A new study has found that global tourism accounts for eight per cent of carbon emissions, nearly triple the previous estimate of around 2.5 per cent to 3 per cent of emissions.
The data also includes emissions from travel itself as well as from food, hotels and holiday activities such as shopping.
Dr Arunima Malik from the University of Sydney, the lead author of the study, told BBC News: "It definitely is eye opening. We looked at really detailed information about tourism expenditure, including consumables such as food from eating out and souvenirs. We looked at the trade between different countries and also at greenhouse gas emissions data to come up with a comprehensive figure for the global carbon footprint for tourism. If you have visitors from high income countries then they typically spend heavily on air travel, on shopping and hospitality where they go to. But if the travellers are from low income countries then they spend more on public transport and unprocessed food, the spending patterns are different for the different economies they come from. The small island states are in a difficult position because we like travelling to these locations and those small island states very much rely on tourist income but they are also at the same time vulnerable to the effects of rising seas and climate change."
The travel and tourism industry is worth more than $7 trillion and grows at around 4 per cent every year.
WTTC research director Rochelle Turner added: "It would be unfair to say that the industry is not doing anything. We've seen a growing number of hotels, airports and tour operators that have all become carbon neutral so there is a momentum. There is a real need for people to recognise what their impact is in a destination and how much water, waste and energy you should be using compared to the local population. All of this will empower tourists to make better decisions and only through those better decisions that we'll be able to tackle the issue of climate change."