AAP: Tourists visiting Australia’s natural wonders in large numbers are threatening the environment they want to enjoy, a leading futurist says. Sydney-based writer and futurist Richard Watson warned an eco-tourism and green travel conference in Adelaide on Monday that there was a dark side to tourism. “In the short term there is a definite problem that people are possibly going to destroy the very thing they came to experience. “That is without a shadow of a doubt true …