SW NRM Region Projections


ClimateChange

Key Findings for SW NRM Region

Below is a summary of key findings for the SW NRM Region. The latest climate change projections from CSIRO and BoM for the globe, Australia and the south west of Western Australia can be found here.

Two important datasets available from CSIRO include:

Mean Annual Rainfall (as a % change of initial)

Best case scenario (MIROC5 GCM) at a high emissions scenario (RCP8.5) from 2025 to 2090

AnnualRainLegend

Summer daily maximum temperature change

Best case scenario (MIROC5 GCM) at a high emissions scenario (RCP8.5) from 2025 to 2090

DailyMaxLegend

Model and Emissions Scenario Selection

Global Climate Models

To understand the nature of climate change projections, it is important to understand that there are many different Global Climate Models (GCM’s), and that they vary in their projections. The range of models, the variance in projections, the number of different climate variables and the range of time steps involved makes for an extremely complex field. Each GCM offers a reasonable approach to future climate, although these approaches may lead to differing projections. For this reason many assessments of climate change projections will refer to a suite of models rather than a single model.

One important point is that projections for certain climate attributes (such as rainfall) from one model should not be combined with attributes from a different model at the same time. In other words, you should not take the best case or the worst case for rainfall, temperature etc. from a range of models to make a case.

Fifth Climate Model Intercomparison Project (CMIP5)

The AdaptNRM project (Implications of Climate Change for Biodiversity – Williams et al 2014) uses two CMIP5 climate models—the Model for Interdisciplinary Research on Climate produced by the Japanese research community (MIROC5) and the Canadian Earth System Model (CanESM2). For both models, they project ecological change by 2050 under the emissions scenario defined by a Representative Concentration Pathway (RCP) of 8.5.

Representative Concentration Pathways follow a set of greenhouse gas, air pollution (e.g. aerosols) and land-use scenarios that are consistent with certain socio-economic assumptions of how the future may evolve over time. The well mixed concentrations of greenhouse gases and aerosols in the atmosphere are affected by emissions as well as absorption through land and ocean sinks. There are four Representative Concentration Pathways (RCPs) that represent the range of plausible futures from the published literature.

Ecotones Report (May, 2015) independently evaluated models suitable for the SW of WA.

The process used was facilitated by the Climate Change in Australia website from CSIRO, which contains tools for model evaluation and selection. The evaluation process is described in Appendix 1 taken from Ecotones (2015). Based on this assessment, we were comfortable in selecting models that have already been used by the AdaptNRM team in their bioclimatic modelling:

  • Best Case – MIROC5
  • Worst Case – CanESM2
  • Maximum Consensus – ACCESS1-0

CMIP3 vs CMIP5

Ecotones originally undertook MCAS-s analysis of projected climate change impacts for the region – discussion of rainfall and temperature change in relation to SWCC assets using CMIP 3 GCMs (specifically CSIRO Mk3.5 at an A2 (high) and A1B (moderate) emissions scenarios). This was appropriate at the time with the data available. At the time it was also understood that “While they have been superseded by the CMIP 5 scenarios (e.g. RCP 8.5) and datasets, the differences in both the climate projects and the scenarios are relatively minimal (Dr Leanne Webb, CSIRO, pers. Comm.)” (Neville 2014a).

Once CMIP5 GCMs were made available to us (accessed through http://www.climatechangeinaustralia.gov.au) and used by Ecotones to update the report, significant changes in the CMIP3 and CMIP5 data for the SWCC NRM Region is being seen. For example:

CMIP3 vs CMIP5

Overall the CMIP5 best case model used is projected to be more severe than the results from the CMIP3 CSIRO model used. The worst case model is projected to be significantly more severe.

Representative Concentration Pathways (RCPs)

The Climate Change in Australia Technical Report describes the development of four Representative Concentration Pathways (RCPs) in detail.

The future of anthropogenic greenhouse gas and aerosol emissions (and hence their resultant radiative forcing) is highly uncertain, encompassing substantial unknowns in population and economic growth, technological developments and transfer, and political and social changes. The climate modelling community has developed Representative Concentration Pathways (RCPs) to explore credible future options.

Four RCPs are used in the fifth Climate Model Intercomparison Project (CMIP5) and the latest IPCC Assessment Report (2013).

  • RCP 2.6 – requiring very strong emission reductions from a peak at around 2020 to reach a carbon dioxide (CO2) concentration at about 420 parts per million (PPM) by 2100
  • RCP4.5 – slower emission reductions that stabilise the CO2 concentration at about 540 ppm by 2100
  • RCP6.0 – results in the CO2 concentration rising less rapidly than RCP8.5, but still reaching 660 ppm by 2100
  • RCP8.5 – assumes increases in emissions leading to a CO2 concentration of about 940 ppm by 2100.

Ecotones (2015) use RCP4.5 and RCP8.5 as representative of plausible future pathways. RCP2.6 is generally considered quite unrealistic.

Limitations of Climate Modelling

Chapter 6 of CSIRO and Bureau of Meteorology (2015) Climate Change in Australia: Technical Report discusses in detail the limitations and uncertainties in climate change data and in the interpretations of projections. It also goes into detail about downscaling GCMs for application at the whole of Australia as well as at regional levels.

SWCC has prepared a report in order to:front page image2

  • Synthesis all the available climate change data and information available and relevant to the South West NRM Region.
  • Describe the limitations of this data and identify knowledge gaps.
  • Discuss the possible interpretations and use of the data in regards to strategic planning.
  • Discuss future uses and considerations in tracking and integrating climate change and adaptive management into strategic planning.

The document is quite large in size and can be downloaded in full or in sections below.

Full Report (17 MB)

Download Climate Change Data Review - Report in sections

Contents page (click images to enlarge)

contents1contents2

Key Findings and Recommendations (1 MB)

Section 1 – 6 (673 kb)

Section 7 – Data Summary Table (685 kb)

Section 8 – Climate Projections for the SW NRM Region (1 MB)

Section 9 – Biosequestration (2.3 MB)

Section 10 Part 1 – Biodiversity Section 10.1 – 10.8 (3.5 MB)

Section 10 Part 2 – Biodiversity Section 10.9 – 10.14 (10 MB)

Section 11 – Agriculture (1.1 MB)

Section 12 – Weeds (631 kb)

Section 13 and 14 – Coastal and Marine and Community and Culture (576 kb)

References (374 kb)

Appendix 1 – Global Climate Model (GCM) Selection (Ecotones, 2015) (865 kb)

Appendix 2 – Self-Evaluation by SWCC using the AdaptNRM Checklist (585 kb)

Appendix 3 – CENRM SDM Modelling – Species Lists & Groups (580 kb)

Appendix 4 – Summary of modelling of climatic suitability for listed weed species (CSIRO) (526 kb)

Some key findings include:

Annual Rainfall Stress at 2090 (RCP 8.5 – high emissions scenario)

Best Case at 2090 - Annual Rainfall Change as a % of Initial (red - loss of over 25%; green - loss of 15-20%).

Best Case at 2090 – Annual Rainfall Change as a % of Initial (red – loss of over 25%; green – loss of 15-20%).

Best Case at 2090 - Annual Rainfall Change (red - loss of over 250 mm; dark blue - loss of less than 100 mm).

Best Case at 2090 – Annual Rainfall Change (red – loss of over 250 mm; dark blue – loss of less than 100 mm).

Best case (MIROC5) –

A loss of over 250mm in annual rainfall is projected for the northern jarrah forest and the entire south-coast, while the projected % loss in rainfall is over 25% (over 200mm) for the north-west of the region and never less than 20% for the entire SWCC Region.

Annual rainfall stress (annual rainfall change + 3 x annual rainfall change as a % of initial) is significant over the entire west of the region.

 

 

 

worst case rain yr pc change

Worst Case at 2090 – Annual Rainfall Change as a % of Initial (red – loss of over 25%; yellow – loss of 20-25%).

worst case rain yr change

Worst Case at 2090 – Annual Rainfall Change (red – loss of over 250 mm; dark blue – loss of less than 100 mm).

Worst case (CanESM) –

Almost the entire region is projected to have a greater than 25% drop in annual average rainfall: a reduction of over 250mm for the entire south and west.

 

 

 

 

Growing Season Stress at 2090 (RCP 8.5 – high emissions scenario)

Best case gorwing season stress

Best Case Growing Season Stress (orange – class 9; dark blue – class 2 where class 10 is the most stressed).

Best case (MIROC5) –

Northern near-coastal areas have the highest growing season stress risk with projected rainfall reduction of over 200mm (30% of current).

Growing season rainfall stress is also indicated for the southern coast, projected rainfall reduction of over 200mm (25-30% of current).

Far east – growing season rainfall is projected to drop below 250mm, the percentage change is less.

 

 

Worst case growing season stress

Worst Case Growing Season Stress (red – class 10; green – class 7 where class is the most stressed)

Worst case (CanESM) –

Changes are projected to be significantly more severe.

Projected rainfall reduction of over 200mm (some 30% of current) covers all of the west of the region.

Area where growing season rainfall is projected to drop below 250mm extends almost to the centre of the region.

 

 

 

Temperature stress at 2090 (RCP 8.5 – high emissions scenario)

best case temp stress

Best Case Temperature Stress (red – class 6; green – class 4 where class 6 is the most stressed)

Best case (MIROC5) –

Greatest in the north-eastern part of the region, grades south and west.

Annual increase of between 2-3 degrees for the region.

 

 

 

Worst case (CanESM) –

worst case temp stress

Worst Case Temperature Stress (red – class 6 most stressed)

Greatest in the north-eastern part of the region, grades south and west.

Max temp increase of at least 3 degrees over the entire region.

Up to 4.7 degrees in the north-east.

 

 

 

AdaptNRM 

AdaptNRM have produced several technical guides that can assist in planning for biodiversity in a changing climate. The first guide is called Implications of Climate Change for Biodiversity and the second, Helping Biodiversity Adapt. Both are available on the AdaptNRM website here along with some other useful tools.

The two biodiversity planning guides use community-level modelling; combining data from multiple species and locations, simultaneously, to estimate change in biodiversity composition between places or over time. One of the measures in the guides is the potential degree of ecological change; completed for each of the four biological groups (amphibians, reptiles, mammals and vascular plants) and using the two models (MIROC5 – best case and CanESM2 – worst case) with high emissions scenario of RCP8.5.

Combined potential degree of ecological change at 2050

MCAS-s has been used to combine the outputs of potential degree of change of the four biological groups.

best case combined potential degree of change

Best case – climate impact on biodiversity (combined potential degree of ecological change where yellow is the most stressed, dark blue – least stressed)

 

Best Case (MIROC5)
The highest combined impact is projected to occur in the north-west corner of the region, with a change of up to 75% of species.

 

 

 

 

worst case combined potential degree of change

Worst case – climate impact on biodiversity (combined potential degree of ecological change where orange is the most stressed, dark green – least stressed)

Worst Case (CanESM)

A very similar pattern to the best case modelled projections can be seen; although with an increase in severity. As well as the highest combined impact being projected for the north-west corner, Cape Leeuwin is projected to be equally impacted, both with a loss of over 80% of species projected.