Although North America is now a full month into astronomical spring, the Great Lakes are still almost half frozen. As of April 22, 2014, the Great Lakes were 33.9 percent ice covered. Some scientists say that the amount of ice that still remains could have a big impact on the environment in the months and years ahead.
- Lake Superior is the world’s largest freshwater lake by area (82,100 square kilometers or 31,700 square miles) and the third largest by volume. The waters average 147 meters (483 feet) in depth, and the basin is believed to hold about 10 percent of the world’s liquid fresh water.
- Lake Superior had 3.6 percent ice cover on April 20, 2013; in 2012, ice was completely gone by April 12.
- In the last winter that ice cover grew so thick on Lake Superior (2009), it reached 93.7 percent on March 2 but was down to 6.7 percent by April 21.
Image credit: Environment Canada / Canadian Ice Service
In the early afternoon on April 20, 2014, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this natural-color image of Lake Superior, which straddles the United States – Canada border. At the time Aqua passed over, the lake was 63.5 percent ice covered, according to the NOAA Great Lakes Environmental Research Lab (GLERL). Averaged across Lake Superior, ice was 22.6 centimeters (8.9 inches) thick; it was as much as twice that thickness in some locations.
NASA image courtesy Jeff Schmaltz LANCE/EOSDIS MODIS Rapid Response Team, GSFC
According to NASA's Earth Obsevatory, GLERL researcher George Leshkevich affirmed that ice cover this spring is significantly above normal. For comparison, Lake Superior had 3.6 percent ice cover on April 20, 2013; in 2012, ice was completely gone by April 12. In the last winter that ice cover grew so thick on Lake Superior (2009), it reached 93.7 percent on March 2 but was down to 6.7 percent by April 21.
"Average water temperatures on all of the Great Lakes have been rising over the past 30 to 40 years and ice cover has generally been shrinking. (Lake Superior ice was down about 79 percent since the 1970s.) But chilled by persistent polar air masses throughout the 2013-14 winter, ice cover reached 88.4 percent on February 13 and 92.2 percent on March 6, 2014, the second highest level in four decades of record-keeping.
Air temperatures in the Great Lakes region were well below normal for March, and the cool pattern is being reinforced along the coasts because the water is absorbing less sunlight and warming less than in typical spring conditions.
The graph below, based on data from Environment Canada, shows the 2014 conditions for all of the Great Lakes in mid-April compared to the past 33 years.
Image credit: NASA / Earth Observatory
Lake Superior ice cover got as high as 95.3 percent on March 19. By April 22, it was reported at 59.9 percent; Lake Huron was nearly 30.4 percent.
News outlets noted that as many as 70 ships have been backed up in Lakes Michigan, Huron, and Erie, waiting for passage into ports on Lake Superior.
The U.S. Coast Guard has been grouping ships together into small convoys after they pass through locks at Sault Ste. Marie, in order to maximize ice-breaking efficiency and to protect ships from damage." (EO)
And as the Great Lakes slowly lose their historically large ice covers over the next few months, the domino effects could include lingering cold water, delayed seasonal shifts, and huge jumps in water levels.
Like the shipping troubles, some of the more unexpected things the lakes and their ecosystems could face in the next few months are the direct result of the lingering ice and cold:
- Throughout the winter, huge numbers of ducks that feed by diving below the water for fish ended up starving to death. Connie Adams, a biologist in New York's Department of Environmental Conservation, told the AP that the die-off was "unprecedented."
- Next in line for concern are a huge number of the Lakes' fish species. Warming water temperature often biologically triggers migration to traditional spawning grounds, and experts expect that Northern Pike, lake sturgeon, steelhead, and rainbow trout could make moves far later this year. As Shedd Aquarium research scientist Solomon David told Michigan Radio, later egg laying could mean younger and far weaker fish come next winter, leading to an even longer impact. ("Why It's a Big Deal That Half of the Great Lakes Are Still Covered in Ice" by The Atlantic Cities)
Featured image courtesy Jeff Schmaltz LANCE/EOSDIS MODIS Rapid Response Team, GSFC