This and other facts are outlined by two scientists from the Bureau of Meteorology here.
Some other interesting facts:
- Janurary 2013 when we had that massive heatwave was the hottest month in Australia on record, hotter than every other month going back to 1910.
- Sept 2012 - Feb 2013 was the hottest 6 month period on record.
- This record hot summer occurred without an El Nino event. El Nino's give temperatures a short term boost and generally mean hotter summers for Australia (the previous three hottest summers all occurred in El Nino years). This is consistent with increasing temperatures allowing records to fall without an El Nino "bump".
- This last summer saw record heat across the southern hemisphere land mass as a whole.
- "Six of Australia’s ten hottest summers on record have come in the last 11 years, meaning that very hot summers have been occurring at about five times the rate you would expect without a warming trend"
- "With higher average temperatures come more extremes of heat. In the last decade, record high temperatures have outnumbered record low temperatures in Australia by a ratio of about three to one"