Climate

The Australian Climate

Climate and Physical Changes

What has happened

What is likely to happen this century

Temperature

• Average annual surface temperatures in Australia have risen +0.94ºC over the past 100 years³.

• 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

Rainfall

• 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

• 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}

Snow and frost

• Late-season snow depth has declined significantly in the Snowy Mountains since the late 1950s¹⁰

• 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

Sea level

• 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

• 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 

Extreme events*

Temperature extremes

• Hot days (>35ºC) have become more frequent and cold days (<0^oC) 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}

• Increased numbers of warm nights, fewer frosts and longer heat-waves are predicted to be very likely ^{13,14, 17}

Precipitation extremes

• 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

• Extreme rainfall events are projected to increase ⁵, although considerable spatial variation is expected¹⁸

Drought

• Regional warming has increased the intensity of recent droughts in south-eastern Australia ^{19, 20,21}

• Climate models project that drought occurrence is likely to increase in southern Australia ^22,23,24,25  

Tropical cyclones

• There has been no significant change in the number of tropical cyclones or the proportion of intense storms since the 1980s ²⁶

• It is possible that tropical cyclones may increase in intensity but decrease, or stay similar, in frequency ²⁷

Fire

• Extreme fire weather has increased since the 1970s especially in the southeast of the continent²⁸

• 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

Extreme sea level events

• There is some evidence of an increase in the incidence of extreme high sea levels (excluding tsunamis) ³⁴

• Projected sea level rise are highly likely to lead to large increases in the frequency of extreme sea level events^{12, 35}