Frost will become less and less common across much of the world as global warming accelerates, researchers at a leading U.S. climate center say in a new report.
The report, from the National Center for Atmospheric Research in Boulder, Colo., predicts fewer days and nights when the air temperature dips below freezing, particularly in western North America and western Europe.
It joins a study from the same group released earlier this month predicting more severe and common heat waves in cities such as Paris and Chicago and another one focusing on California that showed higher temperatures would threaten the dairy and grape industries.
Also this month, the European Environment Agency predicted that cold winters could disappear almost entirely from Europe by 2080 and that heat waves and floods would become more common.
U.S. West saw less frost in recent decades
In the United States, NCAR noted that over the last 50 years many weather stations across the West reported a decrease of 10 or more frost days a year, mostly due to warmer conditions in springtime.
Writing in the journal Climate Dynamics, NCAR researchers Gerald Meehl, Claudia Tebaldi and Doug Nychka used a Department of Energy climate model to forecast day-to-day changes in temperature at the end of this century.
The model predicted a steady loss of days when there will be a frost in 2080 to 2099 compared to 1961-1990.
“In general, there is a gradient from west to east across the continent, with greater decreases in frost days in the western regions,” Meehl said in a statement.
More than 40 fewer frost days a year by 2080-2099 are projected along and near the West Coast from Washington State north into British Columbia, Canada. Areas west of the Great Plains could see more than 20 fewer frost days in a typical year.
Wind predicted to be key factor
Changes in atmospheric circulation will cause the change, Meehl said.
The model predicts that in northwestern North America, low-level winds will blow more often from the Pacific, carrying mild air during the winter.
Eastern North America will get more cold Canadian air, however. A similar pattern is seen in Europe and Asia, with Northern Europe getting more warm ocean air and Asia getting cold continental blasts.
But the researchers do not find that the change in frost patterns will affect agriculture.
For example, the average first frost and last frost dates do not change, although the technical growing season may lengthen because more days, on average, will see average temperatures of above 41 degrees F.
