The Illawarra can expect warmer temperatures and more intense rain events, but the climate change jury is still out on what could happen with average rainfall in coming years.
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The CSIRO and Bureau of Meteorology’s latest projections, which outline how the climate may change to the end of the 21st century, were revealed on Tuesday.
Lead author of the technical report, and honorary CSIRO research fellow Penny Whetton said the region could expect temperatures warming about half to one degree by 2030.
Dr Whetton said longer-term temperatures were dependent on future greenhouse gas emissions.
‘‘If you follow a fairly low emissions path, the warming will be about 1.3 to 2.5 degrees [by the end of the century], but if you follow a high emission path it’s around 3 degrees to 4.5 degrees,’’ Dr Whetton said.
‘‘Along with that you’re getting an increase in the number of hot days and fewer cold days.
‘‘Quite a lot more days over 35, for example, than currently experienced.’’
In terms of rainfall, Dr Whetton said heavy rain would likely be more intense due to the warmer atmosphere.
‘‘Intense heavy rainfall events are something the Illawarra region does get from time to time and there’s the potential for them to be more extreme,’’ she said.
The projections might have been released on what was a gloomy Illawarra day, however, the region’s long-term average rainfall picture isn’t so clear.
‘‘The strongest evidence we have for future changes is for a decline in winter rainfall, but our models actually give inconsistent lines of evidence for changes in the warmer half of the year,’’ she said.
‘‘It’s clearer in other parts of Australia, but the east coast seems to be one of the trickier parts for us to get all of our evidence lining up and giving us a strong message.’’
The projections indicated with ‘‘very high confidence’’ mean sea level would continue to rise – between 10 and 20 centimetres by 2030.
The figure could jump as high as 88 centimetres by 2090 if future greenhouse gas emissions were high, Dr Whetton said.
‘‘We’ve seen sea level rise in the past, but certainly under those high emissions that represents quite an acceleration in sea level rise over the decades to come,’’ she said.
As a result, storm surges are predicted to be higher and there is an increased likelihood of flooding and erosion.
- Average temperatures will continue to increase in all seasons (very high confidence).
- More hot days and warm spells are projected (very high confidence) and there will be fewer frosts (high confidence).
- Decreases in winter rainfall are projected with medium confidence. Other changes are possible, but unclear. Increased intensity of extreme rainfall events (high confidence).
- Mean sea level will continue to rise and height of extreme sea-level events will also increase (very high confidence).
- A harsher fire-weather climate in the future (high confidence).
- Time spent in drought is projected, with medium confidence, to increase over the course of the century.
- Little change in relative humidity in the near future, but medium confidence of a decrease later in the century.