More than 400 locations across the United States reached record-breaking temperatures last week. During that same span, only about 100 areas saw record-breaking lows.
While this 4-1 record ratio can mainly be attributed to this week’s heat wave, it doesn’t stray too far from the 2-1 ratio of record highs and lows that we’ve seen over the past decade in the US.
Weather variability can cause this ratio to change from year to year, such as in 2012, when record highs out numbered lows by a staggering 6-to-1 — but the next year saw extreme highs and lows around the same pace.
Record-high temperatures occurring twice as frequently as record lows directly reflects our climate crisis, as you would expect increasing the average temperature to increase the number of extreme highs, while extreme cold happens less frequently.
Since our record-keeping began in 1895, the country’s average temperature has climbed somewhere between 1.3 and 1.9 degrees Fahrenheit.
The National Center for Atmospheric Research (NCAR) recently conducted research into how this ratio should behave moving forward.
“We looked at a model simulation — where we were increasing carbon dioxide and other greenhouse gasses going off into the 21st century — and as the climate continued to warm, the ratio continued to grow,” said NCAR scientist Gerald Meehl.
Current projections place that ratio as high as 20-to-1 by 2050 and 50-to-1 by the end of the century.
What are the implications?
If this ratio continues to grow over time, many temperatures we currently label as extreme may become nothing more than an ordinary occurrence.
The same excessive heat warnings and advisories that affected nearly 200 million Americans this week would become more frequent and long-lived. Not only will this impact the elderly and young, who are already particularly vulnerable to heat-related illnesses, it will affect everyone.
Heat-related illnesses would only continue to rise globally, with cases ranging from nausea to heatstroke — which claimed two lives during last week’s heat wave.
The UN Intergovernmental Panel on Climate Change (IPCC) warns that the planet will reach the crucial threshold of 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial levels by as early as 2030, bringing with it the increased risk of extreme drought, wildfires, floods and food shortages for hundreds of millions of people.
According to the Fourth National Climate Assessment for the US, the economic costs of climate change could reach hundreds of billions of dollars annually. The Southeast alone will probably lose over a half a billion labor hours by 2100 due to extreme heat.