Well-off people jetting off on holidays abroad have helped to make tourism a major and growing source of carbon emissions, research has shown.
Scientists found that world-wide tourism accounts for 8% of all the world's carbon emissions - a figure four times larger than previously estimated.
The biggest single contributor to the tourism carbon footprint was international air travel, which in turn was fuelled by growing affluence.
Dr Ya-Yen Sun, one of the researchers from the University of Queensland, Australia, said it was time to rethink the idea of tourism being an environmentally "low impact" industry.
"Given that tourism is set to grow faster than many other economic sectors, the international community may consider its conclusion in the future in climate commitments such as the Paris Accord, by tying international flights to specific nations," she said.
"Carbon taxes or carbon trading schemes - in particular for aviation - may be required to curtail unchecked future growth in tourism-related emissions."
Previous studies had estimated that tourism accounted for 2.5% - 3% of global greenhouse gas emissions, said the researchers writing in the journal Nature Climate Change.
As luxury travel becomes more affordable, aviation is likely to play an increasingly significant role in greenhouse gas emissions, said the scientists.
They suggested that restricting the environmental impact of air travel could increase the cost of trips significantly.
The research, covering 160 countries, took a year and a half to complete and incorporated more than a billion supply chains.
Co-author Dr Arunima Malik, from the University of Sydney, Australia, said: "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."
High-income countries were responsible for most of the tourism carbon footprint with the US producing the biggest share of emissions overall.
The growing middle classes in China and India were also playing an increasingly significant role, said the scientists.
They wrote: "The rapid increase in tourism demand is effectively outstripping the decarbonisation of tourism-related technology."