- Climate change and the state of Australia's roads
- This chapter considers the ongoing impacts of climate change on Australia’s climate,and extreme weather events. It discusses the accuracy of existing climate predictions, and the role of the Australian Climate Service (ACS) and the Commonwealth Scientific and Industrial Research Organisation’s (CSIRO) Transport Network Strategic Investment Tool (TraNSIT) model in these projections.
- This chapter also examines the relationship between severe weather events, climatechange and their impact on road infrastructure throughout Australia, and the need for a ‘single point of truth’ regarding climate-related data and models to inform infrastructure planning and investment.
Climate trends and characteristics
Severe weather events over recent years
2.3The Bureau of Meteorology (the BoM) submitted that since Australia began recording temperatures in 1910, the country’s climate has warmed by an average of 1.47±0.24°C. Other key indicators of a changing climate include increased sea surface temperatures, declines in rainfall and streamflow in many regions of Australia, and increased fire weather across large parts of the country since the 1950s.
2.4The BoM further noted that rainfall anomalies in northern Australia have increased over recent years. In addition, annual mean temperature anomalies have increased in recent years, along with an increase in the number of extremely warm days each year, in which mean temperatures were in the warmest one per cent of historic records.
2.5The CSIRO submitted that the ‘frequency, severity and duration of extreme fire weather conditions’ have increased in southern and eastern Australia, while projections also indicate that flood magnitudes will be increased by climate change in northern and eastern Australia.
2.6The Australian Research Council Centre of Excellence for Climate Extremes (ARCCECE) submitted that the impact of humanity’s greenhouse gas emissions on climate change is unambiguous, and the risks are clearly increasing for some extreme events like heatwaves and flooding.
2.7The BoM’s State of the Climate 2022 report stated that there is both a present and ongoing need for planning and adaptation to climate risk, as it changes. The pace of these changes is increasing, and the record-breaking extremes experienced in the last decade have led to natural disasters exacerbated by human-caused climate change.
2.8The ARCCECE stated that existing weather events have already threatened Australia’s road network, with increased risk of severe and more frequent flash flooding due to high intensity, short-duration rain events, particularly in the past two decades. The past two decades in Australia were also warmer than any decade in the 20th Century.
2.9The ARCCECE further submitted that with each additional fraction of a degree, the risk of extreme weather events is increased:
There are likely to be more intense extremes in the future, particularly for heatwaves and rainfall, along with more frequent swings from extreme droughts to flooding rains. It is crucial that climate risk is considered across the infrastructure portfolio.
2.10The impact of extreme weather events on road infrastructure is discussed later in this chapter.
Box 2.1Defining the term ‘compound events’ The term ‘compound events’ was used multiple times in the ARCCECE’s submission. It describes multiple weather and climate elements occurring at the same time. These events impact socioeconomic or ecological systems and may result from a combination of hazards or drivers. One example is a simultaneous 10 per cent increase in rainfall andwind gusts – in isolation these two events are unlikely to be significant, however together the impact can be considerable. The ARCCECE submitted that such compound events should be included in future climate risk assessments. However, data records are currently insufficiently long or too incomplete to be reliably used for statistical analyses. Future climate change in Australia will lead to increased compound events across the country, which the ARCCECE submitted will include prolonged hot and dry compound events, likely leading to an increase in wet and windy compound events in the north, and a decrease of extreme wind and rain events in the south. |
Climate modelling and prediction
Accuracy of climate predictions
2.11A key factor in addressing the issue of climate change is the inherent uncertainty in long-term predictions for weather and climate, especially across different locations within Australia.
2.12The BoM’s State of the Climate 2022 report noted that there has been a consistent picture of ongoing, long-term climate change interacting with underlying natural variability, with climate extremes and weather events including heavy rainfall, coastal inundation, extreme heat, fire, and drought all impacted by these long-term changes.
2.13Engineers Australia stated that while climate change is certain, the extent of that change is unknown. In order to appropriately design infrastructure, it is important to quantify the magnitude of the change, the frequency and the duration.
2.14The BoM noted that climate and weatherfactors like rainfall, stream flow, heat and fire weather all impact the road infrastructure network, but there is variation in the certainty of projections for each of these phenomena, and further variation in certainty for different phenomena in different places.
2.15The ARCCECE reiterated this concern around certainty of location‑based forecasting, stating that:
Climate science has made some profound contributions for our understanding of risk both now and in the future, but that does not mean we have the skill to forecast extreme events at a specific location for a specific period of time in the future with useful skill. I'm talking here not about tomorrow or the day after or next week; I'm talking about the risk to a specific location in 20 or 30 years’ time.
2.16The ARCCECE recommended that when modelling climate change impacts, uncertainty in climate and weather estimates should be accounted for in future projections. When generating quantifiable estimates, the ARCCECE submitted that uncertainty is created by:
- the complexity of natural variability
- limitations of existing climate projections
- the ongoing study of the climate’s effects
- the complexity of the climate’s impacts on Australian society.
- The ARCCECE noted that engineers require a specific data point to be selected for planning, and they then do a terrific job of building to that line drawn on a map. However, the accuracy of that line is based on inherently uncertain estimates and as a result, developments that appear resilient can end up being catastrophically vulnerable to certain weather events:
It's a wicked problem. We know that the temperature extremes are heading in one direction, but, even though on average rainfall extremes will intensify, that does not mean that for a particular place rainfall will intensify. So there is a high risk of gross overinvestment in resilience in some regions and a failure to account for uncertainty in extreme events in other locations.
2.18The BoM submitted that the value of location-specific forecasting can be demonstrated by current issues with flood and inundation mapping. While the BoM has provided flood models according to a fixed number of forecast locations, these locations are usually in the river channel itself. The BoM noted that communities and regions may struggle to use this information to predict what a flood will look like:
The other thing that is happening with that modelling effort is that the bureau's flood models have typically—as they are required to do under the service level agreements—focused on a fixed number of forecast locations. The forecast product is generally limited to 'we expect the water level to be this high at this time and at this location', and those locations are typically in the river channel. That has historically made it difficult for some communities and businesses to translate a forecast river height into the flood that they can expect away from the river.
2.19The BoM has been working in the Hawkesbury Nepean region, creating forecasts that incorporate inundation mapping, which demonstrate the actual regional impact of the floodwaters, as well as the traditional flood mapping. Key features of this approach are higher accuracy, timeliness, and more probabilistic data.
2.20The BoM submitted that as climate change intensifies, extreme weather events, data and modelling that assists in predicting rainfall and flood levels will become more important when designing resilient infrastructure.
2.21Such climate modelling also relies on location-specific data. The ARCCECE said that while infrastructure construction can allow for increased risk of extreme events, more intense rainfall, or hotter overall temperatures:
That is different from designing a particular piece of infrastructure with an apparent deep awareness of what the climate is going to be like and what the extremes are going to be like in 2050 or 2100 at that location.
Role of the Australian Climate Service and TraNSIT
2.22The ACS and the TraNSIT model play an important role in climate projections and future transport network resilience.
2.23The ACS has been developing nationally consistent climate and hazard projections for future use by bringing together relevant hazard, socio-economic, environmental, and built domain data, and intelligence in order to provide local information on the potential impacts of current and future climates on communities. It has sought to provide decision-makers with an evidence base to assess key vulnerabilities and make informed decisions to strengthen the infrastructure network.
2.24The BoM provided further detail on the function of the ACS:
It does things like provide a national picture of when and where natural hazards are likely to occur, now and in the future, and the likelihood, frequency and intensity of those events, combined with the effects of a changing climate.
2.25The CSIRO’s TraNSIT is a mathematical model that has mapped millions of vehicle trips across thousands of supply chain routes across Australia to assess the impacts of disruptions to the road and rail supply chain.
2.26The BoM said that the TraNSIT model has been used by the ACS to understand the immediate, real-time and short-term impacts on the road network by weather forecasts. This flood forecasting and inundation tool has been made available as a web mapping service to the National Emergency Management Agency (NEMA).
2.27The NEMA noted in its submission the existence of road and traffic disaster information sources such as the New South Wales (NSW) Government’s Live Traffic portal, which provides standardised information across state, territory and local government levels. The NEMA suggested that by strengthening the national approach to road information through tools such as TraNSIT, rural, regional and remote communities in particular could be better supported.
2.28The ACS and CSIRO worked together using the TraNSIT model to develop inundation mapping that can provide real-time forecasts of flooding on transport routes and enable the re-routing of traffic to avoid flooded routes. The ACS also worked to connect the fire and national hazard information across the Commonwealth into a single national view.
2.29The ACS has been working on understanding the risk profile of specific locations by downscaling climate models, so that their data might be put into models like TraNSIT. However, the BoM noted that ‘the first step is to have the climate data available at a more granular scale,’ so that greater detail is available to understand weather and climate risks’.
2.30The Department of Infrastructure, Transport, Regional Development, Communications and the Arts (DITRDCA) noted that although TraNSIT has been considered the ideal model for understanding supply chain resilience for road and rail, there are the limitations due to access to existing data, including the current condition of road and rail assets, and the availability of commodity data.
The relationship between climate change and road infrastructure
Impacts on road infrastructure from severe weather events
2.31Engineers Australia submitted that roads networks throughout rural, regional, and remote Australia play a critical role during natural disasters. Road closures due to natural disasters such as flooding and fires can prevent the movement of emergency services to provide aid, and of residents travelling to safer areas.
2.32Engineers Australia further submitted that severe weather events impact road infrastructure through flooding, coastal inundation, bushfire, extreme heat and cold, and landslides. Roads damaged by these extreme weather events can be rendered unsafe for use, leading to road closures.
2.33As noted above, Engineers Australia submitted that while natural disasters have always existed in Australia, they have become more intense and frequent due to the impacts of climate change and will continue to increase into the future. There is also an increasing probability that extreme weather events including more intense rainfall and higher temperatures will impact road infrastructure.
2.34The ARCCECE submitted that the risks to road infrastructure vary depending on the location of the road network and its vulnerability to extreme weather events. Assessing the risk to road infrastructure becomes more difficult when multiple hazards are identified. The extent to which extreme events intensified by climate change impact road networks also depends upon how exposed the roads are to different hazards.
2.35Extreme rain events and flooding are another significant source of stress on road infrastructure that must be accounted for in the design and construction of roads. The BoM used the following example:
The intensity of short-duration (hourly) extreme rainfall events has increased by around 10 per cent or more in some regions over recent decades. These have placed increased stress loading on transport infrastructure, such as scouring damage to foundations and road formation. Design specifications used for transport infrastructure do not take this change into account.
2.36Engineers Australia stated that reducing the severity of extreme weather events is a critical goal, which should be aided through decarbonising infrastructure and the Australian economy through a more holistic approach.
2.37The BoM’s State of the Climate 2022 report echoed this sentiment, noting that the impacts on Australia’s environment and infrastructure will depend on how quickly greenhouse gas emissions can be reduced globally.
A single point of truth
Climate data and sharing
2.38Engineers Australia stressed the need for an urgent ‘single point of truth’ regarding information and models referenced for future infrastructure planning, noting that BoM and CSIRO are expert in climate modelling.
2.39Engineers Australia emphasised the need for adequate funding to support this work:
…it's strongly in the interests of the engineering industry that they're [climate models] adequately funded, to make sure that work is done and updated regularly, because we know things are changing. We don't know exactly to what extent they'll change in the future. So, we need not just to know there is climate change; we need to be able to quantify the magnitude of the change, the frequency and the duration. We need that information to design infrastructure…We can't design the right solution unless we have that information.
2.40The ARCCECE further highlighted the importance of CSIRO’s world-leading expertise, stating that it has been undermined and underfunded. The ARCCECE emphasised that there are now climate service providers claiming to provide reliable granular and location-specific information to federal agencies, and this data may be misleading.
2.41Engineers Australia asserted that the sharing of climate data is important for not only engineering standards to determine infrastructure design, but there is also a need for supporting science to inform the existing risk, and future changing risk, of extreme weather events impacted by climate change.
2.42Engineers Australia stated that while current road design has been based off previous forecasts, we are now facing ‘risks that may be greater than the designed infrastructure in the last 30 years’.
2.43The BoM told the Committee that while construction standards draw on weather and climate data to assist with the design of engineered structures, Australia’s Design Rainfall Data System (hosted by the BoM) is entirely based on historical rainfall records which have not been updated since 2016. It said there was an opportunity for a review of construction standards, including the information used to implement standards, to better account for Australia’s changing climate. Road design andconstruction standards are discussed in further detail in ChapterFour.
2.44Both Engineers Australia and the ARCCECE outlined that climate change has created change at a non-natural rate and that past models were no longer a reliable source. The ARCCECE said that due to the unreliability of statistical analyses, they cannot be certain how well climate models reproduce the interactions at play.
2.45The ARCCECE further commented that while they believe a review of current hazards including climate exposure could assist with making future policy decision and actions, there needed to be a rationale before any investment:
Any analysis or interpretation of climate hazard data to inform climate resilience decisions should [be] performed cautiously and with expert help under a robust governance framework. Technical expertise can provide advice and produce information and guidance and should be undertaken with the help or through the climate science community. It is important to convey information in a useful way, for example, describing hazard exposure through ranges such as: severity, likelihood, duration, and frequency, [and] confidence. This helps to convey uncertainty and is not quantitative.
Data sharing opportunities
2.46The Australian Academy of Technological Sciences and Engineering (ATSE) outlined the need for better data collection and the need for accurate, credible and timely data to assist with informed decision making.It said that critical disaster and climate data was not coordinated or standardised and believed that sharing and standardising information and applying nationally consistent data gathering would further improve road resiliency planning.
2.47There is ongoing work to assist with disaster information sharing such as CSIRO’s INDRA platform. INDRA is a data analytics platform which has been created to enable the sharing of disaster information to allow for future planning and management of infrastructure risk, adaptation, mitigation and financial de-risking strategies.
2.48According to CSIRO, with INDRA, the end user will be able to visualise and analyse datasets in a common, federated platform and have greater transparency and insight into the modelling and analytics process. INDRA will assist clients with future proofing of threats and uncertainties associated with climate change and hazarddata.
Investment in forecasting and forecasting tools
2.49The ARCCECE commented that investment in building better quantitative tools for climate scientists and modellers could, in turn, provide useful insights on the future climate. They also believed government funding for institutions was useful to assist with tools and techniques to assess risk and resilience, and that local councils, state governments and local members have an in‑depth understanding of their local communities.
2.50There is a need to invest in forecasting tools like the dynamic TraNSIT model which is used for real-time forecasts to allow for the planning of future design solutions to climate events.
2.51The Australian Automobile Association’s (AAA) submission discussed the use of Cooperative Intelligent Transport Systems (C-ITS), noting that it can supply datasets for analysis including real-time. C-ITS could provide an immediate response and enable more efficient and responsive timeframes for weather events. The AAA statedthat C-ITS has the potential to play a major role in resilience assessment andforecasting.
2.52The ATSE had also released an evidence-based tool to assist operators tomake informed decisions for uncertain events. The ATSE further noted that it supported continuous improvement in risk assessment modelling in line with the evolution of relevant technologies and evidence-based tools.
2.53The BoM noted that the role of the ACS is separate from that of the BoM. While the ACS brings information from a variety of sources together, the BoM makes weather observations, provides forecasts and delivers natural hazard warnings. The BoM stated that the two roles are related but distinct.
2.54The BoM highlighted that inundation mapping was not a traditional function or skill of the Bureau and that inundation maps are held by local councils and state and territory governments. The BoM commented that work is being undertaken to improve models to enable forecast inundation and improve flood forecasting:
There is also across Australia a range of existing inundation maps typically owned by local council and state government. They can be accessed by the Australian Climate Service in order to understand the impacts of given levels of flood or inundation and, in turn, relate that to expected impacts on the flood network. That speaks to one of the main functions of the Australian Climate Service, which is bringing together information from a range of sources so that impacts of all events can be understood.
2.55The BoM provides important data-holding information, such as design rainfall data, that isfundamental for infrastructure planning and works. The BoM’s work is made available through its website and used in Australia by all levels of government as well as the private sector.
2.56CSIRO is working with the BoM to deliver a Climate and Hazard Information service with the ACS. This work will include an authoritative source of information to assist the Australian Government in preparedness, planning, mitigation and adaptation.
Suggested recommendations
2.57Engineers Australia said that funding is needed to reinvest in the expertise and modelling capability of government.They noted modelling was needed for information, research, and development to be made available in order to make effective road infrastructure decisions.
2.58The ATSE noted that in order to develop a comprehensive risk-based approach to road infrastructure climate resilience, scientific data relating to climate projection should be incorporated into engineering standards and guidance should be available. This should be used in both the planning and design of road infrastructure in the future. The ATSE stated that resilience is most sensibly addressed by methods that consider the probability of their occurrence.
2.59The BoM commented that they believed incorporating climate projections in future design rainfall updates could likely enhance the resilience of future road construction. It also believed that the use of design rainfall data could be used to update hydrological modelling to allow future infrastructure to be designed to suit future weather conditions.
2.60The Australian Local Government Association recommended that the Commonwealth government collaborate with state and territory jurisdictions on a sustainable road funding model to allow upfront investment in improve the resilience of roads to severe weather events, and properly maintain road networks.
Committee comment
2.61Unprecedented severe weather events over recent years have resulted in significant levels of road asset infrastructure degradation, with real and ongoing impacts on Australia’s communities and industries.
2.62Our road networks are vital to ensuring communities remain connected to essential health services, food and fuel supplies, social activities, culture, and to each other. A functioning road network is also crucial to ensuring the safe and efficient evacuation of our communities during and following natural disaster events.
2.63However, the nation’s road network, particularly in regional, rural, and remote areas has suffered extensively over recent years. Floods have washed roads and bridges away, inundating networks, isolating and displacing communities, some for weeks and months.
2.64The Committee recognises the evolving impact of climate change on road infrastructure. Australia’s road network must be able to withstand extreme weather events increasing in frequency and intensity. Developing and maintaining a more resilient road network requires accurate projections of extreme weather impacts, particularly along key transport routes.
2.65Models such as TraNSIT are vital for providing more localised data on key transport corridors, particularly for flooding and inundation events. This data will allow for a greater understanding of extreme weather events and the impacts of climate changeon the road network.
2.66The Committee recommends that the Commonwealth Scientific and Industrial Research Organisation’s Transport Network Strategic Investment Tool be utilised by the Australian Climate Service to examine projected impacts on strategic road network routes.
2.67The Committee further recognises that the data needed to accurately forecast changing weather and climate conditions must come from clearly demarcated and reliable sources, to support more resilient road infrastructure design and planning. Appropriate expert advice should be a top priority in the gathering of climate data, to allow adequate warning, planning and risk mitigation against extreme weather events.
2.68The Committee recommends that clearer demarcation of climate data and sharing responsibilities between the Bureau of Meteorology and the Commonwealth Scientific and Industrial Research Organisation and state and territory and local governments be established to facilitate adequate warning and risk mitigation.