Coral bleaching at Heron Island

Climate change

Climate change is the single greatest threat facing the Reef.

#What's happening?

Two of the greatest challenges brought by climate change - an increase in ocean temperatures and acidity levels - are creating severe knock-on effects, putting the entire Reef at risk. 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.

Rising temperatures

Rising sea temperatures mean the Reef is at greater risk of heat stress and mass coral bleaching. Higher temperatures can cause sea levels to rise, which in turn can cause coastal erosion, increased storm surges and lead to a loss of shallow-water habitats for marine organisms. Small changes in sea levels can also lead to coastal inundation, which can cause tidal habitats such as mangroves and saltwater to intrude into low-lying freshwater habitats.

Acidity levels

Since the late 18th century, the ocean has absorbed about 30% of the additional carbon dioxide that human activities have injected into the atmosphere. This extra CO2 in the ocean has changed its chemistry, in a process known as ocean acidification, decreasing its pH level. This makes the world’s coral reefs much more vulnerable to poor health and irreparable damage.

#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 onto the Reef. Take a look at the timeline of extreme weather events occurring on the Great Barrier Reef. ​


Mass bleaching; Cyclone Debbie (cat 4); Drought; Flood


Mass bleaching; Drought


Cyclone Marcia (cat 5); Cyclone Nathan (cat 4); Drought


Cyclone Ita (cat 5)






Cyclone Yasi (cat 5); Flood


Cyclone Ului (cat 3); Flood


Heat stress; Cyclone Hamish (cat 5); Flood


Regional bleaching; Drought


Cyclone Larry (cat 5); Cyclone Monica (cat 3); Drought


Cyclone Ingrid (cat 5); Drought


Mass bleaching; Drought


Mass bleaching; Drought

#What we're doing

Inaugural accelerator workshop, Great Barrier Reef

Resilient Reefs

Partnering with Reef communities to respond to climate change and local threats.

Reef Islands

Reef Islands

Restoring critical island habitats to protect ecosystems and save vulnerable species.



Unlocking the genetic secrets of corals.

Seep site, PNG

Volcanic Seeps

The undersea lab providing a window into the future of coral reefs.

more projects
You can help

#You can help

Your support can help save endangered Reef animals, find solutions to major threats and enable vital research.