By Jim Bloch
We had balmy temperatures of 55 degrees on Christmas day in the Blue Water Area, more than 20 degrees above normal. On a sunny spring-like afternoon, people went for walks, jogged in shorts and rode their new electric scooters in the streets. The low of 42 degrees was 10 degrees above freezing.
The prognosticators at Climate Central saw it coming.
“People dreaming of a White Christmas will be sorely disappointed this year,” said Dr. Andrew Pershing, vice-president of science at Climate Central, in a Dec. 21 statement. Climate central is a nonprofit organization that conducts scientific research on climate change and energy issues, and produces multimedia tools to educate the public and decision-makers about climate topics. “As long as people keep burning coal, oil, and natural gas, events like the string of unusually warm temperatures in the Midwest will become more and more common.”
The burning of fossil fuels, which began on a mass scale with the Industrial Revolution, emits carbon dioxide and other gases into the atmosphere, which function to trap more of the sun’s heat, warming the planet.
The historic probability of having one inch of snow on Christmas in Detroit was 35 percent.
The National Weather Service defines a white Christmas as one in which one inch of snow covers the ground at 7 a.m. on Christmas morning.
Daily average temperatures were expected to be 20-35 degrees F above average (based on average winter temperatures from 1991-2020) in large parts of Minnesota, Wisconsin and Iowa.
“Temperatures are not expected to dip below 32°F on any day between December 21 and 25 across all of Illinois, much of Iowa, and parts of Minnesota, Wisconsin and Michigan,” said the Climate Central report.
That’s exactly what happened.
Climate Central developed a peer-reviewed method called the Climate Shift Index to estimate how much climate change has increased the likelihood of a particular daily temperature.
“The unusually warm conditions have a strong climate change influence,” according to the report. “Most days across the affected states are expected to reach a Climate Shift Index (CSI) level of at least 2, meaning that temperatures in those areas are at least two times more likely because of human-caused climate change.”
Nationally, winters are 3.8 degrees F warmer now than they were in 1970. In Detroit, winters are 5.1 degrees warmer on average than they were in 1970.
As the world warms, there is increased evaporation from the land, lakes and seas, which means more water in the atmosphere and the possibility of snow when the temperatures are right. But that’s happening less frequently than a half-century ago. What used to fall as snow now falls as rain. Climate Central pegged the chance of a white Christmas in Detroit at 35 percent, three percentage points fewer than its prediction for 2019.
Jim Bloch is a freelance writer based in St. Clair, Michigan. Contact him at bloch.jim@gmail.com.
