The film, made from calcium carbonate, is designed to sit on the surface of the water above the corals. Trials on seven different types of coral so far have found that the shield decreased bleaching in most cases, cutting off sunlight by up to 30 percent.

The reef measures 216,000 square miles, so it's unlikely the shield could be deployed across the entire World Heritage site, but managing director of the Great Barrier Reef Foundation, Anna Marsden, says it could play an important role nonetheless: "It could be deployed on a smaller, local level to protect high-value or high-risk areas of reef."

She added that the concept needs more testing before it gets to that stage, "but it's an exciting development at a time when we need to explore all possible options to ensure we have a Great Barrier Reef for future generations."