Name_____________________ Date__________________________ More Activities: http:/www.ldeo.columbia.edu/polareducation 1 Image 1) Glaciers are large expanses of ice, often covering the landscape – images 1 & 3 are Greenland’s Kangerdlugssuaq Glacier (by P. Spector) Image 2) Arrow points to the calving front on Greenland’s Jacobshavn Glacier (by I. Das) REVIEW OF GLACIER BASICS: Glaciers are rivers of ice but how do they develop? Forming a glacier: In some areas snow lasts on the ground all year. Newly falling snow flakes cover the older snow flakes, compressing them to be smaller and denser. Air between snowflakes is pressed out, and over time as the snow deepens it crystallizes into ice. Ice Sheets: Ice sheets are continental size glaciers. They exist today in Greenland and Antarctica. Glacier Growth: Glaciers grow when annually more snow is ADDED (accumulation) than is REMOVED (ablation). Snow can be added directly through snowfall, or blown in from other areas by the wind. Glacier Movement: As glaciers grow from snow accumulation they stack higher and higher causing gravity to tug, pulling them down. Glaciers are called ‘rivers of ice’ since they move constantly flowing from areas of higher elevation to areas of lower elevation. Glacier Change: As a glacier flows to lower elevations it can loose mass (ablation) several ways: melting - lower elevations are generally warmer; wind - wind blowing over the glacier erodes the surface; sublimation - ice can turn directly to vapor without moving through the liquid stage; calving - chunks of ice that break off at the glacier edges. TASK: Where you would expect accumulation and ablation to occur on a glacier? Label the glacier in Image 3 with these words to show your choices. Glacier Retreat: Remember as glaciers flow to lower elevations they lose mass. Glaciers will retreat when there is less new snow accumulation than ablation. Basic Glacier Equations – it is simple math! Steady State Glacier: Annual new snow =Annual snow melt Glacier Expansion: Annual new snow > Annual snow melt Glacier Retreat: Annual new snow < Annual snow melt POLAR I.C.E. (Interactive Climate Education) WHAT IS HAPPENING TO ANTARCTIC’S PINE ISLAND GLACIER? Use your understand of glacier science to figure out what is happening to this Glacier! Image 3) Kangerdlugssuaq Glacier
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Image 1) Glaciers are large expanses of ice, often covering the landscape – images 1 & 3 are Greenland’s Kangerdlugssuaq Glacier (by P. Spector)
Image 2) Arrow points to the calving front on Greenland’s Jacobshavn Glacier (by I. Das)
REVIEW OF GLACIER BASICS: Glaciers are rivers of ice but how do they develop? Forming a glacier: In some areas snow lasts on the ground all year. Newly falling snow flakes cover the older snow flakes, compressing them to be smaller and denser. Air between snowflakes is pressed out, and over time as the snow deepens it crystallizes into ice. Ice Sheets: Ice sheets are continental size glaciers. They exist today in Greenland and Antarctica. Glacier Growth: Glaciers grow when annually more snow is ADDED (accumulation) than is REMOVED (ablation). Snow can be added directly through snowfall, or blown in from other areas by the wind. Glacier Movement: As glaciers grow from snow accumulation they stack higher and higher causing gravity to tug, pulling them down. Glaciers are called ‘rivers of ice’ since they move constantly flowing from areas of higher elevation to areas of lower elevation.
Glacier Change: As a glacier flows to lower elevations it can loose mass (ablation) several ways: melting - lower elevations are generally warmer; wind - wind blowing over the glacier erodes the surface; sublimation - ice can turn directly to vapor without moving through the liquid stage; calving - chunks of ice that break off at the glacier edges. TASK: Where you would expect accumulation and ablation to occur on a glacier? Label the glacier in Image 3 with these words to show your choices. Glacier Retreat: Remember as glaciers flow to lower elevations they lose mass. Glaciers will retreat when there is less new snow accumulation than ablation.
Basic Glacier Equations – it is simple math! Steady State Glacier: Annual new snow =Annual snow melt Glacier Expansion: Annual new snow > Annual snow melt
Glacier Retreat: Annual new snow < Annual snow melt
POLAR I.C.E. (Interactive Climate Education)
WHAT IS HAPPENING TO ANTARCTIC’S PINE ISLAND GLACIER?
Use your understand of glacier science to figure out what is happening to this Glacier!
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4) Antarctic Map (by NASA) - Annotated to show the PIG section from Image 6 in the boxed area; arrow shows ice flow direction.
5) Map of the larger Antarctic Ice Shelves by color and ice volume – T. Scambos
MEET P.I.G. - ONE OF ANTARCTICA’S FASTEST GLACIER! Scientists are measuring the polar ice sheets to determine both how fast and how much (total amount) they have changed over the last few years but it isn’t easy! Why? The polar regions are large, the weather is extreme and there are few roads to travel on. Much of the ice is nor smooth, and hugs breaks in the ice, called crevasses, can appear suddenly in the snow adding to the travel difficulties! One of the most efficient ways scientists have found to collect measurements is from above the Earth surface using satellites and aircraft. These types of measurements are called ‘remote sensing’, which simply means the instruments are not physically touching the objects they are measuring. A lot of our understanding of the Earth has come from remote sensing. Since the 1990s satellites have been collecting information on the Earth surfaces. In 2003 NASA launched a satellite specifically to collect measurements of the polar-regions. “Ice, Cloud and Land Elevation Satellite” (ICESat) collects ice sheet surface elevation (height) as one of its measurements since a glacier that is dropping in elevation is losing ice! You will be working with ICESat data!
When ICESat was launched scientists were already interested in Pine Island Glacier (PIG) ‘stream’ of fast moving ice. Shown in Image 6, PIG is considered the largest of 3 major drainage pathways moving ice from the West Antarctic Ice Sheet directly into the Amundsen Sea (see Image 4). Satellite measurements show that PIG is accelerating, moving ice at speeds measured at 3.5 km/yr, and pushing more ice into the ocean than any other glacier in Antarctica! Much of Antarctica is surrounded by large ice shelves that isolate the glaciers from the warming ocean. There is evidence that warming ocean water is being forced up around the edges of Antarctica by shifting ocean currents, causing melting where the ocean touches the ends of the glacier. Melting the edges causes ice flow to accelerate and ice surface elevation to drop. Look closely at Image 5. There is no large ice shelf protecting PIG. PIG’s shelf is small ~40
X 20 kms. Task: Calculate and compare its area to that of the ice shelves in image 5___.
(6) A MODIS Satellite image of Pine Island Glacier Flow. This arrow matches the the location arrow on image 4.
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PART 1: WORKING WITH ICESat DATA Activity: Are changes occurring in the elevation (height) of PIG? Scientists have been reviewing satellite data on the surface elevation (height) of the PIG glacier over several years to see if there is a loss of ice. Remember, if the height of the glacier drops it shows a loss of ice and a shrinking glacier. If the height increases it means the glacier is growing larger. Help the scientists determine what is happening!
The data: You are working with real data collected over PIG survey line # 279 on three separate times: Nov. 2003, April 2007 and Oct. 2007. We will examine these three sets of data to see if there are changes occurring in the glacier over this four year time period. What was measured: The data you will work with was collected looking at the face of PIG the same way that Image 7 looks at a glacier face. The data measures the elevation (height) across the glacier face at
multiple points, just like the red dotted line shown in this image. Collected in this way along a line, the series of data points represents a ‘slice across the glacier’. Data was collected in the same location repeatedly in different months and years in order to assess any changes. PIG 279 – Part I
1. The full PIG #279 dataset contains hundreds of data points. A small section of the data is provided here for you to analyze.
2. Let’s start by looking at just the first four columns and what each represents.
• Location km - Shows the location of each data point as a km from a central starting point. Since we are looking at only a section of the data we have only data points between km 253 through km 239. What is the total distance represented by the data points in this graph?________
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• Elevation & Dates of Measurements – There are three columns of elevation data for PIG 279, labeled by month and year 11/2003, 4/2007 and 10/2007. Each of these is called a ‘data series’ as it represents the ice elevation at the same set of locations for the three time periods. The elevation measurements are listed as the depth of ice in meters.
3. What is the first step in analysis? When scientists collect more than one ‘data series’
they look at them together by plotting or graphing them to see if there is a relationship. Plots and graphs can help us to ‘see’ the data to recognize patterns and trends. For this data we have the locations by km and the elevation by date so let’s plot it on a graph.
4. Using the Graph Paper labeled Graph #1 create one graph that includes all three
sets of data from the first 4 columns on your sheet. First set up the ‘X’ and ‘Y’ axes. Start with the ‘X’ axis, this will be the distance in km. Decide how to set up your graph. Since your numbers range from 253 to 239, do you need to start your axis with ‘0’? Decide how you will set up the ‘X’ axis and label it. Now let’s look at the ‘Y’ axis. Locate the highest_____ and lowest____ elevations between the three years. Now set up your axis to cover the range you need.
5. You are ready to start plotting the official ICESAT ice elevation data! Select a
different color pencil to plot each of the three sets of data so that they will be easily recognized as a separate line with its own label and color. Be sure to make a color key on the graph. Starting with ‘Elevation 11/2003’ plot each of the three sets of data.
6. Examine your chart. Can you tell if there is a story in the data displayed? Do you see
elevation changes or does it appear that the ice surface has been fairly stable? Discuss what you see. __________________________________________________________________________________________________________________________________________
7. Let’s look a little closer. The data collected is from an length of approximately ___
kms, with altitude changes of almost ____ meters. This is a fairly large area to examine for what could be small-scale changes. We need to figure out a better way to look at the data given this large-scale comparison. Let’s try something new!
PIG 279 – Part II
8. What if we used the (mean) average of the data points and compare each data set against the mean? This will show us how each number differs from the mean. Using the mean the numbers will be much smaller and it will be easier to see if there has been a change over the four years of data collected. Let’s look at the last 4 columns of the chart to see what each one represents.
• Mean # - this is the mean (average) of the three sets of measurements (11/2003, 4/2007, 11/2007) for each of the locations in the data series.
• Delta Nov 03, Delta April, Delta Oct 07 – Delta means change. These three columns represent the change from the mean for each of the original measurements. For example for at km 253 the Nov. 03 reading of 690 is 2 above the mean of 688 so the Delta Nov 03 amount listed is 2. If the number is below the mean it will be a negative number. The first row is complete for you – fill in the missing numbers for the rest of the graph.
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9. Before we start to chart the data think about what the numbers will mean. What would a positive Delta number mean? What would a negative Delta number mean? In other words, which would mean LESS ice and the glacier is shrinking___________, and which would mean MORE ice and the glacier is growing? _______________
10. Chart the data on the sheet marked Graph #2 using the change from mean, or the
delta number for each year. The numbers you put for the ‘X’ axis will be the same as the last graph since the distances have not changed. The ‘Y’ axis will still be called “Elevation” but this time the ‘X’ axis will be the difference from mean for each of the three years of ice elevation measured by ICESat. What is the highest_____ and lowest____ elevations for all three years? Now set up your axis to cover the range you need. Use the same key and colors as you did for graph in Part I and remember each set of data will be a separate line with its own label and color.
11. Now that it is graphed let’s examine your chart. Can you find a story in the data
displayed? Do the data points overlap, or are there clear differences? Discuss a comparison of the data from November 03 to the data from April 2007 and then to Oct. 2007? Be sure to use measurements in your answer. ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
12. What does this data tell us about the PIG glacier? After looking at this data what
would you tell the scientists about the ice surface, has it been fairly stable or is the elevation changing? _________________________Explain what you think this means about this area of Antarctica? __________________________________________________________________________________________________________________________________________
13. We have looked at one series of PIG data, however scientists would want to look at
more than one data set. Why would this be important? ______________________________________________________________________
What could cause the glacier elevation to behave this way? In Part III you will create your own hypothesis about glacier movement. Following the scientific method you will experiment with glacier behavior using a physical model:
1. Construct a hypothesis 2. Test it by doing an experiment 3. Analyze your data 4. Draw a conclusion 5. Communicate your results
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PART III: HANDS ON LAB ACTIVITY - WORK WITH GLACIER GOO TO DEVELOP A MODEL TO SUPPORT THE DATA (For this section students work in a team of 2-4. Give each student a recording sheet)
8) Supplies used in lab
SUPPLIES: Set up needed for each team: • Batch of Glacier Goo (recipe attached) • Small Rectangular container (we used
plastic box ~13" x 7-1/2" x 4-1/4" h) • Flat ‘ramp’ for container firm enough to
support glacier goo (wood, plastic, etc.) • Marked graph measuring paper (attached)
laminate or place in plastic sleeve • Dry erase marker • Tape • Plastic knife • Stop watch • Calculator • Ruler with centimeter measurements
LAB ACTIVITY: The set up can be done in advance by the teacher or by the students with teacher supervision. SET UP:
• Set up your rectangular container with a sturdy ramped surface for the glacier (goo) to flow on (the goo can be surprisingly heavy so less rigid surfaces will bend).
• Tape one copy of the laminated gridded graph paper to the ramp, underneath if it is clear or on top of the ramp if it is not (see photo #9)
• Make sure each team has the full list of supplies. Before You Start: You will be using glacier goo as a model for polar glaciers in this section. Before you start review the following questions answering in full sentences:
1. Thinking back to the ‘Glacier Basics’, are glaciers rigid blocks of ice? Explain. ___________________________________________________________________________________________________________________________________
2. What is needed for a glacier to maintain a steady surface elevation (height)?
Remember the equation! ___________________________________________________________________
3. Could a change at the ablation zone of the glacier cause a change in the elevation of
the glacier? _________________________________________________________
4. Recall the data you graphed for PIG. State your hypothesis below to explain the
changes in the PIG glacier. ________________________________________________________________________________________________________________________________________
Now you will use your model to test this hypothesis.
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ACTIVITY # 1: TEST YOUR HYPOTHESIS: Let’s collect some observations and measurements of our glaciers (goo).
#9) Mark the glacier surface height and 1 cm below the surface with lines. Mark the terminus (end) of the glacier with a line.
#10) Measuring the grid. The arrow is pointed to the pre-marked square on the grid.
DIRECT OBSERVATIONS:
1. What makes glaciers move in nature? ____________________ Place your glacier (goo) at the top of the ramp in a mound. Release and observe your glacier (goo). Describe what you see. ________________________________ How is the glacier goo like a real glacier?______________________________________________
2. Establishing The Base Level: Use ¾ of a batch of glacier (goo). Have one student
place it in a mound at the top of the ramp, and hold it in place during the set up. Arrange the glacier (goo) in the container so that any change in elevation will be visible through the side ‘wall’ of the container. Set the goo slightly away from the wall since the goo will stick to the ‘walls’ of the container. (Note: As the goo moves if it does stick to the wall carefully use your plastic knife to skim it off so the true surface level is visible.)
Have a second student place a piece of clear tape on the outside of the plastic container and using a dry erase marker put a mark at the surface height of the glacier. Use your ruler to make a parallel line 1 cm below this surface mark and label it 1 cm drop (see image #9). Now place a mark at the end point (this is called the ‘toe’) of the glacier. These lines mark your glacier ‘base level’. You will now be able to return to this base level with each ‘run’ of your experiment and be able to see what happens to this base level with changes you make in the conditions.
3. Elevation Run #1: Remove your hold on the glacier (goo). Observe for 2 minutes.
Measure and describe any changes to the surface elevation. (Refer to your markings on the side of your container.) _________________________________________________________________
4. Elevation Run #2: Start your glacier over again. This time as the glacier flows add
some of your remaining glacier (goo) to the top of the glacier on a regular ongoing basis. Does this addition of ‘new snow’ to the glacier affect the elevation? Does one of the glacier equation from Glacier Basics match this demonstration? __________________________________________________________________
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5. Elevation Run #3. Start your glacier over again. What if the ice sheet at the base of the glacier were to melt from the ocean water warming it? Remove some of the ice sheet at the toe of the glacier by cutting a section off with a plastic knife. Watch what happens. Does the glacier speed up to fill in the removed ice?______ Does it thin out losing elevation? ___________________
6. Compare to Your Hypothesis. Does the behavior of this model glacier support your
ACTIVITY #2: COLLECTING MEASUREMENTS: 8. Elevation Change: Next let’s see how your glacier measures up to the PIG glacier.
Using the stopwatch you are going to measure how long it takes the glacier to lose the 1 cm of elevation you have marked on the outside of your container. Place the glacier (goo) in a mound at the top of the ramp. Set up the goo so the glacier surface lines up with the markings you have noted on the ‘wall’ and the toe of the glacier is in line with the terminus mark. Release the goo and start your stopwatch. Stop the watch when the glacier has dropped to the 1 cm drop marked on the wall. (Report in seconds)
Repeat 2 other times and compute an average.
________________ ________________ ______________ ________________ Time 1 Time 2 Time 3 Average The elevation change you calculated is:
1cm/_____secs
9. Velocity: Now you will look at the velocity (rate of flow). Using a stopwatch you are going to measure the velocity of your glacier & then compare it to the velocity of PIG. In its fastest flowing sections PIG has been measured at ~3.5 km/yr.
To start, use your ruler to measure the specially marked grid on graph paper attached to your ramp. This will be your distance (D). How many cm long is it?__________
Reposition the glacier at the top of the ramp. Place your glacier (goo) so that the ‘toe’ (end) of your glacier is above the grid you just measured (Image #10). Using your stopwatch you will time the glacier as it flows the length of the measured square on your grid. Start the stopwatch as soon as the tip of the glacier reaches the top of the marked square and stop timing as soon as it touches the bottom of the marked square. Record the time below. Repeat twice more to get an average time (report in seconds).
_______________ _________________ _________________ ___________ Time #1 Time #2 Time #3 Average Time
What is your Velocity? Velocity = Distance/Time (V = D/T) ______ = ________/________
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PART IV: COMPARE YOUR GLACIER MOVEMENT TO PIG: How does your glacier match up to PIG? You have measured the elevation change and velocity of your glacier - let’s see how your data matches PIG!
PIG GLACIER GOO
10. Compare your glacier elevation changes to PIG. How long did it take PIG to loose
1 cm in elevation? Use Nov. 2003 to October 2007 as the timeframe rounding the time to 4 years. You have several elevation measures for PIG, but looking at the last 3 columns find the row across that shows the largest change in meters and write it in the blank below. (Remember there are both positive and negative numbers) _______ Start with: meters_____/years_____
To better compare the two sets of measures convert the (a) meters to cm
(a) #meters____ X 100 cm = ______cm/_____years AND then ____cm/1 yr
b) ____days per year IS ___ cm/___days OR _____ cm /1 day How many days to drop 1 cm? PIG ___days/_1_cm - Glacier Goo 1cm/____ secs. PIG 1 cms/______days Glacier Goo 1cm/____secs.
How does your glacier elevation change compare to PIG? _________________ ________________________________________________________________
11. Compare your glacier velocity to PIG’s velocity. You will need to do some conversions to be able to compare these velocities. Let’s convert the PIG velocities into your recording units. Velocity of PIG = 3.5 km/year Compared this to your glacier velocity V____=______cms /_____secs To do this conversion you will need to know how many (a) cm are in a km and how many (b) minutes are in a year. (a) Convert to meters. 1000 meters (m) in a kilometer (km) and100 centimeters (cm) in a
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meter. How many cm are in 3.5 kms? _________ (b) Convert years to minutes. _____ in a year X # hours in a day X # minutes in an hour?________ The Velocity of PIG _______cms/ __________ mins Your glacier velocity _________cms/_________mins
How far each glacier moves in 1 minute? Divide the cms by the number of minutes: The Velocity of PIG _______cms/min Your glacier velocity _________cms/min
Hoe does the velocity of your glacier relate to PIG?____________________________
12. List at least three things you have learned about PIG glacier working with your own
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