Here's something to keep in mind as you plan your vacation this summer: A new study, out today in Nature Climate Change, finds that global emissions from tourism are over three times higher than previously thought.
Global tourism is a $1.2 trillion industry, and it's growing every year. Previous estimates of the tourism industry's carbon footprint put it at between 2.5 and 3 percent of total global carbon dioxide emissions.
But those estimates didn't take into account emissions all along the supply chain of goods and services related to the industry. Tourists don't just expend fossil fuels driving or flying to their destinations—hotels, food, beverages, and other retail items all come with carbon emissions of their own. "There was an evident gap in that no one had done a comprehensive assessment of the carbon footprint of tourism," says Arunima Malik, a lecturer at the University of Sydney and lead author on the new study.
To fill the gap, Malik and her colleagues had to evaluate carbon emissions for a billion supply chains for tourism-related goods and services in countries around the world. They also took into account other greenhouse gas emissions—including methane, nitrous oxide, chlorofluorocarbons, and hydrofluorocarbons, among others—to create a more comprehensive estimate of total tourism emissions. Malik says the assessment took a year and a half to complete.
"It was eye-opening to see that the carbon footprint represents 8 percent of global greenhouse gas emissions," she says.
The team analyzed emissions from two perspectives: residence-based, in which emissions are attributed to tourists' home countries, and destination-based, which attributes emissions to the destination countries. These categories provide researchers and policymakers with distinct but equally important insights into tourism patterns: A residence-based perspective reflects how much each country's travelers are to blame for emissions, and a destination-based perspective allows tourism hotspots to better understand and act on their carbon footprint.
The United States topped the list for both—with U.S. travelers responsible for 1,060 metric tons of emissions, and 909 metric tons of emissions at U.S. destinations—followed by China (528 metric tons to travelers, 561 to Chinese destinations) and then Germany (305 metric tons to German travelers, 329 to destinations).
"Travelling is largely a high-income affair," the authors wrote, with tourism-related emissions "flow[ing] mainly between high-income countries acting both as traveller residence and destinations."
Meanwhile, some small islands had some of the highest destination-based carbon footprints: In the Maldives, Cyprus, the Seychelles, and Mauritius, between 30 and 80 percent of national emissions were related to tourism. The findings call into question the wisdom of pursuing large-scale tourism development as a more sustainable means of economic growth.
Tourism's share of global emissions is only expected to grow, as affluence increases around the world and other industries move to decarbonize to meet the goals of the Paris Agreement. (Both the aviation and shipping industries, whose emissions are hard to attribute to any one country, were left out of the international accord.) And efforts so far to rein in tourism emissions by encouraging travelers to fly less and operators to innovate more to save energy have so far had little effect on industry emissions.
Either way, however, the booming industry could be headed for a bust, given that some of the most popular destinations are also the most vulnerable to climate change. Earlier this year, for example, officials in Thailand and the Philippines announced that some of tourists' favorite beaches would close down temporarily to give the ecosystems a chance to recover from climate change and pollution.