Obama speech could inspire action on Barrier Reef: historian US President Barack Obama delivers his speech at the University of Queensland during the G20. A Great Barrier Reef history expert believes Barack Obama's comments about saving the natural wonder, made at the University of Queensland during the G20, could be the most influential call to action in 40 years. The University of Sydney's Professor Iain McCalman has studied the fortunes of the reef since Captain Cook arrived, and believes Mr Obama's words could be as important as campaigns run in the 1960s and 70s. During his visit to Brisbane, the President said "the incredible natural glory" of the reef was under threat. Author and historian Iain McCalman. I want to come back, and I want my daughters to be able to come back, and I want them to be able to bring their daughters or sons to visit. And I want that there 50 years from now," Mr Obama said on November 15. While his remarks drew a swift response from the Australian government, Professor McCalman hopes they will inspire a wave of activism like what was seen during the Bjelke-Petersen era. He pointed to campaigns run by poet Judith Wright, artist John Busst and ecologist Len Webb, who fought against the government's plan to open the reef to mining. "It must have had some arresting impact, I hope," Professor McCalman said of Mr Obama's speech. I think they were really important [comments] and I don't think they were made lightly. For him to say that, I think he really believes like a lot of people outside of Australia that we're the reef's custodians and it belongs to the world. Professor McCalman has written books and made films about the Barrier Reef's history over the last two decades. While not a scientist, he said he wasn't optimistic that the reef would be recognisable by 2050. "I think people are sympathetic to the idea of the reef but they don't understand what is at stake," he said. Given the complexity and intricacies of the reef, Professor McCalman said the public struggled to understand the extent of potential damage and the causes of reef degradation. He listed cyclones, the Crown of Thorns starfish, pollution, over-fishing, silt dumping and climate change as factors behind the 3000 kilometre-long reef's demise. "This huge "country" has a very large part of its lifeform damaging and dying," he said.