As activists such as Greta Thunberg boycott flying and airlines come under fire for carbon emissions, diaspora communities grapple with the choice between stepping on a plane and cutting physical family ties.
When German teenager Jennifer Asamoah told her mother she wouldn't fly to Ghana for her half-sister's wedding last year, she wasn't being obstinate.
She was trying to save the planet.
"I missed one of the most important days of her life because of climate change," said Asamoah, who chooses not to fly because of the greenhouse gases involved in doing so.
Flying — one of the most carbon-heavy things a citizen can do — is becoming an ever thornier issue for people in rich countries who want to cut their emissions. A YouGov poll in August showed two in three Britons want to limit flying. Climate activist Greta Thunberg has brought air travel into the spotlight this year by taking boats, not planes, across the Atlantic Ocean.
Her native Sweden coined the term 'flygskam', which means flight shame — the guilt of flying as the environment breaks down. It has become synonymous with no-fly movements taking off across the continent.
Overcoming flight shame sounds simple: take trains instead of planes and holiday closer to home. But for migrants, who make up about 8% of Europe's population, and their families, sacrificing flights poses a dilemma that strikes at the heart of some of their identities.
How often, if at all, can they return to ancestral homes?
Foreign-born citizens fly more — but drive less — than people whose families have lived in a country for more than three generations, recent research from the Technical University of Dortmund that has yet to be published suggests. Using data from the UK, and controlling for factors such as income and education, the researchers found migrants fly 38% more than natives of the country they live in.
"Migrants have a need to fly to maintain their families and friendship groups," said Giulio Mattioli, transport researcher and lead author of the study. "Once you migrate, that entails some level of travel and emissions."
Moving country can mean leaving behind children, parents, spouses and friends. Subtler ties also keep people yearning to return, such as being near their birthplace or surrounded by their mother tongue.
Burning huge quantities of jet fuel to launch into the air and soar above clouds, planes emit about 2% of global CO2. They also release pollutants such as water vapor and nitrogen oxides that, at high altitudes, increase the warming effect on the planet further.
Had Asamoah flown with her mother from Germany to Ghana and back for the wedding, she would have emitted about 0.7 tons of CO2, according to an online calculator from the International Civil Aviation Organization. That is about as much as the average Ghanaian emits in a year.
The Dortmund study found that children of migrants — unlike their parents — are no more likely to fly than the rest of the population. The researchers did not link this to environmental concerns.
"My mother supports my decision and she also thinks that this is a very important topic," said Asamoah. "But when it comes to visiting family, she doesn't care [about her emissions], she just wants to see her daughter… and I truly understand that."
Faced with greater reasons to fly, migrants also have fewer other options.
"I refuse to feel ashamed for taking the airplane when there is no better, more sustainable alternative," Quang Paasch, who is of Vietnamese descent and an organizer for the Fridays for Future protest movement in Berlin, told DW via email. "I don't feel guilty about [flying to see family], because our system is built on social injustice."
For those who have settled in different continents, practical connections are scarce. A train from Berlin to Istanbul takes 3.5 days. Reaching cities further afield, such as Delhi or Beijing, could take weeks.
"A train line from here to Nairobi — now that I'd love," joked Anastasia Nganga, a Kenyan living in Germany trying to cut her carbon footprint. "I don't fly back to Kenya every week or month, just every couple of years. There are people here in Europe who fly for a weekend break."
At the heart of the no-fly movement is a question of fairness.
There is no reliable data on what share of the world population flies, but aviation experts agree most people do not. A report released in September by nonprofit research group, the International Council on Clean Transportation, found people in rich countries make up 16% of the world population but account for 62% of CO2 emissions from flying. Even among those who fly, a small group of frequent fliers — including migrants, the Dortmund study found — take a disproportionate share of trips.
That raises difficult questions for environment movements in wealthier countries trying to shake their reputation of privilege while demanding people and governments cut their emissions.
Pressuring migrants to not fly would create a lot of conflict, said Mothiur Rahman, an English lawyer of Bangladeshi descent and member of environmental activist group Extinction Rebellion.
"If everything is measured through CO2 emissions you're flattening [the problem]. There are different qualities of reasons for flying."
We Stay on the Ground, a campaign group that started in Sweden but is active across Europe and North America, says it has collected more than 12,000 signatures from people pledging not to fly in 2020, but has struggled to engage migrant and diaspora communities.
"It's the most difficult question we get," said campaign founder Maja Rosen. "Part of me wants to say 'of course everybody should go see their family when they want' — the problem is the climate doesn't care."
But, said Rosen, there are ways to cut aviation emissions without sacrificing family ties, such as flying less often but staying abroad longer, or stopping foreign holidays. "To me it makes much more sense if somebody who has family in India goes to see them than somebody like me goes on holiday."