As a student at a high school not far from Denver’s main airport, Anthony Muñoz wondered whether the jet fuel from airplanes flying above his campus was harming living things.

An avid gardener, Muñoz partnered with a local university to create a garden on the campus of his charter school, Vista Academy, filling it with native plants that could detect ground-level ozone pollution. He also worked with climate scientists from the National Center for Atmospheric Research, a federal office in nearby Boulder, who directed Muñoz on what data to collect, what the condition of leaves reveals about air quality and why milkweed matters for monarch butterfly migration.

“One garden’s a very good data source,” said Muñoz. “Colorado’s so beautiful, and I would hate to see it wilt away.”

Muñoz built the “ozone garden” for his capstone project as part of Colorado’s seal of climate literacy, a statewide initiative that pairs climate-focused coursework with hands-on community service. To earn the seal – an endorsement on high school diplomas and transcripts – students must complete at least two advanced courses that cover the Earth’s climate systems and an approved project that tackles a climate issue in their community.

Since 2024, when Colorado lawmakers approved the seal, 26 of the state’s 179 school districts have adopted it, according to Lyra Colorado, an education non-profit that advocates for the seal. Now, the model is spreading to other states. Maine adopted its own climate seal earlier this year, and California just signed into law a bill to establish the seal for graduates there. Youth coalitions have pushed for the policy in Hawaii and Minnesota, with varying success.

Proponents of the seal argue that young people must understand and combat the climate crisis, without waiting for political leaders to reach consensus on how it should be taught. They also hope the endorsement will connect students to a rapidly expanding green workforce, preparing them to work on solar grids and climate-resilient farms or in water resource management and urban heat mitigation. And, as climate change begins to alter almost every aspect of human life, the seal could offer anxious teenagers a sense of agency and ability to make some difference.

“Where we can make the most difference is often in our local community,” said Laura Schifter, a senior fellow with the Aspen Institute’s This Is Planet Ed, a climate education group. She said the seal offers students a chance to learn about the climate crisis, a topic rarely covered in depth in K-12 classrooms, and called it “a really promising policy”.

Still, the seal has faced hurdles, including tight school district budgets, concern about new burdens on schools and the federal government’s attempts to refute climate science.

The idea for the seal originated with Lyra Colorado, the non-profit in Denver that supports community-based education programs. Rural students and educators the group was working with on another climate-related project said they wanted a way to explore climate change as a reality in their daily lives, not just through a dense unit in a textbook, according to Mary Seawell, Lyra’s CEO.

To earn the seal, students need to complete two classes that promote “climate literacy”, or basic principles of the climate crisis, such as its causes and how to mitigate it. One of them must be a science class, such as environmental studies, biology or earth science. The other course can be in any discipline, including the humanities or fine arts. For example, this year Denver public schools will build lessons about climate change into its state-mandated civics course, Seawell said. Student projects for the seal have addressed beaver dams, building trails, snow science and forestry management.

An estimated 1,200 students have received the seal so far, said Seawell.

Funding, though, has been a challenge: state lawmakers provided less than $20,000 for the seal’s rollout. Many students fund their projects out of pocket or, like Muñoz, secure grants: he co-wrote a $1m grant proposal to the city to pay for the gardens at his school. Lyra created its own grant program to help local schools pay for teachers’ time, student projects and even graduation cords.

Muñoz, now a sophomore studying mechanical engineering at the Colorado School of Mines, said the seal allowed him to learn climate leadership skills. He’s currently vice-president of the college’s environmental club and tries to inspire his peers to take action.

“Are you going to think beyond yourself and help not only those in need but the environment, or will you sit back and wait for someone else to change the world for you?” he said.

Getting more students involved in climate action

As more students like Muñoz graduate with the seal, many have started to work on climate issues at their colleges and in new states.

Rylan Neumann graduated last year from the Boulder Valley school district, enrolling that fall at the University of California, Berkeley, to study environmental economics. Almost immediately, she joined an eco-club and boarded a train to Sacramento, where she lobbied state lawmakers in support of the state’s pending climate seal bill.

“Getting more students involved in climate action and how they’ll be impacted in the future is essential,” she said. “We’re the ones growing up in this world.”

In Hawaii, a student member of the state board of education championed the endorsement for high schools on the islands. The Minnesota Youth Council, a state advisory board with representatives from middle and high schools, recommended the seal during this year’s legislative session.

State education officials in Maine, meanwhile, adopted the seal directly to avoid legislative debate.

“Students want to be involved in climate action, in environmental literacy, in green careers,” said Teddy Lyman, a K-12 climate education specialist in Maine. “They’re often doing the work already but don’t have the recognition. They didn’t see a sort of pathway to continue that work and embark on that as a potential career.”

During a spring pilot across nine high schools, Lyman expected roughly a dozen students to apply for the seal. Instead, he said, nearly 57 seniors did.

Melissa Luetje teaches science at Freeport high school, which enrolls about 600 students near Casco Bay. Warming and rising sea levels have eroded coastal infrastructure and flooded surface streets.

For a seal-approved class she teaches on research, students will monitor woodlands for insect damage, develop new ways to compost or commodify an invasive crab species, and work on a sustainable fishery.

“How climate impacts the coastal community is very different from the interior or a city,” Luetje said. “It’s up to each community to figure out what they value and how they want to roll this out.”

As the seal expands, proponents have tried to connect the high school endorsement directly to green workforce pipelines.

Lyra Colorado has started working with higher education institutions like Colorado Mountain College to align it with certification in the skilled trades, such as heat pump installation, solar grid maintenance or sustainable agriculture. She hopes universities will offer a partial minor or a course credit for incoming students who have the climate endorsement.

At the same time, Donald Trump has attacked the climate crisis as a “hoax”, and new federal scrutiny of renewable energy projects threatens philanthropic support for such initiatives. The treasury department and Republicans in Congress have targeted the tax-exempt status of non-profits that support climate causes, which Seawell said created a noticeable chilling effect among potential donors.

“Funders are worried,” she said.

The Trump administration has also tried to pull funding from and dismantle the National Center for Atmospheric Research, the climate research center that helped Muñoz with his school garden. He called the proposed cuts “devastating”.

Still, Muñoz, who plans to pursue biomedicine and one day become a professor, remains focused on climate issues.

He met virtually with students pushing for the seal in Minnesota. And he spent his first college break back at Vista Academy, assisting younger kids in the garden. They recently put the final touches on an elevated box designed for gardeners in wheelchairs.

And he’s writing code to make it easier for Vista students to continue collecting data in the ozone garden – even if it’s not clear when, or whether, NCAR scientists will get to use the data.