By Pap Pepper, NCWQ Environmental Adviser

The environmental issues of two major recent occurrences, the 2019-20 bushfires and the coral bleaching of reefs in the Great Barrier Reef Marine Park are discussed – Why they occurred, the consequences and some actions being taken or that have potential.

The 2019-20 bushfire season was disastrous with at least 34 lives lost, over 5,900 buildings (including 2,779 homes) destroyed and an estimated 18.6 million hectares burnt. NASA estimated that 306 million tonnes of CO2 had been emitted as of 2 January 2020. While this might normally be reabsorbed by forest regrowth, prolonged drought has damaged the ability of forests to fully regrow and may take decades. https://en.wikipedia.org/wiki/2019%E2%80%9320_Australian_bushfire_season

Raging bushfire with flames as tall as the trees
Koala after a bushfire sitting on the ground in front of a fence.

                           

Photo: CSIRO                                                       Photo: M Fillinger https://www.abc.net.au/news/science/2020-03-05/bushfire-                                             crisis-five-big-numbers/12007716

Australian Academy of Science Fellow Professor Chris Dickman has estimated that Australia has lost at least a billion birds, mammals and reptiles this bushfire season. This figure does not include insects, bats, fish and frogs.  Even if animals survive the fires by fleeing or going underground, they return or re-emerge into areas that don’t have the resources to support them. Others will fall victim to introduced predators such as feral cats and red foxes. Even for those birds or animals able to flee to unaffected areas they will rarely be able to successfully compete with animals already living there and succumb within a short time. Some endangered species may be driven to extinction.

Australia is at risk of losing a significant proportion of its biodiversity and because much of that biodiversity occurs only here in Australia, it’s a global loss.https://www.sydney.edu.au/news-opinion/news/2020/01/08/australian-bushfires-more-than-one-billion-animals-impacted.html https://www.science.org.au/news-and-events/news-and-media-releases/australian-bushfires-why-they-are-unprecedented Also the bushfires have not only taken a heavy toll on wildlife but have affected water and air quality.

While bushfires form part of the natural cycle of Australia’s landscapes, factors such as climate trends, weather patterns and vegetation management by humans can all contribute to the intensity of bushfires. The most destructive fires have been preceded by extreme high temperatures, low relative humidity and strong winds, combining to create ideal conditions to rapidly spread fire. 

https://upload.wikimedia.org/wikipedia/commons/thumb/b/b2/2019_Spring_BOM_FFDI_scs72.png/200px-2019_Spring_BOM_FFDI_scs72.png

            

FFDI (Forest Fire Danger Index), Spring 2019

The primary causes of the 2019–20 bushfire was seen as severely below average fuel moisture attributed to record-breaking temperatures and drought, accompanied by severe fire weather, and that these are likely to have been exacerbated by long-term trends of warmer and dryer weather observed over the Australian land mass. 

The major cause of ignition of fires during the 2019-20 fire crisis in NSW and Victoria is reported to be lightning strikes with alleged arson accounting for around 1% of NSW fires and 0.3% of Victorian fires by 18 January 2020.https://en.wikipedia.org/wiki/2019%E2%80%9320_Australian_bushfire_season

The significance of major circulation patterns on climate variability in Australia has been studied:- 

  • the El Niño Southern Oscillation (ENSO) referring to the extensive warming of the sea surface region in the central and eastern Pacific, 
  • the Inter-decadal Pacific Oscillation (IPO) similar to El Nino in that it is a change in climate related to sea surface temperatures but tending to last much longer, 20-30 years as opposed to 18 months, 
  • the Indian Ocean Dipole (IOD) – the difference in ocean temperatures between the west and east tropical Indian Ocean, that can shift moisture towards or away from Australia, and 
  • Southern Annular Mode (SAM) – a mode of variation in the atmosphere of the high latitudes in the southern hemisphere. 

One study investigating the influence of the ENSO on fire risk found that the proportion of days with a high, or greater than high, fire danger rating markedly increased during El Niño episodes and was further increased when the IPO was negative during these El Niño eventsVerdon D.C. , Kiem A.S and S.W. Franks (2004) Int. J. of Wildland Fire 13(2) 165-171 https://doi.org/10.1071/WF03034

In another study with data from 39 stations from1973 to 2017, Harris and Lucas (2019) found ENSO to be the main driver for interannual variability of fire weather as measured by the McArthur Forest Fire Danger Index (FFDI). They reported that in general, El Niño-like conditions led to more extreme fire weather, with this effect stronger in eastern Australia but with significant regional variations to this general rule. In NSW, particularly along the central coast, negative SAM was a primary influence for elevated fire weather in late-winter and spring. In the southeast (Victoria and Tasmania), the El Niño-like impact was exacerbated when positive IOD conditions were simultaneously observed. The spring conditions were key, and strongly influenced what was observed during the following summer. On longer time scales (45 years), linear trends were upward at most stations; this trend was strongest in the southeast and during the spring. The positive trends were not driven by the trends in the climate drivers and they were not consistent with hypothesized impacts of the IPO, either before or after its late-1990s shift to the cold phase. Harris and Lucas proposed that anthropogenic climate change was the primary driver of the trend, through both higher mean temperatures and potentially through associated shifts in large-scale rainfall patterns. They also said that variations from interannual factors were generally larger in magnitude than the trend effects observed. 

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Time series of 90th percentile FFDI annual anomaly (July-June) at each station (1973–2017). The thick line indicates the multi-station mean. The thick dotted line indicates the linear trend.  https://doi.org/10.1371/journal.pone.0222328.g012

Harris S, Lucas C (2019) Understanding the variability of Australian fire weather between 1973 and 2017. PLoS ONE 14(9): e0222328.

Bruce Boyes, Knowledge Manager, Environmental manager, Project manager, Educator claimed the scale and seriousness of the current bushfire crisis was caused by the progressive temperature increase due to climate change, the strongest IOD on record, the influence of SAM and a well-advanced IPO progressively drying the landscape of southeastern Australia. While each one of these factors on their own would have been unlikely to have caused something of the scale and seriousness of the current bushfire crisis, all of these factors coming together did. Removing any one of these factors but leaving all of the others would also have been unlikely to have caused such a crisis. https://realkm.com/2020/01/11/the-vital-knowledge-missing-from-australias-bushfire-crisis-debates-part-1-what-can-climate-history-tell-us

In a further paper, Bruce Boyes  addressed hazard reduction burning  and debunks some of the myths about Aboriginal fire management practices.  Rather than practices being widespread and constant, they depended on the species composition of the vegetation communities in the area inhabited.  

To provide a line of defence between buildings and bushland, Boyes promotes a buffer zone completely clear of understorey, midstorey, and any fuel load and if local conditions indicate a high risk of crown fires the overstorey trees. He also discusses firelines  along the boundaries between the buffer zones and the bushland to facilitate easy access for back burning in case of an approaching wildfire, and additional firelines within the bushland areas if possible, to provide additional lines of defencehttps://realkm.com/2020/01/25/the-vital-knowledge-missing-from-australias-bushfire-crisis-debates-part-2-the-popular-narrative-and-the-unpopular-scientific-knowledge/

Citizen Science Forum:  On 14 February, CSIRO hosted a national forum which recognised that in a time of crisis, research capability is under pressure and citizen science could provide an important complement to traditional research-led monitoring campaigns.  To that end, in collaboration with the Atlas of Living Australia (a National Collaborative Research Infrastructure Strategy capability) and the Australian Citizen Science Association, CSIRO has developed the Citizen Science Bushfire Project Finder website which allows members of the public to contribute to projects ranging from air quality, to identifying and confirming animal and plant sightings while maintaining safe social distancing practices. https://www.csiro.au/en/News/News-releases/2020/Citizen-science-to-aid-bushfire-recovery   While citizen scientists can be confronted by the number of tools and protocols aimed at ensuring data is captured in a consistent manner, this is essential to make the best use of the data. In many cases it may only be practical to get a true picture of the composition of the flora and fauna in an area and how it changes with time with the help of dedicated citizen scientists.

Threat to koalas from bats carrying a retrovirus:  On top of the high mortality from the bushfires, and loss of habitat and food supply, the koala population can be exposed, by a koala retrovirus KoRV, to cancer and chlamydia, a leading cause of infertility, blindness and kidney failure. Scientists from Burnet Institute, Melbourne and CSIRO have identified bats as a source of diverse infectious retroviruses related to KoRV. This implicates bats as a reservoir of KoRV-related viruses that potentially can be transmitted to other mammalian species. Bats are reservoirs of emerging viruses that are highly pathogenic to other mammals, including humans. For example, while remaining unaffected, bats, can host viruses including Ebola, Hendra and coronaviruses, and transmit the viruses by droppings and body fluids to other mammals. The research of Hayward et al reported the first exogenous retrovirus described in bats. https://www.theaustralian.com.au/news/batborne-viruses-a-deadly-threat-to-koalas/news-story/46414d893f0f36ea768b11a77ae993d8  Hayward et al  (2020) Infectious KoRV-related retroviruses circulating in Australian bats www.pnas.org/cgi/doi/10.1073/pnas.1915400117While SARS or SARS-like, MERS or MERS-like, 2019-nCOV or 2019-nCoV-like viruses have not yet been found in Australian wildlife (including bats), overseas bats host these viruses. https://wildlifehealthaustralia.com.au/Portals/0/Documents/FactSheets/Mammals/Coronaviruses_in_Australian_Bats.pdf

However, it should be remembered flying-foxes play a crucial role as pollinators and help keep forest ecosystems that support other species like koalas, healthy. https://www.australiangeographic.com.au/topics/wildlife/2020/04/do-our-fruit-bats-carry-the-virus-behind-covid-19/

Coral Bleaching of reefs in the Great Barrier Marine Park (GBRMP): Sea temperatures in February around the Great Barrier Reef were the warmest on record since the Bureau of Meteorology’s sea surface temperature records began in 1900. 

PHOTO: Sea temperatures in February around the Great Barrier Reef were the warmest on record. (Supplied: Bureau of Meteorology) https://www.abc.net.au/news/2020-03-15/cyclone-great-barrier-reef-bleaching-record-seas-temperatures/12050102

Director of the ARC Centre for Excellence in Coral Reef Studies at James Cook University (CCRS JCU) Professor Terry Hughes said serious coral bleaching occurs when coral suffers heat stress due to spikes in sea temperatures caused by unusually hot summers. 

Aerial surveys of 1036 reefs (focusing on shallow water corals, down to five metres) showed a different pattern of bleaching within the GBRMP than from bleaching events in 2016 and 2017:-

https://images.theconversation.com/files/325593/original/file-20200406-74220-1axw6r6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip

https://theconversation.com/we-just-spent-two-weeks-surveying-the-great-barrier-reef-what-we-saw-was-an-utter-tragedy-135197

The aerial surveys accurately record bleaching to only a five metre depth, and bleaching severity generally declines with increasing depth. www.gbrmpa.gov.au/the-reef/reef-health/coral-bleaching-101

Of the 1036 reefs surveyed

  • about 40%  had little or no bleaching and it is anticipated that most will recover,
  • about 25%  were severely (each reef >60%) bleached and
  • about 35%  were moderately bleached with responses dependent on history of disturbance.

http://www.gbrmpa.gov.au/news-room/latest-news/latest-news/coral-bleaching/2020/statement-aerial-surveys-on-the-great-barrier-reef 07/04/20 GBRMPAuthority Weekly Reef health update — 02 April 2020 http://www.gbrmpa.gov.au/the-reef/reef-health.

An aerial survey of coral bleaching on the Great Barrier Reef. Picture: AFP

An aerial survey of coral bleaching on the Great Barrier Reef. Picture: AFP

Professor Hughes said the distinctive footprint of each bleaching event has closely matched the location of hotter and cooler conditions in different years.  But it was difficult to make predictions about how much coral would die, as scientists had found corals were reacting differently after each marine heatwave. To know whether coral is surviving and recovering after bleaching or dying, water surveys are needed.

Professor Morgan Pratchett also from CCRS JCU, who leads the underwater surveys, noted that bleaching isn’t necessarily fatal as some species are affected more than others.  He will be assessing the losses of corals from this most recent event later in the year.  

With the five mass bleaching events (1998, 2002, 2016, 2017, 2020) the number of reefs escaping severe bleaching continues to dwindle and the gap between recurrent bleaching events to shrink, hindering a full recovery. Hughes and Pratchett are concerned the Great Barrier Reef will continue to lose corals from heat stress, until global emissions of greenhouse gasses are reduced to net zero, and sea temperatures stabilise.

https://www.abc.net.au/news/2020-03-15/cyclone-great-barrier-reef-bleaching-record-seas-temperatures/12050102https://www.theaustralian.com.au/inquirer/coral-bleaching-barriers-for-the-reef/news-story/3ea4d163fcc4445b1e3b37cf7bab90a6;https://www.jcu.edu.au/news/releases/2020/april/climate-change-triggers-great-barrier-reef-bleachinghttps://theconversation.com/we-just-spent-two-weeks-surveying-the-great-barrier-reef-what-we-saw-was-an-utter-tragedy-135197

The GBRMPA also urges that the strongest possible global efforts be made to reduce emissions and global warming as large scale marine heatwaves and associated coral bleaching events become more severe and frequent, and the Reef’s natural recovery processes are unable to keep up. Such action is needed in conjunction with their current programme protecting coral cover through crown-of-thorns starfish control, improved water quality, increased monitoring and effective Marine Park management, preventing illegal fishing, and developing potential new restoration and interventions that can occur within the Reef.

http://www.gbrmpa.gov.au/news-room/latest-news/latest-news/coral-bleaching/2020/statement-aerial-surveys-on-the-great-barrier-reef

Recently the Australian Government launched the research and development phase (initially $150million) of its Reef Restoration and Adaptation Science Program to help preserve and restore the Great Barrier Reef in the face of rising ocean temperatures and coral bleaching and endorsed a two-year feasibility study led by the Australian Institute of Marine Science (AIMS) into a range of science-based interventions.

This included: 

  • examining ways to collect and freeze coral larvae for use in year-round coral seeding,
  • seeding reefs with corals that are more resilient to heat to help coral reefs to evolve and adapt to the changing environment, 
  • developing technologies that increase the survival rate of coral larvae and that can produce and deploy large quantities of more resilient coral larvae,
  • an ambitious concept to shade and cool large areas of reef at risk of bleaching by spraying microscopic saltwater droplets into clouds to make them more reflective of sunlight (cloud brightening – see below) and
  • investigating methods to physically stabilise damaged reefs, after cyclone and bleaching events, to facilitate faster recovery.

https://minister.awe.gov.au/ley/media-releases/150-million-drive-innovations-boost-reef-resilience       16 April 2020https://www.theaustralian.com.au/inquirer/coral-bleaching-barriers-for-the-reef/news-story/3ea4d163fcc4445b1e3b37cf7bab90a6

Researchers at Southern Cross University and the Sydney Institute of Marine Science have trialled cloud brightening using a boat-mounted fan similar to a snow cannon to shoot salt crystals into the air and  have achieved promising results. To have a significant impact on the reef, a full-scale experiment would need to be 10 times larger, involving the use of several big barge-mounted turbines. The effectiveness of this cloud-brightening technique would drop significantly as the ocean warms further, hence would need to be used in conjunction with other systems. https://www.sciencealert.com/cloud-brightening-is-the-newest-experiment-to-protect-the-great-barrier-reef-from-warming

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