Wednesday, January 9, 2019

Australia's Christmas-New Year heatwave as global warming at 1.1C above pre-industrial


I followed the heatwave over the Christmas - New Year period at the end of 2018 and start of 2019. Read my climate diary of the event.

I did some charting of temperature maximums for capital cities and a few regional observation points for each state. My selection may not be fully representative of regional temperatures.

The heatwave for most areas really commenced from 24 December. It ended at various dates: on 4 January for South Australia, 5th January for Victoria and Northern Territory, 6th January for New South Wales. Temperatures have remained high in Marble Bar in the Pilbara, and although temperatures have dipped a little, remain elevated in the high 30s for Central Australia and Central Queensland.

The heat has retreated from the south east states to again build in the Pilbara and central Australia for the next blast of heat to the south eastern population centres probably from the 14 January.


Western Australia: The heatwave has its origin in large areas of heat emanating from the Pilbara area and Central Australia. Capital city Perth experienced hardly any impact from this heatwave. It had a 41C day on 22/12 and a 36 degree day on 6 January, but otherwise fairly mild temperatures for Perth. Except for the first 3 days at the start the coastal town of Broome had tropical temperatures below 35C. The real heat was in the Pilbara town of Marble bar with constant temperatures between 42C and 49C for the whole period.


Northern Territory. Darwin had mostly constant tropical maximum temperatures between 32-34 degrees celsius. The real heat was further south at Alice Springs, Tennant Creek and Yulara. Temperatures in central Australia escalated on 24/12 and remained elevated in the low 40s until dropping 7 degrees on 5th January. There is still oncredible heat in central Australia.


Darwin and Alice Springs compared. A clearer comparison of maximum temperatures in Darwin and Alice Springs for the heatwave. Is it any wonder that prisoners at Alice Springs Prison complained about the lack of heat respite and rioted at the overcrowded sweltering inhumane conditions.

Queensland. Brisbane in the south east has remained around the 30 degree maximum temperature level, although started high on 35C. Birdsville in Western Queensland, and Mount Isa further north in western Queensland both show elevated temperaturtes between 40 and 45 degrees for the whole period, with Birdsville dipping below 40C towards the end on 6th January.

South Australia: The heatwave is more pronounced in South Australia. Adelaide and Port Augusta at the top of Spencer's Gulf show two distinct peaks, on 27 December and 3 January. Further north, Moomba and Roxby Downs show temperatures climbing for 5 days, then plateauing above 40 degrees, before all falling on the 5th January.

New South Wales: Temperatures climbed for the first 5 days then leveling off before falli9ng on 5th or 6th January. North Western and south western NSW remain hot with temperatures in many towns still above 35C. The western plains town of Walgett ran out of water when lightning struck a bore water pumping facility. Although the town is near the junction of the Barwon and Namoi rivers, both are merely a series of muddy pools due to the ongoing drought and mismanagement of water in the upper Murray Darling Basin catchments. The town has a significant aboriginal population. Many houses use evaporative air-conditioners for cooling dependant on water supply, so the pumping station out of action meant no cooling during the heatwave for some people.


Comparing Sydney (Observatory Hill} with Penrith. Comparing Penrith to Sydney (Observatory Hill) you can see large differences in maximum temperature, sometimes as much as 11 degrees. This is a pronounced difference caused by the geography of the Sydney Basin with Observatory Hill receiving cooling from sea breezes while the western suburbs often swelter with temperatures several degrees hotter. This is not helped by the level of destruction of remnant woodland for urban development in western Sydney which increases the urban heat island effect boosting temperatures.

Victoria: Melbourne had a two day heat event on 27-28 December, and a single day on 4th January. While there is a difference between Melbourne temperatures and suburbs north and west of the city, the difference is not nearly as pronounced as that between western Sydney and Observatory Hill. While Melbourne may have only had three extreme heat days, north of the Great Divide many towns had continuous period of heat in excess of 35C from 24 December to 4 January, with a cold front dropping temperatures back to the 20s. Towns north of the divide have started to see temperatures climb again.

The heat spiked on 27th December with a new Australia area record for maximum temperature of 40.1 degrees Celcius.


This heatwave did not happen in a vacuum. The Climate Council in their 2014 report on Heatwaves: longer, hotter more often demonstrated that such events would become more common, last longer and be more intense.

Average temperature of last five years at 1.1C above pre-industrial


The latest report from the the Copernicus Climate Change Service (C3S) show that 2018 was the fourth in a series of exceptionally warm years.

2018 as a whole tied with 2015 for 3rd warmest on record globally, behind 2016 and 2017 with +0.43°C above the 1981-2010 normal. The average temperature of the last 5 years was 1.1°C higher than the pre-industrial average (as defined by the IPCC).

According to satellite measurements of global atmospheric CO2 concentrations: CO2 continued to rise in 2018 and increased by 2.5 +/- 0.8 ppm/year.

The largest deviation from normal was in the Arctic, with a hotspot near Svalbard. There was a cool blob in the North-Atlantic.

The report notes for December 2018: that globally, temperatures were just under 0.5°C above the average December for 1981-2010 and that Australia experienced exceptionally hot and dry conditions.