jewish High School in Palo Alto, said he ditched school to come to the march and had asked his mom not to make an excuse for his absence, because he considered the protest an act of civil disobedience.

Climate change is important, he said, because rising sea levels, inhospitable climates and extreme weather events will hit the most vulnerable first.

“The people it’s going to affect most are people in poverty,” he said.

Volunteers along the route handed out water in paper cups, fruit and granola bars to marchers. Some people stood on newsstands or climbed up scaffolding to get a better view. At Embarcadero Plaza, the 40-year-old social justice group Food Not Bombs passed out pastries, and groups set up slices of pizza and boxes of fruit.

Clarke, who already has been interviewed by the Guardian, Democracy Now, Teen Vogue and other outlets, is African American and has both Jewish and non-Jewish family members. She said despite the underlying fear shared by her generation, she and her group were “pumped” to be leaders at Friday’s protest. She draws inspiration from her Jewish heritage when it comes to her activism.

“My Jewish family has always been a part of social justice movements,” she said. “I feel very culturally connected to my Jewish roots.” She is a former member of JYCA but had to step back this year “because there was too much on my schedule,” she told J. “I still consider myself part of that community.”

The rally began with speeches, including by an indigenous Brazilian man who gave a blessing in translation (“Long live the youth!”) and lamented the destruction of the Amazon rainforest. The sound system was powered with the help of people pedaling energy-generating stationary bicycles.

At around 1:45 p.m., a kippah-wearing Saxe-Taller walked out on stage holding a 3-foot-long shofar. He stood in front of the microphone and sounded the traditional t’ruah, tekiyah and shevarim blasts. He then explained to the crowd that the shofar traditionally is sounded to mark the end of the old year and the start of a new one.

“Today, I’m blowing this shofar to mark the end of fossil fuels and greed,” he said to roars of approval. “And the beginning of an era where we unite to stop climate change and environmental destruction!”

Saxe-Taller, 16, who is active with Youth vs. Apocalypse and JYCA and had a spot with other organizers at the head of the march, told J. that Berkeley High sent a note home explaining that protesters would not be considered “truants” for skipping school to attend, but that their absence wouldn’t be excused, either. The teen, son of Rabbi Julie Saxe-Taller, said it is unfortunate when students don’t learn to think outside the constraints of their academic lives.

“We must go to college, and the only way to get into a good college is getting good grades and following all the rules,” he said. The march was one way to show that he and his peers can think for themselves and make decisions that affect their lives and their future.

As to what it means to be part of a youth-led movement, he said young people are driven by a sense of idealism. “We don’t feel as hopeless as adults do.”

“The way adults walk around in the world, it’s so defeated so much of the time,” he said. “I personally believe — actually, I’m very strongly sure — this is not what the world has to look like.”