geo 8.3

• There used to be a constant balance in Greenland between the growth of ice from snowfall and loss of ice due to melting or calving icebergs
• Meltwater flows through a moulin to the bottom of a glacier


  1. Ends up between the land and the ice sheet

  2. Makes glaciers move faster towards the sea

  3. Glaciers melt much faster
• If all the ice in Greenland melted, sea-level rise would be 7 metres
• Methane


  A more powerful gas than CO2
• Methane is produced naturally by bacteria that break down dead plant and animal matter


  1. A huge amount of methane is stored in the soil of the tundra

  2. When permafrost melts, the methane is released
• Methane


  A greenhouse gas that is roughly 25 times more potent than CO2, but doesn't last as long as CO2 in the atmosphere
• Because ground that has been permanently frozen (permafrost) is thawing, huge holes are appearing in landscapes
• Thawing permafrost makes houses and infrastructure sink into the ground
• Thawing permafrost is responsible for additional greenhouse gas emissions: methane and CO2
• Moulin


  A large round shaft in the ice where meltwater forms a whirlpool and drains away
• The water collects underneath the ice


  Causing that ice to melt and break into pieces
• The Greenland ice sheet started to melt sometime after 1990
• The Greenland ice sheet loses ice by calving ice bergs and meltwater
• Specks of soot lower the albedo of the Greenland ice sheet
• The sea ice floating around Antarctica attaches to the glaciers and freezes, creating a kind of buffer
• Because the sea water is warming, the bottom of the ice shelf is melting too
• Ice shelves are gradually thinning
• Ice shelves no longer hold back the land ice flowing into the ocean as they did before
• Ice shelves no longer work as a buffer