| Variable | Historical Trend (since 1950s) | Projected Change (by 2050-2090) | | :--- | :--- | :--- | | Summer temperatures | +1.4°C to +1.6°C on average | +1.5 to +3.0°C (depending on emissions) | | Heatwave frequency | Doubled in some regions | 4 to 10 times more frequent | | Extreme heat days (>35°C) | Increased by 10-20 days/year | 25-50 additional days/year | | Rainfall in southern Australia | Decreased by 10-20% (May–July) | Further drying (10-30% less) | | Fire weather danger | Increased (longer fire season) | Extreme fire days increase by 20-50% | | Sea level rise (coastal summer storms) | ~3-4 mm/year | 0.4-0.8 m by 2090 |