Do global travelers have to leave their environmental ethics at home?

What if the best way to save the planet were simply to stay put?

A study published Monday in Nature Climate Change finds that global tourism is responsible for some 8 percent of total carbon emissions – about three times more than what previous studies had calculated.

In 2013, tourism accounted for 4.5 gigatons of carbon emissions. And the industry is growing by about 4 percent a year.

That carbon footprint raises questions of its own: Who bears the responsibility for it? Individuals? Airlines? Travel companies? Policymakers? And what about the benefits of travel? Do the dollars going into economies that rely on tourism, and the increased global understanding travel can foster, help mitigate tourism’s damage?

“There’s a running joke that the best ecotourist is the one that walks to the neighborhood park,” says Carter Hunt, an assistant professor at Pennsylvania State University who studies the anthropology of tourism. At the same time, he notes, there is good research documenting the positive effects tourism can have on people and their actions. “Whether that’s something that’s an offset or compensates for that environmental impact – that’s really challenging to say. They’re both compelling arguments.”

Previous estimates put tourism’s carbon emissions at 2.5 to 3 percent of global emissions. This new study attributes a much larger carbon footprint to tourism than previous studies have, mostly because it was far more comprehensive. By analyzing both global trade databases and tourism data, the researchers were able to trace more than a billion supply chains that underpin the industry, says Arunima Malik, one of the authors of the study and a researcher at the University of Sydney in Australia.

One issue that gets some attention in the study is the degree to which small island nations – like the Maldives and Seychelles – depend on tourism. International tourism accounts for up to 80 percent of national carbon emissions for such islands.

“People go there and that’s the main source of income,” says Dr. Malik. “But those island states are particularly vulnerable to the effects of rising emissions…. What do those small islands need to do?”

The study looked at 160 countries over five years, and breaks down the footprint by domestic and international travel, and between various nations, with some surprising results. The majority of emissions came from domestic travel, with international travel responsible for 23 percent of tourism’s carbon footprint, says Malik. The biggest impacts stemmed from travelers from and to high-income countries.

And as overall affluence grows, so does tourism, the study’s authors write, noting that “global demand for tourism is outstripping the decarbonization of tourism operations, and, as a result, is accelerating global carbon emission.”

How to mitigate?

Ultimately, Malik says she hopes the study will serve to raise awareness for tourists, the tourism industry, and policymakers. Within academia, she notes, conferences are often the biggest drivers of travels, and she hopes more universities will consider alternatives –  like teleconferencing – to having people fly long distances for a few days. “The key recommendation is to fly less,” Malik says.

That’s a recommendation some individuals are already acting on due to their concern about climate change. A number of earth scientists and academics have made public pledges to cease flying, or fly less, sharing their stories and their reasons at No Fly Climate Sci.

Eric Holthaus, a meteorologist and staff writer for Grist, made headlines in 2014 when he wrote about his decision to stop flying due to climate concerns.

Mr. Holthaus says his decision (he’s made a couple of exceptions over the years to get to family events) has brought unexpected benefits, allowing him to interact more personally with the place he lives in, to slow down, and to plan more local trips to places like national parks.

“What we’re talking about is a change in culture, getting happiness from more local travel, or slower travel,” Holthaus says. A jet-setting culture in which people travel around the globe for a few days or a week is “not compatible with a future that is livable.”

Other individuals look to carbon offsets – money that goes into projects that decrease emissions, like replanting trees, or improving energy efficiency – to mitigate the harm from their travel. The best of these are verified by rigorous standards and third-party certification, but they’re generally voluntary, and have yet to gain in popularity.

Benjamin Hale, an environmental ethics professor at the University of Colorado in Boulder, sees problems with putting too much of the onus for reducing emissions on the individual.

“Most of these global-scale environmental problems can’t be easily addressed by individual actions. They have to be addressed at the policy level,” says Professor Hale. Relying too much on individuals to take the right actions can mean that the individuals who “care” cede ground to those who don’t, allowing people who care less about the environment “to take advantage of a system that enables them to do so.”

He cautions against looking at carbon footprints as the only way to determine the best environmental actions. “Down that road is ascetism, or self-abnegation… It’s a worrisome standard of environmental policy,” he says, arguing instead for policy-level solutions and incentives for the travel industry to change their standards.

A few smaller operators are already doing that. Professor Hunt notes that Nature Air, one of Costa Rica’s two airlines, builds carbon offsets into their flight pricing. So far, he says, most consumers don’t seem to notice, either positively or negatively.

And some tour operators, like Natural Habitat Adventures, which operates dozens of small-scale eco-tours globally, have committed to being carbon-neutral.

The carbon footprint of tourism is “everyone’s responsibility,” says Ted Martens, Natural Habitat’s vice president for marketing and sustainability. Carbon offsets are built into Natural Habitat’s pricing, and the company also encourages all its customers to purchase carbon offsets for their personal airfare at the start of a trip – an option Mr. Martens acknowledges few customers act on, but that he hopes raises awareness of the issue.

Martens knows Natural Habitat’s actions aren’t enough to move the needle on tourism’s carbon footprint, but he hopes that by setting the precedent they encourage both tourists and other, bigger players in the travel industry to follow their lead.

And he hopes that people’s awareness of that carbon footprint pushes them to choose more responsible ways to travel – a locally owned eco-lodge versus an all-inclusive resort owned by a big conglomerate, perhaps – rather than cease travel altogether.

“There’s no doubt in my mind that the benefit of traveling far outweighs the negatives,” says Martens, citing both cross-cultural understanding and the economic benefit to host countries and regions, a benefit that is often much less environmentally destructive than the alternatives.

In the end, says Hale, the ethicist, studies like this recent one are useful in terms of helping industries and governments set policies, and in helping to understand where emissions come from, but it would also be a mistake to see carbon emissions as the only aspect of environmentalism that matters.

“It’s important to have a sense of the footprints we’re creating in the world,”  Hale says, “but there are many more factors that go into determining if that footprint is warranted or justified than just that it’s a footprint.”