Climate Change in Australia

Changes to rainfall are possible but unclear. For the near future natural variability is projected to dominate any projected changes.

PAST RAINFALL TRENDS

The Monsoonal North East experienced an overall slight increase in rainfall during the 20th century, which includes prolonged periods of drying as well as above average rainfall. Year to year variability is strongly influenced by the El Niño Southern Oscillation.

RAINFALL PROJECTIONS

Providing confident rainfall projections for the Monsoonal North East sub-cluster is difficult because global climate models offer diverse results, and models have shortcomings in resolving some tropical processes. Natural climate variability is projected to remain the major driver of rainfall changes in the next few decades. By late in the century, potential summer rainfall changes are approximately -23 to +15 per cent under an intermediate emission scenario (RCP4.5) and approximately -28 to +28 per cent under a high scenario (RCP8.5). Per cent changes are much larger in winter in some models, but these changes are less reliable because average winter rainfall is very low.

Impact assessment in this region should consider the risk of both a drier and wetter climate.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century with daily minimum temperatures increasing more than daily maximums.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.4 to 1.3 °C above the climate of 1986 – 2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.5 to 5.0 °C. Under an intermediate scenario (RCP4.5) the projected warming is 1.2 to 2.7 °C.

More hot days and warm spells are projected with very high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

Increased intensity of extreme rainfall events is projected, with high confidence.

Despite uncertainty in future projections of total rainfall for the Monsoonal North East sub-cluster, an understanding of the physical processes that cause extreme rainfall, coupled with modelled projections, indicate with high confidence a future increase in the intensity of extreme rainfall events. However, the magnitude of the increases cannot be confidently projected.

Drought will continue to be a feature of the regional climate variability, but projected changes are uncertain.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise along the coasts of the Monsoonal Northeast cluster is 0.06 to 0.16 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.28 to 0.61 m and the high case (RCP8.5) a rise of 0.38 to 0.81 m. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of the Monsoonal North East coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 2.2 to 3.9 °C by 2090 under a high scenario (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

With medium confidence, fewer but more intense tropical cyclones are projected.

TROPICAL CYCLONES: Tropical cyclones are projected to become less frequent, but the proportion of the most intense storms is projected to increase (medium confidence).

FIRE WEATHER: The primary determinant of bushfire in the Monsoonal North East is fuel availability, which varies mainly with rainfall. Changes to future rainfall will be the determining factor of change to fire frequency. When fire does occur, there is high confidence fire behaviour will be more extreme.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY: There is little change projected in relative humidity until later in the century under a high emission scenario (RCP8.5), where a decrease in relative humidity is projected (medium confidence).

Changes to rainfall are possible but unclear. For the near future natural variability is projected to dominate any projected changes.

PAST RAINFALL TRENDS

The Monsoonal North experienced an overall slight increase in rainfall during the 20th century, which includes prolonged periods of drying as well as above average rainfall. The strongest increases have been across north-western regions during recent decades. Year to year variability is strongly influenced by the El Niño Southern Oscillation.

RAINFALL PROJECTIONS

Providing confident rainfall projections for the Monsoonal North cluster is difficult because global climate models offer diverse results, and models have shortcomings in resolving some tropical processes. Natural climate variability is projected to remain the major driver of rainfall changes in the next few decades. By late in the century, potential summer rainfall changes are approximately -15 to +10 per cent under an intermediate emission scenario (RCP4.5) and approximately -25 to +20 per cent under a high scenario (RCP8.5). Per cent changes are much larger in winter in some models, but these changes are less reliable because average winter rainfall is very low.

Impact assessment in this region should consider the risk of both a drier and wetter climate.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century. One area of north-west Australia has seen a decrease in mean temperature since 1960 due in part to increases in rainfall and cloudiness.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.5 to 1.4 °C above the climate of 1986 – 2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.8 to 5.1 °C. Under an intermediate scenario (RCP4.5) the projected warming is 1.3 to 2.8 °C.

More hot days and warm spells are projected with very high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence). For Darwin and Broome, for example, days with temperatures over 35 °C could be experienced on average for around a third of the year under an intermediate emisison scenario (RCP4.5) by late in the century.

Increased intensity of extreme rainfall events is projected, with high confidence.

Despite uncertainty in future projections of total rainfall for the Monsoonal North West sub-cluster, an understanding of the physical processes that cause extreme rainfall, coupled with modelled projections, indicate with high confidence a future increase in the intensity of extreme rainfall events. However, the magnitude of the increases cannot be confidently projected.

Drought will continue to be a feature of the regional climate variability, but projected changes are uncertain.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise along the coasts of the Monsoonal Northwest cluster is 0.06 to 0.17 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.28 to 0.65 m and the high case (RCP8.5) a rise of 0.38 to 0.85 m. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of the Monsoonal North West coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 2.5 to 4.1 °C by 2090 under a high scenario (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

With medium confidence, fewer but more intense tropical cyclones are projected.

TROPICAL CYCLONES: Tropical cyclones are projected to become less frequent, but the proportion of the most intense storms is projected to increase (medium confidence).

FIRE WEATHER: The primary determinant of bushfire in the Monsoonal North West is fuel availability, which varies mainly with rainfall. In regions where abundant rain falls (Top End and the Kimberley), climate change is not expected to change the frequency of fire (high confidence). In more southerly locations, changes to future rainfall will be the determining factor of change to fire frequency. When fire does occur, there is high confidence that fire behaviour will be more extreme.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY: There is little change projected in relative humidity until later in the century under a high emission scenario (RCP8.5), where a decrease in relative humidity is projected (medium confidence).

Changes to rainfall are possible but unclear. On annual and decadal basis, natural variability in the climate system can act to either mask or enhance any long-term human induced trend, particularly in the next 20 years.

PAST RAINFALL TRENDS

The Wet Tropics experienced prolonged periods of extensive drying in the early 20th century, but annual rainfall shows no long-term trend between 1910 and 2013.

RAINFALL PROJECTIONS

Providing confident rainfall projections for the Wet Tropics is difficult because global climate models offer diverse results, and models have shortcomings in resolving some tropical processes. In the near future (2030) natural variability is projected to predominate over trends due to greenhouse gas emissions. By late in the century, potential summer and autumn rainfall changes are approximately -25 to +20 per cent under a high emission scenario (RCP8.5) and -15 to +10 per cent under an intermediate scenario (RCP4.5). Impact assessment in this region should consider the risk of both a drier and wetter climate.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960. Mean temperature increased between 1910 and 2013 by around 1.1 °C. Daily minimum temperatures increased by slightly more than daily maximum temperatures.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in mean, maximum and minimum temperatures, in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.3 to 1.1 °C above the climate of 1986–2005. By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.3 to 3.9 °C. Under an intermediate scenario (RCP4.5) the projected warming is 1.0 to 2.0 °C.

More hot days and warm spells are projected with very high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

For Cairns, for example, days with temperatures over 35 °C could increase around 3-fold under intermediate emission scenario (RCP4.5) by late in the century.

Increased intensity of extreme daily rainfall events is projected, with high confidence.

Despite uncertainty in future projections of total rainfall for the Wet Tropics, an understanding of the physical processes that cause extreme rainfall, coupled with modelled projections indicate with high confidence a future increase in the intensity of extreme rainfall events. However, the magnitude of the increases cannot be confidently projected.

Drought will continue to be a feature of the regional climate variability, but projected changes are uncertain.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise is 0.06 to 0.18 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.27 to 0.65 m and the high case (RCP8.5) a rise of 0.40 to 0.87 m. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of the Wet Tropics coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 2.2 to 3.6 °C by 2090 under a high scenario (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

With medium confidence, fewer but more intense tropical cyclones are projected.

TROPICAL CYCLONES: Tropical cyclones are projected to become less frequent, but the proportion of the most intense storms is projected to increase (medium confidence).

FIRE WEATHER: In the Wet Tropics where abundant rainfall (wet season) and bushfires (dry season) are common, the projected changes in rainfall are not expected to significantly change the current seasonal cycle. There is high confidence in projections of little change to fire frequency. When and where fire does occur, there is high confidence that fire behaviour will be more extreme.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

Changes to rainfall are possible but unclear. For the near future, natural variability will dominate any projected changes.

PAST RAINFALL TRENDS

Observations show an increasing trend in summer rainfall over the north-west of the Rangelands, although with intermittent periods of wetter and drier conditions throughout the 20th century. Year to year variability is strongly influenced by the El Niño Southern Oscillation.

RAINFALL PROJECTIONS

In the near future (2030) natural variability is projected to predominate over trends due to greenhouse gas emissions.

Changes to rainfall are possible, but the direction of change cannot be confidently projected given the spread of model results.

Impact assessment in this region should consider the risk of both a drier and wetter climate.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960. Mean temperature increased between 1910 and 2013 by around 0.9 °C.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.6 to 1.5 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 3.1 to 5.6 °C. Under an intermediate scenario (RCP4.5) the projected warming is 1.5 to 3.1 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

For Alice Springs, for example, days with temperatures over 35 °C could occur for more than a third of the year under an intermediate emission scenario (RCP4.5) by late in the century.

Where frosts (minimum temperatures under 2 °C) occur in the sub-cluster, these are projected to decrease.

Increased intensity of extreme rainfall events is projected, with high confidence.

Understanding of the physical processes that cause extreme rainfall, coupled with modelled projections, indicate with high confidence a future increase in the intensity of extreme rainfall events, although the magnitude of the increases cannot be confidently projected.

Time spent in drought is projected, with medium confidence, to increase over the course of the century.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise is 0.07 to 0.17 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.28 to 0.65 m and the high case (RCP8.5) a rise of 0.40 to 0.85 m along the Pilbara coast. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 2.4 to 3.7 °C by 2090 under high emissions. The sea will also become more acidic, with acidification proportional to emissions growth.

With medium confidence, fewer but more intense tropical cyclones are projected.

FIRE WEATHER: Bushfire in the Rangelands depends highly on fuel availability, which mainly depends on rainfall. With an unclear direction in rainfall projections it is difficult to determine the direction of fire weather risk expected in future, furthermore, there is low confidence in the magnitude of fire weather projections.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY: Little change in relative humidity is projected for the near future (2030) while later in the century a decrease is projected in winter (high confidence) and in the other seasons (medium confidence).

SOLAR RADIATION: There is little change projected for solar radiation in the near future (2030), and for later in the century, decreased radiation is projected in March-May (medium confidence).

Changes to summer rainfall are possible but unclear. Winter rainfall is projected to decrease with high confidence. For the near future, natural variability will dominate any projected changes.

PAST RAINFALL TRENDS

Observations show intermittent periods of wetter and drier conditions throughout the 20th century. The recent wet year, 2011, was the highest on record. Year to year variability is strongly influenced by the El Niño Southern Oscillation.

RAINFALL PROJECTIONS

In the near future (2030) natural variability is projected to predominate over trends due to greenhouse gas emissions. Winter rainfall is projected to decline over the century under both intermediate (RCP4.5) and high (RCP8.5) emission scenarios (high confidence). There is a good understanding of the physical mechanisms driving this change (southward shift of winter storm systems together with rising mean pressure over the region). Changes to annual and summer rainfall for late in the century are possible, but the direction of change cannot be confidently projected given the spread of model results.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960. Mean temperature increased between 1910 and 2013 by around 0.9 °C in the north and 1.0 °C in the south.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.6 to 1.4 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.8 to 5.1 °C. Under an intermediate scenario (RCP4.5) the projected warming is 1.3 to 2.6 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

In some areas, days with temperatures over 35 °C could occur for more than a third of the year under an intermediate emission scenario (RCP4.5) by late in the century.

Where frosts (minimum temperatures under 2 °C) occur in the cluster, these are projected to decrease.

Increased intensity of extreme rainfall events is projected, with high confidence.

Understanding of the physical processes that cause extreme rainfall, coupled with modelled projections, indicate with high confidence a future increase in the intensity of extreme rainfall events, although the magnitude of the increases cannot be confidently projected.

Time spent in drought is projected, with medium confidence, to increase over the course of the century.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise is 0.07 to 0.18 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.28 to 0.65 m and the high case (RCP8.5) a rise of 0.40 to 0.85 m (Carnarvon results). Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of the Rangelands coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 2.4 to 3.5 °C by 2090 under high emissions. The sea will also become more acidic, with acidification proportional to emissions growth.

With medium confidence , fewer but more intense tropical cyclones are projected.

FIRE WEATHER: Bushfire in the Rangelands depends highly on fuel availability, which mainly depends on rainfall. A tendency toward increased fire weather risk is expected in future, due to higher temperature and lower rainfall, but there is low confidence in the magnitude of fire weather projections.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY: Little change in relative humidity is projected for the near future (2030) while later in the century a decrease is projected in winter and spring (high confidence) and in summer and autumn (medium confidence).

SOLAR RADIATION: There is little change projected for solar radiation in the near future (2030), and for later in the century, increased radiation is projected in the south in winter (medium confidence).

Average winter rainfall is projected to decrease with high confidence. There is medium confidence in spring decrease. Changes in summer and autumn are possible but unclear. For the near future natural variability is projected to dominate any projected changes.

PAST RAINFALL TRENDS

The Central Slopes experienced notable prolonged periods of extensive drying in the early 20th century, but annual rainfall shows no long-term trend between 1910 and 2013. The seasonal rainfall characteristics are determined by complex interactions of rain-bearing systems from the east, southwest and sub-tropical north. Year to year variability is strongly influenced by the El Niño Southern Oscillation.

RAINFALL PROJECTIONS

In the near future (2030) natural variability is projected to predominate over trends due to greenhouse gas emissions in the Central Slopes cluster. Late in the century, climate model results indicate decreasing winter rainfall with high confidence. There is a good understanding of the physical mechanisms driving this change (southward shift of winter storm systems together with rising mean pressure over the region). Decreases are also projected in spring, with medium confidence.

The direction of change in summer and autumn cannot be confidently projected due to the complexity of rain producing systems in this region, the large spread of model results, and some inconsistent results from finer scale modelling.

Impact assessment in this region should consider the risk of both a drier and wetter climate.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960. Mean temperature increased between 1910 and 2013 by around 0.8 °C. Daily minimum temperatures have warmed more than daily maximum temperatures.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures in the Central Slopes cluster, in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.6 to 1.5 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 3.0 to 5.4 °C. Under an intermediate scenario (RCP4.5) the projected warming is 1.4 to 2.7 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

Frost risk days (minimum temperatures under 2 °C) are expected to decrease across the cluster (high confidence).

Some parts of the cluster could experience around twice the average number of days above 35 °C under an intermediate emission scenario by late in the century.

Increased intensity of extreme daily rainfall events is projected, with high confidence.

Understanding of the physical processes that cause extreme rainfall, coupled with modelled projections, indicate with high confidence a future increase in the intensity of extreme rainfall events, although the magnitude of the increases cannot be confidently projected.

Time spent in drought is projected, with medium confidence, to increase over the course of the century.

A harsher fire-weather climate in the future.

FIRE WEATHER: There is high confidence that climate change will result in a harsher fire-weather climate in the future. However, there is low confidence in the magnitude of the change as this is strongly dependent on the rainfall projection.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY: A decline in relative humidity is projected for winter and spring (high confidence) and summer and autumn (medium confidence), although changes in the near term are projected to be small.

SOLAR RADIATION: Related to the projected decline in winter rainfall, winter solar radiation is projected to increase with medium confidence.

Rainfall changes are possible but unclear. On annual and decadal basis, natural variability in the climate system can act to either mask or enhance any long-term human induced trend, particularly in the next 20 years.

PAST RAINFALL TRENDS

Observed trends in rainfall are not as significant as is the case for temperature. There is no long-term trend in annual rainfall for the sub-cluster during the available record. Year to year variability is strongly influenced by the El Niño-Southern Oscillation.

RAINFALL PROJECTIONS

Natural climate variability is projected to remain the major driver of rainfall changes in the next few decades. Models show a range of results, with little change or decrease being more common particularly in winter and spring.

Impact assessment in this region should consider the risk of both a drier and wetter climate.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960. Mean temperature increased between 1910 and 2013 by around 1.0 °C. The recent decades have been the warmest on record for both daily minimum and daily maximum temperatures in the sub-cluster.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.4 to 1.3 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.5 to 4.7 °C. Under an intermediate scenario (RCP4.5) the projected warming is 1.2 to 2.6 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

Frost risk days (minimum temperatures under 2 °C) are expected to decrease across the cluster (high confidence).

Some parts of the sub-cluster could experience around two to three times the average number of days above 35 °C under intermediate emission scenarios by late in the century.

Increased intensity of extreme rainfall events is projected, with high confidence.

Understanding of the physical processes that cause extreme rainfall, coupled with modelled projections, indicate with high confidence a future increase in the intensity of extreme rainfall events, although the magnitude of the increases cannot be confidently projected.

Time spent in drought is projected, with medium confidence, to increase over the course of the century.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise for the cluster coastline is 0.08 to 0.18 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.30 to 0.65 m and the high emissions case (RCP8.5) a rise of 0.44 to 0.87 m. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of the East Coast coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 2.1 to 3.6 °C by 2090 under a high scenario (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

A harsher fire-weather climate in the future.

FIRE WEATHER: There is high confidence that climate change will result in a harsher fire-weather climate in the future. However, there is low confidence in the magnitude of that change because of the significant uncertainties in the rainfall projection.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY: There is little change in relative humidity for the near future, but medium confidence in a decrease later in the century.

Decreases in winter rainfall are projected with medium confidence. Other changes are possible but unclear. On annual and decadal basis, natural variability in the climate system can act to either mask or enhance any long-term human induced trend, particularly in the next 20 years.

PAST RAINFALL TRENDS

Observed trends in rainfall are not as significant as is the case for temperature. While the sub-cluster experienced extended dry periods in the early 20th century, there is no long-term trend in annual rainfall during the available record. Year to year variability is strongly influenced by the El Niño-Southern Oscillation.

RAINFALL PROJECTIONS

Natural climate variability is projected to remain the major driver of rainfall changes in the next few decades. Models show a range of results, with little change or decrease being more common particularly in winter and spring. However, taking into account uncertainty over driving processes and results from downscaling, it is only in winter that a rainfall decrease is projected with medium confidence.

Impact assessment in this region should consider the risk of both a drier and wetter climate.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960. Mean temperature increased between 1910 and 2013 by around 0.8 °C. The recent decades have been the warmest on record for both daily minimum and daily maximum temperatures in the cluster.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.5 to 1.3 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.9 to 4.6 °C. Under an intermediate scenario (RCP4.5) the projected warming is 1.3 to 2.5 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

Frost risk days (minimum temperatures under 2 °C) are expected to decrease across the cluster (high confidence).

Some areas could experience around two to three times the average number of days above 35 °C under intermediate emission scenarios by late in the century.

Increased intensity of extreme rainfall events is projected, with high confidence.

Understanding of the physical processes that cause extreme rainfall, coupled with modelled projections, indicate with high confidence a future increase in the intensity of extreme rainfall events, although the magnitude of the increases cannot be confidently projected.

Time spent in drought is projected, with medium confidence, to increase over the course of the century.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise for the cluster coastline is 0.09 to 0.19 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.30 to 0.65 m and the high emissions case (RCP8.5) a rise of 0.45 to 0.88 m. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of the East Coast coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 2.8 to 5.7 °C by 2090 under a high scenario (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

A harsher fire-weather climate in the future.

FIRE WEATHER: There is high confidence that climate change will result in a harsher fire-weather climate in the future. However, there is low confidence in the magnitude of that change because of the significant uncertainties in the rainfall projection.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY: There is little change in relative humidity for the near future, but medium confidence in a decrease later in the century.

By late in the century (2090), less rainfall is projected during the cool season, with high confidence. There is medium confidence that rainfall will remain unchanged in the warm season. For the near future natural variability is projected to dominate any projected changes.

PAST RAINFALL TRENDS

The Murray Basin experienced notable prolonged periods of extensive drying in the early 20th century, but annual rainfall shows no long-term trend between 1910 and 2013.

RAINFALL PROJECTIONS

In the near future (2030) natural variability is projected to predominate over trends due to greenhouse gas emissions. Late in the century (2090) cool season (April to October) rainfall is projected to decline under both an intermediate (RCP4.5) and high (RCP8.5) emission scenario. In the warm season (November to March), little change, increases and decreases of rainfall are projected by different models. The magnitude of projected changes for late in the century (2090) span approximately -40 to +5 percent in winter and -15 to +25 percent in summer for a high emissions case (RCP8.5).

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960. Mean temperature increased between 1910 and 2013 by around 0.8 °C. Daily minimum temperatures have warmed more than daily maximum temperatures.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.6 to 1.3 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.7 to 4.5 °C. Under an intermediate scenario (RCP4.5) the projected warming is 1.3 to 2.4 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

Frost risk days (minimum temperatures under 2 °C) are projected to decrease across the cluster (high confidence), and could halve by late in the century.

Even though mean annual rainfall is projected to decline, heavy rainfall intensity is projected to increase, with high confidence.

Understanding of the physical processes that cause extreme rainfall, coupled with modelled projections, indicate with high confidence a future increase in the intensity of extreme rainfall events, although the magnitude of the changes cannot be confidently projected.

Time spent in drought is projected, with medium confidence, to increase over the course of the century.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise for the cluster coastline is 0.07 to 0.18 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.28 to 0.64 m and the high case (RCP8.5) a rise of 0.39 to 0.84 m. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of the Murray Basin coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 1.5 to 3.4 °C by 2090 under high emissions (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

A harsher fire-weather climate in the future.

FIRE WEATHER: There is high confidence that climate change will result in a harsher fire-weather climate in the future. However, there is low confidence in the magnitude of the change to fire weather. This depends on the rainfall projection and its seasonal variation. Enhanced summer rainfall projected in some scenarios could moderate the number of severe fire weather days.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY & SOLAR RADIATION: Small changes are projected for solar radiation and relative humidity for the near future (2030). Later in the century (2090), there is high confidence in projected increased winter and spring radiation (related to decreases in cloudiness associated with reduced rainfall) along with a projected decrease for relative humidity.

Generally little change or an increase in winter rainfall but a decrease in spring is projected with medium confidence. Changes to summer and autumn rainfall are possible but less clear. For the near future, natural variability is projected to dominate any projected changes.

PAST RAINFALL TRENDS

The Southern Slopes Tasmania East region experienced wet and dry decades through the 20th century, and showed a drying trend in rainfall since 1960, especially in autumn. The wet decades of the 1950s and 1970s were followed by a very significant period of drought, known as the Millennium Drought (1996 to 2009).

RAINFALL PROJECTIONS

In the near future (2030) natural variability is projected to predominate over trends due to greenhouse gas emissions.

Rainfall increases are projected (medium confidence) for SSTE in winter. By the middle of the century, and under high emissions, winter and spring changes are projected to be evident against natural variability. Changes to summer and autumn rainfall are possible but not clear, and regional changes specific to eastern Tasmania are possible. Available fine-scale modelling provides further detail on possible spatial variation in rainfall response.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures projected in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.4 to 1.1 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.3 to 4.0°C. Under an intermediate scenario (RCP4.5) the projected warming is 0.9 to 1.9 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

Frost-risk days (minimum temperatures under 2 °C) are expected to decrease across the cluster (high confidence)

Increased intensity of extreme rainfall events is projected, with high confidence.

Even though annual mean rainfall is projected to experience little change or decrease in the region, understanding of the physical processes that cause extreme rainfall, coupled with modelled projections indicate with high confidence a future increase in the intensity of extreme rainfall events. However, the magnitude of the increases cannot be confidently projected.

Time spent in drought is projected, with medium confidence, to increase over the course of the century.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise for the cluster coastline is 0.08 to 0.18 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.31 to 0.66 m and the high case (RCP8.5) a rise of 0.45 to 0.89 m. Under certain circumstances, sea-level rises higher than these may occur.

LLate in the century warming of the Southern Slopes coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 2.1 to 5.1 °C by 2090 under high emissions (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

A harsher fire-weather climate in the future.

FIRE WEATHER: There is high confidence that climate change will result in a harsher fire-weather climate in the future. However, there is low confidence in the magnitude of the change to fire weather. This depends on the rainfall projection and its seasonal variation. Relative changes are comparable across all three sub-clusters.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY AND SOLAR RADIATION: An increase in solar radiation and a decrease in relative humidity is projected in the cool season through the century (high confidence). This will be influenced by changes in rainfall (and associated changes to cloudiness) and temperature in the cluster. Changes in summer and autumn are less clear.

Generally less rainfall in spring (high confidence) and more rainfall in winter is projected (medium confidence). Changes to autumn rainfall are possible but less clear and there is a projected tendency for decrease in summer. For the near future, natural variability is projected to dominate any projected changes.

PAST RAINFALL TRENDS

The Southern Slopes Tasmania West sub-cluster experienced wet and dry decades through the 20th century, and shows a drying trend in autumn rainfall since 1960, with winter and spring increases observed over this period. The wet decades of the 1950s and 1970s were followed by a very significant period of drought, known as the Millennium Drought (1996 to 2009).

RAINFALL PROJECTIONS

In the near future (2030) natural variability is projected to predominate over trends due to greenhouse gas emissions. Understanding of physical rainfall processes (southward shift of winter storm systems), supported by climate model results, indicate a rainfall decrease for spring (high confidence), and little change or increase for winter (medium confidence).

The projected winter increase over Western Tasmania is up to 20 per cent and decrease in spring is up to -33 per cent by 2090 under high emissions. By the middle of the century, and under high emissions, spring and perhaps winter changes are projected to be evident against natural variability. Changes to autumn rainfall are possible but not clear, and there is a tendency for projected decrease in western Tasmania in summer. Available fine-scale modelling provides further detail on possible spatial variation in rainfall response.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures projected in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.2 to 1.1 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.1 to 3.6°C. Under an intermediate scenario (RCP4.5) the projected warming is 0.9 to 1.8 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

Frost-risk days (minimum temperatures under 2 °C) are expected to decrease across the cluster (high confidence)

Increased intensity of extreme rainfall events is projected, with high confidence.

Even though annual mean rainfall is projected to experience little change or decrease in the region, understanding of the physical processes that cause extreme rainfall, coupled with modelled projections indicate with high confidence a future increase in the intensity of extreme rainfall events. However, the magnitude of the increases cannot be confidently projected.

Time spent in drought is projected, with medium confidence, to increase over the course of the century.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise for the cluster coastline is 0.08 to 0.18 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.29 to 0.63 m and the high case (RCP8.5) a rise of 0.41 to 0.83 m. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of the Southern Slopes coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 1.9 to 4.0 °C by 2090 under high emissions (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

A harsher fire-weather climate in the future.

FIRE WEATHER: There is high confidence that climate change will result in a harsher fire-weather climate in the future. However, there is low confidence in the magnitude of the change to fire weather. This depends on the rainfall projection and its seasonal variation. Relative changes are comparable across all three sub-clusters.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY AND SOLAR RADIATION: An increase in solar radiation and a decrease in relative humidity is projected in the cool season through the century (high confidence). This will be influenced by changes in rainfall (and associated changes to cloudiness) and temperature in the cluster. Changes in summer and autumn are less clear.

Generally less rainfall in the cool season is projected with high confidence. Changes to summer and autumn rainfall are possible but less clear. For the near future, natural variability is projected to dominate any projected changes.

PAST RAINFALL TRENDS

The Southern Slopes Victoria East sub-cluster experienced wet and dry decades through the 20th century, and shows a drying trend in rainfall since 1960, especially in autumn. The wet decades of the 1950s and 1970s were followed by a very significant period of drought, known as the Millennium Drought (1996 to 2009).

RAINFALL PROJECTIONS

In the near future (2030) natural variability is projected to predominate over trends due to greenhouse gas emissions. Understanding of physical rainfall processes (southward shift of winter storm systems), supported by climate model results, indicate rainfall decreases for winter and spring (high confidence).

The winter decreases over Eastern Victoria are up to 30 per cent in 2090 under high emissions. By the middle of the century, and under high emissions, winter changes are projected to be evident against natural variability. Changes to summer and autumn rainfall are possible but not clear. Available fine-scale modelling provides further detail on possible spatial variation in rainfall response.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures projected in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.5 to 1.2 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.7 to 4.3°C. Under an intermediate scenario (RCP4.5) the projected warming is 1.3 to 2.2 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

Frost-risk days (minimum temperatures under 2 °C) are expected to decrease across the cluster (high confidence).

Increased intensity of extreme rainfall events is projected, with high confidence.

Even though annual mean rainfall is projected to decrease in the region, understanding of the physical processes that cause extreme rainfall, coupled with modelled projections indicate with high confidence a future increase in the intensity of extreme rainfall events. However, the magnitude of the increases cannot be confidently projected.

Time spent in drought is projected, with medium confidence, to increase over the course of the century.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise for the cluster coastline is 0.07 to 0.17 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.27 to 0.62 m and the high case (RCP8.5) a rise of 0.38 to 0.81 m. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of the Southern Slopes coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 1.6 to 3.4 °C by 2090 under high emissions (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

A harsher fire-weather climate in the future.

FIRE WEATHER: There is high confidence that climate change will result in a harsher fire-weather climate in the future. However, there is low confidence in the magnitude of the change to fire weather. This depends on the rainfall projection and its seasonal variation. Relative changes are comparable across all three sub-clusters.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY AND SOLAR RADIATION: An increase in solar radiation and a decrease in relative humidity is projected in the cool season through the century (high confidence). This will be influenced by changes in rainfall (and associated changes to cloudiness) and temperature in the cluster. Changes in summer and autumn are less clear.

Generally less rainfall in the cool season is projected with high confidence. Changes to summer and autumn rainfall are possible but less clear. For the near future, natural variability is projected to dominate any projected changes.

PAST RAINFALL TRENDS

The Southern Slopes Victoria West sub-cluster experienced wet and dry decades through the 20th century, and shows a drying trend in rainfall since 1960, especially in autumn. The wet decades of the 1950s and 1970s were followed by a very significant period of drought, known as the Millennium Drought (1996 to 2009).

RAINFALL PROJECTIONS

In the near future (2030) natural variability is projected to predominate over trends due to greenhouse gas emissions. Understanding of physical rainfall processes (southward shift of winter storm systems), supported by climate model results, indicate rainfall decreases for winter and spring (high confidence).

The projected decreases over Western Victoria are up to 25 per cent in winter and up to 45 per cent in spring by 2090 under high emissions. By the middle of the century, and under high emissions, winter and spring changes are projected to be evident against natural variability. Changes to summer and autumn rainfall are possible but not clear, although there is a tendency for decrease in western Victoria in autumn. Available fine-scale modelling provides further detail on possible spatial variation in rainfall response.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures projected in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.4 to 1.1 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.4 to 3.8°C. Under an intermediate scenario (RCP4.5) the projected warming is 1.1 to 1.9 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

Frost-risk days (minimum temperatures under 2 °C) are expected to decrease across the cluster (high confidence).

Increased intensity of extreme rainfall events is projected, with high confidence.

Even though annual mean rainfall is projected to decrease in the region, understanding of the physical processes that cause extreme rainfall, coupled with modelled projections indicate with high confidence a future increase in the intensity of extreme rainfall events. However, the magnitude of the increases cannot be confidently projected.

Time spent in drought is projected, with medium confidence, to increase over the course of the century.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise for the cluster coastline is 0.08 to 0.18 m above the 1986–2005 level, with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.29 to 0.64 m and the high case (RCP8.5) a rise of 0.39 to 0.84 m. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of the Southern Slopes coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 1.6 to 3.4 °C by 2090 under high emissions (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

A harsher fire-weather climate in the future.

FIRE WEATHER: There is high confidence that climate change will result in a harsher fire-weather climate in the future. However, there is low confidence in the magnitude of the change to fire weather. This depends on the rainfall projection and its seasonal variation. Relative changes are comparable across the other three sub-clusters of Southern Slopes.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY AND SOLAR RADIATION: An increase in solar radiation and a decrease in relative humidity is projected in the cool season through the century (high confidence). This will be influenced by changes in rainfall (and associated changes to cloudiness) and temperature in the sub-cluster. Changes in summer and autumn are less clear.

A continuation of the trend of decreasing winter rainfall is projected with high confidence. Spring rainfall decreases are also projected with high confidence. Changes in other seasons are unclear, although downscaling suggests a continuation of the observed autumn declines.

PAST RAINFALL TRENDS

There has been a prolonged period of extensive drying from the 1970s in SSWF West to the present, particularly in early winter and autumn. The southward shift of winter storm systems and greater prevalence of high pressure systems are the physical mechanisms that have driven decreases in winter rainfall. Some of this change has been attributed to rising levels of atmospheric greenhouse gases.

RAINFALL PROJECTIONS

Decreases in winter and spring (and annual) rainfall are projected with high confidence. There is strong model agreement and good understanding of the contributing underlying physical mechanisms driving this change (southward shift of winter and spring storm systems).

Early in the century (2030) and under all emission scenarios, winter rainfall is projected to decrease by up to 15 per cent. Late in the century, intermediate emissions (RCP4.5) lead to a projected decrease in winter rainfall of up to around 30%, and under high emissions (RCP8.5) winter rainfall decline is projected to decrease by up to 45%. Changes in autumn and summer are less clear, although downscaling results suggest a continuation of the observed autumn declines.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960. Mean temperature increased between 1910 and 2013 by around 1.1 °C.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures in line with our understanding of the effect of further increases in greenhouse gas concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.5 to 1.2 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.6 to 4.2 °C. Under an intermediate scenario (RCP4.5) the projected warming is 1.1 to 2.1 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

Frost risk days (minimum temperatures under 2 °C) are expected to decrease across the cluster (high confidence).

Increased intensity of extreme rainfall events is projected, with medium confidence.

Even though annual mean rainfall is projected to decrease in the region, projections indicate increases in extreme rainfall. Strongly decreasing mean rainfall in this region gives us medium confidence in this projection, where for all other Australian regions higher confidence is given. Furthermore, the magnitude of the increases cannot be confidently projected.

Time spent in drought is projected (with high confidence) to increase over the course of the century.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise for the cluster coastline is 0.07 to 0.18 m above the 1986–2005 level with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.27 to 0.64 m and the high case (RCP8.5) a rise of 0.38 to 0.84 m. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century, warming of the SSWF coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 1.6 to 3.8 °C by 2090 under high emissions (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

A harsher fire-weather climate in the future.

FIRE WEATHER: There is high confidence that climate change will result in a harsher fire-weather climate in the future. However, there is low confidence in the magnitude of the change as this is strongly dependent on the rainfall projection.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY: A tendency for a decline in relative humidity is projected for winter and spring although changes in the near term will be small (high confidence).

SOLAR RADIATION: Related to the projected decline in winter rainfall, winter solar radiation is projected to increase (high confidence). Radiation in spring is also projected to increase (medium confidence).

A continuation of the trend of decreasing winter rainfall is projected with high confidence. Spring rainfall decreases are also projected with high confidence. Changes in other seasons unclear, although downscaling results suggest a continuation of the observed autumn declines.

PAST RAINFALL TRENDS

There has been a prolonged period of extensive drying from the 1990s, particularly in early winter and autumn. The southward shift of winter storm systems and greater prevalence of high pressure systems are the physical mechanisms that have driven decreases in winter rainfall.

RAINFALL PROJECTIONS

Decreases in winter and spring (and annual) rainfall are projected with high confidence. There is strong model agreement and good understanding of the contributing underlying physical mechanisms driving this change (southward shift of winter and spring storm systems).

Early in the century (2030) and under all emission scenarios, winter rainfall is projected to decrease by up to 15 per cent. Late in the century, intermediate emissions (RCP4.5) lead to a projected decrease in winter rainfall of up to 25%, and under high emissions (RCP8.5) winter rainfall decline is projected to decrease by up to 45%. Changes in autumn and summer are less clear, although downscaling results suggest a continuation of the observed autumn declines.

Average temperatures will continue to increase in all seasons (very high confidence).

PAST TEMPERATURE TRENDS

Temperatures have increased over the past century, with the rate of warming higher since 1960. Mean temperature increased between 1910 and 2013 by around 0.7 °C.

TEMPERATURE PROJECTIONS

There is very high confidence in continued substantial increases in projected mean, maximum and minimum temperatures in line with our understanding of the effect of further increases in greenhouse gases concentrations.

For the near future (2030), the annually averaged warming across all emission scenarios is projected to be around 0.4 to 1.1 °C above the climate of 1986–2005.

By late in the century (2090), for a high emission scenario (RCP8.5) the projected range of warming is 2.4 to 3.9 °C. Under an intermediate scenario (RCP4.5) the projected warming is 1.0 to 1.9 °C.

More hot days and warm spells are projected with very high confidence. Fewer frosts are projected with high confidence.

Extreme temperatures are projected to increase at a similar rate to mean temperature, with a substantial increase in the temperature reached on hot days, the frequency of hot days, and the duration of warm spells (very high confidence).

Frost risk days (minimum temperatures under 2 °C) are expected to decrease across the cluster (high confidence).

Increased intensity of extreme rainfall events is projected, with high confidence.

Even though annual mean rainfall is projected to decrease in the region, understanding of the physical processes that cause extreme rainfall, coupled with modelled projections indicate with high confidence a future increase in the intensity of extreme rainfall events. However, the magnitude of the increases cannot be confidently projected.

Time spent in drought is projected (with high confidence) to increase over the course of the century.

Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).

For 1966 to 2009, the average rate of relative sea-level rise for Australia, from observations along the coast, was 1.4 mm/year.

There is very high confidence in future sea-level rise. By 2030 the projected range of sea-level rise for the cluster coastline is 0.07 to 0.17 m above the 1986–2005 level with only minor differences between emission scenarios. As the century progresses, projections are sensitive to concentration pathways. By 2090, the intermediate emissions case (RCP4.5) is associated with a rise of 0.28 to 0.63 m and the high case (RCP8.5) a rise of 0.39 to 0.83 m. Under certain circumstances, sea-level rises higher than these may occur.

Late in the century warming of the SSWFE coastal waters poses a significant threat to the marine environment through biological changes in marine species, including local abundance, community structure, and enhanced coral bleaching risk. Sea surface temperature is projected to increase in the range of 1.5 to 3.5 °C by 2090 under high emissions (RCP8.5). The sea will also become more acidic, with acidification proportional to emissions growth.

A harsher fire-weather climate in the future.

FIRE WEATHER There is high confidence that climate change will result in a harsher fire-weather climate in the future. However, there is low confidence in the magnitude of the change as this is strongly dependent on the rainfall projection.

EVAPORATION: Potential evapotranspiration is projected to increase in all seasons as warming progresses (high confidence).

HUMIDITY: A tendency for a decline in relative humidity is projected for winter and spring although changes in the near term will be small (high confidence).

SOLAR RADIATION: Related to the projected decline in winter rainfall, winter solar radiation is projected to increase (high confidence). Radiation in spring is also projected to increase (medium confidence).