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STOCKHOLM — That 17-year-old Greta Thunberg became the face of climate change action may have taken the world by surprise, but in Sweden, young people have long been champions of the environment.

While Thunberg made her way to the United Nations climate talks in Madrid earlier this month, students at an elementary school in a suburb of Stockholm removed their sneakers and boots at the door before entering for the day, both for their comfort and to reduce the need for chemical floor cleaners that harm the environment.

Caring for the environment is integrated into every aspect of the day for students at the Orminge Skola Elementary School, where bright classrooms are decorated with world maps and images of animals. Students scrape their leftover lunch off reusable dishes into a compost container, remove their shoes at the door before entering and learn about the impact of plastic pollution on oceans.

Liv Emfel, 11, says she can't imagine that people don't recycle their waste, having grown up learning to recycle at home and in school. Linda Givetash / NBC News

“I have two different visions of the world. It’s either a beautiful world and we fixed everything and we saved the climate and the environment, or it's just getting worse and we can’t do anything and everyone thinks they’re going to die because we didn’t do anything earlier,” said Liv Emfel, 11, who did not seem intimidated talking to journalists in English, which is not her native language.

“I hope it’s going to be a beautiful world, but you can’t know, (so) you have to do something now (for it) to get better.”

The environment — from ecology to conservation — has been an integral part of the Swedish curriculum since 1969. Teachers and education experts couldn’t pinpoint an event that sparked its adoption, but the relationship with nature has long been prominent in Swedish culture.

“My family have recycled all of my life and (when) I heard that some people don't, I thought it was weird,” Emfel said, before joining her class of fewer than 25 students.

The country’s environmentally conscious culture is attributed by many to the fact that more than 80 percent of Swedes live within 3 miles of one of its 30 national parks, 4,000 nature reserves or many other conservation sites. Use of public lands for hiking, camping and other recreation is not only encouraged but is also a legislated right.

Instead of being exceptional, Thunberg, who was named Time magazine’s Person of the Year 2019, reflects the culmination of decades of government educational policies, said Kajsa Holm, 26, a social science teacher at the Vårbyskolan Middle School in southwest Stockholm for children ages 10 to 16.

“She is a representative of this generation. A lot of kids have the feeling that they need to change, that something needs to change,” she said.

Lessons on the environment aren’t compressed into a single course but addressed across subjects, from science to home economics, and in every grade beginning in preschool. Given the breadth of the instruction, the interest in environmentalism isn’t a surprise to teachers, but the level of action that young people are taking is.

“If I compare with my generation — and I’m not so much older than they are — we didn’t have the same thought about doing something like they have,” Holm said.

Ayat Mahdi, 14, says she not only learns about climate change at her school in Stockholm, but through social media as the topic trends among her peers. Linda Givetash / NBC News

Sitting in a large music classroom lined with forest green curtains to dampen the sound, Ayat Mahdi, 14, said she was compelled to take action on climate change after learning in school about the world's ecological crisis.

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“I wanted to learn more so when I got home out of class, I started reading,” Mahdi said, her beaming smile conveying her passion for the issue.

These lessons permeate how she lives every day.

Rather than chasing “fast” fashion trends, Mahdi only shops when she really needs something and prefers to buy second-hand clothes or swaps them with her cousin and her mother. She also avidly ploggs — a Swedish-born trend of picking up litter while jogging.

Like many of her peers, she’s taking home lessons learned in the classroom. Mahdi said she’s taught her mom how to use less water while doing the dishes and has advocated for vegetarianism. While she’s won the water battle, her mom remains hesitant to reduce their meat consumption, believing growing children need the nutrition, Mahdi said with a tone of annoyance.

“We need all humans to change because if just one person does it then, what is going to happen?” she said.

Such action is what the education system set out to achieve by instilling values of democratic engagement and citizenship, said Johan Öhman, a professor of education at Sweden’s Örebro University.

“To encourage independent and critical thinking, encourage students’ own voices, encourage students to take a stand, that’s an important focus in education in general in Sweden,” he said.

Orminge Skola elementary school in Stockholm composts food waste, uses reusable dishware and cleans the building with naturally derived soaps in an effort to be eco-friendly. Linda Givetash / NBC News

That philosophy has influenced how ecology and environmentalism are taught, as well. The fact-based lessons expanded in the 1980s to pose the issue as a moral problem that called for a level of activism to change lifestyles and attitudes, he said.

“We tried to create green revolutionaries, make them think in a specific way,” Öhman said.

However, the modern approach to education that Thunberg and her peers have grown up with is more nuanced. Students are encouraged to think critically, examine the political challenges associated with environmentalism and sustainability, and craft their own arguments, Öhman said.

In addition to encouraging environmental education, Sweden was the first country in the world to establish an environmental protection agency in 1967.

It was also among one of the first countries in the world to introduce a carbon tax in 1995 for carbon-intensive fuels such as oil and natural gas. It appears to have been a success. By 2013, the country’s greenhouse gas emissions were reduced by 22 percent from 1990 levels.

In comparison, total greenhouse gas emissions from the United States have increased 1.3 percent from 1990 to 2017.

However, climate-conscious policies, which often require changes in lifestyle and additional costs, aren’t embraced by everyone.

While protecting the environment, the carbon tax is one of the contributing factors to high prices at the gas pump, which has hit people living in more remote and rural communities hard. A Facebook group against gas taxes has more than 616,000 members — a notable figure for a country of 10 million.

“Everyone wants a better environment and climate conditions but at the same time people don’t want it at a cost,” said Martin Kinnunen, a member of Parliament for the Sweden Democrats, a far-right anti-immigrant party that saw a surge in popularity in the 2018 general election.

The Sweden Democrats, while not opposed to the environmental focus in education, are critical of the country’s target to become carbon-neutral by 2045.

“We don’t know how to fulfill it and at what price,” Kinnunen said.

The target also fails to take into account emissions generated overseas at Sweden’s expense. He pointed to incentives for Swedes to use biofuels for their vehicles. While biofuels create fewer carbon emissions than fossil fuels when burned, the Indonesian palm oil that it’s made from requires harmful deforestation and creates emissions from its importation, he said.

Although Kinnunen calls the targets “extreme,” others think the country is not doing enough. Many citizens are taking their own measures to fight climate change from flying less to reducing waste at home.

Ismahni Bjorkman, 45, who lives 38 miles north of Stockholm, mends clothing, uses reusable cloth diapers and buys toys that are either second-hand or made of sustainable materials to help protect the planet. Linda Givetash / NBC News

In a cozy log house on a quiet street surrounded by forest about 38 miles north of Stockholm, Ismahni Björkman, 45, teaches her children to garden and compost.

Instilling in her children a passion for mitigating their impact on the planet is a priority, she said, after suffering a “crisis” in her teens upon learning about the effects of pollution and environmental degradation.

“I very much had climate anxiety,” she said.

She said she’s managed to cope with her anxiety by deciding “to be a planet-keeper instead of a polluter.” In her day-to-day life, that means using reusable cloth diapers for her four-month-old daughter, repairing clothing instead of buying new, cooking only vegetarian food and only opting for natural soaps over chemicals to clean the house.

She is heartened to see these values mirrored in the classroom where her sons learn about ecosystems, the water cycle and wildlife.

“When that knowledge and that lifestyle is supported in school, you learn why this is important,” she said.