University students should support “badass” teenagers who skip school to strike for climate action by walking out of lectures alongside them, a leading youth activist has said. In recent months more than 20,000 children have skipped school across Germany, Belgium, Switzerland and Australia, demanding governments and politicians do more to limit the effects of global warming. There are more strikes planned in the coming months.

Xiuhtezcatl Martinez, 18, global youth director of Earth Guardians, and one of 21 young people suing the Trump administration for failing to combat climate change, says his peers are now at the “head of the table” when it comes to climate activism and that more of them should take part in walkouts.

So far, school children have taken a lead on strikes, but the first UK-wide strike on Friday asks young people of all ages to take part.

“It would be pretty cool if uni students walk out in solidarity with Greta,” Martinez says, referring to Greta Thunberg, the Swedish 16-year-old who sparked the strikes when she refused to go to school. “If a worldwide movement can do that, it would be crazy.”

Martinez is from Boulder, Colorado and of indigenous heritage. He has been campaigning for environmental justice since he was six and regularly speaks on campuses across America. He’s addressed world leaders at the United Nations (UN) and given TED talks on the topic. He’s also a hip-hop artist, using music to promote his activism, and has recently written songs with Jaden Smith, another vocal activist for the climate. “I see this movement is more global, more connected, more diverse, younger, and more intergenerational than ever before,” he says. “We’re one of the last generations that will have the chance to lead the way on this.”

The next 10 years are crucial; we have just over a decade to limit a climate change catastrophe, a landmark report by the UN Intergovernmental Panel on Climate Change (IPCC) warned in October. Meanwhile scientists say we’re in the middle of what is likely to be the warmest 10 years since records began in 1850.

Martinez reckons his generation “thinks differently”, having grown up in a changing, turbulent world. “We have a greater understanding of technology because we grew up with it.” Plus there’s now a strong sense of urgency to act before it’s “too late”.

A descendent of Meshika or Aztec people, he says he grew up with an appreciation of nature and the environment. “My dad taught me everything we do is in honour of our ancestors,” he says. Martinez was homeschooled until he was 10, and as a result learned “ancient poems and prayers” while “other kids were learning nursery rhymes”.

That didn’t make him popular. “I had long hair, a name no one could pronounce [it’s “shoo-tez-cat”] and was always missing school to go and talk about the environment ... of course kids give you shit, that’s how they are.”

But he’s not lacking in confidence. “I love calling out politicians,” he says. He and the 21 other young activists aged between 11 and 22 are “turning to the courts” as a “powerful force” where politicians have failed, suing the US federal government over climate change.

This week Donald Trump, who has previously said global warming is a hoax invented by China to attack US manufacturing, failed to address the issue in his State of the Union address. Since becoming president, he has also withdrawn the US from the Paris climate agreement, in effect ensuring the world’s second largest emitter of greenhouse gases quit the international effort to address global warming.

With powerful enemies, Martinez sometimes feels the pressure. “There have been moments when I’ve just wanted to go to high school and be a normal kid,” he says. It’s not just politicians he’s up against. “It’s some of the biggest industries in the world, from the pharmaceutical industry, to the agriculture industry, to the prison industrial complex to the fossil fuel industry, and we might lose.”

That’s why young people must stand together and continue to demand politicians pay attention, whether through strikes, legal action or “however it is you connect with the world”. Students should push for universities to divest from fossil fuels and should join school strikers. “Greta Thunberg is a real badass, and now university students have to step up too. Not everyone is outspoken, but we all have a significant part to play,” he says. “So channel your fear, channel your hurt and channel your hatred into action.”