Australia's record-breaking winter warmth linked to climate change

Australia's record-breaking winter warmth linked to climate change
This winter had some extreme low and high temperatures. Credit: Daniel Lee/Flickr, CC BY-NC

On the first day of spring, it's time to take stock of the winter that was. It may have felt cold, but Australia's winter had the highest average daytime temperatures on record. It was also the driest in 15 years.

Back at the start of winter the Bureau of Meteorology forecast a warm, dry season. That proved accurate, as winter has turned out both warmer and drier than average.

While we haven't seen anything close to the weather extremes experienced in other parts of the world, including devastating rainfalls in Niger, the southern US and the Indian subcontinent all in the past week, we have seen a few interesting weather extremes over the past few months across Australia.

Drier weather than normal has led to warmer days and cooler nights, resulting in some extreme temperatures. These include night-time lows falling below -10℃ in the Victorian Alps and -8℃ in Canberra (the coldest nights for those locations since 1974 and 1971, respectively), alongside daytime highs of above 32℃ in Coffs Harbour and 30℃ on the Sunshine Coast.

During the early part of the winter the southern part of the country remained dry as record high pressure over the continent kept cold fronts at bay. Since then we've seen more wet weather for our southern capitals and some impressive snow totals for the ski fields, even if the snow was late to arrive.

Australia's record-breaking winter warmth linked to climate change
Much of the country had drier conditions than average, especially in the southeast and the west. Credit: Bureau of Meteorology

This warm, dry winter is laying the groundwork for dangerous fire conditions in spring and summer. We have already had early-season fires on the east coast and there are likely to be more to come.

Climate change and record warmth

Australia's average daytime maximum temperatures were the highest on record for this winter, beating the previous record set in 2009 by 0.3℃. This means Australia has set new seasonal highs for maximum temperatures a remarkable ten times so far this century (across summer, autumn, winter and spring). The increased frequency of heat records in Australia has already been linked to .

The record winter warmth is part of a long-term upward trend in Australian winter temperatures. This prompts the question: how much has human-caused climate change altered the likelihood of extremely warm winters in Australia?

I used a standard event attribution methodology to estimate the role of climate change in this event.

Australia's record-breaking winter warmth linked to climate change
Winter 2017 stands out as having the warmest average daytime temperatures by a large margin. Credit: Bureau of Meteorology

I took the same simulations that the Intergovernmental Panel on Climate Change (IPCC) uses in its assessments of the changing climate, and I put them into two sets: one that represents the climate of today (including the effects of greenhouse gas emissions) and one with simulations representing an alternative world that excludes our influences on the climate.

I used 14 climate models in total, giving me hundreds of years in each of my two groups to study Australian winter temperatures. I then compared the likelihood of record warm winter temperatures like 2017 in those different groups. You can find more details of my method here.

I found a stark difference in the chance of record warm winters across Australia between these two sets of model simulations. By my calculations there has been at least a 60-fold increase in the likelihood of a record warm winter that can be attributed to human-caused climate change. The human influence on the climate has increased Australia's temperatures during the warmest winters by close to 1℃.

More winter warmth to come

Looking ahead, it's likely we're going to see more record warm winters, like we've seen this year, as the climate continues to warm.

Australia's record-breaking winter warmth linked to climate change
The likelihood of winter warmth like this year is rising. Best estimate chances are shown with the vertical black lines showing the 90% confidence interval.

Under the Paris Agreement, the world's nations are aiming to limit to below 2℃ above pre-industrial levels, with another more ambitious goal of 1.5℃ as well. These targets are designed to prevent the worst potential impacts of climate change. We are currently at around 1℃ of global warming.

Even if global warming is limited to either of these levels, we would see more winter warmth like 2017. In fact, under the 2℃ target, we would likely see these winters occurring in more than 50% of years. The -setting heat of today would be roughly the average of a 2℃ warmed world.

While many people will have enjoyed the unusual warmth, it poses risks for the future. Many farmers are struggling with the lack of reliable rainfall, and bad bushfire conditions are forecast for the coming months. More winters like this in the future will not be welcomed by those who have to deal with the consequences.


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Australia has hottest winter on record

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Sep 01, 2017
I wonder why Australia is experiencing an unusually warm winter but Chile, at the same latitude across the Pacific, is having an unusually cold winter? Couldn't have anything to do with that El Niño / La Niña thing; you know, the natural oscillation of warm and cool water back and forth across the southern Pacific.

https://en.wikipe...i%C3%B1o

Very strange though how Australia's record warmth and droughts (1982-83) correspond to major El Niños and record rain (2010-11) corresponds to La Niñas.

http://ggweather..../oni.htm

An even stranger thing is how someone with degrees in meteorology and climate science never mentions El Niño, which is perhaps the most prominent regularly-occurring weather event on earth.

Sep 01, 2017
Continent size, and lack of any significant mountain ranges would have to feature as explanations behind the differences there.
After the mega El Nino events of recent, this year seems to be a neutral Nina/Nino influence on local climates. The overall effect on Australias climate can be seen without this otherwise large influence, a good glimpse at the baseline being shifted. Australia with it's huge size and lack of mountains and arboreal forests should be seen as a test bed for climate models and weather trends.

Sep 02, 2017
@askdad.
I wonder why Australia is experiencing an unusually warm winter but Chile, at the same latitude across the Pacific, is having an unusually cold winter? Couldn't have anything to do with that El Niño / La Niña thing; you know, the natural oscillation of warm and cool water back and forth across the southern Pacific. An even stranger thing is how someone with degrees in meteorology and climate science never mentions El Niño, which is perhaps the most prominent regularly-occurring weather event on earth.
Some insights/predictions from AGW related increased energy in Earth System is DESTABILIZING and EXACERBATING previous NORMAL 'prevailing wind patterns and ocean temp oscillations'. The danger during present TRANSITIONAL global/local destabilizations etc is that whatever effects of previous patterns/oscillations will become MORE EXTREME/PERSISTENT and UNUSUAL/UNSEASONAL etc. It's more subtle/complex than naive/simplistic perspectives imply. Good luck, mate. :)

Sep 02, 2017
aksdad made some valid comments and then this idiot, RealityCheck, who has no idea about anything, gave his stupid reply. This below explains his cults believes.
They quest endlessly for a "sign in the heavens" – their Holy Grail – the
mythical "hotspot" in the troposphere over the equator.
They speak in tongues, chanting irrational religious utterings – such as –
"global warming causes global cooling causes global warming causes global
cooling" and still expect to be taken seriously.
So, in summary:
They have Gods, a Prophet, priests and sacred sites, an infallible Holy
Book, a Devil, a Holy Grail and a Quest. They preach of impending doom by
plagues if they are not believed and followed.
They divert scarce resources to the construction of useless religious
monuments and the creation of sacred Holy Water. They practice human
sacrifice, they believe in the dispensation of sin through pecuniary
penance, and they chant meaningless dogma.

Sep 02, 2017
hmm, weren't they caught canceling temps below a certain level ? aussie thermometers don't work it seems

Sep 03, 2017
" weren't they caught canceling temps below a certain level ?"

What happened was someone tried to put a minimum of -10.4C as an observation at Goulburn. This is value sits at the extreme of the bell curve of historic values, someone at the Bureau of Meterology set the algorithm for recording these rare events as a rounding to -10C.
The overall histogram of daily minimums n equals 9560, gives an even distribution with a mean of 6.078C. I think a series of histograms using 5 years data to see if the distribution curve has moved would win this debate. My bet is that the mean has shifted to warmer...any takers?

Sep 03, 2017
i looked at the summer weather there, it does seem warmer . what annoys are these 'news' flashes , never do they report that it was cold somewhere.

Sep 03, 2017
The thing is that records are being broken with heat, not cold. There is only a tiny set of data for small areas that have generated a 'cold record'. And even then it's a minor event, i.e a 0.1C colder temperature recorded...Heat records are abundant and widespread, i.e number of consecutive days above 30C, highest overnight temperature, highest June average....and on it goes.

Sep 03, 2017
The thing is that records are being broken with heat, not cold.


"New Record for Coldest Place on Earth, in Antarctica
Scientists measure lowest temperature on Earth via satellites
[…]Using new satellite data, scientists have measured the most frigid temperature ever recorded on the continent's eastern highlands: about -136°F (-93°C)—colder than dry ice.
The temperature breaks the 30-year-old record of about -128.6°F (-89.2°C), measured by the Vostok weather station in a nearby location.
Although they announced the new record this week, the temperature record was set on August 10, 2010."
http://news.natio...science/

Sep 03, 2017
If you care to look, manfredparticleboard, you will find many new records for "cold".
Denver cold shatters two records, wind chill warning in effect 11/12/2014 http://www.denver...ednesday
"Heat waves have actually diminished, not increased.
http://journals.a...13-071.1

Heat Mortality Versus Cold Mortality: A Study of Conflicting Databases in the United States
http://journals.a...86-7-937

"Cold weather kills far more people than hot weather"
The Lancet
http://www.scienc...3831.htm

Sep 03, 2017
We've officially just had our COLDEST December since records began 100 years ago!
The Met Office reckons this December was absolutely freezing, as across the country we shivered through temperatures that averaged -1C.
Since BBC has pushed this scam called Anthropogenic Global Warming from the very beginning, they just felt obliged to end this story with this bit of unsubstantiated nonsense
"But globally, 2010 was one of the hottest years on record".(If you believe this you would believe everything that James Hansen told you and he has yet to be caught telling the truth, about anything)
http://cdnedge.bb...1080.stm

Sep 04, 2017
Compared to EHEs based on both the maximum and minimum temperatures (Tmnx), EHEs based on the daily maximum (Tmax type) and those based on the daily minimum (Tmin type) had roughly twice the number of events per summer, 1.5 times the duration but 75% of the intensity. These results also indicate Tmax‐type EHEs are typically slightly longer, more frequent, and more intense than Tmin‐type EHEs.

That's their conclusion,it's far less than certain than the way in which you try to state it ' Heat waves have actually diminished, not increased' I read it that intensity has reduced but events are twice the number per summer and 1.5 times the duration. If I said stick you hand in hot water once quickly or do it with 3/4 the temperature 1.5 times as long and for two times, which would you pick?

Sep 04, 2017
Sydney residents not being proactive or taking heatwaves seriously, researcher warns
ABC Radio Sydney
By Amanda Hoh
Heatwaves have killed more Australians than any other hazards combined, yet residents in New South Wales are not being proactive enough when warnings are issued, researchers say.

Sydney experienced its hottest summer on record during the 2016-17 season and sweated through consecutive nights with temperatures over 24 degrees Celsius.

Yet in a survey conducted by natural hazards research centre Risk Frontiers on households in western Sydney and the northern rivers area, 50 per cent of people did not think it was necessary to take action or make preparations....

Sounds like heatwaves are of concern if you live in Aus!

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