World Heritage Identification Number: 154
World Heritage since: 1981
Category: Natural Heritage
WHE Type: Natural Landscapes & Geographic Features
Transboundary Heritage: No
Endangered Heritage: No
Country: 🇦🇺 Australia
Continent: Oceania
UNESCO World Region: Asia and the Pacific
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The Great Barrier Reef: A Natural Wonder of the World
The Great Barrier Reef, located off the northeast coast of Australia, is a natural wonder of the world and a UNESCO World Heritage Site since 1981. Stretching over 2,300 kilometres (1,400 mi) and covering an area of approximately 344,400 square kilometres (133,000 sq mi), this vast coral reef system is the largest of its kind on Earth.
Composed of over 2,900 individual reefs and 900 islands, the Great Barrier Reef is home to an incredible array of marine life. With 400 types of coral, 1,500 species of fish, and 4,000 types of molluscs, this underwater ecosystem is a veritable treasure trove of biodiversity. The reef is also of great scientific interest due to its unique habitats, including seagrass beds, mangrove forests, and lagoons.
One of the most notable inhabitants of the Great Barrier Reef is the dugong, or sea cow. This large, herbivorous marine mammal is critically endangered, with populations estimated at only around 6,500 individuals. The reef also provides refuge for the large green turtle, another threatened species. These animals play essential roles in maintaining the health and balance of the reef ecosystem.
The Great Barrier Reef can be seen from outer space and is one of the largest single structures made by living organisms. This reef structure is composed of and built by billions of tiny organisms, known as coral polyps. These polyps secrete calcium carbonate to form the hard structures that make up the reef. Over thousands of years, these structures have grown and accumulated, creating the complex and diverse ecosystem we see today.
Despite its immense size and importance, the Great Barrier Reef faces numerous threats. Climate change, pollution, and overfishing are major concerns. Rising ocean temperatures can lead to mass coral bleaching events, which can kill large areas of the reef. Pollution from land-based sources, such as agricultural runoff and plastics, can harm marine life and degrade water quality. Overfishing can deplete fish stocks and disrupt the food chain.
Efforts to protect the Great Barrier Reef include strict fishing regulations, marine protected areas, and education and awareness campaigns. The Great Barrier Reef Marine Park was established in 1975 to manage and protect the reef and its surrounding waters. Visitors to the reef are encouraged to follow sustainable practices, such as using reef-safe sunscreens and not touching or feeding the wildlife.
In conclusion, the Great Barrier Reef is a natural wonder of the world and a vital ecosystem that supports an incredible array of marine life. Despite facing numerous threats, efforts to protect and preserve this unique and important ecosystem continue. As a UNESCO World Heritage Site, the Great Barrier Reef is a testament to the importance of conserving our natural heritage for future generations.
UNESCO Description of the World Heritage Site
The Great Barrier Reef is a site of remarkable variety and beauty on the north-east coast of Australia. It contains the world’s largest collection of coral reefs, with 400 types of coral, 1,500 species of fish and 4,000 types of mollusc. It also holds great scientific interest as the habitat of species such as the dugong (‘sea cow’) and the large green turtle, which are threatened with extinction.
UNESCO Justification of the World Heritage Site
Criterion (vii): The GBR is of superlative natural beauty above and below the water, and provides some of the most spectacular scenery on earth. It is one of a few living structures visible from space, appearing as a complex string of reefal structures along Australia's northeast coast. From the air, the vast mosaic patterns of reefs, islands and coral cays produce an unparalleled aerial panorama of seascapes comprising diverse shapes and sizes. The Whitsunday Islands provide a magnificent vista of green vegetated islands and spectacular sandy beaches spread over azure waters. This contrasts with the vast mangrove forests in Hinchinbrook Channel, and the rugged vegetated mountains and lush rainforest gullies that are periodically cloud-covered on Hinchinbrook Island. On many of the cays there are spectacular and globally important breeding colonies of seabirds and marine turtles, and Raine Island is the world’s largest green turtle breeding area. On some continental islands, large aggregations of over-wintering butterflies periodically occur. Beneath the ocean surface, there is an abundance and diversity of shapes, sizes and colours; for example, spectacular coral assemblages of hard and soft corals, and thousands of species of reef fish provide a myriad of brilliant colours, shapes and sizes. The internationally renowned Cod Hole near Lizard Island is one of many significant tourist attractions. Other superlative natural phenomena include the annual coral spawning, migrating whales, nesting turtles, and significant spawning aggregations of many fish species.
Criterion (viii): The GBR, extending 2,000 kilometres along Queensland's coast, is a globally outstanding example of an ecosystem that has evolved over millennia. The area has been exposed and flooded by at least four glacial and interglacial cycles, and over the past 15,000 years reefs have grown on the continental shelf. During glacial periods, sea levels dropped, exposing the reefs as flat-topped hills of eroded limestone. Large rivers meandered between these hills and the coastline extended further east. During interglacial periods, rising sea levels caused the formation of continental islands, coral cays and new phases of coral growth. This environmental history can be seen in cores of old massive corals. Today the GBR forms the world’s largest coral reef ecosystem, ranging from inshore fringing reefs to mid-shelf reefs, and exposed outer reefs, including examples of all stages of reef development. The processes of geological and geomorphological evolution are well represented, linking continental islands, coral cays and reefs. The varied seascapes and landscapes that occur today have been moulded by changing climates and sea levels, and the erosive power of wind and water, over long time periods. One-third of the GBR lies beyond the seaward edge of the shallower reefs; this area comprises continental slope and deep oceanic waters and abyssal plains.
Criterion (ix): The globally significant diversity of reef and island morphologies reflects ongoing geomorphic, oceanographic and environmental processes. The complex cross-shelf, longshore and vertical connectivity is influenced by dynamic oceanic currents and ongoing ecological processes such as upwellings, larval dispersal and migration. Ongoing erosion and accretion of coral reefs, sand banks and coral cays combine with similar processes along the coast and around continental islands. Extensive beds of Halimeda algae represent active calcification and accretion over thousands of years. Biologically the unique diversity of the GBR reflects the maturity of an ecosystem that has evolved over millennia; evidence exists for the evolution of hard corals and other fauna. Globally significant marine faunal groups include over 4,000 species of molluscs, over 1,500 species of fish, plus a great diversity of sponges, anemones, marine worms, crustaceans, and many others. The establishment of vegetation on the cays and continental islands exemplifies the important role of birds, such as the Pied Imperial Pigeon, in processes such as seed dispersal and plant colonisation. Human interaction with the natural environment is illustrated by strong ongoing links between Aboriginal and Torres Strait Islanders and their sea-country, and includes numerous shell deposits (middens) and fish traps, plus the application of story places and marine totems.
Criterion (x): The enormous size and diversity of the GBR means it is one of the richest and most complex natural ecosystems on earth, and one of the most significant for biodiversity conservation. The amazing diversity supports tens of thousands of marine and terrestrial species, many of which are of global conservation significance. As the world's most complex expanse of coral reefs, the reefs contain some 400 species of corals in 60 genera. There are also large ecologically important inter-reefal areas. The shallower marine areas support half the world's diversity of mangroves and many seagrass species. The waters also provide major feeding grounds for one of the world's largest populations of the threatened dugong. At least 30 species of whales and dolphins occur here, and it is a significant area for humpback whale calving. Six of the world’s seven species of marine turtle occur in the GBR. As well as the world’s largest green turtle breeding site at Raine Island, the GBR also includes many regionally important marine turtle rookeries. Some 242 species of birds have been recorded in the GBR. Twenty-two seabird species breed on cays and some continental islands, and some of these breeding sites are globally significant; other seabird species also utilize the area. The continental islands support thousands of plant species, while the coral cays also have their own distinct flora and fauna.
Encyclopedia Record: Great Barrier Reef
The Great Barrier Reef is the world's largest coral reef system, composed of over 2,900 individual reefs and 900 islands stretching for over 2,300 kilometres (1,400 mi) over an area of approximately 344,400 square kilometres (133,000 sq mi). The reef is located in the Coral Sea, off the coast of Queensland, Australia, separated from the coast by a channel 160 kilometres (100 mi) wide in places and over 61 metres (200 ft) deep. The Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organisms. This reef structure is composed of and built by billions of tiny organisms, known as coral polyps. It supports a wide diversity of life and was selected as a World Heritage Site in 1981. CNN labelled it one of the Seven Natural Wonders of the World in 1997. Australian World Heritage places included it in its list in 2007. The Queensland National Trust named it a state icon of Queensland in 2006.Additional Site Details
Area: 34,870,000 hectares
Number of Components: 1
(viii) — Outstanding example representing major earth stages
(ix) — Outstanding example representing ecological and biological processes
(x) — Contains most important habitats for biodiversity
Coordinates: -18.28611111 , 147.7
IUCN World Heritage Outlook
The 2025 Conservation Outlook on Great Barrier Reef reports the following assessment:
Source: International Union for Conservation of Nature (IUCN) · View assessment
World Heritage Research
Discover scientific research and academic studies that deepen our understanding of Great Barrier Reef from its history and significance to its conservation, management, and contemporary challenges.
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Highest ocean heat in four centuries places Great Barrier Reef in danger
Recent ocean heat extremes in the Coral Sea, including the warmest January–March periods on record (2017, 2020, and 2024), exceed the 95th-percentile limit of pre-1900 maximum temperatures over a 400-year span. These events, driven by human-induced climate change, have caused unprecedented mass coral bleaching on the Great Barrier Reef (GBR). Climate models confirm that rapid warming in recent decades is attributable to anthropogenic influences, posing an existential threat to the GBR ecosystem. Without urgent intervention, near-annual bleaching could become the norm, endangering biodiversity and the reef's ecological function and outstanding universal value.
Henley, B. J., McGregor, H. V., King, A. D., Hoegh-Guldberg, O., Arzey, A. K., Karoly, D. J., Lough, J. M., DeCarlo, T. M., & Linsley, B. K. (2024). Highest ocean heat in four centuries places Great Barrier Reef in danger. Nature, 632(8024), 320–326. https://doi.org/10.1038/s41586-024-07672-x
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Large-scale interventions may delay decline of the Great Barrier Reef
Large-scale, coordinated interventions could significantly delay the decline of coral cover on the Great Barrier Reef (GBR), according to a new systems modeling study. The research found that combining strategies—such as controlling crown-of-thorns starfish populations and managing solar radiation—to protect corals from both predation and thermal stress offers the most promise. Without intervention, climate change projections suggest severe coral loss within 50 years due to cumulative impacts like tropical cyclones, marine heatwaves, and ocean acidification. The study used a dynamic meta-community model of 3753 reefs to simulate the effects of multiple interventions, revealing that large-scale implementation could buy one to two decades for natural adaptation and climate action.
Condie, S. A., Anthony, K. R. N., Babcock, R. C., Baird, M. E., Beeden, R., Fletcher, C. S., Gorton, R., Harrison, D., Hobday, A. J., Plagányi, É. E., & Westcott, D. A. (2021). Large-scale interventions may delay decline of the Great Barrier Reef. Royal Society Open Science, 8(4). https://doi.org/10.1098/rsos.201296
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Long-term shifts in the colony size structure of coral populations along the Great Barrier Reef
A significant decline in coral colony abundances across all size classes and taxa has been observed along the Great Barrier Reef, with particularly severe impacts in northern and central regions following mass bleaching events in 2016 and 2017. While large colonies appear stable in relative terms, their absolute numbers have sharply decreased, raising concerns about the potential for recovery of older, fecund corals amid increasing disturbance frequency and intensity. The study, which compared current data to historical baselines from 1995/1996, also found that smaller colonies have systematically declined across regions, habitats, and taxa, indicating a broader erosion of recruitment and resilience in coral populations.
Dietzel, A., Bode, M., Connolly, S. R., & Hughes, T. P. (2020). Long-term shifts in the colony size structure of coral populations along the Great Barrier Reef. Proceedings of the Royal Society B: Biological Sciences, 287(1936), 20201432. https://doi.org/10.1098/rspb.2020.1432
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Reef Grief: investigating the relationship between place meanings and place change on the Great Barrier Reef, Australia
Approximately half of residents, tourists, and tourism operators associated with the Great Barrier Reef, along with nearly one-quarter of fishers, report significant 'Reef Grief' due to ecological degradation such as coral bleaching. This emotional response is closely linked to place meanings like biodiversity or scientific value but inversely related to aesthetic appreciation. The study, based on surveys of 3759 individuals, highlights the profound psychological impacts of ecosystem loss and suggests that managing ecological grief will be crucial amid future climate-driven declines.
Marshall, N., Adger, W. N., Benham, C., Brown, K., I Curnock, M., Gurney, G. G., Marshall, P., L Pert, P., & Thiault, L. (2019). Reef Grief: investigating the relationship between place meanings and place change on the Great Barrier Reef, Australia. Sustainability Science, 14(3), 579–587. https://doi.org/10.1007/s11625-019-00666-z
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Spatial resilience of the Great Barrier Reef under cumulative disturbance impacts
A high-resolution, spatially explicit model of coral dynamics on the Great Barrier Reef reveals that coral resilience is negatively impacted by river plume conditions and reef accessibility, with outer shelf communities exhibiting the highest growth rates due to favorable environmental conditions. Despite being in no-take marine protected areas, inner-shelf reefs showed lower resilience primarily due to poor water quality. The model projects a mean annual coral loss of −0.67%/year from 1996 to 2017, driven mainly by cyclones, crown-of-thorns starfish outbreaks, and bleaching. This validated platform identifies reefs at risk of biodiversity loss and those with potential to persist under increasing disturbance regimes.
Mellin, C., Matthews, S., Anthony, K. R. N., Brown, S. C., Caley, M. J., Johns, K. A., Osborne, K., Puotinen, M., Thompson, A., Wolff, N. H., Fordham, D. A., & MacNeil, M. A. (2019). Spatial resilience of the Great Barrier Reef under cumulative disturbance impacts. Global Change Biology, 25(7), 2431–2445. Portico. https://doi.org/10.1111/gcb.14625
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Sources, distribution and fate of microfibres on the Great Barrier Reef, Australia
A comprehensive study on the Great Barrier Reef reveals widespread contamination with microdebris, primarily microfibres, which constitute 86% of detected items. The research highlights non-random intake patterns of microdebris by coral reef fish, differing significantly in chemical composition, shape, and colour from that found in surface waters. Additionally, riverine discharge is identified as a likely source for inshore microdebris contamination but not for offshore locations. This study underscores the complexities in determining marine microdebris exposure and fate, providing critical insights to improve ecological assessments and prioritize source reduction efforts.
Jensen, L. H., Motti, C. A., Garm, A. L., Tonin, H., & Kroon, F. J. (2019). Sources, distribution and fate of microfibres on the Great Barrier Reef, Australia. Scientific Reports, 9(1). https://doi.org/10.1038/s41598-019-45340-7
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Mangrove lagoons of the Great Barrier Reef support coral populations persisting under extreme environmental conditions
Researchers have identified two extreme mangrove lagoons on the Great Barrier Reef (GBR) that support taxonomically diverse coral populations thriving under conditions of low pH (<7.6), low oxygen (<1 mg l-1), and highly variable temperatures (>7°C). These environments, which mimic predicted seawater conditions for the coming century, act as hot-spots of resilience for corals, challenging current understanding of their stress tolerance mechanisms. The study found that coral cover in these lagoons was typically low but patchy, with established colonies present. Physiological plasticity and flexibility in Symbiodiniaceae taxa associations were crucial in supporting coral survival. The research highlights the ecosystem service value of mangrove lagoons for corals, spanning from refuge to stress preconditioning, and underscores the need to study such extreme environments to better understand coral resilience.
Camp, E., Edmondson, J., Doheny, A., Rumney, J., Grima, A., Huete, A., & Suggett, D. (2019). Mangrove lagoons of the Great Barrier Reef support coral populations persisting under extreme environmental conditions. Marine Ecology Progress Series, 625, 1–14. https://doi.org/10.3354/meps13073
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