coral bleaching
Header source: https://www.cnn.com/2017/04/10/asia/great-barrier-reef-coral-bleaching/index.html.
These warming waters described on the last page have also triggered the coral bleaching now at record levels in the Great Barrier Reef with the unusual sustained warmth causing stressed corals to expel the tiny marine algae that gives them the colour and energy to grow: Unprecedented back to back annual coral bleaching events have affected two-thirds of the Great Barrier Reef, and 2017’s event has already led to the mortality of half the corals in some key tourist tracts.
While this year’s event may not result in as much coral mortality as the previous year (see comparative analysis below), there are worrying signs that the corals bleached at lower temperatures than a year earlier, which may suggest that they are in a weakened more stressed state following the previous year’s event[1]. Coral reefs, of which the Great Barrier Reef is but one example, will largely be long gone by the time the temperature rises anywhere near 3 degrees. A UN report on global diversity in May 2019 reported that as little as 1% of the Great Barrier Reef will remain if global temperatures rise 2 degrees above pre-industrial levels and we are halfway there.[2] Well before it appeared, an expert panel urged the Federal government to rethink and revise the existing plan, known as Reef 2050, to protect the reef to include steps to cut emissions and help the reef to adapt to climate change[3].
Modern technology has provided us with the capacity to survey the reef from top to bottom, showing us how the reef has evolved over time, and revealing evidence of an earlier reef. Rising water levels have previously flooded the reef, drowned it, so to speak, on at least 4 occasions that we know of, the water level being such that it prevents the coral from growing. The last of these occurred some 14,000 years ago. So given enough time, the reef can regenerate, given its capacity for self-renewal.
However, the present focus is what is likely to happen to the reef in the future with the imminent threats it is facing. As Sir David Attenborough says “The twin perils brought by climate change, an increase in the temperature of the ocean and its acidity, if they continue to rise at the present rate the reefs will be gone within decades and that would be a global catastrophe." In the period he first dived the reef in the early 1980s and his latest programme in 2015, half of the reef as it then existed has since disappeared. [4]
These warming waters described on the last page have also triggered the coral bleaching now at record levels in the Great Barrier Reef with the unusual sustained warmth causing stressed corals to expel the tiny marine algae that gives them the colour and energy to grow: Unprecedented back to back annual coral bleaching events have affected two-thirds of the Great Barrier Reef, and 2017’s event has already led to the mortality of half the corals in some key tourist tracts.
While this year’s event may not result in as much coral mortality as the previous year (see comparative analysis below), there are worrying signs that the corals bleached at lower temperatures than a year earlier, which may suggest that they are in a weakened more stressed state following the previous year’s event[1]. Coral reefs, of which the Great Barrier Reef is but one example, will largely be long gone by the time the temperature rises anywhere near 3 degrees. A UN report on global diversity in May 2019 reported that as little as 1% of the Great Barrier Reef will remain if global temperatures rise 2 degrees above pre-industrial levels and we are halfway there.[2] Well before it appeared, an expert panel urged the Federal government to rethink and revise the existing plan, known as Reef 2050, to protect the reef to include steps to cut emissions and help the reef to adapt to climate change[3].
Modern technology has provided us with the capacity to survey the reef from top to bottom, showing us how the reef has evolved over time, and revealing evidence of an earlier reef. Rising water levels have previously flooded the reef, drowned it, so to speak, on at least 4 occasions that we know of, the water level being such that it prevents the coral from growing. The last of these occurred some 14,000 years ago. So given enough time, the reef can regenerate, given its capacity for self-renewal.
However, the present focus is what is likely to happen to the reef in the future with the imminent threats it is facing. As Sir David Attenborough says “The twin perils brought by climate change, an increase in the temperature of the ocean and its acidity, if they continue to rise at the present rate the reefs will be gone within decades and that would be a global catastrophe." In the period he first dived the reef in the early 1980s and his latest programme in 2015, half of the reef as it then existed has since disappeared. [4]
In August 2019, The Federal Government's 5-year Great Barrier Reef Outlook Report 2019 assessed the reef to be at "a critical point" with the marine park's outlook downgraded from "poor" to "very poor" due to climate change resulting in rising sea temperatures. Another factor is ongoing deforestation from from high levels of land clearing in areas adjacent to the reef. The mass bleaching in the summers of 2016 and 2017, depicted above, resulting in the deaths of about half the corals from marine heatwaves causing the stressed corals to expel the algae that give them most of their energy and colour, often killing them, are also mentioned as symptomatic indicators.
Separately, the inshore reef scored a "D" for overall condition, according to the annual Reef Report Card, released by the federal and Queensland governments. The score is based on the state of coral, seagrass and water quality and matches seven of the previous eight reports.
Then, on 2 December 2019, a separate Federal government State Party Report to UNESCO's world heritage committee made three significant findings on Australia's progress since 2015 to protect the Great Barrier Reef.
A glimpse of the future
Further to the north, there is a “coral triangle” comprising four groups of island clusters shared between the Philippines, Indonesia and Papua New Guinea. Included within it is the four million hectare group of islands known as Raja Armpat, containing a number of land-locked salt water lakes.
The corals growing elsewhere in the archipelago do not flourish here because, at 31 degrees centigrade the temperature is about 2 degrees warmer than in the open sea, in other words, what we may expect if global warming continues at its present rate.
So, despite considerable difficulties in gaining access on foot in the rocky limestone rainforest terrain, these rock pools have become a fertile field for exploration to see what we have in store. Within them, scientists have been able to find generally sponge like organisms, and yes the occasional coral, leading to further research to find out what forms of coral can survive in such an unsuitable environment. [5]
[1] Peter Hannam, “Damage to Great Barrier Reef creeps closer into tourist sites”, Sydney Morning Herald, 10 April 2017, 6-7. It has, however, been suggested that deeper coral ecosystems (mesophotic coral ecosystems or MCEs) are less likely to be affected by bleaching, but more research in this area is required: Marcus Strom, “Coral may find respite from bleaching”, Sydney Morning Herald, 25 April 2014.
[2] Adverted to in Peter Hannam's article "What's next for the Adani mine?", Sydney Morning Herald, 26 May 2019: https://www.smh.com.au/environment/conservation/what-s-next-for-the-coal-mine-that-helped-return-morrison-to-power-20190520-p51p7j.html
[3] Adam Morgan. “Expert panel urges dramatic rethink on coral bleach”, Sun-Herald, 21 May 2017.
[4] David Attenborough's Great Barrier Reef: Part 3: "Survival".
[5] The explorations of Christiaan de Leeuw in this area are shown in the BBC documentary Equator from the Air: Pacific, Episode 3 (2019).
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Separately, the inshore reef scored a "D" for overall condition, according to the annual Reef Report Card, released by the federal and Queensland governments. The score is based on the state of coral, seagrass and water quality and matches seven of the previous eight reports.
Then, on 2 December 2019, a separate Federal government State Party Report to UNESCO's world heritage committee made three significant findings on Australia's progress since 2015 to protect the Great Barrier Reef.
- first, that the mass coral bleaching events in 2016 and 2017, six tropical cyclones, flooding and a coral-eating crown-of-thorns starfish outbreak had "impacted the outstanding universal values" of the reef;
- second, that the Great Barrier Reef Marine Park Authority had found the long-term outlook for the reef’s ecosystem had "deteriorated from poor to very poor";
- third that climate change, especially the rise in sea temperature, remained the most serious and pervasive threat to the Great Barrier Reef.
A glimpse of the future
Further to the north, there is a “coral triangle” comprising four groups of island clusters shared between the Philippines, Indonesia and Papua New Guinea. Included within it is the four million hectare group of islands known as Raja Armpat, containing a number of land-locked salt water lakes.
The corals growing elsewhere in the archipelago do not flourish here because, at 31 degrees centigrade the temperature is about 2 degrees warmer than in the open sea, in other words, what we may expect if global warming continues at its present rate.
So, despite considerable difficulties in gaining access on foot in the rocky limestone rainforest terrain, these rock pools have become a fertile field for exploration to see what we have in store. Within them, scientists have been able to find generally sponge like organisms, and yes the occasional coral, leading to further research to find out what forms of coral can survive in such an unsuitable environment. [5]
[1] Peter Hannam, “Damage to Great Barrier Reef creeps closer into tourist sites”, Sydney Morning Herald, 10 April 2017, 6-7. It has, however, been suggested that deeper coral ecosystems (mesophotic coral ecosystems or MCEs) are less likely to be affected by bleaching, but more research in this area is required: Marcus Strom, “Coral may find respite from bleaching”, Sydney Morning Herald, 25 April 2014.
[2] Adverted to in Peter Hannam's article "What's next for the Adani mine?", Sydney Morning Herald, 26 May 2019: https://www.smh.com.au/environment/conservation/what-s-next-for-the-coal-mine-that-helped-return-morrison-to-power-20190520-p51p7j.html
[3] Adam Morgan. “Expert panel urges dramatic rethink on coral bleach”, Sun-Herald, 21 May 2017.
[4] David Attenborough's Great Barrier Reef: Part 3: "Survival".
[5] The explorations of Christiaan de Leeuw in this area are shown in the BBC documentary Equator from the Air: Pacific, Episode 3 (2019).
Next