The Great Barrier Reef is in grave danger. The twin perils brought by climate change – an increase in the temperature of the ocean and in its acidity – threaten its very existence.

Sir David Attenborough

Rapid, human-induced climate change is one of the greatest threats to the long-term future of the Great Barrier Reef.

Climate change has the potential to affect the Reef in a number of ways, including:

  • Increased frequency of severe weather events
  • Rising sea temperature
  • Ocean acidification
  • Rising sea levels

Tropical sea surface temperatures have risen by 0.4–0.5 °C since the late 19th century

Impact on the Reef

Increased frequency of severe weather events 

  • More intense cyclones can destroy and weaken the reef structure.
  • More extreme rainfall events will send more freshwater and sediment further out from the coast and on to the Reef.

Rising sea temperature

  • Greater risk of heat stress and mass coral bleaching.

Ocean acidification

  • Changes in the ocean's chemistry can decrease the capacity of corals to build skeletons, decreasing their capacity to create habitat for the Reef's marine life. 
  • Since the late 18th century, the 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, with the pH of oceans decreasing.

Rising sea levels

  • Higher seas can impact many areas including coastal erosion, the size of storm surges and the area available for shallow water 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.

Facing these and other natural and human-induced pressures, coral reefs will be more vulnerable to coral bleaching, disease, crown-of-thorns starfish and tropical cyclones.

Science with Impact

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Science with Impact

10 coral genomes: Sea-quence project

The secret as to why some coral species naturally survive at higher temperatures than the same species on the Great Barrier Reef could be in their genes.