Tourist operators on the Great Barrier Reef are shifting their stance on climate change, with the peak industry body opposing Adani's "mega coal mine", and acknowledging fossil fuel use has to be phased out.

In an unprecedented declaration, a year in the making, the Association of Marine Park Tourism Operators (AMPTO) and Australian Marine Conservation Society (AMCS) called on "all our political leaders...to fight for the future of our reef".

"The carbon pollution from coal, oil and gas is heating the air and the oceans to dangerous levels," the statement said, noting the record marine heatwaves in 2016 and 2017 had damaged coral reefs worldwide. "It’s not too late to save our Reef but time is critical."