Researchers at the University of Sydney analysed the carbon footprint of the tourism sector across 189 countries, taking in its entire supply chain, such as hotels, events, and transportation, according to Climate Action release copied to the Ghana News Agency.

The results showed that tourism’s carbon footprint was four times higher than previous estimates, making it a major contributor to overall greenhouse emissions.

It was also a fast-growing industry, increasing from 3.9 to 4.5 gigatonnes of carbon dioxide equivalent between 2009 and 2013.

The majority of these emissions came from air travel, particularly domestic and business, which the researchers said could not be distinguished from tourism.

The US was the highest emitter by country, followed by China, Germany, and India. Small-island states, such as the Maldives, Mauritius, and Cyprus, also accounted for a disproportionately high level of emissions due to international arrivals, largely from rich countries.

Dr Ya-Yen Sun, one of the co-authors of the report, at the University of Queensland, said: “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.”

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

Luxury travel is also more likely to become a factor as wealth increases and it also becomes more affordable. Lead researcher Professor Manfred Lenzen recommended consumers fly less and pay for carbon offset schemes to address the issue.

“We found the per-capita carbon footprint increases strongly with increased affluence and does not appear to satiate as incomes grow,” he said.

Making the tourism industry more sustainable has so far made slow progress; a recent index from The Economist showed European countries, such as France, Germany, and the UK were making the strongest advances in the area.