Previous estimates of tourism’s climate footprint have fallen far below the mark. Between 2009 and 2013 it increased four times more than earlier estimated, according to a comprehensive new study.

By 2013 the worldwide tourism industry was spilling an estimated 4.5 billion tons of carbon dioxide into the atmosphere and contributing about 8% of global greenhouse gas emissions. World tourism is now growing faster than international trade.

Scientists from Australia, Taiwan and Indonesia who explored the link between leisure and global warming report in the journal Nature Climate Change how they calculated the carbon footprint of the tourism business, in what must be one of the most complex studies of the global holiday sector ever undertaken.

“Our analysis is a world-first look at the true cost of tourism – including consumables such as food from eating out and souvenirs – it’s a complete life-cycle assessment of global tourism, ensuring we don’t miss any impacts,” said Arunima Malik from the School of Physics at the University of Sydney.

“This research fills a crucial gap identified by the World Tourism Organisation (UNWTO) and World Meteorological Organisation to quantify, in a comprehensive manner, the world’s tourism footprint.”

Ironically, researchers have identified the cost of global warming to tourism, directly, in the case of winter sports, and in particular to the travel industry.

They have warned that some airfields may become too hot to permit takeoff: they have warned that more atmospheric turbulence promises bumpier flights; and that stronger headwinds could increase fuel costs. But there has been less focus on the holiday industry’s impact on global warming.

Souvenirs and shopping

To complete the accounting, the researchers looked at data from 160 countries and what they estimate to be around a billion supply chains: that is, they counted among many other things the food grown and animals reared to feed tourists, the building undertaken to shelter tourists, the climate costs of road and air transport and the souvenir-and-shopping trades associated with tourism.

They used two different accounting techniques and some advanced mathematical analysis to predict the growth of the travel and leisure business to 2025. And they find that tourism is growing: travel, they say is “income-elastic and carbon intensive … consumers’ demand for travel has grown much faster than their consumption of other products and services.

“Driven by a desire for exotic travel experiences and an increasing reliance on aviation and luxury amenities, affluence has turned tourism into a carbon-intensive consumption category.”

This is counter to assumptions so far. Economists have tended to see tourism as an industry with a relatively low impact. But the researchers say that in 2016 tourism accounted for one billion international arrivals and cash receipts of around US$1.2 trillion.

No slowdown ahead

The global holiday business is growing at between 3% and 5% a year and is now contributing significantly to global warming and climate change, precisely as a consequence of greenhouse gas emissions.

Nor do the researchers see any evidence that the appetite for travel to exotic locations and lavish holiday developments – to ski resorts or coral atolls or historic cities – is likely to slow. As affluence increases, so does the appetite for travel. Future international negotiations to limit climate change and reduce the hazards of global warming must confront a carbon-greedy industry.

“Given that tourism is set to grow faster than many other economic sectors, the international community may consider its inclusion in the future in climate commitments, such as the Paris Accord, by tying international flights to specific nations,” said Ya-Yen Sun, of the University of Queensland’s business school and the National Cheng Kung University in Taiwan.

“Carbon taxes or carbon trading schemes – in particular for aviation – may be required to curtail unchecked future growth in tourism-related emissions.”