According to researchers at the University of Sydney, global tourism’s carbon footprint is four times greater than previously believed Some gases, including carbon dioxide and methane, trap heat in the atmosphere, producing a "greenhouse effect" that makes the planet warmer. The amount of released by a specific activity is referred to as its "carbon footprint."

Analyzed data revealed a 3% annual growth in emissions between 2009 and 2013. Most was produced by and in high-income countries, with transport, shopping and food being significant contributors. Tourism contributes significantly to global gross domestic product and forecast to grow at an annual 4%.

The rapid increase in tourism demand is outpacing the decarbonization of tourism-related technology. Due to its high carbon intensity and continuing growth, tourism will contribute an increasing share of the world’s greenhouse gas emissions.