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Climate change in the South West Queensland Region
Rainfall Data Temperature Data This regional summary describes the projected climate change for the South West Queensland (SWQ) region.
Projected average temperature, Murweh Quilpie Shire Charleville rainfall and evaporation for Shire Council Aero Council 2030, 2050 and 2070 under low, Paroo Shire medium and high greenhouse Bulloo Council Shire gas emissions scenarios are Council Thargomindah Cunnamulla Post Office Post Office compared with historical climate records. New South Wales
SWQ_Map A regional profile
Climate and landscape The SWQ region, one of the most remote areas in the state, has a semi-arid to arid climate, with summers being very hot while winters are generally warm and dry. Rainfall in the region is highly seasonal and irregular, with most rain falling during the summer (October–March) either as heavy
Photo: Tourism Queensland Tourism Photo: thunderstorms or rain depressions. Key findings Demographics In 2007, the region’s population Temperature was 8 172, and is projected to • Average annual temperature in the SWQ region has increased decline marginally to around by 0.8 °C over the last decade (from 21.6 °C to 22.4 °C). 8 160 by 2026. (OESR, 2007; DIP, 2008) • Projections indicate an increase of up to 5.2 °C by 2070, leading to annual temperatures well beyond those experienced over the last 50 years. Important industries • By 2070, Charleville may have over twice the number of days of the region over 35 °C (increasing from an average of 64 per year, to 130 per Major economic activities include year by 2070) and Thargomindah may have more than 1.5 times oil, gas and gemstone (opal) the number of days over 35 °C (increasing from an average of extraction, beef, sheep and game 91 per year, to an average 147 per year by 2070). meat processing, small areas of wheat cropping, and irrigated crops Rainfall of dates, grapes and organic wheat • Average annual rainfall in the last decade fell nearly 16 per cent (Warrego River system). compared to the previous 30 years. This is generally consistent Approximately 30 per cent of the with natural variability experienced over the last 110 years, region’s population is employed which makes it difficult to detect any influence of climate in the agriculture, forestry and change at this stage. fishing industries. Pastoral • Models have projected a range of rainfall changes from an annual production contributes as much as increase of 20 per cent to a decrease of 38 per cent by 2070. $162 million per annum. The ‘best estimate’ of projected rainfall change shows a decrease under all emissions scenarios. Tourism and the retail trade are also major contributors to Evaporation employment in the rural centres. Possible future industries are • Projections indicate annual potential evaporation could increase based on natural gas export 3–15 per cent by 2070. and power generation. Extreme events Charleville (3 500) is the major • More intense and long-lived cyclones have a greater chance business and service hub for South of impacting on inland regions such as in SWQ, from the decay West Queensland. of cyclones into rain-bearing depressions, or the cyclones (Extracted from the Draft South themselves tracking further inland. West Queensland Regional Plan)
SWQ2 ClimateQ: toward a greener Queensland Understanding the climate and how it changes Queensland’s climate is naturally variable; however, climate change will lead to shifts beyond this natural variability. To assess the risk of human-induced climate change requires an understanding of the current climate using historical data and future climate scenarios. These future scenarios are prepared using data from Global Climate Models. Method Historical climate data Historical climate data collected by the Bureau of Meteorology (BoM) were aggregated across the SWQ region. The fluctuations and trends in the observed data are presented including extremes in temperature and the frequency of cyclones. Greenhouse emission scenarios The World Meteorological Organization (WMO) and the United Nations established the Intergovernmental Panel on Climate Change (IPCC) in 1988. The IPCC assesses the latest scientific, technological and socio-economic literature on climate change. To estimate the potential impacts of future climate change on Queensland, climate change projections were developed using the IPCC low (B1), medium (A1B) and high (A1FI) greenhouse gas emissions scenarios. The low-range scenario (B1) assumes a rapid shift to less fossil fuel intensive industries. The mid-range (A1B) scenario assumes a balanced use of different energy sources. The high (A1FI) scenario assumes continued dependence on fossil fuels. Greenhouse gas emissions are currently tracking above the highest IPCC emissions scenario (A1FI). The low and medium scenarios are presented to show the potential benefits of action to reduce greenhouse gas emissions. Climate change projections Queensland climate change projections were produced by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Bureau of Meteorology (BoM) based on the results from 23 Global Climate Models. Projections were provided for 2030, 2050 and 2070. However, as the climate can vary significantly from one year to the next, these projections show changes in average climate for three future 30-year periods centered on 2030, 2050 and 2070. Current climate Temperature (BoM, 2008) Historical temperature records indicate the average temperature in the SWQ region has risen, with this increase accelerating over the last decade (1998–2007). The average annual temperature was 21.6 °C in the 30-year period from 1971–2000, which is a 0.1 °C increase on the 1961–1990 average. However, over the last decade it has risen Photo: Tourism Queensland Tourism Photo: by a further 0.8 °C, suggesting an accelerated rise in temperature.
ClimateQ: toward a greener Queensland SWQ3 The increase in annual maximum temperature Temperature extremes (BoM, 2008) is presented in Figure 1. The trend over time Extremes in temperature (such as a number of days is represented by the black line in each graph. exceeding 35 °C) are single events that usually do not The change in maximum temperatures is greater extend past a couple of days. Due to the influence in the autumn with the average over the last decade of regional topography and prevailing winds, location- increasing 1.3 °C, compared to the 1961–1990 average. specific data are required when considering changes Average maximum temperature has risen in the in these extreme events over time. South West Queensland region Historical temperature records for Charleville (Figure 2) suggest that there has been a very slight increase, since the late 1970s in the number of days each year 33 Annual 32 31 where the maximum temperature exceeds 35 °C. 30 29.6 29 28.5 No similar increase has been detected for 28 27 Thargomindah (Figure 3).
39 38 Summer 37 36.8 36 35.8 35 The number of days over 35˚C has risen slightly 34 33 in Charleville 32 32 31 Autumn 30 29 29.4 100 28 28.1 mperature (°C) Te 27 90 26 25 80 70 25 Winter 24 Maximum Maximum 23 60 22 21.2 50 21 20.3 20 40 19 30 34 Spring 33 °C 35 > days of Number 20 32 31 30.9 10 30 29.9 0 29 28 1950 1960 1970 1980 1990 2000 27 1950 1960 1970 1980 1990 2000 Year Year
FIGURE RS_SWQ_2 FigureFIGURE 1: RS_SWQ_1 Historical annual and seasonal maximum Figure 2: Number of days where the temperature temperatures for the South West Queensland region exceeded 35 ˚C for Charleville for the period 1950–2007, compared to the base Blank spaces are those years where the maximum period 1961–1990 temperature did not exceed 35 ˚C. ‘X’ denotes year for which the full data set is not available The black line is a five-year running average. (i.e. the actual values may in fact be greater than what The mean for both the baseline of 1961–1990 and the last is shown). decade 1998–2007 are shown by the green lines and indicated numerically at the right of the graph. Data source: BoM, 2008 Note: vertical scales may differ between graphs Data source: BoM, 2008
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SWQ4 ClimateQ: toward a greener Queensland There is no observable increase in the number Historical rainfall shows high variability of days over 35 ˚C in Thargomindah
800 120 Annual 600 352 100 400 322 (−8.8%) 200 80 Summer 60 400
200 137 40 121 (−11.7%)
Number of days > 35 °C 35 > days of Number 0 20 300 Autumn 0 200 1960 1970 1980 1990 2000 102 100 71 (−30.4%) Year 0 tal rainfall (mm) rainfall tal To 200 Winter FigureFIGURE 3: RS_SWQ_3 Number of days where the temperature 100 55 exceeded 35 ˚C for Thargomindah 53 (2.5%) Blank spaces are those years where the maximum 0 temperature did not exceed 35 ˚C. 200 Spring ‘X’ denotes year for which the full data set is not available 100 74 (i.e. the actual values may in fact be greater than what 61 (21.4%) is shown). 0 Data source: BoM, 2008 1900 1920 1940 1960 1980 2000 Year Rainfall (BoM, 2008) FIGURE RS_SWQ_4 Annual and seasonal average rainfall is strongly Figure 4: Historical annual and seasonal total influenced by natural variability, local factors such rainfall for the South West Queensland region for as topography and vegetation, and broader scale the period 1897–2007 weather patterns, for example El Niño-Southern The black line is a five year running average. Oscillation (ENSO) events. To understand how this The mean for both the baseline 1961–1990 and the last natural temporal variation changes rainfall patterns, decade 1998–2007 are shown by the green lines and long-term rainfall records are required. The BoM has indicated numerically at the right of the graph. been collecting rainfall data for the SWQ region The difference in rainfall between the baseline and last since 1897. decade is shown in per cent. Note: Vertical scales may differ between graphs. The variability in annual rainfall is shown in the top graph in Figure 4. The dominant wet period of the Data source: BoM, 2008 1950s and 1970s contrasts with the dry years that have been experienced for most of the last decade.
Figure 4 shows the dominant summer rainfall pattern with a 1961–1990 average rainfall around 140 mm, compared to the autumn average (the next most dominant rainfall period) of around 100 mm.
Over the most recent decade, there has been a 30 per cent decline in the average autumn rainfall compared to the 1961–1990 average. This change in the autumn rainfall is the major contributor to the overall 9 per cent decline in the annual rainfall for the region over the last decade (1998–2007). Photo: Tourism Queensland Tourism Photo:
ClimateQ: toward a greener Queensland SWQ5 Evaporation Projected climate change Potential evaporation is a measure of the evaporative in South West Queensland (or drying) power of the atmosphere. The potential Global Climate Models simulate the earth’s climate evaporation rate assumes that there is an unlimited system using a complex set of mathematical rules that supply of water to evaporate (either from the soil or describe the physical processes of the atmosphere, from water bodies). Although potential evaporation ocean, land and ice. They are currently considered to can differ from actual evaporation, a change in be the best tools for projecting climate change. CSIRO potential evaporation gives a good indication of the has recently released climate change projections for change in the evaporative power of the atmosphere. Australia (CSIRO & BoM, 2007) based on the results from 23 Global Climate Models. Projections for the Networks to measure potential evaporation are not SWQ region have been extracted from this dataset for as well developed as those that measure temperature the Queensland Climate Change Centre of Excellence and rainfall and there are insufficient data available (QCCCE). The projections presented here are relative to to indicate the changes over time. the base period of 1980–1999. Averaged over the SWQ region, the annual mean The Global Climate Models show little difference under potential evaporation over the period 1971–2000 the high, medium and low emissions scenarios to (2588 mm) is nearly seven times larger than the 2030. Therefore, the 2030 climate change projections annual mean rainfall over the same period (383 mm), for the SWQ region have been presented on a mid- which contributes to the depletion of soil moisture. range emissions scenario.
Cyclones However, the projections diverge at 2050 under Strong winds, intense rainfall and ocean effects different emissions scenarios. Therefore, the 2050 such as extreme waves combine to make the total and 2070 projections are based on low and high cyclone hazard. This hazard is greatest in Queensland emissions scenarios. between January and March, but tropical cyclones The full range of projected changes for temperature, in Queensland can occur anytime over the period rainfall and potential evaporation for the SWQ region from November to April. in 2030, 2050 and 2070 are described in Table 2. While having little direct effect on the inland South The numbers shown in brackets indicate the range West Queensland region, tropical cyclone systems of the results from the Global Climate Models. can be associated with flooding in inland regions through the weakening of such systems into Overview of climate projections significant rain-bearing depressions. In summary, the changes to temperature and rainfall under the three emissions scenarios are: After the decay of tropical cyclone Ita (23–24 February 1997) into a rain-bearing depression, flooding was 2030 (medium emissions scenario) recorded in the Warrego River in Charleville, with • Annual and seasonal temperature: annual mean flood gauges reading 7.39 m—which is greater than temperature (the average of all daily temperatures the major flood level for the town (6.0 m). There was within a given year) is projected to increase by significant damage to houses, businesses, roads and 1.1 °C. There is little variation in projections across bridges as a result of this flooding. the seasons. • Annual and seasonal rainfall: annual rainfall (the total rainfall received within a given year) is projected to decrease by three per cent (-11 mm). The largest seasonal decrease of seven per cent (-5 mm) is projected for spring. • Annual and seasonal potential evaporation: across all seasons the annual ‘best estimate’ increase is projected to be around 2–3 per cent (52–78 mm), with some models projecting up to a seven per cent increase in winter (21 mm). Photo: Tourism Queensland Tourism Photo:
SWQ6 ClimateQ: toward a greener Queensland 2050 (low and high emissions scenarios) Temperature extremes • Annual and seasonal temperature: annual Global Climate Models indicate that increasing temperature is projected to increase by 1.4 °C and greenhouse gas concentrations in the atmosphere 2.2 °C under the low and high emissions scenarios will increase the likelihood of a record high respectively. There is little variation in projections temperature in a given region. The Global Climate across the seasons. Models project a rise in extreme temperatures • Annual and seasonal rainfall: annual rainfall is (CSIRO & BoM, 2007). Table 1 shows the projected projected to decrease by four per cent (-15 mm) number of days above 35 °C for two observing stations and six per cent (-23 mm) under the low and high in SWQ with good historical records. emissions scenarios respectively. The largest seasonal decrease of 14 per cent (-11 mm) under Under a high emissions scenario in 2070 for the high emissions scenario is projected for spring. Charleville, the number of hot days above 35 °C is projected to increase from 64 days to 130 days. • Annual and seasonal potential evaporation: Under the same scenario for Thargomindah, the under a high emissions scenario an increase in number of hot days would increase from 91 days to annual potential evaporation of up to nine per cent 147 days. (233 mm) is projected with the best estimate being five per cent (129 mm). Winter is projected to have the greatest increase of up to 14 per cent (43 mm). Station Name Current 2030 2050 2050 2070 2070 2070 (low and high emissions scenarios) Mid Low High Low High Charleville 64 84 89 106 99 130 • Annual and seasonal temperature: annual (77–95) (80–103) (90–126) (85–116) (107–162) Thargomindah 91 108 112 126 120 147 temperature is projected to increase by 1.9 °C and (101–117) (104–123) (113–142) (109–135) (127–172) 3.6 °C under the low and high emissions scenarios respectively. There is little variation in projections across the seasons. Table 1: Number of hot days per year above 35 ˚C projected for 2030 (mid emissions scenario) and • Annual and seasonal rainfall: annual rainfall is 2050 and 2070 (low and high emissions scenarios) projected to decrease by five per cent (-19 mm) Current number of days calculated using a base period of and 10 per cent (-38 mm) under the low and high 1971–2000. emissions scenarios respectively. The largest seasonal decrease under a high emissions scenario of 21 per cent (-16 mm) is projected Cyclones for spring. Extreme weather events, such as cyclones, • Annual and seasonal potential evaporation: have a complex link to ocean surface temperatures, under a high emissions scenario, annual characteristics of a region and global climate patterns evaporation is projected to increase by as much such as the ENSO, making it difficult to predict their as 15 per cent (388 mm). Winter is projected to frequency of occurrence. This results in discrepancies be the season most impacted with increases in cyclone frequencies between different up to 22 per cent (67 mm) in some models. climate models.
More intense and long-lived cyclones have a greater chance of impacting on inland regions such as in the SWQ region, from the decay of cyclones into rain-bearing depressions or the cyclones themselves tracking further inland.
TABLE 1. Photo: Tourism Queensland Tourism Photo:
ClimateQ: toward a greener Queensland SWQ7 2030† 2050† 2070† (1971–2000) Emissions Scenarios Variable Season Current medium low high low high historical mean* Projected Changes# Temperature Annual 21.6 °C +1.1 +1.4 +2.2 +1.9 +3.6 °C [+0.8 to +1.6] [+0.9 to +2.0] [+1.5 to +3.2] [+1.2 to +2.7] [+2.4 to +5.2] Summer 29.1 °C +1.1 +1.4 +2.3 +1.9 +3.7 [+0.7 to +1.7] [+0.9 to +2.1] [+1.4 to +3.5] [+1.2 to +2.9] [+2.3 to +5.6] Autumn 21.7 °C +1.1 +1.3 +2.2 +1.8 +3.5 [+0.7 to +1.7] [+0.8 to +2.0] [+1.3 to +3.4] [+1.1 to +2.8] [+2.2 to +5.4] Winter 13.6 °C +1.0 +1.2 +2.0 +1.7 +3.2 [+0.6 to +1.5] [+0.8 to +1.8] [+1.3 to +3.0] [+1.1 to +2.5] [+2.1 to +4.9] Spring 22.4 °C +1.2 +1.5 +2.4 +2.0 +3.9 [+0.8 to +1.8] [+1.0 to +2.1] [+1.6 to +3.5] [+1.4 to +2.9] [+2.6 to +5.6] Rainfall Annual 383 mm -3 -4 -6 -5 -10 % [-14 to +7] [-16 to +8] [-25 to +13] [-22 to +11] [-38 to +20] Summer 153 mm -1 -1 -2 -1 -3 [-13 to +12] [-15 to +14] [-25 to +24] [-21 to +20] [-36 to +38] Autumn 97 mm -3 -3 -5 -4 -8 [-19 to +13] [-21 to +15] [-33 to +25] [-29 to +21] [-48 to +40] Winter 56 mm -6 -7 -11 -9 -17 [-21 to +8] [-23 to +9] [-36 to +15] [-31 to +13] [-52 to +24] Spring 77 mm -7 -9 -14 -12 -21 [-22 to +7] [-25 to +8] [-39 to +13] [-34 to +11] [-55 to +21] Potential Annual 2588 mm +3 +2 +5 +4 +8 evaporation [+1 to +5] [-1 to +5] [+2 to +9] [+2 to +8] [+3 to +15] % Summer 972 mm +3 +1 +5 +4 +8 [+1 to +5] [+1 to +3] [+2 to +10] [+1 to +8] [+3 to +15] Autumn 572 mm +3 +3 +7 +5 +10 [+1 to +6] [+1 to +6] [+2 to +12] [+2 to +10] [+4 to +19] Winter 304 mm +3 +4 +7 +6 +11 [0 to +7] [+1 to +7] [+1 to +14] [+1 to +12] [+1 to +22] Spring 740 mm +2 +2 +4 +3 +6 [0 to +4] [-1 to +5] [-1 to +9] [-1 to +7] [-1 to +14]
Table 2. Summary of projections for South West Queensland* * To enable the projections for each of the regions to be referenced against historical climate, observational means have been calculated using a 30-year base period of 1971–2000. # Projections represent the change in temperature, relative change in rainfall and potential evaporation relative to the model base period of 1980–1999. The numbers in brackets are the 10th and 90th percentiles and depict the range of uncertainty; the number outside the brackets is the 50th percentile (i.e. the best estimate). The changes are the average change over the region. † These projections show changes in average climate for three future 30-year periods centred on 2030, 2050 and 2070. Data source: CSIRO & BoM 2007. Regional summaries prepared by QCCCE.
SWQ8 ClimateQ: toward a greener Queensland Impacts of climate change large infrequent floods, an increase in runoff of nearly 50 per cent could have very large flooding impacts. on the South West Queensland In contrast, a decrease of nearly 25 per cent will have region large negative impact on flows in the major rivers. Increasing temperatures and evaporation, In the rangelands ecosystems more frequent and more prolonged drought combined with periodic severe droughts would be detrimental to groundcover extreme flow events are projected to be the main and possibly grassland composition. Increased deep climate change impacts in South West Queensland. soil cracking with more frequent or intense droughts The temperature projections for inaction on climate may particularly affect perennial grasses. The lower change suggest a temperature increase well outside moisture regime and higher CO2 is likely to reduce the range of temperatures ever experienced over the quantity and quality of pasture resulting in lower the last 50 years. The projections for temperature carrying capacities, animal production and and number of hot days are all in the same enterprise viability. direction—increasing. Communities themselves are also exposed to the In 2007 a sustainable yields study on water availability impact of climate change, particularly the temperature in the Warrego (the eastern part of the SWQ region) increases. Heatwaves characterised by extreme was undertaken by the CSIRO. It was found that temperatures—high 30s or even 40s—persisting climate change could significantly change rainfall and for a number of days, can result in significant health runoff; however, the extent of change by 2030 is impacts such as heat exhaustion and increased uncertain. The sustainable yields study presented the mortality among vulnerable sectors of the community range of projections for both low and high emissions such as the very young or old. scenarios for 2030. Under these scenarios, mean Communities in South West Queensland are often annual rainfall could fall by up to eight per cent or exposed to these extremes on a regular basis, and increase by up to 11 per cent, respectively. Given these therefore may be better able to adapt to these changes in rainfall, the mean annual runoff could fall conditions compared to communities that don’t have by up to 25 per cent or increase by up to 46 per cent this current exposure. However, if these extremes (CSIRO, 2007). become more frequent and of longer duration, there As less than two per cent of the rain that falls in the will be greater challenges and energy demands for Warrego portion of the Murray Darling Basin currently creating a comfortable environment in which to live. ends up as runoff, and as streamflow mostly occurs as Photo: Tourism Queensland Tourism Photo:
ClimateQ: toward a greener Queensland SWQ9 References
Bureau of Meteorology (BoM) 2008, Bureau of Meteorology, Department of Infrastructure and Planning (DIP) 2007, Draft South Canberra,
SWQ10ClimateQ: toward a greener Queensland