Scientists say climate crisis and El Niño put Australia’s Great Barrier Reef at risk of another mass die-off this year

On Wednesday 9 August, Australia’s top marine body said that the Great Barrier Reef could deteriorate if warming ocean temperatures spark another mass coral bleaching event later this year.

Sections of the reef had been showing promising signs of recovery until a bleaching event in 2022 turned swathes of the vibrant coral a sickly, pale white.

The Australian Institute of Marine Science said that although the reef’s condition had stabilised during a “relatively mild” summer in 2023, it remained in a precarious position.

Institute research director David Wachenfeld said the reef was at:

increased risk with climate change driving more frequent and severe bleaching events.

Australia’s weather bureau has said it is “likely” an El Niño weather pattern will develop over the country in the coming weeks. The World Meteorological Organisation (WMO) declares the El Niño when sea temperatures in the the tropical eastern Pacific exceed 0.5C above the long-term average. These are naturally-occurring periodic warming events.

On 4 July, the WMO announced that El Nino was underway. The event has been bringing warmer ocean temperatures to the Pacific. As a result, this has renewed the risk of coral bleaching.

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Soaring sea temperatures and coral bleaching

Globally, the average ocean temperature has been topping seasonal heat records on a regular basis since April. On 31 July, climate modelling service Copernicus recorded the highest ever global sea surface temperature of 20.96C.

Coral bleaching occurs when sea temperatures rise by 1-2C for a prolonged period. The increased temperature causes corals to expel the algal organisms living in their tissues. This exposes the coral and makes it more vulnerable.

As a result of the current sustained high sea surface temperatures, corals in Australia’s Great Barrier Reef are at risk of a mass bleaching event. Australian Institute of Marine Science director David Wachenfeld said the reef was:

only one large-scale disturbance away from a rapid reversal of recent recovery.

Marine heatwaves have caused mass coral bleaching on the Great Barrier Reef in 2016, 2017, 2020 and 2022.

Researcher Mike Emslie said even the most minor bleaching event was enough to “put the brakes” on the reef’s recovery. Emslie explained that:

This means the reef is still at risk of decline from more frequent disturbances

Fossil-fuel-driven climate crisis to blame

Of course, the fossil-fuel-driven climate crisis is exacerbating the soaring sea surface temperatures.

The Intergovernmental Panel on Climate Change’s (IPCC) most recent report detailed that incidences of marine heatwaves had doubled since 1980. Crucially, the report stated that:

human influence has very likely contributed to most of them since at least 2006.

In other words, greenhouse gas (GHG) emissions from the burning of fossil fuels is largely to blame.

Moreover, the IPCC stressed that on the current climate trajectory, marine heatwaves are likely to increase in number throughout the 21st century. This would have a devastating impact on coral reef ecosystems. At 1.5C of warming, scientists have projected that over 90% coral reefs could die.

A 2019 study also found that the climate crisis is causing more intense El Niño events.

As the Canary has previously reported, rich Global North nations are the main climate culprits. For instance, the same IPCC report highlighted that wealthy ‘developed’ nations were responsible for 57% of GHG emissions between 1850 and 2019.

Naturally, these are the same rich nations who are still funding the extraction and expansion of fossil fuels.

World Heritage Site at risk

The Great Barrier Reef extends over 2,300km of coastline and is home to over 9,000 marine species. This includes 400 types of coral, 1,500 species of fish and 4,000 types of mollusc.

In 1981, The United Nations Educational, Scientific and Cultural Organization (UNESCO) designated the reef system a World Heritage Site (WHS). UNESCO defines these sites as:

places on Earth that are of outstanding universal value to humanity

After a damning report in 2021, World heritage body UNESCO considered listing the reef as “in danger”. However, following intense lobbying from Australia’s previous conservative government, it left the fading wonder off the list of endangered sites. The current Labor government in Australia has also continued to lobby UNESCO to keep the reef off the list.

The reef is one of Australia’s premier tourist attractions. Successive Australian governments have been concerned that putting it on the in-danger list could substantially tarnish its allure for international visitors.

Instead, UNESCO has set up a monitoring mission within Australia to assess the impact of pollution, fishing, the climate crisis, and coral bleaching. The UNESCO committee’s decision went against the scientific advice from experts who conducted a mission to reef.

Australia’s environment minister Tanya Plibersek told reporters that:

Lobbying is about telling the truth about what we’re doing

Plibersek was referring to the Labor government’s efforts to tackle the climate crisis and pressures to the reef. However, much like other Global North governments, Australia is continuing to develop reckless oil, gas and coal projects. As the climate crisis intensifies, taking the impacts on the world’s largest coral reef system seriously should mean finally bringing the era of fossil fuels to an end. Thousands of unique marine species are depending on it.

Additional reporting via Agence France-Presse

Feature image via Gökhan Tolun/Wikimedia, cropped and resized to 1910 by 1000, licensed under CC BY-SA 4.0.