For some people, summer holidays are a relaxing break from daily life, a blissful chance to hit the sunbed and lie flat for as long as humanly possible. Other people are on the hunt for new places and adventure – plummeting down a hill on the back of a bike or tied to flimsy fabric and pulled through the air. Others still are on a quest for culture, cuisine or enlightenment – or, ideally, all three and then a nap. Travel is, most people seem to feel, amazing.
The result has been an economic boon for some parts of the world that has shifted money across oceans and into impoverished communities. But it has come at a cost to the planet that travellers have long overlooked.
Summer 2024 has been the hottest on record, the EU’s Copernicus Climate Change Service said on Friday, with a warning that the “devastating” consequences of extreme heat will keep getting worse without urgent action to cut greenhouse gas pollution.
But the carbon footprint of the tourism sector, which hovers at about 8% of planet-heating emissions, is likely to soar as more of the world attains European and North American levels of wealth. What makes its climate impact more alarming than many other sectors of the economy is that the single biggest source of its pollution – flying – is fiendishly difficult to decarbonise.
Tried and tested options such as trains are limited by time and space. Electric planes could work well over short distances but crash into the walls of physics when trying to cross oceans. The most promising alternatives to paraffin are costly synthetic fuels – derived from carbon captured from the atmosphere and hydrogen made with renewable energy – and biodiesel, which would take up vast amounts of land.
Some industry players have touted more eccentric fuels such as chip fat but these, too, struggle at scale. “You want everybody running around collecting fucking cooking oil?” Ryanair’s chief executive, Michael O’Leary, asked the Guardian in December. “There isn’t enough cooking oil in the world to power more than one day’s aviation.”
The environmental demands that a traveller makes on arrival stack up too. Waste litters previously pristine nature, crowds swarm towns built for far fewer people, and water taken for pools and baths leave locals fuming in drought-stricken resorts. Protests against “overtourism” have broken out across southern Europe in response to the damage done by unthinking visitors.
The tourism sector has started to tackle some of these problems as criticism has mounted. The industry can even make sizeable savings on its emissions by putting solar panels on hotels, offering electric rental vehicles instead of combustion-engine cars, and swapping steaks for plant-based burgers on restaurant menus.
But the journeys there and back are likely to rub up against engineering limits for decades. The tension between the hunger for travel and the bleak prospects of rapid technological progress has left transport scientists scratching their heads.
In its roadmap for reaching net zero emissions by 2050, the International Energy Agency found that governments must deploy clean technologies at “unprecedented speeds” but would struggle to ignore measures to address demand. Recent studies from scientists in Sweden and the Netherlands have come to even stronger conclusions about flying less.
“We’re not saying definitely that demand should decrease,” said Andrea Papu Carrone, a transport analyst at the International Transport Forum (ITF), an intergovernmental organisation that is part of the OECD but politically independent from it. “We’re just saying that the rates of aviation growth that we have seen over the past 10, 20 years are unfeasible.”
For a European who flies on holiday once a year, this might sound like a welcome pass to carry on. After all, the richest fly the most, even within rich countries. In the UK, for instance, 15% of people take 70% of flights, while about half the population do not fly at all in a given year.
But zoom out to the global scale and the distinction between the two groups begins to blur. More than a century after the first commercial flight took off in 1914, researchers estimate that less than 5% of the global population flies abroad in a given year. If total demand for flying must soon plateau, and people in rich countries enjoy the lion’s share of flights, then each flight enjoyed by a European or North American still means one fewer for an Asian or African.
So far, one serious effort has been made to untangle this knot. In 2018, a 15-year-old climate activist from Sweden tweeted a selfie from an electric vehicle charging station with the hashtag #jagstannarpåmarken – “I stay on the ground”. Though Greta Thunberg did not invent the concept of flygskam (flight shame), she has done more than most to normalise other modes of travel. The following year, she sailed to New York on a zero-emissions boat for a UN climate summit.
The idea of consciously avoiding flights has since rippled across the world, nudging people to forgo far-flung destinations and holiday closer to home. It alarmed airline executives so much in the early days that the industry subtly reframed it from “flight shame”, an internal feeling of guilt or discomfort, to “flight-shaming” – an act of moral superiority that carries an unpleasant air of snobbery.
But neither version has taken off. Passenger traffic at European airports reached pre-Covid levels in the first half of this year, according to industry data, driven by a rise in leisure and family travel. “Flight shame is dead,” said Stefan Gössling, a researcher at Lund University, who studies tourism and climate change. “Partly what killed it is that governments promised to act on climate change … You can’t keep up momentum if people don’t still believe they need to fight.”
Airlines have marketed carbon offsets, a tool that can help steer money to climate protection, as a way to fly guilt-free. But scientists have repeatedly found the offset market to be riddled with flaws and courts have clamped down on airlines that advertise them as such.
The tourism industry, for its part, would like to focus on the benefits that travel can bring. Ecotourism funds conservation projects in poor countries, and some of these projects have helped bring back species from the brink and provided sorely needed sources of income. When the Covid pandemic grounded flights and kept would-be tourists at home, conservationists saw an immediate threat to their efforts to protect wildlife.
“There are many excellent examples of ecotourism across the world,” said Anna Spenceley, chair of the independent advisory group at the travel sector non-profit Travalyst, “where nature-based travel conserves the environment, sustains the wellbeing of local people, and improves knowledge and understanding”.
But such schemes are still a niche form of travel – and finding genuinely successful examples can still be a struggle in a market rife with greenwashing. Some players have set up certification schemes to ensure tourists get what they pay for and locals benefit from their visits, but their standards around transport lack the same levels of ambition. A tourist who holidays in a certified resort might be forgiven for thinking their green acts on the ground compensate for their behaviour in the air.
The economic boosts, however, are powerful – though the benefits are often shared unequally, tourism generates about 10% of global GDP and can be the biggest single source of jobs in some sought-after destinations.
Although the global economy is unlikely to suffer if people holiday closer to home, less wealth may flow from rich countries to poor ones. Luis Martinez, a transport analyst at the ITF, said: “The countries that suffered from the restrictions from Covid were poor countries that could not replace international tourism with domestic tourism.”
Campaigners seeking to curb demand for flights have proposed solutions such as setting a global tax on aviation that could fund recovery efforts in poor countries hurt by extreme weather. Analysts have also argued for frequent flyer levies, where the imposed costs rise with each extra flight a person takes.
The International Council on Clean Transportation, a thinktank, found that such a policy would generate 90% of its revenue from the richest 10% of the global population – and could then be invested in the fledgling technologies that were still needed to green the industry.
Campaigners have also called on governments to remove the generous subsidies that airlines and luxury forms of transport enjoy.
Thomas Earl, the director of modelling and data analysis at nonprofit Transport and Environment, said: “After a year of record breaking temperatures, it’s ridiculous that the most carbon-intensive ways to travel are still the most under-taxed.”
The arguments for targeting the richest flyers first seems to be the most likely to chime with the public. A poll of 12,000 Europeans found the most popular policies to cut emissions from aviation included forcing private jets to use sustainable aviation fuel, making airlines publish their environmental impact and bringing down the price of train tickets to the level of flights.
The research also found that the vast majority of Europeans believe people could have a “real holiday” without flying – but that many did not realise flying was worse for the planet than taking the train.
“The system we live in incentivises people to fly,” said Hannah Lawrence, from the campaign group Stay Grounded, noting the glut of cheap flights and misleading adverts. “Addressing the huge climate injustice of aviation requires people to change their behaviour – but it also requires system changes which support and encourage that behavioural change.”
• This article was amended on 7 September 2024. An earlier version referred to Anna Spenceley as chair of the International Union for Conservation of Nature’s commission on tourism and protected areas; she is its former chair.
