The travel industry has no long-term future unless it can demonstrate a positive effect on destinations.

That is the view of PwC global head of sustainability and climate change Malcolm Preston, who challenged the sector to become “net positive”.

Preston described the level of demand on the earth’s water and impact on the atmosphere of having “2,400 coal-fired power stations going 24/7”.

He told Abta’s Travel Convention in Dubrovnik: “The world’s water and atmosphere are treated as infinite and they are not.”

Preston said: “Put aside getting to a destination, if you’re not having a net positive impact [on a destination] you’re having a net negative impact.”

He issued a challenge: “Can you as an industry work out how to have a net positive impact? If you can, you have a future. If not, why would you be allowed into destinations in future?”

Preston argued: “I hear that travel reduces poverty in destinations. I hear we create wealth in developing countries. But we have to move from measuring inputs and outputs to measuring the outcomes of what we do and the value.

“Every company must make a profit – without it they can do nothing. But how do you reduce your negative impacts and still make a profit?”

Preston reported a study which found 68% of material used to construct a hotel would go to waste. He said:: “A hotel operator who does not understand that is building hotels they could not afford to take down.”

He described sustainability as a combination of “environment and ethics”.

Abta chief executive Mark Tanzer said: “The idea we can send millions of people to destinations without taking into account the impact is untenable.”