In particular for coral, analysis of coral cover data from about 1960 onwards suggests that cover across the GBR has fallen from about 50% in the 1960s to about 16% now. As yet unpublished estimates by Dr Glenn De’ath and his colleagues suggest that if current trends continue coral cover could be as low as 5% in 20 years.
Climate change is driving the record-breaking sea surface temperatures that are bleaching the reef.
Coral reefs are highly vulnerable to a changing climate.
Climate change is driven by the greenhouse gas pollution produced from the burning of coal, oil and gas for energy, land-clearing and some other sources.
What the Future Holds
Annual bleaching on the Great Barrier Reef is expected by 2030, if today’s trends in global warming pollution and rising ocean temperatures continue
Some scientists think the reef in its current diverse form could be largely gone by 2050 if nothing is done.
Scientists predict that a 1.5°C temperature rise will result in 97% of the Great Barrier Reef being bleached.
Higher summer water temperatures are the main cause of bleaching.
Mass bleaching events in 1998, 2002, 2006 and most recently 2016 were caused by unusually warm sea surface temperatures during the summer season. Bleaching in 2008 and 2011 was caused by an influx of freshwater.
Mass coral bleaching was not documented in the scientific literature before 1979; however, significant mass bleaching events have since been reported in 1982, 1987, 1992 and the strongest sea surface warming event ever recorded occurred in 1998, where an estimated 46% of corals in the western Indian Ocean were heavily impacted or died. In 2005 sea surface temperatures in the Caribbean were the highest reported in more than 100 years,
It was placed on the World Heritage List in 1981
Populations of the COTs have increased since the 1970s and large outbreaks of starfish can occur wiping out huge tracks of coral reef.
There have been three major periods (“waves”) of COTS outbreaks on the GBR: 1962 – 1976; 1978 – 1991; 1993 – 2005; and it is now accepted that we are at the beginning of the next wave which appears to have started off Cairns in 2009.