Malcolm Roberts (Queensland, Pauline Hanson's One Nation Party) Share this | Hansard source

When discussing coral bleaching recently, the assumption defaults to blaming claimed human climate change instead of asking what actually caused it. Coral bleaching in simple terms is a loss of colour in coral, most often due to symbiosis dysfunction, a severing of the join between the coral polyp and the host tissue—the calcium carbonate that gives coral its white colour.

Bleaching is a response to environmental stress. It has many causes, including changes in salinity, ultraviolet radiation, increased sedimentation and high nutrient levels after flooding or pollution. Kamenos from the University of Glasgow found evidence of Great Barrier Reef bleaching in the 1600s. His paper has been contested, yet the many citations used to support his paper have not been. Hendy documented two hiatuses in coral skeleton growth, associated tissue death and subsequent regrowth in eight multicentury coral cores collected from the central Great Barrier Reef accurately dated to 1782 to 1817. This period was before humans are claimed to have influenced the weather. Dunne recorded bleaching on the reef in 1928. Woolridge documented the bleaching caused by floodwaters carrying nutrients impacting on the reef. Kenkel found coral has plasticity to adapt to different environmental conditions and is more resilient than previously thought. Maynard found that coral adapts to bleaching by becoming more resilient. During the past 2.5 million years, there have been 40 glacial maximums and 40 interglacial periods. Eighty times, coral has had to rise or fall by up to 140 metres, and our coral reefs are still there. How resilient they are.

Our reefs have been subjected to bleaching for millennia, and they always recover, as they did in 2022, when the Greens were telling us the reef was dead, and tourists believed them. Tourist numbers are below the long-term average, COVID excluded. It's time climate carpetbaggers were called out for selective pseudoscience designed to protect their taxpayer funding. Bleaching is a part of nature. It recovers. It's cyclical.