avatarLuke Gloege, Ph.D.

Summary

Increased heavy snowfall events in Minnesota are a consequence of global warming, which leads to warmer winters and more atmospheric moisture, rather than evidence against it.

Abstract

The article discusses the counterintuitive relationship between global warming and increased heavy snowfall events, particularly in Minnesota. It explains that despite the warming of the planet, areas like Minnesota are experiencing more frequent snowstorms with over 12 inches of snow. This phenomenon is attributed to the greenhouse effect, where increased atmospheric carbon dioxide (CO2) traps more heat, leading to warmer winters. Warmer winters result in less snow cover, which in turn reduces the reflectivity of the Earth's surface, causing more sunlight to be absorbed and further warming the atmosphere. A warmer atmosphere can hold more moisture, which, when conditions are right, can fall as heavy snow. The article also references historical data and scientific predictions, such as those by Svante Arrhenius, to support the claim that global warming is causing winter temperatures to rise faster than summer temperatures, and that this trend is associated with an increase in extreme snow events.

Opinions

  • The author asserts that the increase in heavy snowfall events is not a contradiction to global warming but rather a consequence of it.
  • The article suggests that the public's intuition about snowfall being incompatible with global warming is incorrect.
  • The author emphasizes that the greenhouse effect, amplified by increased CO2 and reduced snow cover, is responsible for the observed changes in winter weather patterns.
  • The author implies that the historical increase in snowfall events greater than 12 inches in the Twin Cities, particularly post-1960, supports the theory of global warming-induced changes in climate.
  • The author posits that the warming atmosphere, which holds more moisture, sets the stage for extreme snow events under the right conditions.
  • The author concludes optimistically for those who enjoy winter activities, suggesting that snow-days are not likely to become scarce due to the warming we are causing.

Does Record Snowfall Disprove Global Warming?

Photo by Pixabay on Pexels

December 2020 marked the tenth anniversary of the aptly named “Domebuster” snowstorm, which caused the roof of the Metrodome in Minneapolis, Minnesota to collapse under 17.1 inches of snow. Although it may seem counterintuitive, Minnesota is experiencing more events with greater than 12 inches of snow coincident with warming winters. In other words, global warming from a rampant increase in atmospheric carbon dioxide (CO2) is causing climate change; in this case heavy snow events. I aim to explain why the climate is warming, especially in winter, and how this increases the likelihood of memorable snowstorms.

Greenhouse Effect

In winter, much of the land is covered with very reflective snow, which bounces sunlight back into space. This reflected light does not get absorbed by greenhouse gases, such as CO2, in the atmosphere. As sunlight beats down on snowless ground, the soil heats up and, consequently, gives off heat. It is this ground-emitted heat that is captured by CO2 and redirected back to Earth, forming a cycle that continually heats the atmosphere. This is the greenhouse effect (Fig. 1).

Fig. 1: Schematic of the greenhouse effect. Snow and ice reflects sunlight back into space largely without interacting with greenhouse gases. Heat given off of land is absorbed by land. [Schematic inspired by NASA ClimateKids]

Winter warming

A rule of thumb for the greenhouse effect is: cold things are warming faster

The greenhouse effect is amplified by two factors, adding greenhouse gases such as CO2 to the atmosphere and a global reduction in snow cover, which prevents some of the sunlight from being reflected back into space. The atmosphere is our planet’s jacket, keeping it at a hospitable temperature. Adding additional CO2 to the atmosphere is akin to replacing a wind-breaker with a parka. As a result of reduced snow cover, winter is warming faster than summer (Fig. 2); a prediction made by Svante Arrhenius in 1897 which is now coming true. Winter warming faster than summer, along with many other lines of evidence, is a fingerprint for the greenhouse effect. A rule of thumb for the greenhouse effect is: cold things are warming faster. In addition to winter warming, nights are warming faster than days and the arctic is warming faster than the tropics.

Fig. 2: Average temperature in winter and summer in Twin Cities. Solid lines indicate mean over 60 year periods. Data source MN-DNR.

Warmer winters = increased snowfall

So, now that we know why winter is warming faster, how does this increase the chance of extreme snow events? The first reason is that a warmer atmosphere can hold more moisture, via evaporation from oceans and lakes. The increased atmospheric moisture means more of it can be dumped as snow. The second reason is that heavy snow typically occurs when the atmospheric temperature is between 15–32 degrees Fahrenheit. This Goldilocks range is when ice crystals can lock together, forming the large fluffy flakes we all find so pretty. Snow that forms at colder temperatures is more like diamond dust. Thus, a warmer, moist atmosphere in the Minnesotan winter sets up conditions conducive for extreme snow events. So, if the conditions are right, this extra moisture can get dumped as snow in a short period of time. In the Twin Cities, snow events greater than 12 inches have seen a marked uptick post 1960, which occurred seven times in the past 60 years and only twice between 1900 and 1960 (Fig. 3). Bringing the above information together, we see that maybe extreme snow events under global warming are not counterintuitive after all and record snowfall does not disprove global warming.

Fig. 3: Seasonal snowfall in the Twin Cities. Solid lines indicate mean over 60 year periods. Red dot indicates snowfall events with greater than 12 inches of snow. Data source MN-DNR.

In 1991, I was only two years old during the epic “Halloween blizzard,” where a record 28 inches of snow got dumped on parts of the Twin Cities. It is said that history doesn’t repeat itself, but it often rhymes. Maybe we won’t see another “Halloween blizzard”, but there will definitely be similar events. So, if you enjoy sledding at Theodore Wirth Regional Park or snow-ball fights on the quad, you can be rest assured knowing the warming we are causing in the atmosphere is not making snow-days in short supply.

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Climate Change
Science
Global Warming
Winter
Minnesota
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