BERLIN — Not long ago, Europe’s young urban residents used to brag about their latest adventures on the other side of the planet, in Asia, Australia or the Pacific.

These days, you better be quiet about that, or at least make it clear that you feel a bit conflicted about how you got there.

The phenomenon has a name: “flight shame,” or “flygskam,” in Sweden, “flugscham” in German, and “vliegschaamte” in the Netherlands. Amid mass youth protests for more decisive climate action in Europe and around the world, younger people especially have started to examine their own lives — and their roles in driving up emissions. Globally, about 2 percent of all carbon dioxide emissions are connected to aviation. Planes’ efficiency has increased over the last few decades, meaning that a trip from Berlin to New York City, for instance, emits far less CO2 than two or three decades ago. But international air travel has also increased, eclipsing those gains.

Earlier this year, European travel agencies first started to notice a drop in flight bookings, a development they quickly named the “Greta impact” — in a reference to 16-year old Greta Thunberg, whose climate protest, including a refusal to fly, has inspired thousands around the world.

The debate over whether to abandon air travel or not — which regularly features on top of European news sites — has now also reached global politics. Ahead of European elections next week, in which 400 million people will be eligible to vote, the issue is quickly becoming a key topic.

On Thursday, during a televised debate, the election’s top candidates, the Social Democrat Frans Timmermans, and his conservative contender Manfred Weber both advocated for finding ways to reduce short-haul aviation. Timmermans even said he would support a total ban on such flights, which took viewers across the continent by surprise and significantly upped the stakes, even though it remained unclear how short-haul flights would be defined.

The question both candidates responded to appeared to primarily relate to domestic flights, but there is no official definition for what constitutes a short-haul flight.

Both Timmermans and Weber are hoping to become the next president of the European Commission. Although European Commission president’s sway is limited, it would be difficult for E.U. member states to completely ignore a key campaign promise without undermining the commission’s role.

Thursday’s remarks come as climate change is emerging as a major campaign issue in a number of countries, including Australia, where worsening droughts have eroded the conservative Liberal Party’s traditionally strong standing among farmers who are especially affected.

A growing number of previously conservative voters has grown skeptical of the Liberal Party’s stance on global warming, ahead of elections there this Saturday.

Prime Minister Scott Morrison’s conservative government has so far resisted calls to reduce emissions to the extent researchers deem necessary, including those employed by the Australian government itself. Public research institutes have warned that Australia would be among the nations most severely affected by global warming.

The continent has already heated up by one degree Celsius over the last 100 years. Unless emissions are significantly reduced, extreme temperature events that now occur every two decades are expected to strike almost annually by the end of the century. Floods, combined with longer drought periods, would turn fertile farm land barren.

While Australia’s conservative party has remained hesitant to change course, the more left-wing Labor Party is aiming to generate about 50 percent of its electricity from renewable sources such as solar or wind power by 2030. To achieve that goal, it plans to rely on subsidies, tougher vehicle emission standards and a compulsory carbon trading system.

All of those changes would have been unthinkable not long ago in a country that has prided itself for having the fourth-largest coal reserves in the world.

In Europe, similar measures became part of mainstream political discourse more than a decade ago, with varying degrees of success.

The more far-reaching idea of banning flights is still unlikely to be widely embraced, however. While some critics have suggested that reducing industrial emissions or pollution in developing nations would have a far bigger impact while leading to fewer disruptions for consumers, there are lingering questions over the alternatives.

Weber and Timmermans both agree that Europe’s reliable train network would need to be expanded to make up for a reduction (or even ban) on short-haul flights.

But Central and Eastern European nations could argue that such a proposal would disadvantage them, given that rail networks operate far more efficiently and faster in Western Europe.

In Western Europe, travelers from London can reach Paris or Brussels within only a couple of hours.

In eastern or central Europe, the same time might not even get you to the neighboring city.

Eliminating those imbalances could take decades.

Banning short-haul flights could also lead to other unexpected repercussions. One Europe’s biggest cities, Berlin, for instance, is not an international flight hub and Berliners often travel abroad via Munich or Frankfurt. If those domestic connections were to be banned, Berlin’s two aging airports may suddenly be very empty.

That would solve at least one problem: their lack of capacity.

Originally supposed to open in 2011 or 2012, a bigger airport that was expected to replace the two existing, strained alternatives is still not completed.

Officials recently said that next year’s planned opening of the BER Airport may once again have to be delayed, in the next chapter of a never-ending national embarrassment, which is pushing German humor to its limits.

For Berliners, the question may now be what will come first: the airport’s opening, or a ban that would render it mostly useless.

A. Odysseus Patrick contributed in Sydney.