Do the Great Lakes Ever Completely Freeze Over in the Winter?

Introduction

The Great Lakes are a group of five freshwater lakes known for their size and beauty. These lakes play major roles in environmental stability and weather patterns. During winter, though, the lakes are prone to freezes. Some of these freezes cover over half of a body of water, while others only make up a small portion of the water’s surface. In some rare cases, the Great Lakes have frozen over completely. Discover which of the Great Lakes have completely frozen and whether these freezes will continue to occur in the future.

Background on the Great Lakes

The Great Lakes lie in North America between the United States and Canada. They border the states of Michigan, Wisconsin, Ohio, and New York, to name a few. These huge freshwater lakes have a combined area of 94,250 square miles! The names of the lakes are Ontario, Huron, Erie, Superior, and Michigan. Three of the Great Lakes rank in the top five largest lakes in the world. For instance, Lake Superior places second behind the vast Caspian Sea.

While it is possible that Vikings first discovered and explored the Great Lakes, European introduction to the region likely occurred when Jacques Cartier discovered the lakes on his journey up the St. Lawrence River. Native Americans residing near Lake Huron gave information to Cartier about the remaining Great Lakes. After Cartier’s discovery, other explorers followed him in investigating the Great Lakes and the region that surrounds them.

The French and Indian War, the American Revolution, and the War of 1812 were all affected by the Great Lakes and resulted in changes near the region. For instance, the border between America and Canada was formally established after the American Revolution. During the War of 1812, Lake Erie acted as a site for a naval battle.

Animals and Climate

Climate in the region is subject to the lakes’ presence. The lakes absorb heat during the summer that is released into the atmosphere during the winter. This process results in cool summers and warm winters. Without the Great Lakes, climate in this area would look drastically different. Precipitation during the winter is heavier on the eastern side of the Great Lakes, and storms often afflict the areas that surround the lakes.

Plant and animal life in and near the Great Lakes is abundant and beautiful. Within the water lies algae, and around the lakes beautiful beaches are flanked by a diverse assortment of tree species. Organisms like plankton and microscopic crustaceans can be found within the water. Fish include trout, lake herring, and bass, to name a few. On the other hand, birds like the ring-billed gull live near these bodies of water.

The Great Lakes also provide a wide variety of resources that humans have used for agriculture, lumber, and more. Crops that are farmed near the Great Lakes include corn, wheat, soybeans, several fruits and vegetables, and animal products. Furthermore, the freshwater that the Great Lakes provide has been used in energy production. Additionally, areas near Lake Superior have produced a large amount of iron ore and copper. However, much of these resources have been depleted from the lakes over time.

Do the Great Lakes Ever Completely Freeze Over?

While the Great Lakes will freeze over partially during the winter, they almost never freeze completely. This is mainly due to their size. The Great Lakes are too large to freeze over entirely on a regular basis. States that border the Great Lakes experience freezes before the bodies of water themselves because water heats up and cools down at a slower rate than land. This distinction is primarily due to water’s specific heat capacity, which is higher than that of land, as well as its molecular capacity.

Nevertheless, the Great Lakes typically begin to freeze at the end of December heading into January. Their peak freeze occurs in late February and early March. The Great Lakes average an ice coverage of 55%, meaning that at least half of the lakes’ surface areas are bound to freeze during the winter months. In the last 50 years, the Great Lakes have experienced ice coverage over 80% on five separate occasions.

Lake Superior

One of the highest ice coverages for Lake Superior occurred in 1979 when the lake recorded an ice coverage of 94.7%. Thus, the lake had almost frozen over completely but did not quite meet the mark. This does not mean Lake Superior has never frozen over completely, though. Great Lakes that have completely frozen include Lake Superior, Lake Huron, Lake Erie, and Lake Ontario. Lake Michigan is the only Great Lake to have never frozen entirely.

Lake Ontario

While Lake Ontario has frozen over, Lake Ontario and Lake Michigan are prone to resisting complete ice coverage. The two lakes experience lower latitudes and are much deeper than their three counterparts. Increased depth of a lake allows it to store more heat than a shallow one. Therefore, the two lakes have been able to avoid a complete freeze over most years.

On rare occasions, all the lakes have experienced little ice coverage. In 2002, the Great Lakes experienced the least amount of ice coverage ever recorded at 9.5%. On the other hand, the lakes have also undergone an excessive amount of ice coverage all together. In the winter spanning 2013 and 2014, the Great Lakes recorded 92% ice coverage. During this year, Lake Erie froze over completely.

Weather and the Great Lakes

Did you know that the Great Lakes can increase snowfall on land? This phenomenon is called Lake Effect Snow (LES). Warm lake waters aid in evaporation and cold air, deriving from Canada, meets the heat and moisture that rises from the lakes into the atmosphere. Thus, the cold air turns the moisture resulting from warm lake evaporation into snowfall, or LES.

Something interesting about LES is that it is subject to variability. It is difficult to predict when LES will occur and dump inches of snowfall on the land surrounding the Great Lakes. On the other hand, LES might only cause a small trace of snow that barely sticks to the ground. Either way, a sunny winter day could suddenly be interrupted by blankets of fresh powder in surrounding areas.

Climate Change and the Great Lakes

While the Great Lakes may have frozen over in the past, the likelihood of complete freezes reoccurring decreases every year. Climate change has caused a decrease in snow and ice depth in and around the Great Lakes. Therefore, decreased ice coverage on the Great Lakes allows evaporation to continue. Evaporation from the Great Lakes bolsters the lake effect, resulting in increased precipitation. Thus, although the lakes may not freeze over, the land will experience heavier snowfall.

According to the Environmental Protection Agency, the Great Lakes have all experienced a decrease in ice coverage in the last 50 years. Interestingly, Lake Superior’s decrease in ice coverage was greater than the other four lakes’ decrease in ice. Furthermore, both Lake Superior and Lake Erie have experienced deceasing ice coverage at a greater rate in the last 20 years when compared to the rate of decrease during the late 20^th century.

In addition, the number of days during which the lakes have been completely frozen over has decreased. In current times, the Great Lakes have experienced ice coverage for eight to 46 fewer days than they did in the 1970s. Lake Ontario and Lake Superior are the two Great Lakes that have been most affected by decreased days of ice coverage. Overall, the decrease in ice coverage and the decrease in days for which ice coverage has been experienced are the results of climate change, which affects habitats, temperatures, and precipitation.

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The photo featured at the top of this post is © Christopher Meder/Shutterstock.com