Greta Thunberg, the 16-year-old environmental activist-phenom, has helped lead an anti-air travel movement in her native Sweden.

Thunberg and her allies point out that cutting down on flying is one of the best ways for individuals to reduce their carbon footprint.

Germany's Green Party, which has surged in popularity recently, wants to make domestic flights "obsolete as far as possible" by 2035 through new taxes and investments in high-speed rail.

Many young Europeans are following Thunberg's lead and adjusting their lifestyles to shrink their carbon footprints. Some told Insider they don't fly. But they're also pushing for structural change.

"I'm more of an anti-capitalist climate fighter," Shinkai Hassan, 17, told Insider at a climate strike in Berlin. "I don't think it's the common people's fault as much as the companies'."

While the "flight shame" movement is spreading across Europe, Rep. Alexandria Ocasio-Cortez's attempts to discourage flying and promote investments in high-speed rail haven't yet caught on.

Experts say the US is poorly positioned to replace air travel with rail alternatives, both as a result of geography and decades of public policy.

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BERLIN, Germany — Sixteen-year-old environmental activist Greta Thunberg is currently en route to the US from Europe in a 60-foot, carbon-neutral racing yacht scheduled to complete its zero-emission journey to New York in a few days.

The young activist-phenom is helping inspire international action against climate change, and she's also a powerful ambassador for a growing anti-air travel movement in Europe, dubbed "Flygskam," or "flight shame," in her native Sweden.

Thunberg and her anti-air travel allies point out that cutting down on flying is one of the best ways for individuals to reduce their carbon footprint.

One round-trip flight from New York to San Francisco emits one-fifth of the greenhouse gases per passenger that the average American's car produces in a year.

The boycott and awareness-raising campaign appears to have already made a dent in the Swedish airline industry. The country's air traffic dropped 3.8% in the first half of 2019, even as air travel rose 4.4% across Europe in the first quarter of 2019. Experts attribute the dip in part to environmental activism, also known as the "Greta effect."

And the phenomenon is spreading across Europe.

'Flight shame' and 'train bragging'

The German Green Party, the country's second-most popular political party, wants to make domestic flights "obsolete as far as possible" by 2035. They've proposed major investments in the country's rail system and taxes on kerosene for domestic flights.

And the shame is real: about 200,000 fewer Germans flew domestically between 2017 and 2018. Green Party politician Katharina Schulze provoked a scandal earlier this year when she posted an Instagram photo taken from her vacation in California, where she ate ice cream with a plastic spoon.

Shinkai Hassan, 17, holds a sign reading, "Preserving our existence isn't a conflict of interest." Eliza Relman/Insider

The flipside of the "flight shame" movement is "tagskryt," Swedish for "train bragging," or boasts about taking trains instead of planes.

Thunberg famously journeyed 65-hours by rail to and from the World Economic Forum in Davos, Switzerland and Stockholm last January.

"I think it is insane that people are gathered here to talk about the climate and they arrive here in private jet," she said.

Swedish rail travel has risen by one-third this summer as compared to summer 2018. And airlines have begun to take note. The Dutch airline KLM launched a "Fly Responsibly" campaign urging customers to fly less frequently and promoting the company's efforts at sustainability.

Lufthansa spokesman Tal Muscal told Insider the company has "decided to reduce the environmental impact of its business activities to the unavoidable minimum," and is introducing more environmentally-friendly aircraft, even as the airline called the "flight shame" impact minimal.

Kids protesting at Fridays for Future Berlin. Eliza Relman/Insider

Young people shun flying and demand structural fixes

Thunberg has become an international celebrity ever since she conducted her first "climate strike" by skipping school to protest outside the Swedish parliament building in August 2018. The effort went viral and now school kids across Europe are joining so-called "Fridays for Future" strikes.

Many of these young people are following Thunberg's lead and adjusting their lifestyles to shrink their carbon footprints.

Emma Fuchs is a 15-year-old climate activist in Berlin. She has been a vegan for over three years, tries to buy only second-hand clothes, and doesn't fly anymore. She said many of her friends live similarly, but she doesn't hold it against people who can't or choose not to make the same lifestyle choices.

"It's okay to fly — you don't have to change your whole life," she told Insider, adding that those who fly should offset that carbon production by living more sustainably in other ways.

Read more: 'People are dying': Alexandria Ocasio-Cortez passionately defends her Green New Deal resolution as Republicans bring it up to fail in the Senate

Gideon Einarsson, 16, regularly participates in Berlin's "Fridays for Future" climate strikes in a park in the German capital's downtown. He's a vegetarian and doesn't fly.

Advocates say the flight shame movement is about feeling a sense of personal responsibility, rather than shaming others. But Stefanie Groll, the head ecology and sustainability at the German Heinrich Böll Foundation, said some take offense at the suggestion that they should alter their lifestyles.

"I know that my eco-friendly or healthy choices sometimes make other people act funny. For example, when I say I am vegan some people get really aggressive," Groll told Insider. "They act as if I was attacking them because they eat meat. I think that's cognitive dissonance. They yell at you, start a fight or get defensive to reduce their own discomfort. Same happens when a 'flight shamer' and an 'air traveler' meet."

Middle-schoolers participating in the Fridays for Future strike in Berlin on August 23. Eliza Relman/Insider

Many, including environmental activists in the US and Germany, are wary of shaming or guilting people into action.

"There is ample research on climate and social communication that shows expressions of personal values — like those often found with personal boycotts — as more effective than telling other people how they should or should not live," said Greg Carlock, the World Resources Institute's Manager for Climate Action & Data whose 2018 report formed the foundation for the Green New Deal resolution.

Shinkai Hassan, a 17-year-old Fridays for Future regular in Berlin, thinks policy and structural changes are more important than individuals' lifestyle choices. She argued that governments and corporations are more to blame than individuals.

"I'm more of an anti-capitalist climate fighter," Hassan, a vegetarian who tries to "live as plastic-free as it gets" and has only flown on a plane once, told Insider. "I don't think we should blame each other for using plastic straws when there are companies who make us consume them even though there are better alternatives. I don't think it's the common people's fault as much as the companies'."

Climate activists, of course, have much bigger fish to fry: Air travel makes up between 2 and 3% of global annual greenhouse gas emissions.

Teenagers attend a "Fridays for Future" protest in Berlin on August 23. Eliza Relman/Insider

Why 'flight shame' hasn't caught on in the US

No equivalent "flight shame" campaign has yet made its way across the Atlantic.

The closest the US has come to seeing an anti-flying push was when Rep. Alexandria Ocasio-Cortez, the 29-year-old democratic socialist, made reducing air travel an official goal of her Green New Deal proposal.

The climate activist and her allies called to "build out high-speed rail at a scale where air travel stops becoming necessary," but conceded "we aren't sure that we'll be able to fully get rid of farting cows and airplanes," in a controversial document describing the GND resolution earlier this year.

The statement sparked outrage on the right and hand-wringing on the left. Some conservatives falsely claimed Ocasio-Cortez wanted to "outlaw air travel" — and some progressive Democrats voiced skepticism.

"That would be pretty hard for Hawaii," the state's US senator, Mazie Hirono, told reporters.

Hirono has since co-sponsored the official Green New Deal resolution, which doesn't mention airplanes, but calls for investments in "clean, affordable, and accessible transportation; and high-speed rail."

Read more: Alexandria Ocasio-Cortez outlines legislation for a Green New Deal to turn the US carbon-neutral in 10 years

Asking Americans to fly less is challenging for a few reasons. Culturally, flying has long been associated with "a sense of independence, adventure, national wealth, commerce and business," Carlock said.

And there are, of course, significant structural and political obstacles.

The US rail network is far less robust than Europe's, both as a result of geography and decades of policy that's prioritized planes and cars over trains. It's much more inefficient and costly to travel by train than by plane between many US destinations.

Rep. Alexandria Ocasio-Cortez (D-NY) and Senator Ed Markey (D-MA) hold a news conference for their proposed "Green New Deal." Jonathan Ernst/REUTERS

And with urban sprawl and a lack of public transport, Americans are just as likely to live near the airport as the rail station, said Seth Kaplan, an aviation expert.

"If you're gonna tell people don't fly, you gotta give them an alternative," he told Insider. "Rail works best with cities you can connect by train in a few hours and also by people who can get to the rail station easily."

American public policy also hasn't encouraged train usage in many places. Aviation fuel — unlike car fuel — mostly goes untaxed, which climate advocates see as a major missed opportunity. Carlock said domestic aviation fuel taxes should be paired with investments in travel alternatives.

"In the end, people act in accordance with their wallets and their time – cost and convenience; changing modes of transportation means changing incentives around these two factors," Carlock said. "Without these changes, moving Americans to more rail and less flying will be gradual, even with education and political campaigns."

Eliza Relman is reporting from Germany on an Arthur F. Burns fellowship from the International Center for Journalists.