Climate change in Australia

CSIRO and the Bureau of Meteorology have released climate change projections for Australia that provide updated national and regional information on how the climate may change to the end of the 21st century. The projections are the most comprehensive ever released for Australia and have been prepared with an emphasis on informing impact assessment and planning in the natural resource management sector. Material has been drawn from observations and from simulations based on up to 40 global climate models and four scenarios of greenhouse gas and aerosol emissions during the 21st century. The 2015 projections provide greater levels of detail and confidence compared to previous projections. Findings are consistent with previous projections research and analysis for Australia, and incorporate an increased knowledge base. The new climate change projections for Australia are funded by the Department of the Environment through the NRM Planning for Climate Change Fund with co-funding from CSIRO and the Bureau of Meteorology. The Technical Report is intended to provide detailed information for researchers and decision makers. It is a comprehensive report outlining the key climate change projection messages for Australia across a range of variables. The report underpins all information found in other products, including this website. It contains an extensive set of figures and descriptions on recent Australian climate trends, global climate change science, climate model evaluation processes, modelling methodologies and downscaling approaches. The report includes a chapter describing how to use climate change data in impact assessment and adaptation planning. Key findings Overarching findings Australia’s climate has already changed. It has become hotter since 1910, with warming across Australia of 0.9°C Rainfall has increased in northern Australia since the 1970s and decreased in south-east and south-west Australia More of Australia’s rain has come from heavy falls and there has been more extreme fire weather in southern and eastern Australia since the 1970s. Sea levels have risen by approximately 20cm since 1900. Projections for Australia’s future climate vary regionally and depend on which of the four greenhouse gas and aerosol emissions scenarios is considered. Overarching findings include: Australia’s average temperature will increase and we will experience more heat extremes and fewer cold extremes. Extreme rainfall events that lead to flooding are likely to become more intense. The number of tropical cyclones is projected to decrease but they may be more intense and reach further south. Southern and eastern Australia is projected to experience harsher fire weather. Sea levels will continue to rise throughout the 21st century and beyond. Oceans around Australia will warm and become more acidic. Additional findings Temperature Australian average temperature has increased by 0.9° C since 1910. We have seen more hot days and less cold days. Temperatures will continue to increase over the 21st century. The extent of those increases will depend on global emissions of greenhouse gases and aerosols. By late in the century (2090), Australian average temperature is projected to increase by 0.6 to 1.7°C for a low emission scenario, or 2.8 to 5.1°C under a high emission scenario. Hot days are projected to occur more frequently while there will be fewer frost days. Rainfall Winter and spring rainfall in southern Australia is projected to decline while changes in other areas are uncertain. For the rest of Australia, natural climate variability will predominate over rainfall trends caused by increasing greenhouse gases until 2030. By 2090, a winter rainfall decrease is expected in eastern Australia. Overall, extreme rain events are projected to become more intense. This finding is consistent across Australia even in areas where average rainfall is projected to decrease or the average direction of change is uncertain. This is largely due to the ability of a warmer atmosphere to hold more water. However, the projected reduction in average rainfall in south-west Western Australia may be so strong as to weaken this extreme rainfall tendency. Drought The time in drought will increase over southern Australia, with a greater frequency of severe droughts. The time in drought and the frequency of extreme droughts may increase elsewhere in Australia. A projected increase in evaporation rates will contribute to a reduction in soil moisture across Australia. Tropical cyclones Tropical cyclones may occur less often; however they will likely be more intense. Snow There will be a decrease in snowfall, an increase in snowmelt and thus reduced snow cover. Fire Weather Southern and eastern Australia are projected to experience harsher fire weather, including an increase in the number of days with a ‘severe’ fire danger rating. Projections for fire weather in northern Australia and inland areas are less certain. Sea level rise Sea levels will continue to rise throughout the 21st century and beyond. Projections of sea level rise for the Australian coastline by late in the century (2090) are comparable to, or slightly larger than, the projected global mean sea level rise of up to 82 cm under a high emission scenario. A collapse in the marine based sectors of the Antarctic ice sheet could make sea level rise projections several tenths of a metre higher by late in the century