Heat hazard data for the National Climate Risk Assessment

Brief description

Heat hazard regional change summaries for the National Climate Risk Assessment (NCRA). The heat hazards have been summarised for boundaries relating to the assessment of freshwater and terrestrial natural environments.

Australian Climate Service (ACS) heat hazard datasets (https://github.com/AusClimateService/hazards-heat)
1. TXx - the hottest day of the year
2. TXm - annual mean daily maximum temperature
3. HWF - heatwave frequency

Each hazard dataset includes an ensemble of climate models for four global warming levels (GWLs), 1.2, 1.5, 2.0 and 3.0 degrees Celsius, above a pre-industrial mean for 1850 to 1900.

Either the absolute change (difference to GWL1.2) or the relative change (difference to GWL1.2 divided by GWL1.2) was calculated for each of the higher GWLs compared to GWL1.2.

Regions of interest boundaries
1. Australia
2. NCRA regions
3. Aggregate Ecological Groups (AEGs)
4. Combined NCRA regions and AEGs
5. Level 2 drainage basins from the Australian Hydrological Geospatial Fabric (AHGF)
6. Spatially combined AHGF Level 2 drainage basins and hazard dataset grid cells which intersect with perennial drainage lines from the AHGF Network Streams
7. Spatially combined AHGF Level 2 drainage basins and hazard dataset grid cells which intersect with ephemeral drainage lines from AHGF Network Streams

For each hazard/GWL-change combination, a set of statistics (the mean, 10th percentile, 50th percentile, 90th percentile and standard deviation) was calculated for each climate model in the ensemble over the regions of interest areas. From these, the median of each statistic from all the models in the ensemble was calculated.

Collection data files
The outputs are tabular data in comma-separated value (csv) files with one file per hazard/GWL-change combination. The columns are ID and region name that link to the boundary datasets for visualising in GIS software, and the medians of the statistics. Rows are the individual region of interest polygons.
Lineage: DATASETS
Hazard data
The National Climate Risk Assessment (NCRA) hazard data were supplied by the Australian Climate Service (ACS) from data stored on the National Computational Infrastructure (NCI) as part of Project ia39. The hazard data came in the form of an ensemble of climate models, with outputs for four global warming levels (GWLs) from each of the individual models. The GWLs are 1.2, 1.5, 2.0 and 3.0 degrees Celsius above a pre-industrial mean for 1850 to 1900.

Heat hazards in this collection (https://github.com/AusClimateService/hazards-heat):
1. TXx - the hottest day of the year
2. TXm - annual mean daily maximum temperature
3. HWF - heatwave frequency

Regions of interest boundaries
The hazard data were summarized by regions of interest using polygon shape files for the following areas:
1. Australia - 2021 - Shapefile (https://www.abs.gov.au/statistics/standards/australian-statistical-geography-standard-asgs-edition-3/jul2021-jun2026/access-and-downloads/digital-boundary-files)
2. NCRA regions (https://www.acs.gov.au/datasets/4f8b960fd3694fc28d6ff3d1278e9e75_0/about)
3. Aggregate Ecological Groups (AEGs) derived from National Vegetation Information System (NVIS) data (https://data.csiro.au/collection/csiro:64128)
4. Spatially combined NCRA and AEG polygons (https://data.csiro.au/collection/csiro:64133)
5. Level 2 drainage basins from the Australian Hydrological Geospatial Fabric (AHGF) (http://www.bom.gov.au/water/geofabric/download.shtml)
6. Spatially combined AHGF Level 2 drainage basins and hazard dataset grid cells which intersect with perennial drainage lines from the AHGF Network Streams (where the Perennial attribute is "Perennial") (https://data.csiro.au/collection/csiro:64133; drainage lines from http://www.bom.gov.au/water/geofabric/download.shtml)
7. Spatially combined AHGF Level 2 drainage basins and hazard dataset grid cells which intersect with ephemeral drainage lines from AHGF Network Streams (where the Perennial attribute is "Non Perennial") (https://data.csiro.au/collection/csiro:64133; drainage lines from http://www.bom.gov.au/water/geofabric/download.shtml)


METHODS
The heat hazard datasets were summarised for each set of region of interest boundaries using methods and code from the ACS (https://github.com/AusClimateService/plotting_maps).

Either the absolute change (difference to GWL1.2) or the relative change (difference to GWL1.2 divided by GWL1.2) was calculated for each of the higher GWLs compared to GWL1.2.

Absolute change was calculated for HWF, TXm, and TXx using the Australia, NCRA, AEG and combined NCRA-AEG boundaries. Relative change was calculated for TXx for the drainage basins, the combined drainage basins-perennial drainage lines, and the combined drainage basins-ephemeral drainage lines boundaries.

For each hazard/GWL-change combination, a set of statistics (the mean, 10th percentile, 50th percentile, 90th percentile and standard deviation) was calculated for each climate model in the ensemble over the regions of interest areas. From these, the median of each statistic from all the models in the ensemble was calculated. For a more detailed description of the methods, see the 'Spatial data processing methods' file in the Supporting Documentation section.


OUTPUTS - COLLECTION DATA FILES
The outputs are tabular data in comma-separated value (csv) files with one file per hazard/GWL-change combination. The columns are ID and region name (linking to the boundary datasets for visualising in GIS software), and the medians for each of the statistics. Rows are the individual region of interest areas (polygons).