Australia’s Iconic Great Barrier Reef World Heritage Site at Risk from Global Warming

, Deputy director, Climate & Energy | May 26, 2016, 3:06 pm EDT
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A lot has changed since Captain Cook became the first European to try to navigate the Great Barrier Reef in 1770. It was the reports of Cook and naturalist Joseph Banks on their return to England that first alerted the scientific world to the existence of this biological marvel. The Great Barrier Reef is now one of the world’s most important coastal and marine tourism areas, but its future is at risk, and climate change is the primary long-term threat.

A World Heritage site since 1981, the Great Barrier Reef is one of the world’s most complex and diverse ecosystems, with at least 400 species of hard coral, 150 species of soft corals and sea fans, and more than 2,900 individual reefs and some of the most important seagrass meadows in the world. It teems with marine life of all sorts, including more than 1600 fish species, seabirds, seahorses, whales, dolphins, crocodiles, dugongs and endangered green turtles. The reef extends for 2,300km along the coast of Queensland in Northeast Australia and has evolved over a period of 15,000 years. The region is important for the indigenous heritage of First Australians who are Traditional Owners including Aboriginal and Torres Straits Islander people. Climate change threatens hunting and fishing as well as other traditional and cultural practices. Some sacred sites are also at risk for the more than 70 Traditional Owner groups for whom natural resources are inseparable from cultural identity.

Snorkeler, Great Barrier Reef. Photo: Robert Lindell

Snorkeler, Great Barrier Reef. Photo: Robert Lindell

Tourism is an important economic driver

Today, tourism (including touring, diving, beaches, sailing, fishing and cruising) is the most important economic sector in the GBR communities, contributing $5.2 billion dollars to the Australian economy in 2012 and supporting 64,000 jobs, or about 90% of the total economic activity in the region. Visitors spent nearly 43 million total nights in the GBR region in 2012, of which nearly 2 million nights were on the reef, mainly at Cairns and the Whitsunday Islands. Direct reef-related tourism alone contributes 4,800 jobs. Approximately 500 commercial boats operate bringing tourists out to dive and snorkel on the reef, and there can be negative impacts associated with this, including damage from fuel spills and walking and dropping anchors on fragile corals. Tourism infrastructure, along with other coastal developments, can cause habitat degradation and damaging pollution and sediment run-off. Australia is the world’s fourth largest coal producer and debate currently swirls around the risks embodied in plans to expand coal mining and coal shipping near the Great Barrier Reef.

Higher temperatures and ocean acidification threaten reefs

The biggest threat to the GBR today, and to its ecosystems services, biodiversity, heritage values and tourism economy, is climate change, including warming sea temperatures, accelerating rates of sea level rise, changing weather patterns and ocean acidification. Coral reefs worldwide are being directly impacted by warming waters and ocean acidification, and climate change is exacerbating other localized stresses. Ocean acidification is occurring because of increased levels of carbon dioxide in the atmosphere. A significant portion of this CO2 is being absorbed by the oceans and the resulting increases in seawater acidity reduces the capacity of some marine life, such as corals, to build their calcium carbonate based skeletons. Significant drops in coral growth rate have been recorded in the last two decades for massive Porites corals on the Great Barrier Reef.

Great Barrier Reef: Photo: Greens MPs

Great Barrier Reef: Photo: Greens MPs

Worst ever coral bleaching

Other significant threats to the reef include coastal development, agricultural run-off pollution, port-based shipping activities, illegal fishing and outbreaks of the coral-eating crown-of-thorns starfish. Assailed by multiple threats, the status of the GBR has been assessed as being poor and deteriorating. Half of its coral cover has been lost over the last three decades. Unusually high sea temperatures have caused nine mass coral bleaching events on the GBR since 1979, and until this year, the worst had been in 1998 and 2002 (Great Barrier Reef Marine Park Authority 2012, Steffen et al 2009, Hughes et al 2015). But higher water temperatures and a severe El Nino have been pushing corals into the danger zone all over the world in 2015-16, and the Great Barrier Reef is currently suffering the most severe bleaching episode ever recorded.

Coral bleaching occurs when higher than usual maximum temperatures disrupt the relationship between corals and the photosynthetic zooxanthelae algae that live in their tissues in a vital and mutually beneficial biological relationship. Bleaching can kill corals, but depending on the severity of the impact and local factors they can also recover. The same is true for coral damage from storms, but damaged or bleached corals and reefs need time to recover. All indications are that bleaching events will become more frequent and tropical storms more intense with continued global warming, and that this combined with a continued trend in warming water and ocean acidification will be massively detrimental to the GBR. The current bleaching episode has affected more than 90% of the reef, with the worst damage being in the northern region where surveys have confirmed 50% mortality in some places.

Without global efforts to reduce greenhouse gas emissions coupled with local management responses to increase resilience, current projections suggest that coral cover could decline to 5-10% of the GBR by the early 2020s from 28% in 1985—a potential loss of 80% in just 40 years. Similar fears are associated with one of the other keystone ecosystems of the GBR, seagrass meadows representing 20% of the world’s 72 seagrass species. These shallow-water habitats provide vital nursery areas for fish and shrimps, critical food resources for turtles and dugongs, and act as carbon sinks, sequestering organic carbon in marine sediments. The combination of agricultural runoff, fishery impacts and climate change may exceed seagrass beds’ natural ability to adapt. Sea turtles too are at risk from climate change as high temperatures and sea level rise impact their breeding and nesting beaches.

Coral at Eddy Reef off Mission Beach. Photo: Paul Toogood

Coral at Eddy Reef off Mission Beach. Photo: Paul Toogood

A need for action

Spurred by the direct evidence of climate change already impacting the GBR, degradation of the reefs and the likelihood of much worse to come, the Australian government has begun to plan and implement actions to reduce the risk of future damage. At the core of the adaptation strategy are efforts to build ecosystem resilience, fill gaps in scientific knowledge, and monitor environmental, social and economic impacts of climate change. Collaborative management strategies are also being developed and tested with local communities, Traditional Owners, as well as with business and industry. The GBR was also the first World Heritage property for which a comprehensive Tourism and Climate Change Action Strategy was developed. The strategy recognizes the vital importance that a healthy GBR ecosystem plays for the Australian economy and that the tourism industry must quickly come to grips with the problem. Recommended actions include reducing direct impacts and greenhouse gas emissions from tourism companies operating on or near the reef; increased training and awareness for guides and operators; helping to raise public understanding of the threat, and; supporting scientific research and monitoring activities. The plan also calls for the industry itself to plan adaptive responses for declining reef conditions and to contribute to risk management strategies for climate disasters.

Despite these measures, international concern has continued to grow, however, that without a comprehensive response more in keeping with the scale of the threat, the GBR’s extraordinary biodiversity and natural beauty may lose its World Heritage values. The World Conservation Outlook 2014 published by IUCN (International Union for Conservation of Nature) assessed the status of the World Heritage values of the GBR as of “high concern” and experiencing a deteriorating trend. The most recent strategy from the Australian government, the Reef 2050 Long-term Sustainability plan addressed this issue head on and has been designed to “ensure the Great Barrier Reef continues to improve on its Outstanding Universal Value every decade between now and 2050 to be a natural wonder for each successive generation to come”.

Note: This blog is an updated version of the draft case study that UNESCO removed from the report World Heritage and Tourism in a Changing Climate at the request of the Australian government.  UCS believes that we need to have these important conversations publicly, which is why we published the case study on our blog on the same time the report was released internationally. 

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  • Ron Mader

    Thank you for sharing the deleted text. Adding a link to this page from Planeta:

  • Marty Gwynne

    and guess how all these “scientists” test the results of acidity on corals, they turn aquarium water into flippin acid and kill the corals to see the effects

    Makes me ANGRY

    • David Holdaway

      Why exactly does that make you angry?

  • Marty Gwynne

    Ocean acidification from CO2 is junk science.

    Waterways and forests have been seeing acidic conditions since the at least the 1900s from sulfates which turn waterways and forest soils acidic.

    Sea water is 8-9.0 dKH (calcium hardness) and 8.1 pH (base alkalinity)

    To reduce those parameters you need to inject 240mg of CO2 PER LITER OF SEA WATER.

    Of the impossible 240mg, only a small amount actually becomes carbolic acid and even less drops protons upon becoming bicarbonate

    Furthermore, corals like warm water, what they dont like is sudden sustained increases like El Nino

    The northern part of the reef is in the equator hot zone, and that is where the damage is, where changes in Ozone from El Nino have made UV dosage fluctuate as much as 1000+ joules according to NCEP Eyrthermal UV dosage maps for April and May 2016. Coral do not like large light or UV fluctuations AT ALL

    most of the bleaching are sps corals, and they are not dead and when they recover, sps coral skeletons are made from aragonite, ie calcium, and leech calcium ions into the water (which raises pH) as well as provides the perfect conditions for an even more diverse and healthy reef ecology once temperatures stabilize after El Nino.

    Junk science, junk, I have built coral reefs for 20 years, every day I spent for 20 years caring for corals in large aquariums which is far more difficult than caring for them in open waters. OA is junk science.

    • Marty Gwynne

      Where are you Nye, I will debate and absolutely destroy you, m0r0n

  • Ricci

    Exclusive: All mentions of Australia were removed from the final version of a Unesco report on climate change and world heritage sites after the Australian government objected on the grounds it could impact on tourism

    • Marty Gwynne

      The guardian are an eco extremist garbage site who sanitise facts from their comments and their mods are also commenting and deleting your replies to make it look like they win.

      The comments were not allowed on that UNESCO report, there was not even a link or mention of UNESCO, they called it “UN sponsored”, it wasnt it was the French Energy and Renewable ministry that funded it, Graudiad are literally Skeptical science in sheep’s clothings

  • Kevin O’Dea

    The Great Barrier Reef is one of the Natural Wonders of the World, rightfully an icon of World Heritage. The Liberal/NP Govt of Australia, with its myopic dry economic rationalist obsessions, is scrambling to avoid its responsibilty to maintain the pristine status of this area, which just happens to adjoin a huge lump of coal. Coal is now dying as a viable energy source. I do look forward to the impending collapse of this immoral government with its fossilized outlook on the world we live in.

  • johnward154

    As a result of war, corporations have been enthroned and an era of corruption in high places will follow, and the money power of the country will endeavour to prolong its reign by working upon the prejudices of the people until all wealth is aggregated in a few hands, and the Republic is destroyed. I feel at this moment more anxiety for the safety of my country than ever before, even in the midst of war. God grant that my suspicions may prove groundless.”

    Abraham Lincoln​

  • I suggest reading The Coral Bleaching Debate: Is Bleaching the Legacy of a Marvelous Adaptation Mechanism
    or A Prelude to Extirpation

  • Marcus Gibson

    And now the Australian government is scrubbing scientific reports to remove any mention of this issue:
    Rather than fixing the problem, deny it.
    Rather than pursuing knowledge, destroy it.
    Rather than being honest, lie.