Climate Change Projections
The information presented here is a summary of the region from projections provided by the CSIRO Climate Change in Australia modelling.
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 and for rainfall.
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.
Average temperatures will continue to increase in all seasons.
Past temperature trends
Temperatures have increased over the past century with daily minimum temperatures increasing more than daily maximums.
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.
Extreme Rainfall & Drought
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.
Marine & Coast
Mean sea level will continue to rise and height of extreme sea-level events will also increase.
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.
Fewer but more intense tropical cyclones are projected.
Tropical cyclones are projected to become less frequent, but the proportion of the most intense storms is projected to increase.
Fire Weather Conditions
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.
Potential evapotranspiration is projected to increase in all seasons as warming progresses.
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.
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