Booking.com, Skyscanner, Ctrip, and TripAdvisor, alongside payment giant Visa, have come together to form Travalyst in an effort to "mobilize the travel industry as a catalyst for good, aiming to transform the future of travel for everyone."

In short, they will work together in a series of initiatives to educate, raise awareness and, in their words, "promote positive change."

The Travalyst project is being launched on the back of data it claims illustrates there is a growing awareness by travelers over issues around sustainability.