Emerging threatsRecord-breaking hot days ahead
If society continues to pump greenhouse gases into the atmosphere at the current rate, Americans later this century will have to endure, on average, about fifteen daily maximum temperature records for every time that the mercury notches a record low, new research indicates. That ratio of record highs to record lows could also turn out to be much higher if the pace of emissions increases and produces even more warming.
If society continues to pump greenhouse gases into the atmosphere at the current rate, Americans later this century will have to endure, on average, about fifteen daily maximum temperature records for every time that the mercury notches a record low, new research indicates.
That ratio of record highs to record lows could also turn out to be much higher if the pace of emissions increases and produces even more warming, according to the study led by scientists at the National Center for Atmospheric Research (NCAR).
Over the last decade, in contrast, the ratio of record high temperatures to record lows has averaged about two to one.
“More and more frequently, climate change will affect Americans with record-setting heat,” said NCAR senior scientist Gerald Meehl, lead author of the new paper. “An increase in average temperatures of a few degrees may not seem like much, but it correlates with a noticeable increase in days that are hotter than any in the record, and nights that will remain warmer than we’ve ever experienced in the past.”
UCAR notes that the 15-to-1 ratio of record highs to lows is based on temperatures across the continental United States increasing by slightly more than 3 degrees Celsius (5.4 degrees Fahrenheit) above recent years, which is about the amount of warming expected to occur with the current pace of greenhouse gas emissions.
The new research appears this week in the “Proceedings of the National Academy of Sciences.” It was funded by the Department of Energy (DOE) and the National Science Foundation (NSF), which is NCAR’s sponsor. The study was coauthored by NCAR scientist Claudia Tebaldi and by Dennis Adams-Smith, a scientist previously at Climate Central and now at the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory.
Hotter days
In a 2009 study, Meehl and colleagues found that the ratio of record daily high temperatures to record daily low temperatures has steadily increased since the 1970s as average temperatures over the United States have warmed. Computer models at that time indicated that the ratio could continue to increase during this century, although the research team looked into just one scenario of future emissions. The scientists also found that the models were overstating the ratio of record highs to record lows in recent years, compared to observations.
