Australia has its warmest summer on record

The historic summer of 2012 - 2013 is now in the books in Australia as the hottest summer on record, beating the previous mark set in 1997 - 1998 by more than 0.1°C. Australia also roasted through its hottest month on record this summer, with January 2013 topping out as Australia's warmest month since record keeping began in 1910. The oceans surrounding Australia were at their second warmest levels on record during January, contributing to the exceptional heat over the nation. The summer heat peaked during a remarkably long and widespread heatwave in late December and the first half of January, when fourteen of the 112 sites used by the Bureau of Meteorology for long-term monitoring had their hottest day on record. Sydney's 45.8°C (114.4°F) on January 18 and Hobart's 41.8°C (107.2°F) on January 4 were among the places which set new records. The highest temperature during the heatwave was 49.6°C (121.3°F) at Moomba in the far northeast of South Australia--Australia’s highest temperature since 1998. The extreme Australian heat helped push the average land temperature over the entire Southern Hemisphere to its warmest value on record during both December 2012 and January 2013. Many parts of southern Africa also had their warmest January on record.


Figure 1. Devastating wildfires swept through many areas of Australia during January 2013, the nation's hottest month on record. In this photo provided by the New South Wales Rural Fire Service, a wildfire near Deans Gap, Australia, crosses the Princes Highway Tuesday, Jan. 8, 2013. (AP Photo/NSW Rural Fire Service, James Morris)

Record heat without an El Niño: an unusual occurrence
What's notable about the new summer heat record is that is occurred during a “neutral” period in the El Niño-Southern Oscillation (there was neither a La Niña nor El Niño event present.) El Niño conditions add an extra natural bump to temperatures over Australia, and it is difficult to set all-time heat records unless there's an El Niño present. Before 2013, the hottest three summers on record in Australia occurred during El Niño years. Breaking an all-time hottest month and hottest summer record during a non-El Niño year is the type of event that would be difficult to have in Australia without a warming climate.


Figure 2. The departure of temperature from average for Australia from 1910 - 2013 shows that summer temperatures have warmed by about 0.8°C (1.4°F.) Most of this warming has occurred since 1950. Image credit: Australian Bureau of Meteorology.

Global warming expected to make the summer of 2012 - 2013 seem cool by late this century
According to the Australian Bureau of Meteorology, "the most significant thing about all of these extremes is they fit with a well established trend in Australia--it’s getting hotter, and record heat is happening more often. Six of Australia’s ten hottest summers on record have come in the last eleven years, meaning that very hot summers have been occurring at about five times the rate you would expect without a warming trend. In the last decade, record high temperatures have outnumbered record low temperatures in Australia by a ratio of about three to one. About a third of the all-time record high temperatures at the Bureau’s long-term stations have occurred since 2000…Australia has warmed by nearly a degree Celsius since 1910. This is consistent with warming observed in the global atmosphere and oceans. And it’s going to keep getting hotter. Over the next century, the world will likely warm by a further 2 to 5 degrees, depending on the amount of greenhouse gases emitted into the atmosphere. Under mid-to-high emissions scenarios, summers like this one will likely become average in 40 years time. By the end of the 21st century, the record summer of 2013 will likely sit at the very cooler end of normal."

Jeff Masters