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The Australian Climate
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Climate and Physical Changes
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What has happened
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What is likely to happen this century
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Atmospheric CO2
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- CO2 emissions have risen from ~280 ppm since ~1850 to ~400 ppm in 2013
- The rate of emissions is accelerating, from ~1% p.a. in the 1990s, to nearly 6% in 20101
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- Emissions trajectories will depend on global mitigation efforts but the general expectation is for a doubling of pre-industrial levels by the end of the 21st century2. Emissions are currently tracking the highest emissions scenario described by the IPCC in 2007
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Temperature
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- Average annual surface temperatures in Australia have risen +0.94ºC over the past 100 years3.
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- It is likely that warming will be greatest over inland Australia 4,5, however, coastal regions are predicted to experience the greatest change relative to current climate208
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Rainfall
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- SW Australia has become drier since the 1970s and autumn/winter rainfall has declined in the SE since the mid-1990s6
- The NW has become wetter since the 1950s 7
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- There is high probability that rainfall will decline further in the SW and potentially in the SE 4,5, 8
- In eastern and northern Australia, the direction of future rainfall change remains uncertain 4,5, 9
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Snow and frost
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- Late-season snow depth has declined significantly in the Snowy Mountains since the late 1950s10
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- Models predict a very high probability that both snow depth and area will decline - e.g.: the area in mainland Australia with an average annual snow cover of at least thirty days is projected to decline by 14 - 54% by 2020, and by 30 - 93% by 205010
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Sea level
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- Mean sea level has risen by around 1-2mm/year across Australia over the past century17 with rates of over 6 mm/year in northern Australia over the last 20 years11
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- There is a high probability that sea level will rise, e.g.: up to 80cm this century, and continue to rise for at least several more centuries12
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Extreme events*
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Temperature extremes
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- Hot days (>35ºC) have become more frequent and cold days (<0oC) have declined 13,14,15,16
- Increased numbers of warm nights, fewer frosts and longer heat-waves are predicted to be very likely 13,14, 17
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- Increased numbers of warm nights, fewer frosts and longer heat-waves are predicted to be very likely 13,14, 17
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Precipitation extremes
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- There has been a strong decrease, since 1910, in the intensity of rain falling on very wet days, and in the number of very wet days, in south-west Australia. There has been a strong increase in the proportion of annual rainfall falling on very wet days in the north-east18
- Extreme rainfall events are projected to increase 5, although considerable spatial variation is expected18
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- Extreme rainfall events are projected to increase 5, although considerable spatial variation is expected18
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Drought
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- Regional warming has increased the intensity of recent droughts in south-eastern Australia 19, 20,21
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- Climate models project that drought occurrence is likely to increase in southern Australia 22,23,24,25
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Tropical cyclones
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- There has been no significant change in the number of tropical cyclones or the proportion of intense storms since the 1980s 26
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- It is possible that tropical cyclones may increase in intensity but decrease, or stay similar, in frequency 27
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Fire
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- Extreme fire weather has increased since the 1970s especially in the southeast of the continent28
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- It is highly likely that the number of very high fire danger days will increase in the south-east. Less certain projections are for no change or a decrease in the north-east) 29,30
- The effects of fire regimes will depend on interactions between weather, fuel mass and moisture, and ignition events 31,32,33
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Extreme sea level events
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- There is some evidence of an increase in the incidence of extreme high sea levels (excluding tsunamis) 34
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- Projected sea level rise are highly likely to lead to large increases in the frequency of extreme sea level events12, 35
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