When Australia’s bush fire emergency unfolded amidst days of record high temperatures, the unprecedented scale of the destruction quickly saw positions taken on the causes of the disaster and the role of climate change. Against the backdrop of Australia’s bitter ‘climate wars’ which have raged for more than a decade, speculation and misinformation have been rife across communities, news and social media channels.
For businesses seeking to understand how their risks are changing, the CSIRO, the Bureau of Meteorology and the Australian Academy of Science are trusted sources of facts and analysis, together with scientific research bodies such as the Centre for Climate Extremes and the National Environmental Science Programme Earth Systems and Climate Change Hub, as well as a number of state-focussed research institutions.
Energetics uses these sources extensively. In this knowledge centre we share our list of information sources, and a short Q&A using these references.
Climate science - information sources
- Climate Change in Australia: A comprehensive website and suite of reports providing information about climate change projections for Australia, funded by the Australian Government Department of the Environment, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Australian Bureau of Meteorology (BoM).
- Bureau of Meteorology: BoM is the national source of historical and current climate and weather data. The organisation provides information on changes currently occurring to our climate in their biennial "State of the Climate" reports. Easy to use interactive maps and charts are also available showing historical changes to key climate variables. The Annual Climate Statement 2019 provides the most recent data and information on Australia’s climate, considering trends in temperature, rainfall and extreme weather.
- Australian Research Council, Centre of Excellence on Climate Extremes (CLEX): A research centre across several universities dedicated to researching climate extremes. Partners include CSIRO, BoM, the National Computational Infrastructure (NCI) and international partners including NASA and the UK Met Office Hadley Centre.
- National Environmental Science Programme Earth Systems and Climate Change Hub (NESP ESCC Hub): A collaboration between CSIRO, BoM and several leading universities with funding from the Federal Government. The Hub's research mandates includes improving understanding of past, current and future climate change and building the utility of that information. They run technical webinars, drive climate science and risk research groups and information for the general public.
- Victorian Climate Projections 2019: The Victorian Government, in partnership with CSIRO, recently developed Victoria-specific climate projection data sets. They have provided technical reports on the methodology, summary and detailed data sets and summary brochures per region on the projected changes.
- Climate Smart South Australia: A government initiative released in 2017, Directions for a Climate Smart South Australia policy statement sets the agenda for practical measures to address climate related impacts. There are a number of initiatives outlined in the statement, including the Hydrogen Action Plan, a Climate Change Science and Knowledge plan, an Electric Vehicle Strategy, State waste strategies and Blue Carbon Strategy.
- Goyder Water Research Institute: The Institute is a collaboration with the SA Government, CSIRO, Flinders University, the University of Adelaide, UniSA and the International Centre of Excellence in Water Resources Management (ICE WaRM). Developed the ‘SA Climate Ready’ dataset: the most comprehensive downscaled climate projections data for South Australia.
- Department of Primary Industries and Regional Development: While focussed on agriculture, this site considers the importance of climate trends, temperature and rainfall changes, the fall in agricultural water supplies, tropical cyclones (while frequency is stable, intensity has increased) and fire risks.
The Bureau of Meteorology’s Annual Climate Statement, released 9 January 2020, has the following key findings about 2019:
- Australia's warmest year on record, with the annual national mean temperature 1.52°C above average.
- Both mean annual maximum and minimum temperatures above average for all states and the Northern Territory.
- Annual national mean maximum temperature was the warmest on record (2.09°C above average).
- Widespread warmth throughout the year; January, February, March, April, July, October, and December all amongst the ten warmest on record for Australian mean temperature for their respective months.
- Significant heatwaves in January and in December.
- Australia's driest year on record.
- Nationally-averaged rainfall 40% below average for the year at 277.6 mm.
- Rainfall below average for most of Australia.
- Rainfall above average for parts of Queensland's northwest and northern tropics.
- Much of Australia affected by drought, which was especially severe in New South Wales and southern Queensland.
- Widespread severe fire weather throughout the year; national annual accumulated Forest Fire Danger Index highest since 1950, when national records began.
- One of the strongest positive Indian Ocean Dipole events on record; El Niño–Southern Oscillation neutral throughout the year.
For more details, including the summary video, visit the Bureau of Meteorology website.
Climate change event attribution research is an emerging field which offers insights into Australian climate extremes. Below is a series of excerpts from Climate change and extreme events – quantifying the changing odds by CSIRO and BoM, November 2019.
“We have always lived with large climate variability in Australia. We experience heatwaves and other heat events, cold outbreaks and frosts, extreme bushfire conditions, hail, floods, droughts, marine heatwaves, storms such as East Coast Lows or tropical cyclones, coral bleaching events and more. We have experienced years like 2010-2011 when there was so much rainfall over Australia it contributed to lower global sea-levels. Usually though, much of the country is very dry. Underlying this variability, we know that the globe is warming due to increasing levels of atmospheric greenhouse gases, and this is affecting the entire climate system, including the climate and weather extremes.
Quantifying how much climate change has affected the magnitude or probability of an individual event becomes a ‘signal to noise’ problem. This means we need to carefully tease apart any climate change ‘signal’ from the ‘noise’ of natural variability. Doing so is not just of academic interest, it can be used to better plan for and respond to current and future extreme events.
Asking the right questions
An important part of event attribution is posing the appropriate question. Natural variability and climate change come together to give us what we experience, thus “did climate change cause this event?” is the wrong question – climate change didn’t start a fire or create a drought. What climate change may do is change the likelihood of the event or make the event more severe or last longer than would have been the case without climate change.
For example, we always get heatwaves but in a warmer climate a heatwave of a given intensity is more likely than in a cooler climate unless the variability changes significantly. Or to pose it another way, a given heatwave was hotter than it would have been without climate change. So, useful questions to ask of event attribution are “Was the recent event made more likely due to climate change? Was the event more severe than it would have been without climate change? By how much?”
Also, we need to look critically at the actual drivers of the extreme event and define the question appropriately. For example, an extreme rainfall event may have been delivered by a storm such as an East Coast Low, so to gain insights into this extreme we need to know about the effect of climate change and climate drivers such as El Niño on this phenomenon specifically, and not heavy rainfall from other weather patterns such as cold fronts.
We also need to look out for confounding factors when we consider the drivers of an extreme event, and particularly the impacts of an extreme event. Changes to built infrastructure, resource management actions, agricultural practice developments and changes to the land cover can all change the extreme event or its impact. Changing the landscape to have more concrete can affect the intensity of flash flooding and the heat experienced due to urban heat island effects. When attributing the impact of an event, we need to carefully distinguish between the hazard and our exposure to the hazard to the overall impact. For example, a tropical cyclone passed through the Gold Coast in 1954, if it passed through again today there would be far more buildings in the path. In this way, the changes to risk exposure can be more important than the changes to the hazard itself to the overall impact.
When looking to adjust our infrastructure, management, and systems to manage climate risk, attribution of events can be useful in two ways. First, it tells us what climate changes we have already experienced that we need to adapt to right now. Attribution can tell us whether an extreme event was just a rare occurrence expected from climate variability, or whether the likelihood has increased, and we should expect them more often. This helps us to correctly calibrate our climate risk.
Second, attribution of the anthropogenic component in climate and weather extremes is a useful context to interpret future climate projections. This helps us see where we are tracking in terms of climate change relative to historical change and possible future change. This can then guide policy both on emissions reductions to limit future climate change, and to adapt to the inevitable further climate change we will experience.”
To view the article in full, go to the CSIRO website.
There is a relationship between climate change and drought, however it is not a direct link. Some aspects of drought are linked with climate change, while others are not.
The Australian Research Council Centre of Excellence, Climate Extremes states, “Global warming is leading to higher temperatures, more intense heatwaves, sea-level rise, ocean acidification, more intense rainfall and so on. Global warming can also lead to increased aridity, and worse droughts, by changing rainfall patterns and the spatial distribution of energy at the surface (i.e., sunlight) – these can combine to significantly change the available water at the surface. However, the statements in the media and elsewhere that a warmer atmosphere causes higher evaporation is more tenuous, although the statement that lower evaporation causes a warmer atmosphere is much more reasonable.”
The Bureau of Meteorology uses rainfall deficiencies to identify regions that are under drought conditions. In their Annual Climate Statement 2019, they report, “2019 was..the driest year on record for Australia at 277.6 mm, well below the previous record in 1902 (previous lowest was 314.5 mm). Nationally-averaged rainfall for 2019 was 40% below the 1961–1990 average of 465.2 mm. The national rainfall dataset commences in 1900. Although every period of rainfall deficiency is different, the extraordinarily low rainfall experienced this year has been comparable to that seen in the driest periods in Australia's recorded history, including the Federation Drought and the Millenium Drought.”
Climate scientists from the University of Melbourne and Australian National University explained some of the complexity further, “Droughts are also exacerbated by low humidity, higher wind speeds, warmer temperatures, and greater amounts of sunshine. All of these factors increase water loss from soils and plants. This means that other metrics are often used to describe drought which go beyond rainfall deficiencies alone. These include the Palmer Drought Severity Index and the Standardised Precipitation Evaporation Index, for example.
This means that there are hundreds of metrics which together can provide a more detailed representation of a drought. But this also means that droughts are less well understood and described than simpler phenomena such as temperature and rainfall.”
1. Stone, A: "Briefing note 009. Does global warming cause droughts, drying or increased aridity?", Climate extremes, ARC Centre of Excellence, Australian Government, 20.9.2019.
2. King, A, Ukkola, A and Henley, B: "Is Australia’s current drought caused by climate change? It’s complicated", The Conversation, 8.6.2018.
3. Bureau of Meteorology, Annual climate statement 2019, 9.1.2020.
Below is an excerpt from, Sullivan, A: “A dry landscape and a dire season: we explain the current bushfire environment“, CSIRO ECOS, 18.12.2020.
It’s difficult to attribute any single weather event such as a drought to climate change. Australia has always experienced extended periods of rainfall deficit. But the increasing frequency of the combination of synoptic weather patterns bringing hot, dry winds from the centre of continent and the extensive dryness of the fuels may be considered indicators that climate change is having an impact on traditional fire weather patterns.
Many parts of Australia have historically experienced extensive and severe bushfire seasons (for example 1994 and 1968 in NSW) so in that sense it isn’t unusual. However, we expect the impacts of climate change will mean we will have more of this type of weather and that may result in an increase in the number and severity of bushfire events.
Below is an excerpt from, Sullivan, A: “A dry landscape and a dire season: we explain the current bushfire environment“, CSIRO ECOS, 18.12.2020.
“While it seems the fires recently experienced in southern Queensland and northern NSW started well before the onset of the summer bushfire season, the fire season in these regions generally ranges from August to December. So, the fires have been during the traditional fire season and not ‘early’ at all.
These fires have been particularly severe because much of the east coast of Australia has been suffering from drought. For the last 18 months, large sections of NSW and south-east Queensland have received the lowest rainfall totals on record.
Extended drought means vegetation across large parts of the countryside is available to burn as fuel. Therefore, areas usually moist and green at this time of year are more easily ignited, burning more and not impeding the progress of bushfires. Combined with many sources of ignitions and several days of hot strong winds, this has led to the large and numerous bushfires we’ve seen.”
Climate change will increase the frequency of Australia’s most dangerous fires, as explained by the Australian Research Council’s Centre of Excellence, Climate Extremes. An article released in November 2019, by Alvin Stone, prior to the recent new year’s fires, stated,
“Catastrophic wildfires like the Black Saturday wildfires in 2009 and Canberra Wildfires of 2003, which were so large and dangerous that they generated their own weather systems – including the world’s first filmed fire tornado – are likely to be more frequent in the future as a result of climate change across southeast Australia.
New research in Geophysical Research Letters has found that the coupling between the fire and atmosphere, that helps generate these catastrophic pyrocumulonimbus wildfires in Australia will occur more frequently in the future as global warming takes hold. Importantly, these conditions will also occur earlier – in late spring, not just in summer.”
The following was also noted in the article, “..it’s not just conditions on the ground, represented by the McArthur Forest Fire Danger Index, which leads to catastrophic pyrocumulonimbus wildfires. Historical observations showed the conditions in the lower troposphere were much better indicators of the development of these extreme fire events.
When the air 1.5km above the land surface is dry and unstable it can link with a large, very intense fire and get drawn down by convective mixing to fill the space where the plume of heat has pushed up air from closer to the ground. The process generates its own hot and dry wind completely separate from conditions across the rest of the landscape around the fire. This is when fire behavior is at its most erratic and dangerous.
Rugged landscapes again amplified the odds of the formation of these extreme fires. When these future changes to the atmosphere with climate change were modelled, it enabled the researchers to identify particular areas in Australia that were most at risk of pyrocumulonimbus events.”
References and footnotes
1. Stone, A: "Climate change will increase frequency of Australia’s most dangerous fires", ARC Centre of Excellence, 26.11.2019.
2. For further information see Australian Academy of Science, VIDEO: Climate Science: "Extreme weather linked to climate change".
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