Ahead of the COP22 meeting in Marrakech, Morocco, on the same day the Paris agreement on limiting carbon emissions became law, a research paper warned that if carbon emissions kept rising at their current rate, “the hottest year on record globally in 2015 could be just another average year by 2025.” It went on to add that a “new normal” for average temperatures globally had already been locked in, and would be in effect by 2040, irrespective of what actions we take to keep them down.
The team of researchers, led by Dr. Sophie Lewis from the Australian National University hub of the ARC Centre of Excellence for Climate System Science in Australia, first went about scientifically defining what “new normal” meant.
“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,” Lewis said in a statement.
Using this definition, examining seasonal temperatures across Asia, Australia, Europe and North America, and running climate models, the team found that global average temperatures will enter the new normal inevitably in any of the four scenarios presented by the Intergovernmental Panel for Climate Change.
However, researchers found some seasonal and regional exceptions.
“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,” Lewis said.
The research appeared in the Bulletin of American Meteorological Society under the title “Defining a new normal for extremes in a warming world.”