One in five travelers is flying less as "flight shaming" propels travelers to shun air travel for the sake of the planet, according to a survey of 6,000 Western travelers.

The survey predicted environmental concerns would keep denting air traffic, as activists such as Swedish teenager Greta Thunberg lead the way and turn people off planes.

Emma Kemp, 25, a campaigner and fundraising manager at British climate change charity 10:10, said she skipped flying for her last holidays to Italy and Croatia and opted to get around by coach, train and ferry instead.

"I felt I was really travelling," she told the Thomson Reuters Foundation. "And I felt at peace with myself, having done something for the planet."

If these trends continue, the expected growth in passenger numbers could be halved, Swiss bank UBS said in a report published this week.

A survey of more than 6,000 respondents in July and August showed that, on average, one in five travelers in the United States, France, Britain and Germany had cut air travel by at least one flight in the past year because of climate concerns.

Commercial flying accounts for about 2% of global carbon emissions and about 12% of transport emissions, according to the Air Transport Action Group, an aviation industry group.

The survey also found that the percentage of people thinking of reducing their flying for the same reason had climbed to 27%, up from 20% in a previous survey during May 2019.

"With the pace of the climate change debate, we think it is fair to assume that these trends are likely to continue in developed markets," wrote UBS analyst Celine Fornaro.

UBS said it expects the number of flights in the European Union will increase by just 1.5% per year, which is half the rate predicted by plane maker Airbus.

Any cut in air travel will hit air manufacturers hard, with new plane orders at risk if travelers increasingly turn to trains and boats to travel with a cleaner conscience.

Read also: Greta Thunberg, it's OK to fly to New York

'Real thing'

In August, 16-year-old Thunberg - an icon for young environmental protesters - crossed the Atlantic in a racing yacht with no shower or toilet to join protests in the United States and take part in a United Nations summit.

Thunberg said the voyage cut her own carbon footprint and "sends a signal to other people around you that the climate crisis is a real thing.”

Her homeland of Sweden has led a movement that rests on the notice that travelling on kerosene-guzzling jets is shameful.

It was also responsible for the phrase 'flygskam'- exported as "flight shaming" in English and trending as 'avihonte' on French social media.

Scandinavian airline SAS AB has seen passenger traffic shrink 2% this year, while Sweden's airport operator said it handled 9% fewer passengers for domestic flights this year than in 2018. Both have blamed 'flight shame'.

Companies, such as Klarna Bank AB, are cutting back on business flights. The Swedish bank has banned all employee air travel within Europe and discourages long-haul flights.

The anti-flying movement, which emerged in 2017 after singer Staffan Lindberg pledged to give up flying, has now spread well beyond its native Sweden.

Germany has announced plans to cut taxes for train journeys and boost levies on flights. And as world leaders met in New York last month, delegates were quick to quiz each other on how they got to New York as 'flight shame' reached peak attention.

“If there’s an elephant in the room ... of course it’s aviation,” Norway’s Minister for Climate and Environment Ola Elvestuen told the event.