Melting Ice, Rising Seas

Name: _________________________________       Date: _____________

Earth's cryosphere, its layer of ice and snow, is going through big changes these days. This is especially true in the polar regions where ice sheets, ice caps, and glaciers are melting at an alarming rate. If the melting continues, rising sea levels will spell disaster for humans and wildlife. In this activity, you'll learn more about the extent of this global meltdown and its possible effects.

1. To begin, visit the State of the Cryosphere page. Scroll to the graph of global temperature change since 1880. How much has mean global temperature increased since 1880?
   
   
   
   
2. Next, click to find out how this temperature change affects Northern Hemisphere snow cover. Scroll to the picture of Northern Hemisphere snow and ice cover then read the paragraph to its right. Compare the amount of solar energy reflected by a snow-covered surface vs. one that's snow-free.
   
   
   
   
3. Explain how your answer to question 2 causes snow to melt.
   
   
   
   
4. What is the difference between the extent of the snow cover (in millions square kilometers) in 1979 vs. 1999?
   
   
   
   
5. Scroll down to the paragraph below the last graph.
   1. What is the annual (per year) percentage decrease of snow cover over the past 20 years?
      
      
      
      
   2. Multiply your answer to question 5a by 20. What was the percentage decrease of the snow cover over the past 20 years?
      
      
      
      
6. Go to the State of the Cryosphere Mountain Glacier page. Compare the two pictures of the South Cascade Glacier. Describe how it has changed since 1928.
   
   
   
   
7. Scroll to the graph of glacier volume. How much has it decreased since 1960?
   
   
   
   
8. Find out about changes in global sea ice. Read the caption below the picture on the right. What happened to Arctic sea ice in the summer of 2002?
   
   
   
   
9. Read the paragraph to the left of the caption. Describe how shrinking sea ice affected bears and other cold climate mammals.
   
   
   
   
10. Scroll to the graph of Annual Average Ice Extent. Estimate (in millions square kilometers) how much the sea ice shrank from 1955 to 1998.
    
    
    
    
11. Next, you'll see what's happened to ice shelves.
    1. What is an ice shelf?
       
       
       
       
    2. Describe what happened to the Larsen ice shelf in Antarctica between January and March 2002.
       
       
       
       
12. All of this melting ice has to end up somewhere. Click to see how it's affecting global sea level. Scroll to the last paragraph.
    1. How much has sea level risen over the past 100 years?
       
       
       
       
    2. How much of this rise is due to melting ice?
       
       
       
       
13. To learn how rising sea levels may affect the planet, visit the EPA's So What's the Big Deal? page. Scroll to the section on Sea Level Rise. Describe some of the possible effects.