The year 2015 didn’t just break climatic records, it shattered them, as IFLScience reported over and over again. Global temperatures were unprecedented, and often surpassed previous extremes by unheard of amounts. Yet within a decade, if we don’t take action, years like 2015 will be ordinary, and some years will be much, much worse.
When discussing the effects of climate change, activists and science communicators often talk about “the new normal”, a phrase that also appears in some influential scientific papers. But what is normal anyway? Dr Sophie Lewis of the Australian National University searched the literature and found that although there are many references to “the new normal” the term hasn’t been defined, and is often used in an ambiguous way.
To address this Lewis created a clear, measurable definition. In the Bulletin of the American Meteorological Society, she writes: “A new normal is defined here as having occurred when more than 50 percent of future anomalies exceed a reference event in magnitude or intensity.” If 2015 is the chosen reference point, it will have become the new normal when half the annual temperatures are higher still.
As Lewis notes, this definition is not limited to global annual averages. A summer heat wave in a particular city can be used as the reference event, allowing predictions of when temperatures will rise to the point that half of all summers will be that hot or hotter.
Having created this useful definition, Lewis tested 11 climate models to see when the devastating heat of 2015 would be the new normal, both globally and at regional levels. The majority of models indicated we will reach this point between 2020 and 2030. All but one have it happening by 2040. With 2016 set to be hotter than its predecessor, we are already well on the way.