Context: 

The Great Lakes ecosystem have for the second consecutive year recorded a  below average ice cover as per the National Oceanic & Atmospheric Administration (NOAA).

About The Great Lakes

• Location:  They are a series of large interconnected freshwater lakes in the east-central interior of North America  on or near the Canada–United States border 
  • It connects to the  Atlantic Ocean via the Saint Lawrence River.
  • The lakes are divided among the jurisdictions of the Canadian province of Ontario and the U.S. states of Michigan, Wisconsin, Minnesota, Illinois, Indiana, Ohio, Pennsylvania, and New York.
• Comprise of: It comprise of 5 major lakes namely,
  • Lake Superior
  • Lake Michigan: It is the largest freshwater lake that is entirely situated within one country i.e. USA
  • Lake Huron
  • Lake Erie 
  • Lake Ontario 
• The Freshwater Source: The Great Lakes are the largest group of freshwater ecosystem on Earth by total area and are second-largest by total volume, containing 21% of the world’s surface fresh water by volume.
• Characteristics: It has sea-like characteristics, such as rolling waves, sustained winds, strong currents, great depths, and distant horizons therefore also called the inland seas.

Ice Cover on the Great Lakes:

• Historical Ice Cover: The Great Lakes are covered with a thick layer of ice in late February or early March usually. 
  • That is when the ice cover reaches its peak. But that has not been the case during the winter of 2023-24.

• Recent Trends:

• • Winter of 2023-24:
    • The total ice coverage across all lakes till feb 11 measured just 2.7%. 
    • Lakes Erie and Ontario basically both remained essentially ice-free this season.
  • Declining Ice coverage: The maximum basin-wide annual ice coverage has been 53 per cent since reliable satellite data collection began in 1973, but the amount of ice has seen a 5 % drop every decade, amounting to a  total 25 per cent decrease
  • The Ice season: It has shortened in duration by approximately 27 days on average over the last 5 decades.

The Changing Winters:

• The Great Lakes are among the fastest-warming lakes in the world with recent years witnessing Decembers exhibiting above-average temperatures according to the Fifth National Climate Assessment
• Reasons for Decreased Ice Cover on the Great Lakes:
  • Global warming induced climate change is responsible for the lack of ice this winter
    • 2023 has already been declared as the hottest year on record and January 2024 the hottest January on record
  • El Nino: The warming is  exacerbated by the active phase of  El Nino, (the warmer phase of the El Nino-Southern Oscillation) since mid 2023
  • Warmer Winters: The delayed formation of ice due to the lack of cold air early in the season makes ice concentration harder to achieve
  • Weakening Arctic cold winds: Fewer and generally shorter intrusion of blasts of cold air from the Arctic exacerbates the situation and results in diminishing ice cover.

Significance of an Icy Great Lakes:

• Ecosystem balancing: Ice is a natural part of the yearly cycle of the Great Lakes, upon which many animal species, ranging from microbial to larger fauna, rely on for protecting their young and harboring eggs.
• Coastal resilience: The ice sheets along the shore act as an important buffer against the  (storms and large wave events during the colder months of jan to march) protecting the coast from erosion and damage to shoreline infrastructure. 
• Economy: The lack of ice is also affecting tourism and recreational activities of the region
  • The John Beargrease Sled Dog marathon was cancelled last month due to lack of snow. It is one of the most beloved dog sled competitions in the Midwest.

News source: DTE