International tourism accounts for 8 percent of all carbon emissions worldwide

Global Tourism Has a Bigger Share of Carbon Emissions Than Thought
The U.S. has the biggest footprint, both from foreign visitors and Americans travelling abroad
Article by Chelsea Harvey, E&E NewsMay 8, 20

In general, affluence has a major influence on global tourism emissions—as the researchers note, “wealthier people travel more.” The association is so strong, in fact, that for groups making any more than $40,000 per capita, a 10 percent increase in wealth results in a carbon footprint increase of 13 percent.
A transportation expert said the study comports with current estimates of aviation’s contribution to emissions. “Globally, aviation we think is responsible for between 2.5 and a little under 5 percent of anthropogenic climate change effects,” said Dan Rutherford, aviation and marine program director for the International Council on Clean Transportation.

https://www.scientificamerican.com/article/global-tourism-has-a-bigger-share-of-carbon-emissions-than-thought/