Climate Matters: It’s beginning to look a lot less like Christmas

Snow does much more than create beautiful landscapes and cause traffic jams. It is a crucial part of Earth's ecosystem year-round, but we're seeing fewer flurries as the world warms.

Connecting a warming planet to less snow is simple: as temperatures rise, freezing conditions become less common, and precipitation that would have fallen as snow in colder weather now falls as rain.

Ben Herzog, the science and operations officer at the National Weather Service in St. Louis, says that their office has studied how heavy snow events have changed over recent decades as the climate warms. Their results weren't surprising.

"What we found is that the number of heavy snowfall events, so that snowfall where we had at least six inches reported in our forecast area, has decreased by about 17% between 1980 and 2020," Ben explains. While the St. Louis National Weather Service typically forecast about 22 heavy snowfall events per year in the 1980s, this number fell to 16 annually in the 2010s.

Snow is also arriving much later in the season in Missouri. "If you look back in the 80s, December used to be the month with the most frequent, heavy snowfall events," Ben says. But this has changed as winter temperatures have warmed.

"Whereas back in the 2010s, February was actually the month with the most heavy snowfall events. That shows how temperatures directly impact snowfall," Ben notes, "February was generally colder in those later decades."

According to a Climate Central analysis of over 2,000 U.S. locations, nearly two-thirds are experiencing less snow today than in past decades. This has significant implications, from the environment to the economy.

Snow is an important environmental resource even outside winter. Snowmelt makes up over 50% of runoff that replenishes reservoirs and groundwater in the western U.S. It also accounts for nearly a quarter of runoff for the Missouri River in the spring. This runoff is used for irrigation, commerce, and recreation throughout the year, and water demand is increasing as the supply melts away.

A 2018 study found that the Western U.S. has already lost 15-30% of its snow-derived freshwater since 1950, with further losses expected as the climate continues to warm.

Climate Central's analysis also revealed that over 700 U.S. locations are actually seeing more snow with climate change. While warmer temperatures are expected to reduce overall snowfall, the increased moisture in the air means that when snow does fall, it often falls more heavily.

The decline in snow will reduce the chances of a White Christmas in Mid-Missouri. Columbia's historical probability of a White Christmas is 15%, or about 1 in every 6 Christmases. That percentage will decline further as Missouri's climate continues to warm.