Global Sea Ice Cover Dipped to Record Low

Context: Global Sea Ice Cover dropped to a record low of 15.76 million sq km in February 2025.

What is Sea Ice?

• Sea ice refers to free-floating ice in the polar regions, formed when ocean water freezes.
• It is different from: Icebergs, glaciers, ice sheets, and ice shelves, which originate from land.
• Seasonal Changes:
  • Expands in winter and melts in summer.
  • Some sea ice remains year-round.

Historical Trends in Sea Ice Decline

Arctic Sea Ice Loss

Shrinking at a rate of 12.2% per decade.

• Since the late 1970s: Arctic sea ice has been declining rapidly.
  • An estimated 77,800 sq km of sea ice is lost every year.
• Current Situation: Arctic sea ice is at its lowest recorded extent for this time of year.

Antarctic Sea Ice Loss

• Different Trend Until 2015: Antarctic sea ice increased slightly year-on-year.
• 2014-2017: Antarctica lost 2 million sq km of sea ice, equal to four times the size of Spain.
• 2023: Antarctic sea ice reached historically low maximum levels.
• 2024-2025: Ice cover improved slightly from 2023 but still 55 million sq km below the 1981–2010 average.

What is Causing the Record-Low Ice Cover?

Arctic Factors

• Warmer ocean waters: Oceans are taking longer to cool, delaying sea ice formation.
• Storms in the Barents and Bering Seas: Thinner ice is more fragile and breaks apart easily.
• Higher-than-normal air temperatures: Particularly in Svalbard (Norway), and Hudson Bay (Canada).

Antarctic Factors

• Ice-breaking winds: Unlike the Arctic (surrounded by land), Antarctic sea ice is surrounded by the ocean, making it more mobile and thinner.
• Warmer air and water temperatures: More melting at the edges of the ice sheet (ice shelves).

Consequences of Declining Sea Ice

Accelerated Global Warming

• Less ice = more heat absorption:
• White sea ice reflects sunlight back into space.
• Darker ocean water absorbs more heat, leading to higher temperatures.
• Polar regions are warming faster than the rest of the world.

Impact on Ocean Currents & Global Climate

• Melting ice releases freshwater into the ocean.
• Lower salinity and density: Reduces the downward flow of surface water & Slows ocean overturning circulation.

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