Yes, heatwaves and extreme heat events are going to get worse for many years, even if we do everything possible to reduce emissions. Week long heatwaves, and extreme heat events with temperatures over 50 degrees Celsius may be seen in a decade or so in Sydney and Melbourne.

That is the inertia in the climate system. In the meantime we need to rapidly increase renewables while making energy savings through energy efficiency, and cutting emissions particularly from the electricity generation sector.

Dr Sophie Lewis, in a study published in Geophysical Research Letters in October 2017, assessed the potential magnitude of future extreme temperatures in Australia under Paris targets of an increase in global temperatures of 1.5 and 2 degrees Celsius above pre-industrial levels.

“Major Australian cities, such as Sydney and Melbourne, may experience unprecedented temperatures of 50 degrees Celsius under 2 degrees of global warming,” said Dr Lewis from the Fenner School of Environment and Society and the Centre of Excellence for Climate System Science at ANU.

“The increase in Australian summer temperatures indicates that other major cities should also be prepared for unprecedented future extreme heat.

“Our climate modelling has projected daily temperatures of up to 3.8 degrees Celsius above existing records in Victoria and New South Wales, despite the ambitious Paris efforts to curb warming.”

Dr Lewis said immediate climate action internationally could prevent record extreme seasons year after year.

“Urgent action on climate change is critical – the severity of possible future temperature extremes simulated by climate models in this study poses serious challenges for our preparedness for future climate change in Australia,” she said in a statement at ANU

Another study by Papalexiou and colleagues published January 2018 has identified that extreme heat event days with highest temperature of the year is an accelerating trend globally and particularly in Asian and Australian cities, “with rates higher than 0.60°C per decade.” Read the Sydney Morning Herald story: Australia among countries growing hotter faster: report

“The global average annual temperature has increased over the past three decades at a rate of 0.20 degrees Celsius per decade, but we have found that the maximum temperature of the year has climbed at a much faster rate — two to three times higher in such regions as Eurasia and parts of Australia and more than three times higher in some megacities,” said Efi Foufoula-Georgiou, UCI Distinguished Professor of civil & environmental engineering and senior author on the study. “These results are alarming and yet more evidence of the harsh impact of global warming being felt by people around the world today.”

The research team analyzed data on the hottest day of the year from 8,848 land surface weather stations around the world. Looking at thermometer readings for the 50-year period ending in 2015, they saw an average international increase in short-term highest temperatures of 0.19 degrees Celsius per decade; the growth accelerated to 0.25 degrees per decade in the 30 years from 1986 to 2015.

But for major cities such as Paris, Moscow and Tokyo and Australian cities such as Sydney and Melbourne the temperature trend climbed precipitously by as much as 0.60 degrees per decade during the period studied.

Lead author Simon Michael Papalexiou, a postdoctoral scholar in the Department of Civil & Environmental Engineering at University of California at Irvine. “We chose to drill down into conditions in megacities, where temperature extremes matter the most. Our question now is: Will this acceleration continue into the future? Because if it does, adverse effects for human societies are inevitable.” he warned, in a media statement.

Meanwhile, we have a Federal Government doing it’s darndest to limit effective climate action and the energy transition, with a review of climate policies finding no major changes necessary despite our targets being rated as insufficient by the Climate Action Tracker for our fair share of global climate action under the Paris Agreement.

References

* Lewis, S. C., King, A. D., & Mitchell, D. M. (2017). Australia’s unprecedented future temperature extremes under Paris limits to warming. Geophysical Research Letters, 44, 9947–9956. https://doi.org/10.1002/2017GL074612 (abstract)

* Papalexiou, S. M., AghaKouchak, A., Trenberth, K. E. and Foufoula-Georgiou, E. (2018), Global, Regional, and Megacity Trends in the Highest Temperature of the Year: Diagnostics and Evidence for Accelerating Trends. Earth’s Future. doi:10.1002/2017EF000709 (Full study)