Coral Reef Forecast: grim but hope and action will ensure survival

May 17, 2021

Australia’s mish mash of climate policies are consistent with a 2.5 – 3.0°C rise in global average temperature compared to pre-industrial levels. That would wipe out all the world’s coral reefs, force half a billion people into food insecurity and destroy one of the seven natural wonders of the world.

A future for coral reefs is possible but it demands bold leadership, an emergency response to the climate crisis and drastic action to reduce emissions this decade.

Question: When does an animal look like a plant? Answer: When it is a coral. Many people think corals are plants because at first glance a coral reef looks like an underwater garden. But looks can be deceptive. These “gardens” are actually comprised of millions of tiny animals that are constantly creating great limestone structures known as coral reefs.

Coral reefs are very busy and important communities. They occupy less than one percent of the ocean floor yet provide food and accommodation for one quarter of the world’s marine life.

From a heritage and aesthetic point of view, their loss would be a global tragedy. More importantly, half a billion people depend on coral reefs for their food security. Coral reefs also provide a wide range of ecosystem services.

For our own interests, we should be doing everything to preserve these wonderful ecosystems. It won’t be news to readers of Pearls and Irritations that we are not doing so. Coral reefs are in deep trouble.

Many papers and reports have documented recent and accelerating declines of coral reefs due to the cumulative impacts of overfishing, local pollution, poor governance and climate change. Many have forecast likely future impacts for coral reefs in a warming world.

One recent paper looks at the decline in the capacity of corals to build coral reefs under various ocean warming and ocean acidification scenarios. Predictably, the outlook is grim.

 The paper looked at the ability of 183 coral reefs worldwide to maintain calcium carbonate production to build reef structures by the year 2100 under three representative concentration pathways: the high emissions scenario RCP8.5, the intermediate RCP4.5 and the well below 2°C scenario RCP2.6.

 The authors found that, under the three emission scenarios, coral reef growth rates will decline by 76, 149, and 156%, respectively, by 2100. In other words, under RCP’s 4.5 and 8.5 corals will be unable to continue building coral reefs.

 This finding is consistent with the IPCC Special Report on 1.5°C which found that coral reefs are projected to experience large losses (>99%) at 2°C. Put more simply, they will not be able to survive.

Under RCP2.6, the paper found that 63% of reefs are projected to continue growing coral reef structures by 2100. This is good news. However, even under this scenario, the authors expect profound changes in growth rates and in the ability of coral reefs to provide ecosystem services.

 The paper did not examine RCP 1.9 which is consistent with a 1.5°C scenario, the long-term goal of the Paris Agreement. The 1.5°C pathway is the most positive for coral reefs. At 1.5°C, the IPCC Special Report found that coral reefs will decline by a further 70–90%. Put the other way, we could save 10-30% of the world’s coral reefs if the global community met the goal of the Paris Agreement.

 The paper highlighted the urgency and importance of acting now to drastically reduce carbon dioxide emissions.

 In the last five years, the Great Barrier Reef has experienced three severe coral bleaching events that have resulted in mass mortality. In 2019, the Great Barrier Reef Marine Park Authority released its third Outlook Report, downgrading the Reef’s outlook from poor to very poor.

 The purpose of the Outlook Report is to provide advice to governments on the current and projected state of the Reef to allow the Australian Government to develop appropriate policy responses.

 The report found that climate change is a current threat to the Reef, no longer a potential catastrophe. There were no surprises there.

 Of course, the fossil-led Morrison Government has not responded directly to this threat other than to recognise that the Reef is in trouble. It maintains a focus on local management measures such as reducing agricultural pollution. Efforts to reduce local threats are very important but the factors that drive them do not constitute an existential threat to the Reef.  

 Late last year, the International Union for the Conservation of Nature released its third World Heritage Outlook report and downgraded the Reef’s outlook to Critical.

 The IUCN report assesses all 252 natural and mixed (i.e. properties listed for their natural and cultural heritage value) World Heritage properties. The report identified 18 properties with a Critical Outlook. Since its previous outlook report in 2017, only two properties were downgraded to Critical: the Great Barrier Reef and a property in Mexico. Of the 18 Critical properties, 16 are already inscribed on the List of World Heritage In Danger.

 The Prime Minister and his government will soon face a reckoning about the Great Barrier Reef. The World Heritage Committee is meeting 16-31 July and the Reef will be on the agenda. Originally to be held in Fuzhou, China, it will now be a fully virtual meeting. The World Heritage Centre will be releasing documents soon, starting 4 June, and one of them will be about the Great Barrier Reef. It will contain a draft decision for the Committee to consider.

 The question is: will the draft decision hold Australia to account for its failure to commit to a 1.5°C compatible pathway to fulfil its legal obligations under the World Heritage Convention to protect the Outstanding Universal Value of the Great Barrier Reef?

Australia’s mish mash of climate policies are consistent with a 2.5 – 3.0°C rise in global average temperature compared to pre-industrial levels. That would wipe out all the world’s coral reefs, force half a billion people into food insecurity and destroy one of the seven natural wonders of the world.

That is quite a legacy to leave. 

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