Going, going...gone?
Analyzing Glacier Change
Your name:
LABORATORY PURPOSE: In this laboratory, you first connect your knowledge of the
scientific principles and concepts of glacier advance and retreat to the ongoing debate
over the potential effects of global climate change. You then make your hypothesis of
what you would expect to find in a quantitative study of glacier length. You go on to test
your hypothesis by analyzing historic geomorphology records and compare your
findings with climate records. Your analysis of historic photos and maps will also include
your assessment of how much confidence you have in making measurements from
different historical sources.
Activity 1: Analyze a sampling of media imagery in terms of glacial
processes
Background: You will use prior knowledge of glacial mass balances and glacial
processes to interpret a sampling of media articles on the topic of how global climate
change affects glaciers. If you are unsure of your prior knowledge, you are encouraged
to read this article http://www.eoearth.org/article/Glacier, and focus on the section
Glacier Mass Balance
Instructions: Read the following articles, a random sampling of media presentations on
the subject of global climate change and glacial retreat:
MediaBostonGlobe.pdf
MediaBBC.pdf
MediaNPR.pdf
MediaNewsBusters.pdf
MediaNewYorkTimes.pdf
Using your prior background knowledge on the topic of glacial mass balance, please
explain in your own words why glaciers would retreat. Why could global climate
change cause the retreat of alpine glaciers?
Activity 2: Point and Counterpoint
Instructions: In this activity, you read two different articles discussing the retreat and
advance of glaciers. Whereas Pelto presents the case for ongoing glacial retreat, Hecht
argues that we should prepare for another ice age because the glaciers are growing
and advancing.
HectAdvance.pdf
PeltoRetreat.pdf
After reading each article, please finish a scientific hypothesis for what Hecht and
Pelto would expect to find if they examined 150 years of historical records of
maps and photos of one glacial system in the Cascades of the Pacific Northwest
USA.
Hecht Hypothesis: A glacial system in the Cascades of the Pacific Northwest USA has
been ...
Pelto Hypothesis: A glacial system in the Cascades of the Pacific Northwest USA has
been ...
Background to this question: You understand that scientists make hypotheses and
(supposedly) test them objectively, ideally not caring whether the hypothesis is
supported or falsified by data and data analysis. Science, geomorphology included, can
never “prove” that a hypothesis is true; that is for faith. Thus, in science, results and
analysis can only support a hypothesis, not support (falsify) a hypothesis, or neither
support nor not support a hypothesis.
You will now make a hypothesis for what you would expect to find by examining 150
years of historical records of a glacial system in the Cascades of the Pacific Northwest
USA.
The first sentence of your hypothesis that you write should explain whether you think
you would predict glacier retreat, glacier advance, or some combination. The second
sentence of your hypothesis will explain the reason for your first hypothesis. The source
of the second part of your hypothesis can be a hunch, an intuition, or it can be based on
prior readings.
What is your hypothesis? Finish the two sentences:
I hypothesize that, over the last 150 years, ...
I also hypothesize that this has been caused by ...
Activity 3: Testing your hypotheses by examining maps and photos of
the Nisqually Glacier, Mount Rainier
Background: Glacial geomorphologists use many different types of data to analyze
how glaciers change. Some make direct measurements of glaciers in the field. Others
use satellites to monitor changes. A very common strategy is to make repeat
observations over time, using maps and historical photographs. This website provides
you a summary of some of the methods that have been used to study glacier change on
Mount Rainier: http://www.glaciers.pdx.edu/MRNP/Res00.html
Instructions: In this activity, you will test your hypothesis analyzing a mixture of
historical maps and photographs of the Nisqually Glacier on Mount Rainier, as well as
different temperature records.
Task 1. Estimate the length of the Nisqually Glacier, starting at the Summit of
Mount Rainier.
Nisqually Glacier Length Data Instructions:
-- Use the map and photographs (linked on the webpage version of this
assignment) to estimate the length of the Nisqually Glacier of Mount Rainier.
o In the 1856 map, you will need to use the scale bar to estimate the
glacier’s length. The map is fuzzy, so just do your best.
o In the 1917, 1924, 1994, and 1997 maps (and the 1983 aerial
photograph), you will estimate the distance to the road (bridge) that
crosses the Nisqually River and then subtract that distance from the 8.8
kilometer estimate of the distance from the summit of Mount Rainier to the
bridge. Look at the 1971 map for an example.
o In all of the other photographs, you will be making your best estimate
(guess) of the position, looking at the surrounding features on the photos
and comparing them with the topographic map.
-- In the Your Confidence column, please indicate your confidence level of your
estimate, from high (put number 1) to very low (put number 4). You will have to
answer questions in the next task related to your confidence and the ability to
make interpretations later.
Data Table of Nisqually Glacier Length. Use the linked map and photo sources to
estimate the length of the Nisqually Glacier in different time periods.
Instructions: Fill in the blanks in this data table.
Year
Source (and
link)
1856
Map
1907
Map
1917
Map
1924
1929
1940
1943
1951
1956
1958
1960
1966
1969
1971
1983
1994
1997
2003
Map
Ground Photo
Ground Photo
Ground Photo
Ground Photo
Ground Photo
Ground Photo
Aerial Photo
Ground Photo
Ground Photo
Map
Aerial Photo
Map
Map
Aerial Photo
Your
Confidence
(high-1,
medium-2, low3, very low-4)
Distance in
Kilometers from
Nisqually River
Bridge to terminus of
Nisqually Glacier
(round up to the
nearest 0.1 km)
Note: Bridge not
present, so you will
have to estimate the
length from the map
and the scale bar
At the bridge
Length of Nisqually Glacier in
Kilometers
(subtract distance from bridge
from 8.8 kilometer distance from
summit of Mount Rainier)
____________
Note: you will have to measure
in miles and convert to km by
multiplying miles times 1.6. The
scale bar has increments of 1/4
mile
8.8 km
____________
Note: you will have to measure
in miles and convert to km by
multiplying miles times 1.6.
1.9 km
6.9 km
1.4 km
7.4 km
Task 2. Analyzing uncertainty.
You gave your opinion regarding your confidence in the Nisqually Glacier length. You
probably put a 1 for the values that were already entered in the table. You may have put
a 4 down for many of the ground photos, where you found it very difficult to estimate the
position of the terminus.
Explain your confidence ranking. The answer does not have to be detailed, but
your answer must be based on your observations of looking at the maps and
photos.
Task 3. Plot your data of glacier length on NisquallyGraph.jpg.
This is the graph of Nisqually Glacier Length vs Year. For your convenience, the
different dates on the maps and photos are indicated on the X axis with a triangle. An
electronic version of this graph is linked on the webpage version of this assignment
here: NisquallyGraph.jpg
Instructions: Using the data entries in the table you created, plot the length of the
Nisqually Glacier (in kilometers) on this timeline. For your convenience, the dates are
indicated on the X axis with a triangle. Then, after you have plotted the data points,
connect them. You do this by drawing a line between the points. HOWEVER, DO NOT
CONNECT THE DATA POINTS WHERE YOU HAVE LOW OR VERY LOW
CONFIDENCE. ONLY CONNECT THE DATA POINTS WHERE YOU HAVE A
MEDIUM OR HIGH CONFIDENCE OF YOUR LENGTH ESTIMATE. In other words,
draw the lines directly between only those data where you have a medium or high
confidence. The goal is for you to see all of your data, but create a curve only from data
that you consider more reliable.
Example: After gathering data from a different glacier at Mount Rainier, the following
graph presents a plot of the raw data. In the case of Glacier X, the raw data suggest
that the glacier front receded from 1856 until the mid-1960s. Since then, Glacier X
appears to have advanced, retreated and then advanced.
Not all of these data points had "high" or "medium" confidence. By "high"
confidence, I felt that the position of the terminus was well within the request to measure
to the closet 0.1 kilometers (100 meters). By "medium" confidence, I felt that the
position of the terminus on the map or photograph could be established pretty closely to
within 100 meters (0.1km) or 200 meters (0.2 km). By "low" confidence, I felt that I had
some general idea of locating the terminus within a few hundred meters, but I really
didn't know where to put the estimate within a broad area, so I selected the middle point
of several hundred meters. By "very low", my judgment of where to place the terminus
was based on maybe one or two possible matches between a feature on the ground
photograph and the topographic map.
Thus, when I connected the different terminus positions, I only connected those
data points with a medium and high confidence. You do not have to put arrows for the
points of low and very low confidence. I just did this to emphasize that you will not use
these low confidence points in making a trend line.
Task 4. Comparing your curve to atmosphere temperature records.
Background: The graphs below show different temperature trends. The upper graph
shows some common global compilations that are often seen in the popular press in
different forms. The lower graph shows the mean annual temperature of the Puget
Sound through dots, where the line represents one way to calculate the general 20 th
century trend. This task has you accept these temperature trends, for now, and think
about how your record of glacier length compares with these trends.
Different Global Annual Temperature Trend (higher is warmer):
Puget Sound Annual Temperatures (with line showing the general trend):
Example: For my plot of "Glacier X" at Mount Rainier...this is an example answer to the
next question...
Are there similarities and differences between the plot of "Glacier X" glacier
length and Global Temperature? Puget Sound Temperature?
Using only the "Glacier X" trend line with points of high and medium confidence, there does
appear to be a reasonable match between warming global temperatures between 1913-2000 and
the recession of Glacier X. The slight advance around 1980, however, does not match the global
temperature curve. The same holds true for the gradual trend of Puget Sound warming and the
recession of "Glacier X".
Since the temperature plot of Puget Sound seemed to have a lot of scatter, I feel comfortable
speculating about my points of low and very low confidence. I hypothesize that the lowconfidence glacier advance in the 1980s might relate to the cooler years in the early 1980s in the
Puget Sound.
Instructions: Now, you answer the questions below for your graph of the Nisqually
glacier length.
Are there similarities and differences between your plot of Nisqually glacier
length and Global Temperature? Puget Sound Temperature? [Keep in mind that
your glacier length plot and this temperature record go in different directions, where
cooler temperatures typically product longer glaciers.] Please identify similarities and
differences that you see.
Task 5. Comparing your curve to other glacier length records.
The graph below is a reconstruction of temperature change based on glacier length
records by J. Oerlemans, published in Science. In other words, the changes in glacier
length was used to estimate temperature change in different regions (different colors)
and then globally. For example, the light blue line uses a combination of different glacier
lengths in the Pacific Northwest (including the Nisqually Glacier) to reconstruct
temperature.
What are the similarities and differences between your plot of Nisqually glacier
length and J. Oerleman’s calculation for the Pacific Northwest? [Keep in mind that
your glacier length plot and this temperature record go in different directions, where
cooler temperatures typically product longer glaciers.]
Do you think that you would have a greater confidence in your interpretations if
you had a greater degree of confidence in all of the raw data? If so, explain why.
If not, explain why.
Activity 4: Comparing your study with other glaciers in the western
USA
Instructions: In this activity, you will select 2 glaciers in the American West and
analyze changes. You will use glaciers presented on this website:
http://glaciers.pdx.edu/GlacierTimeline/GlacierTimeline.html
Select 1 glacier from two different regions identified by red boxes on the webpage.
Then, fill out this table. Remember, you need to select 1 glacier from 2 different
regions. However, you cannot select Dana Glacier.
Region
Example:
Sierra Nevada
Glacier and
Photograph Years
Dana Glacier,
1883, 1916, 1932,
1939, 1940, 1954,
2004
Analysis
Dana glacier retreated from 1883 to 1939,
readvanced very slightly in 1940, and then
retreated from 1940 to 2004
1.
2.
How does your detailed study of the Nisqually Glacier compare with your
observations of your two randomly selected glaciers?
Activity 5: What does the future hold?
Do you now favor a hypothesis on why the glaciers you analyzed have
experienced these changes? What is your new hypothesis? Also, please predict
the future of your six glaciers. In other words, design a second hypothesis on
what will happen in the next 20 years to your glaciers.
I also hypothesize that the changes I observed in Activities 3 and 4 has been caused by
I hypothesize that the following changes will occur in the next 20 years. The Nisqually
Glacier will
The _______ Glacier will
The _______ Glacier will
Note: You are encouraged to actually visit your two glaciers over the next two
decades and rephotograph them from the same position. Then, please submit
your photographs to Professor Andrew Fountain and this project:
http://glaciers.research.pdx.edu/