New ground-breaking scientific research in 2014 can now tell us just how much of an influence climate change has on a single heatwave or heat records.
1. Climate change is making Australia hotter. Hot days are happening more often while heatwaves are becoming hotter, longer and more frequent.
- The annual number of record hot days across Australia has doubled since 1960. Over the past 10 years the number of record hot days has occurred three times more frequently than the number of record cold days.
- The annual occurrence of very hot days across Australia has increased strongly since 1950 and particularly sharply in the last 20 years.
- Over the 1950-2013 period many characteristics of heatwaves have changed across Australia. They are becoming hotter, lasting longer, occurring more often and starting earlier.
- All extreme heat events are now occurring in an atmosphere that is significantly hotter than it was 50 years ago
2. While it has been clear for many years that climate change is a major factor in intensifying heat, recent scientific advances now allow us to understand the extent of the impact on individual extreme events. Climate change has significantly worsened recent extreme heat events in Australia.
- The record hot year of 2013 in Australia was virtually impossible without climate change.
- Climate change tripled the odds that the heatwaves of the 2012/2013 Australian summer would occur as frequently as they did.
- Climate change doubled the odds that the 2012/2013 heatwaves would be as intense as they were.
3. The new research showing the strong influence of climate change on heat events strengthens the case for strong action on climate change.
- Carbon emissions must be reduced rapidly and deeply if the worst of extreme heat in the second half of the century is to be avoided.
- Clean energy technologies are advancing rapidly and international action is ramping up, building momentum towards a decarbonised future.
This Climate Council report synthesises recent scientific advances, including a set of papers from a special supplement to the Bulletin of the American Meteorological Society, Vol. 95, No. 9, September 2014, 'Explaining Extreme Events of 2013 from a Climate Perspective': Arblaster et al (2014); King et al (2014); Knutson et al (2014); Lewis and Karoly (2014) and Perkins et al (2014). See journal edition here: http://journals.ametsoc.
The Climate Council acknowledges the role of the ARC Centre of Excellence for Climate System Science at providing funding, computational, and networking support for some of the primary research that this report draws from, including the set of BAMS papers.