“There was a time some years ago when climate science wasn’t developed enough to attribute individual weather events to climate change, but that’s in the past tense.”

By Mohamed Ibrahim

MinnPost.com

Minnesota saw one of the warmest, wettest and snowless Decembers on record this past month, either breaking or challenging the record in each category.

Climate scientists say a cause of the relatively extreme temperatures and lack of snow is the climate pattern known as “El Niño” that can result in milder winters but the consistent global warming due to man-made climate change from the use of fossil fuels also played a major role. While big investments to mitigate climate change have been made by both Congress and the Minnesota Legislature, environmentalists continue sounding the alarm and point to this toasty winter as a harbinger of things to come should no further action be taken on that front.

Record-breaking warmth

According to the Minnesota Department of Natural Resources (DNR), the warmth in the Twin Cities last month broke the record for the region’s warmest December ever, shattering the nearly 150-year record held by December 1877. Statewide figures go back to 1895 and that record was broken as well.

“This is the warmest December that we have observed by probably five degrees Fahrenheit, which is a huge margin when you’re talking about a statewide monthly temperature record, it’s just an enormous margin,” said Kenny Blumenfeld, the state’s senior climatologist.

Four out of the state’s five climate stations recorded their warmest Decembers ever, each by double-digit margins. Rochester saw just two days with below-normal temperatures, while Duluth and International Falls had one each, and St. Cloud and the Twin Cities experienced none.

December had several warm days, including broken records on Dec. 7 and Dec. 8, as well as on Dec. 14. But it all came to a head during the “Holiday Heat Wave,” when warmth detected Dec. 22 caused temperatures to jump 5-to-10 degrees followed by another leap in temperatures that peaked during Christmas Eve and Christmas Day with high temperatures in the 50s.

El Niño

One cause of the warm winter weather is the climate pattern known as El Niño, which is characterized by unusually warm ocean temperatures in the Equatorial Pacific. Weakened trade winds cause warm water to be pushed towards the west coast of the American continents, changing the paths of atmospheric winds and affecting weather patterns globally.

For Minnesota, that means cold air masses remain trapped in northern Canada, leading to warmer and drier conditions in the state on average.

Blumenfeld said while it’s still early to tell how exactly this year’s El Niño event compares with previous years, climatologists can already tell it will end up as one of the strongest since the climate pattern started being recorded.

December snow depth maps from the DNR also showed that more than 95% of the state lacked any snow cover at all, with just the far northwestern part of the state showing just 1-to-4 inches of snowpack. This was the only year on record where certain parts of northern and northern Minnesota were free of snow cover in the first week of the year.

The lack of snow helped enable the warmer temperatures due to bare ground being 10-to-20 times more effective at warming the air after absorbing sunlight than snow-covered ground. The cooler air from snow cover helps precipitation fall as snow instead of rain, but bare ground enables temperatures to keep rising, resulting in rain instead of snow which prevent the ground from maintaining snow cover.

“If you think of the really cold winters that you might remember in Minnesota, they usually have a pretty healthy snowpack because that snow is basically preventing really warm air from establishing,” Blumenfeld said. “It’s a classical feedback — if you have snow on the ground, then the heat doesn’t get absorbed by the ground and you end up with lower temperatures, and then it’s more likely to snow.”

Climate change

The El Niño climate pattern was a big cause of the relatively extreme warmth last month, and a warmer winter was to be expected because of it.

But Blumenfeld said the shattering of records that climatologists witnessed would also not have been possible without the consistent warming of the globe due to man-made climate change, which has given the El Niño conditions an “extra boost.” One of the most clear indications of that, he said, is the fact that the average temperature on a normal winter day is about 5 degrees higher today than it was in 1970. 

“There was a time some years ago when climate science wasn’t developed enough to attribute individual weather events to climate change, but that’s in the past tense,” said Peter Wagenius, legislative and political director for the local chapter of national environmental group the Sierra Club. “Climate scientists have been really clear that 2023 — which is going to go down as the hottest year on record, not just December — is an insane record breaker on a string of record breakers because of climate change.”

Wagenius said he’s hopeful recent efforts on the state and federal levels will begin to help mitigate climate change. Those include investments in clean energy within the Inflation Reduction Act passed by Congress in 2022, which include solar, wind and geothermal projects, as well as investments in electrification, which will greatly reduce greenhouse gas emissions while keeping costs low.

He also pointed to the climate bills passed by the DFL-controlled Legislature last year, like the 100% clean energy bill, as well as other climate provisions within the transportation and energy omnibus packages.

“We don’t need to be distracted by the fossil fuel industry, and we don’t need to be distracted by fake carbon capture schemes, and ethanol is not the answer, either,” he said. “As long as we stay focused on these real clean technologies that both the federal government and our state government are rushing forward on, there’s a lot of hope for the future.”