Climate change is the single greatest threat facing the Reef.
Climate change poses the greatest threat to the Great Barrier Reef and coral reefs globally.
Two of the greatest challenges brought by climate change—an increase in ocean temperatures and acidity levels—are creating severe knock-on effects, jeopardising the Reef’s survival. Tropical sea surface temperatures have risen by 0.4–0.5 °C since the late 19th century, with rapid, human-induced climate change the greatest overall threat to the long-term future of the Great Barrier Reef. These dramatic changes in the Reef’s environment are making it increasingly challenging for it to recover and protect itself from the devastating effects of climate change.
#Rising sea temperatures
Rising sea temperatures mean the Reef is at greater risk of heat stress and mass coral bleaching, decreasing the capacity for corals to build skeletons—which act as key habitats for the Reef's irreplaceable marine life. Higher sea levels impact many areas of overall ocean health including coastal erosion, the size of storm surges and protected shallow waters for marine organisms. Small changes in sea levels will mean land inundation which will cause significant changes in tidal habitats such as mangroves and saltwater intruding into low-lying freshwater habitats.
Since the late 18th century, the earth’s oceans have absorbed about 30% of the additional carbon dioxide that human activities have injected into the atmosphere. This extra CO2 in the oceans has changed their chemistry, a process known as ocean acidification, decreasing oceans pH levels. These combined pressures make the world’s coral reefs much more vulnerable to poor health and irreplaceable damage, with the survival of the Reef for generations to come looking bleak.
#Severe weather events
Increased frequency of severe weather events, such as cyclones and record rainfall levels can destroy reef structures and send an influx of freshwater and sediment further out from the coast on to the Reef. Take a look at the timeline and increased episodes of extreme weather events occurring on the Great Barrier Reef.