- 2018 was the third-hottest year on record
- Rainfall was down 11 per cent on average, and was the lowest since 2005
- The low rainfall, particularly over parts of the eastern states, culminated in “severe drought” in the second half of 2018
According to Karl Braganza, BOM’s head of climate monitoring, it was the third-warmest year on record for Australia as a whole.
“That’s just beating the previous year, which was the third-warmest year on record in 2017,” Dr Braganza said.
The warmest year on record was 2013, when temperatures were 1.33 degrees Celsius above the 1961 to 1990 mean. Second was 2005 at 1.15C above the mean, narrowly beating out 2018 at 1.14C above.
Drought really kicked in
Dr Braganza said it was the sixth-driest year for New South Wales, but overall, it was not record-breaking.
“Across Australia rainfall was about 11 per cent below average and again, it’s the lowest since 2005, which again goes back to that millennium drought period,” he said. “It’s the most significant dry period, post-millennium drought.”
He said rainfall across 2017 and 2018 had been low, particularly over parts of NSW, Queensland, and the eastern states, which had culminated in “severe drought” in the second half of last year.
September saw the lowest rainfall on record nationally and the second-lowest for any month since April 1902, during the Federation Drought, according to Dr Braganza.
In addition, high temperatures and winds had worked to exacerbate the drying.
‘Catastrophic fire conditions’
The dry conditions had a big impact on 2018.
“Looking at the inland river systems, they’re really suffering from a lack of rainfall now in Queensland and New South Wales,” Dr Braganza said.
“That’s had a large impact on agriculture and then the impact on fire weather on the fires themselves.”
Dr Braganza said some really significant out-of-season fires, like the August fires in eastern Victoria and those in Bega, were really stretching our ability to manage fire in Australia.
“That lengthening fire season, which we’ve seen trends for over the last 30 years or so, was certainly evident in 2018,” he said.
Another major event of 2018 were the late November and early December fires in Queensland.
“That was again associated with existing dry conditions leading into that [in] late November.
“We saw really significant bushfires along about a 600-kilometre stretch of coast in Queensland and catastrophic fire conditions.
“That’s been a feature of the southern states for quite some time [and] unfortunately, in 2018 parts of Queensland saw what Victoria, South Australia, Tasmania and parts of NSW and West Australia have seen over the last 10 years or so.”
Climate drivers at play
This year the Indian Ocean and the Indian Ocean dipole had a big impact on our weather.
“Australia gets a large influence from both the Indian Ocean, the Pacific Ocean, and then from things like climate change at the global scale,” Dr Braganza said.
“Spring was a really good example; we had conditions in the Indian Ocean that weren’t favourable to rainfall and that’s exactly what we saw across Australia.”
Across in the Pacific, the year started off with weak La Nina conditions before transitioning into a developing El Nino which has yet to eventuate.
The fact that it has been so hot for two years in a row without a strong El Nino event is significant.
“2017 and 2018 saw us reach those really high temperatures consistently across eastern Australia without that additional push from El Nino, [it] highlights the importance of the background warming trend in Australia.”
However, it was not just drought, but heatwaves too.
“We finished off the year with a burst of heat,” Dr Braganza said.
“Over the Christmas/New Year period [we] saw temperatures at least 10 degrees warmer than average across SA, Victoria, [and] southern NSW and that was enough to see Australia record its hottest December on record.”
But there was wet weather too with tropical cyclones Irving, Joyce, Kelvin, Linda, Marcus, and Nora at the beginning of the year and Owen in December, which brought 681 millimetres of rain to Halifax, near Ingham, in 24 hours.
Dry set to continue
If you were hoping some of that rain would make its way south, do not get your hopes up.
Dr Braganza said there was no relief on the cards and it is looking to stay dry until March at least.
“So we will see an extension of the warmth and the dry — and the fire season obviously has a little while to go, particularly in southern parts of the continent and inland NSW.”
The dry is only adding to the heat.
“The lack of moisture out there in the environment actually assists the sort of heatwaves that we saw around the Christmas period,” Dr Braganza said.
“I would expect we’ve got a few more heatwaves to go in summer, looking at the long-range outlook.
“So we’ll be keeping vigilance to the fire weather, probably through into autumn.”
Source: ABC News 2019-01