Science says Australia's record hot summers will become normal

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Australian scientists say the hottest year on record globally in 2015 could be an average year by 2025 if carbon emissions continue to rise at the same rate.

The latest study has tried to define the concept of what is a new normal when talking about climate change.

Dr Sophie Lewis of the Australian National University says human activities have already locked in higher temperatures but immediate action could prevent record extreme seasons year after year.

“If we continue with business-as-usual emissions, extreme seasons will inevitably be the norm within decades and Australia is the canary in the coal mine that will experience this change first,” says Dr Lewis.

“If we don’t reduce our rate of emissions the record hot summer of 2013 in Australia — when we saw temperatures approaching 50 degrees Celsius in some areas — could be just another average summer season by 2035.”

The recent State of the Climate report by the peak science body, the CSIRO, and the Bureau of Meteorology also says severe fire seasons fueled by increasingly hot days will continue for Australia.

Australia’s climate has warmed by around 1 degree celsius since 1910. Extreme fire weather, and a longer fire season, has increased across large parts of Australia since the 1970s.

And 2015 was the warmest year since modern record-keeping began in 1880, according to analysis by NASA’s Goddard Institute for Space Studies.

However, the latest Australian research shows record-breaking temperatures can be prevented from becoming average.

“Based on a specific starting point, we determined a new normal occurred when at least half of the years following an extreme year were cooler and half warmer,” says Dr Lewis. “Only then can a new normal state be declared.”

Using the National Computational Infrastructure supercomputer at ANU to run climate models, the researchers explored when new normal states would appear.

The research team looked at temperatures from December to February across Australia, Europe, Asia and North America.

“The results revealed that while global average temperatures would inevitably enter a new normal under all emissions scenarios, this wasn’t the case at seasonal and regional levels,” says Dr Lewis.

“We found that with prompt action to reduce greenhouse gases a new normal might never occur in the 21st century at regional levels during the Southern Hemisphere summer and Northern Hemisphere winter.”

The research is published in the Bulletin of the American Meterological Society.

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