The Great Barrier Reef is the world's largest reef systems, stretching along the East coast of Australia from the northern tip down at Cape York to the town of Bundaberg, is composed of roughly 2,900 individual reefs and 940 islands and cays that stretch for 2,300 kilometres (1,616 mi) and cover an area of approximately . The reef is located in the Coral Sea, off the coast of Queensland in northeast Australia. A large part of the reef is protected by the Great Barrier Reef Marine Park.
A 2014 report of the Australian Government's Great Barrier Reef Marine Park Authority (GBRMPA) says that climate change is the most significant environmental threat to the Great Barrier Reef. Other major environmental pressures listed are decreased water quality from land-based runoff, impacts from coastal development, and some persistent impacts from fishing activities. The reef is also threatened by storms, coral bleaching and ocean acidification. The 2014 report also shows that, while numerous marine life species have recovered after previous declines, the strength of the dugong population is continuing to decline. Terry Hughes, Federation Fellow, ARC Centre of Excellence for Coral Reef Studies at James Cook University, wrote in a 14 August 2014 Conversation piece that harmful government policies and ongoing conflicts of interest over mining royalties are risks of an equivalent magnitude. Reef scientists Jon Day, Bob Pressey, Jon Brodie, and Hughes have stated that the "cumulative effects of many combined impacts" is the real issue.
In a Conversation article, Mathieu Mongin, a biogeochemical modeller at CSIRO and colleagues mapped parts of the Great Barrier Reef that are most exposed to ocean acidification. This map of pH on the Great Barrier Reef presents the exposure to ocean acidification on each of the 3,581 reefs, providing managers with the information they need to tailor management to individual reefs. The Great Barrier Reef is not a singular reef nor a physical barrier that prevents exchange between reefs; it is a mixture of thousands of productive reefs and shallow areas lying on a continental shelf with complex oceanic circulation.
In March 2022, UNESCO launched a monitoring mission to assess the impact of pollution, fishing, climate change and coral bleaching. The report concluded that the Great Barrier Reef should be included on the list of World Heritage in Danger, which would probably have had an impact on tourism. In May 2023, after years of warnings from UNESCO, Australian Environment Minister Tanya Plibersek promised in a letter to UNESCO Director Audrey Azoulay a "combined investment of A$4.4 billion" to protect the reef. In the letter, Australia committed to following UNESCO's recommendations, creating no-fishing zones in one third of the site by the end of 2024, completely banning gillnetting by 2027 and meeting targets for improving water quality by 2025. The Albanese government has pledged to set targets for reducing CO2 emissions, to align with the objective of limiting global temperature rise to 1.5 °C.
History
In 1967, efforts began to conserve the Great Barrier Reef. It was proposed to mine lime from Ellison Reef, but surveys showed that the reef supported a diverse community of corals and fish.
The Australian and Queensland Governments committed to act in partnership in 2007 to protect the reef, and water quality monitoring programmes were implemented. However, the World Wildlife Fund criticised the slow progress of the governments, raising a concern that as many as 700 reefs continued to be at risk from sediment runoff.
The World Heritage Committee has raised concerns about the Great Barrier Reef since 2010. The Australian government then outlined further action after the World Heritage Committee (WHC) called for the completion of a strategic assessment of the Reef area in 2011. The committee also urged the government to use the assessment data to develop a long-term plan for protecting the "Outstanding Universal Value" of the reef, which is the basis for its World Heritage listing. Again, criticisms emerged from the expert community—due to vague quantitative targets, the absence of clear, specific strategies, and no mention of the implications of climate change—but the significant efforts of both state and federal governments addressed key recommendations from the WHC.
A 2012 UNESCO report, published by the WHC, then criticised the government's management of the Great Barrier Reef, warning that the area could be downgraded to a world heritage site "in danger" unless major changes were implemented. The report expressed "extreme concern" at the rapid rate of coastal development, highlighting the construction of liquefied natural gas plants at Gladstone and Curtis Island, and recommended that thorough assessments are made before any new developments that could affect the reef are approved. UNESCO specifically recommended no new port development in Abbot Point, Gladstone, Hay Point, Mackay and Townsville.
Minister for Foreign Affairs Julie Bishop informed the Australian media that she would use climate change talks, held in Lima, Peru, in December 2014, to avoid the WHC—consisting of experts from 20 nations—applying the "in danger" listing in 2015. Bishop believed that "no justification" existed for the downgrading:
It would send a message around the world that even if you meet all of the criteria set out by the world heritage committee, there is still a risk that they will place an area on the in-danger list ... It [downgrading] would have significant implications for Australia but it would also set a very dangerous precedent for countries who don't have the opportunity to take the action that Australia has.
To avoid the Great Barrier Reef being listed as "in danger", the Queensland Government introduced the Ports Bill 2014 on 25 November 2014. The Bill seeks to restrict further port development along the coast to Brisbane and four "Priority Port Development Areas", with the latter including four ports identified by the WHC in its 2012 report. The Bill also restricts dredging over a decade-long period, with the exception of priority ports. Additionally, a long-term sustainability plan and the expansion of water-quality activities were introduced by state and federal governments, and their partner agencies.
However, in response to the Ports Bill, University of Queensland (UQ) academics said on 19 December 2014 that, although the issues are "not insurmountable", "the health of the reef is still declining and consequently more needs to be done." Australian Marine Conservation Society (AMCS) Great Barrier Reef campaign director Felicity Wishart was more damning and stated in a press release:
The new Ports Bill fails to rule out any currently proposed new dredging, the dumping of dredge spoil in the Reef's waters and is silent on maintenance dredging across the region. The millions of tonnes of dredging and dumping for mega port developments that are in the pipeline will be able to go ahead under the Bill. Despite the establishment of four Priority Port Development Areas along the Reef (Townsville, Abbot Point, Mackay/Hay Point and Gladstone), the Bill will still allow port expansion in Cairns. This fails to meet the recommendation by the World Heritage Committee that no new port developments be permitted outside of the existing port areas. The Bill contains no protections for the most northern section of the Reef or the Fitzroy Delta, and it does nothing to improve water quality in Reef waters, all matters which the World Heritage Committee wants action on.
The Reef 2050 plan began in 2015 and was updated in 2021 to focus on the current issues the Great Barrier Reef is experiencing prioritizing resilience. The Australian government, Queensland government, the Great Barrier Reef Marine Park Authority, Australian Institute of Marine Science (AIMS), and the Great Barrier Reef Foundation are all working together and have put 5 billion dollars towards protection efforts. This includes reducing the impact of the ports, phase out gill-net fishing by 2027, net free fishing zones, beginning the Queensland Government Sustainable Fisheries Strategy, strengthening regulations, and reducing impact of vegetation clearing. UNESCO considers that the Reef 2050 Long-Term Sustainability Plan has been effective, noting that progress had been made to reduce agricultural runoff sediments.
Water quality
Water quality was first identified as a threat to the Great Barrier Reef in 1989. Thirty "major rivers" and hundreds of small streams comprise the Great Barrier Reef catchment area, which covers of land. Queensland has several major urban centers on the coast including Cairns, Townsville, Mackay, Rockhampton and the industrial city of Gladstone. Dredging in the Port of Gladstone is raising concern after dead and diseased fish where found in the harbor. Cairns and Townsville are the largest of the coastal cities, with populations of approximately 150,000 each.
There are many major water quality variables affecting coral reef health including water temperature, salinity, nutrients, suspended sediment concentrations, and pesticides. The species in the Great Barrier Reef area are adapted to tolerable variations in water quality however when critical thresholds are exceeded they may be adversely impacted. River discharges are the single biggest source of nutrients, providing significant pollution of the Reef during tropical flood events with over 90% of this pollution being sourced from farms. When the 2019 Townsville flood waters reached the Great Barrier Reef, the flood plumes covered a large area of corals, even reaching 60 km out to sea, however water quality analysis showed damage to the outer reef from the flooding was less than previously feared.
As of 1995, water visibility had decreased to 10 metres.
Due to the range of human uses made of the water catchment area adjacent to the Great Barrier Reef, some 700 of the 3,000 reefs are within a risk zone where water quality has declined due to the naturally acidic sediment and chemical runoff from farming. Coastal development and the loss of coastal wetlands—the latter acts as natural filter—are also major factors From mid 2012 to mid 2016, 596,000 hectares of forest in the catchment zone was cleared.
Industries in the water catchment area are cotton growing, comprising approximately ; 340 dairy farms with an average area of each, cattle grazing, horticulture including banana growing, sugarcane farming, and cropping of approximately wheat, barley, and 6,000 to 7000 km2 sorghum and maize. Fertiliser use in the cotton, dairy, beef, horticulture and sugar industries is essential to ensure productivity and profitability. However, fertiliser and byproducts from sugar cane harvesting methods form a component of surface runoff into the Great Barrier Reef lagoon.
The principal agricultural activity in the wet tropics is sugar cane farming, while cattle grazing is the primary industry in the dry tropics regions. Both are considered significant threats to high water quality. Copper, a common industrial pollutant in the waters of the Great Barrier Reef, has been shown to interfere with the development of coral polyps.
Flood plumes are flooding events associated with higher levels of nitrogen and phosphorus. In February 2007, due to a monsoonal climate system, plumes of sediment runoff have been observed reaching to the out most regions of the reef.