The hottest year on record globally in 2015 could be an average year by 2025 and beyond if carbon emissions continue to rise at the same rate, new research has found.

An Australian study published today in the Bulletin of the American Meteorological Society indicated that human activities had already locked in this new normal for future temperatures - but immediate climate action could prevent record extreme seasons year after year.

Its lead author, Dr Sophie Lewis of the Australian National University, said if the world continued with business-as-usual emissions, extreme seasons would inevitably be the norm within decades and Australia was the "canary in the coal mine" that would experience the change first.

"This research tells us we can potentially prevent record-breaking season
"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," she said

The idea of a "new normal" had been used repeatedly when talking about climate change but had never been clearly defined until Lewis and colleagues developed a scientific definition for the term.
"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," she said.

"Only then can a new normal state be declared."