Friday, 30 January 2015
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…..
…..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.
EXTREME RAINFALL & DROUGHT
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.
MARINE & COAST
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.