This 2017 NOAA Report version of Coastal Risk Australia (CRA) has been made available to show the difference between the high emission scenario from recent modelling published by NOAA and the previous high scenario that was published by the IPCC in 2013. The result is that what was previously thought to be the worst case scenario for global sea level rise is now considered a likely result. The summary of the NOAA report states "In order to bound the set of GMSL rise scenarios for year 2100, we assessed the most up-to-date scientific literature on scientifically supported upper-end GMSL projections, including recent observational and modeling literature related to the potential for rapid ice melt in Greenland and Antarctica. The projections and results presented in several peer-reviewed publications provide evidence to support a physically plausible GMSL rise in the range of 2.0 meters (m) to 2.7 m, and recent results regarding Antarctic icesheet instability indicate that such outcomes may be more likely than previously thought. " CRA is an interactive map tool designed to communicate coastal inundation associated with sea level rise to the year 2100. Using Google Earth Engine technology, CRA allows you to investigate the extent of coastal inundation using the latest 3D models of the Australian coastline. Data have been captured using airborne LiDAR technology to create detailed digital elevation models (DEMs), which are then combined with ‘bucket-fill’ inundation modelling to create the map-based visualisations. How It Works Inundation = Sea Level Rise Scenario + High Tide + Water-Land (MSL-AHD) Offset The inundation height for each area is computed using the above calculation. The default high tide level for each area is computed using the mean value of the virtual tide gauges hidden within the default view. To read more on the virtual tide gauges check the Guide, or to see them click on the tide gauges under the Layers panel. Sea Level Rise Scenarios CRA allows users to investigate projected 2100 sea level rise prediction for their locality. These predictions are based on findings from the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report from 2013 and the NOAA Technical Report from 2017. The sea level rise predicted from the 2013 Report is the high scenario from the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report from 2013. This high scenario aligns to RCP 8.5, which has a median sea level rise of 0.74 metres by 2100. This value has been obtained from the IPCC Fifth Assessment Report, Climate Change 2013: The Physical Science Basis, Chapter 13 Sea Level Rise, Table 13.5 Median Values and Likely Ranges for Projections of Global Mean Sea Level Rise. The seal level rise predicted from the 2017 Report is the high scenario from the NOAA Technical Report NOS CO-OPS 083, Chapter 5.1 Global Mean Sea Level Rise Scenarios, Table 4. Tides, Tide Gauges and Virtual Tide Gauges People overwhelmingly want to know whether the tide will affect them. This means that a high tide needs to be used in addition to the sea level rise scenario to give an estimate of the of inundation extent. So in addition to the sea level rise scenarios, CRA uses a network of “virtual tide gauges” which provide estimates for the heights of high tide along the Australian coast. The technical level for the high tide used in CRA is the highest astronomical tides (HAT). The HAT values along the Australian coast have been computed from the CANUTE tide model relative to mean sea level. The CANUTE model has been developed by the Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC) and provides estimates for 12,000 ‘virtual tide gauges’ spaced approximately every 2.5km around the coast. Aligning the Tides to the DEMs Whilst the tide is modelled relative to mean sea level (MSL), the DEMs are modelled relative to the Australian height datum (AHD). AHD was established using MSL values for 1966-1968 for 30 tide gauges around the coast of Australia. Since the establishment of AHD MSL has increased by approximately 3-4cm around the Australian coast. Whilst there is variation locally around the coast, a national average has been added into the scenarios to account for this historical increase. Digital Elevation Models (DEMs) The DEMs are 3D models of the land which are used to compute the low-lying areas susceptible to inundation. The DEMs have been mapped in great detail using airborne LiDAR technology. The DEMs used in CRA have a resolution of 5m, or in other words, a height value for every 5m along the Australian coast. To get access to the Australian Coastal DEM or find out more about LiDAR technology go to Further Information under the Useful Links on CRA.
Quick and Easy Pan and zoom to your places of interest to see the high tide flood extent for 2100 from the 2013 IPCC report (dark blue) and the 2017 NOAA report (light blue). Type in a location in the top left Google Search once you're in the map and you can go to any coastal location around Australia where there is data. Using the 2100 Sea Level Rise Scenarios Click on the Background link to read about the details of each prediction and links to the respective reports. Seeing More or Less Information You can go to the Layers panel on the left hand side to reveal the DEM layer button. The DEM box turns on and off the underlying data which shows the heights of the land. The DEM is used to calculate which are the low-lying areas that get flooded.
Zoom in to an area of the coast and you will see the Virtual Tide Gauges (VTG). The VTG map layer is scale dependant and will not appear if you are not zoomed in close enough. Click on any VTG as shown in the image below to visualise the value in a flood inundation layer. The flood inundation layers are only valid for the immediate area around the selected VTG.
The data provided in this tool has been developed to help communicate the risks of sea level rise and storm surge. The data is not provided as professional advice, and should not be relied upon for site specific decision making or for making financial or any other commitments.
While every effort has been made to ensure the accuracy and correctness of materials presented, the developers make no expressed or implied warranties (including warranties of merchantability and fitness) with respect to the accuracy, completeness, character, function, or capabilities of the tool and the data and images accessed through it. Appropriate use and conclusions drawn from the data and images are the responsibility of the user. The developers expressly disclaims liability for any loss, however caused and whether due to negligence or otherwise, arising directly or indirectly from the use of, or reliance on, this visualisation tool or the information contained in it, by any person. The Coastal Risk Australia website does not include the dynamic response of unconsolidated shorelines (eg. sand, mud and shell) or the increase in tidal flows in coastal waterways that will result from different coastal configurations in some locations. Nor does the model take account of the effects of catchment flooding from coincident extreme rainfall events. More detailed local study may be required to ensure that particular local circumstances and dynamics are adequately considered in any adaptation response to sea level rise.
We would love to get your feedback. If you are a returning vistor and you have a spare minute we would like to know how you are using the site, what other information and capability you would find useful and any improvements you think we can make to the site.