The idea of what the term "new normal" actually means was the cornerstone of this new research. It has often been used when talking about climate change but it had seldom been clearly defined. Dr Lewis and colleagues have now 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 a record year were cooler and half warmer. Only then can a new normal state be declared," she said.
After this process was used by the researchers to determine new normal conditions for global average temperatures, it was used again to examine record hot seasonal temperatures at a regional level.
Using the National Computational Infrastructure supercomputer at ANU to run climate models, the researchers explored when new normal states would appear under the Intergovernmental Panel for Climate Change's four emissions pathways.
The research team then examined seasonal 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.
"It gives us hope to know that if we act quickly to reduce greenhouse gases, seasonal extremes might never enter a new normal state in the 21st Century at regional levels for the Southern Hemisphere summer and Northern Hemisphere winter," Dr Lewis said.
"But if If we don't act quickly Australia's "angry summer" of 2013 may soon be regarded as mild. Imagine for a moment, if a summer season like 2013 became average. The likely impacts of an extremely hot year in 2035 would beyond anything our society has experienced."