Temperature pushes Great Barrier Reef to tipping point

In this post we find that the 2020 global average surface temperature was 1.25°C hotter than pre-industrial, equal first with 2016, according to The European Copernicus Climate Change Service. This is important for the Great Barrier Reef, because in a little known report in 2013 scientists found that 1.2°C is the warmest compatible with the Reef remaining a coral-dominated system. Focus recently has been on the emergence of annual severe bleaching (ASB) when the affected reefs are effectively dead. Climate change action of the type we are engaged in will only delay the emergence of ASB on average from about 2034 to 2045.

According to the New York Times 2020 Ties 2016 as Hottest Yet, European Analysis Shows.

The European Copernicus Climate Change Service is first out of the blocks for 2020 warming finding that the global average surface temperature was 1.25°C above the 1850-1900 baseline, the same as in 2016. This is especially significant because 2016 was a strong El Niño year, whereas 2020 would have been cooled somewhat by the emergence of La Niña in the last months.

Berkeley Earth, NASA and NOAA will release their analyses later this month, but the story is expected to be much the same. One of my concerns is that 1.2°C is an important tipping point for the Great Barrier Reef, as I will explain, but first the graph:

CNN has an article 2020 was tied for the hottest year ever recorded – but the disasters fueled by climate change set it apart. This image shows forest fires in the Sakha Republic in northern Russia where temperatures were up to 6°C on average hotter than usual:

While the temperature at the poles is warming at least twice as much as near the equator, and land temperatures warm more than sea, everyone knows now that coral reefs are increasingly subject to bleaching, and that the future for coral reefs subject to bleaching is not bright. Marian Wilkinson’s excellent book The Carbon Club tells of concern about the Great Barrier Reef in the context of massively increased coal and gas export facilities, and threats to the heritage status of the GBR under the stewardship of Rudd-Gillard-Rudd governments in Canberra, Queensland Labor governments under Peter Beattie and Anna Bligh, then Campbell Newman in 2012, who was equivocal about coal seam gas development before the election, but went full steam ahead when elected.

Much concern was about turgidity and the dumping of waste as massive facilities were carved out of the harbour in Gladstone. As the work proceeded barramundi were caught with awful skin lesions and exploding red eyes, crabs with ulcers, sharks with bright red skin lesions. Fishermen too suffered skin lesions. Further north there was much concern about the expansion of Abbot Point in Mackay to cope with more mines in the Bowen Basin let alone the opening of the Galilee Basin, bringing possible turbidity from dumped waste, as well increased traffic through the Reef.

All the while there had also been concerns about the crown of thorns attack of course, but climate change was not so much in the picture, despite emerging concerns about increased ocean acidity and coral bleaching, as:

    widespread and intense events occurred in the summers of 1998 and 2002, with 42% and 54%, respectively, of reefs bleached to some extent, and 18% strongly bleached.

Wilkinson tells us that in 1987, a year before James Hansen made climate change a public policy issue by addressing the US Senate, a young student called Ove Hoegh-Guldberg was doing his PhD on coral reefs at UCLA California. He heard of this strange phenomenon of patches of coral bleaching, no-one knew why, and did his PhD on the topic.

A decade later having studied coral reefs at Lizard Island, worked at the Australian Museum and Sydney University, Hoegh-Guldberg knew that coral bleaching was associated with heat. With a young European climate modeller he looked at the projections, and came to the conclusion that serious bleaching would occur every year by about 2050. Some scientists agreed but no Australians at that time. He was staggered, checked his calculations again and again, and then put his career on the line by publishing his findings, which was duly done courtesy of the CSIRO in 1999.

That should have given him scientific cover, but he has probably been seen as an alarmist ever since.

Wikinson reports that GBR politics was quite fraught going into the second decade of this century. Unfortunately there were other matters to distract, so when a truly humungous report on the GBR hit the desk of the last Labor environment minister in 2013 (that would have been newby Mark Butler, taking over from Tony Burke) the timing could scarcely have been worse.

The report was a response to the World Heritage Committee’s threat to put the GBR on the ‘List of World heritage in Danger’.

Down the back of the report:

    under the heading, ‘The Future of the Great Barrier Reef’, there was an unavoidable, grave warning: ‘Climate change remains the most serious long-term risk facing the Reef and is likely to have far reaching consequences for the Region’s environment,’ it stated.

    In blunt terms it spelt out the threat: ‘The urgent need to limit global; warming to two degrees Celsius above pre-industrial levels has been recognised by almost 200 nations. At present global emissions are not on track to achieve such a target and even a two-degree Celsius rise would be a very dangerous level of warming for coral reef ecosystems, including the Great Barrier Reef and the people who derive benefits from them.

Now here’s the important bit:

    To ensure the Reef remains a coral-dominated system, the latest science indicates global average temperature rise would have to be limited to 1.2 degrees Celsius.’ (Emphasis added)

The report could not have been clearer. It rated the likelihood of damaging warming as ‘almost certain’ and the consequences for life on the reef as ‘catastrophic’.

There, friends, you have it. We’ve crossed the line.

Within weeks Tony Abbott was installed as Prime Minister, and within 24 hours of swearing in, Greg Hunt sacked Tim Flannery as head of the Climate Commission. His colleague Prof Will Steffen was also duped. Flannery thinks his sacking was the first act of the new government.

The rest, as they say, is history.

In 2020 we had the third mass bleaching in five years the most widespread yet:

Just out is the latest United Nations Environment Programme (UNEP) report on the future of reefs. I’m confused, but if you start with Time is running out for coral reefs: new report published on 21 December 2020 and follow the links you arrive at Coral Bleaching Futures dated 2017.

My recommendation is that you skip all that unless you really need to, and read Vijay Prasad’s You don’t want to imagine an ocean without coral reefs, but you might have to instead.

The key concept is ‘annual severe bleaching’ (ASD). Seems that if we do nothing about global warming ASB will be reached on average around 2034. If countries try harder than they have already promised to do, then we can extend ASD to 2045. The report is really helpful to policy makers in identifying where reefs will hang on a bit longer, and where there might be refugia.

Here’s Leticia Carvalho, head of the Marine and Freshwater Branch of UNEP:

    “Coral reefs will soon disappear,” said Carvalho, if the current levels of inaction persist. The UNEP report is written by highly qualified scientists who make closely argued points and do not offer loose statements. So, it is pretty chilling to confront—early in the report—the suggestion that corals will be wiped out by the 2040s.

I must stress that is on average, some areas of reef will linger longer.

Carvalho also said:

    “Humanity must act with evidence-based urgency, ambition, and innovation to change the trajectory for this ecosystem.”

Prasad has something to say about that, but in the end it comes down to:

    The reefs will die. That seems certain. The UNEP report will not circulate. That seems equally certain.

It’s not just heating and bleaching we need worry about. There is also acidification, sea level rise, storm damage, over-fishing and more. However, I honestly do not think limiting warming to 1.5°C in climate policy is compatible with offering hope of a sustainable world, and intergenerational equity.

To offer hope we need to turn the global warming dial down by aspiring to 350 ppm of CO2e.

To me the report exemplifies the problem with much climate science, where much of it is funded to assist the implication of decisions made in a broader political context. Prior to the so-called IPCC 1.5°C report there was virtually no science looking at the implications of 1.5°C. Now we have masses of research helping policy makers to achieve the aim of ‘avoiding the worst impacts of global warming’. So in the UNEP report we have something truly grotesque. The concept of a preserving coral-dominated system is nowhere in sight. Instead the effective death of reefs as significant ecological systems is assumed, it is a matter of when, and what scraps can be saved.

I’ll finish with something we seem prepared to lose:

See also:

The ‘change the trajectory’ Carvalho seeks will only come if we change out target to 350ppm ASAP, rather that zero emissions by 2050, not exactly in a dawdle, but without world war style disruption which I’m afraid marks a true ‘climate emergency’.

Update: It looks as though Hoegh-Guldberg over-estimated how long reefs will last.

This article from NASA looks at what was a world-wide bleaching cycle from 2014-2017. They say that on average reefs bleached once every 25–30 years in the 1980s. Now bleaching returns about every six years and is expected to further accelerate.

I’m betting that the scientists who gave 1.2°C as the tipping point in 2013 would have narrowed that to at least 1°C in the light of what happened.

5 thoughts on “Temperature pushes Great Barrier Reef to tipping point”

  1. In theory at least the reef may extend further south.
    Giant kelp is another issue since there is no place to go when the die-out in Tasmania is complete and a major ecology disappears

  2. John, it’s all happening very fast in geologic time. The good news is that it took less than 2 million years for reefs to after the Permian–Triassic extinction 252m years ago, not 10 million as previously thought.

    In summary, it looks as though Hoegh-Guldberg was wrong. He looks to have over-estimated how long they will last.

    This article from NASA looks at what was a world-wide bleaching cycle from 2014-2017. They say that on average reefs bleached once every 25–30 years in the 1980s. Now bleaching returns about every six years and is expected to further accelerate.

    I’m betting that the scientists who gave 1.2°C as the tipping point in 2013 would narrow that to at least 1°C in the light of what happened.

  3. It is not just the coral that is under threat: “Baby shark study reveals impacts of climate change on Great Barrier Reef species.” https://www.abc.net.au/news/2021-01-13/baby-shark-kryptonite-found-in-new-great-barrier-reef-research/13051124 “Baby sharks will find it difficult to survive on the Great Barrier Reef by the end of the century, scientists say, with climate change and warmer oceans leading to the creatures being born smaller, exhausted and undernourished.
    Key points:
    The study looked at the growth of epaulette shark hatchlings in controlled settings simulating future ocean temperatures
    It found sharks were born smaller and lacking the energy needed for their first days of life
    Researchers are concerned about shark species not as strong and adaptable as the epaulette shark
    A new study by James Cook University’s (JCU) ARC Centre of Excellence for Coral Reef Studies focused on epaulette sharks, an egg-laying shark found only on the Great Barrier Reef.
    Study co-author Jodie Rummer said the epaulette shark was a species that was “really tolerant” to challenging and changing conditions, including ocean acidification.
    “We started investigating the effects of [rising] temperatures … and what’s particularly alarming is that temperatures seem to be its kryptonite,” Dr Rummer said.
    Problem is that kelp and coral are not the only things under threat. Even though swimming species can swim south many need the physical protection the coral provides and/or something else that can’t migrate south very quickly.

  4. John I’ll see if I can find it, but somewhere in this house is a book about the sickness of the sea, probably around 2010, I think, which talked about a study which showed there would be essentially no fish in the ocean by 2050.

    We’ve also looked at the multiplication of jellyfish.

    Fish farming depends on the mass harvesting of smaller species, to small to be usable for direct consumption. The whole thing is horrible.

    Jo Chandlers book Feeling the heat suggests that acidification is a bigger and sneakier problem than bleeching.

    My basic issue in this post is that 1.5 degrees is incompatible with a policy that claims it will preserve the GBR.

  5. John, I’ve found the book, and it’s one of the most depressing reads ever.

    It’s by Alanna Mitchell with the title Seasick: The hidden ecological crisis of the global ocean. She is a Canadian science writer. The link is to a review in 2009 where the title is specifically given a “Sea sick” – two words. The copy I have has “Seasick” and was published in 2008, printed at Griffin Press, Australia.

    She travelled the world, talking to scientists on site.

    Did we know that every second breath we take uses oxygen created by planckton?

    She talks about at least two papers where the authors were subject to vilification and derision. One was Overview of CO2-induced Changes in Seawater Chemistry.

    It showed that if CO2 reached 560 ppm marine organisms would have access to 30% less calcium.

    The second was known as the ‘crazy paper’. I think it was Impacts of biodiversity loss on ocean system services, which found that if trends in commercial fishing persisted then they forecast the global collapse of all taxa currently fished by the mid–21st century, ie 2048.

    In other words, there would be nothing left to fish.

    They said the situation was retrievable, and no doubt policies have changed, but at that time 90% of large predator fish had disappeared and any rules are hard to police. Fishing is a classic case of ‘the tragedy of the commons’.

    If I had more time I would do an investigation, but at present I don’t. However, I might try to see whether I can get a look at a video of Alanna Mitchell’s theatrical performance. If in Sydney 2018 she was devoting her life to travelling the world warning us about an impending but avoidable human and ecological tragedy, I’d say things are not in good shape.

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