155 LAB 11: CLIMATE CHANGE Past, Present, and Future In this lab you will learn about the changes to Earth’s climate in the past, and the current and future global warming of the planet. You will then investigate the impacts of past, present and future climate change on glacial and coastal environments. 156 LAB 11: CLIMATE CHANGE Past, Present, and Future The Earth’s climate has been changing throughout its 4.6 billion-year history. These climatic shifts can be gradual or dramatic. Our planet has experienced numerous “Ice Ages”, when glaciers have advanced and large portions of North America have been covered in ice and global sea level dropped. Conversely, our planet has also undergone periods of warming, where global temperatures rise, ice melts, and sea level rises. Our planet is currently in a period of unprecedented global warming: global temperatures are rising dramatically, glaciers and ice caps are rapidly retreating and melting, and sea level is rising. In this lab you will explore how Earth’s climate has changed in the past, and how current climate changes are affecting us presently and in the future. PALEOCLIMATE Geologists have studied Earth’s past climate, or paleoclimate, and learned that temperature and sea level have changed dramatically throughout Earth’s history. We now have a good record of Earth’s paleoclimate from several sources, including tree rings, the rock record, fossils, and ice cores. Tree rings can give us a short-term record (past several thousand years) of past temperatures. Geologists can also piece together the paleoclimate from the rock record and fossils. For example, the occurrence of marine limestones at A- Mountain in Las Cruces tells us that, in spite of the arid climate and high elevation today, this part of New Mexico was once under an ocean. Animals live in distinct climates on Earth, so their fossils are good indicators of paleoclimate as well. For example, the fossils of wooly mammoths are commonly found in Michigan, indicating that the climate in Michigan was much cooler in the past. The chemistry of ice cores from thick ice sheets, like those in Greenland and Antarctica, provide detailed paleoclimate records. The ice in the cores is composed of many layers of snow and ice trapped over hundreds of thousands of years. It is these ice core records that have provided us with the most detailed look at temperature changes in Earth’s past (for example, the Antarctic ice cores are ~ 3 km long and record Earth’s temperature over the past ~800,000 years). Using these datasets, geologists have pieced together Earth’s paleoclimate. We now know that Earth has been both much warmer and also much cooler in the past than it is today. The Earth has clearly experienced natural fluctuations in temperature over time. For example, the Earth’s climate periodically cools significantly, producing times of glaciations or “Ice Ages” that have occur.

1. 155
LAB 11: CLIMATE CHANGE
Past, Present, and Future
In this lab you will learn about the changes to Earth’s climate in
the
past, and the current and future global warming of the planet.
You
will then investigate the impacts of past, present and future
climate
change on glacial and coastal environments.
156
LAB 11: CLIMATE CHANGE
Past, Present, and Future
The Earth’s climate has been changing throughout its 4.6
billion-year history. These

2. climatic shifts can be gradual or dramatic. Our planet has
experienced numerous “Ice
Ages”, when glaciers have advanced and large portions of North
America have been covered
in ice and global sea level dropped. Conversely, our planet has
also undergone periods of
warming, where global temperatures rise, ice melts, and sea
level rises. Our planet is
currently in a period of unprecedented global warming: global
temperatures are rising
dramatically, glaciers and ice caps are rapidly retreating and
melting, and sea level is
rising.
In this lab you will explore how Earth’s climate has changed in
the past, and how current
climate changes are affecting us presently and in the future.
PALEOCLIMATE
Geologists have studied Earth’s past climate, or paleoclimate,
and learned that temperature
and sea level have changed dramatically throughout Earth’s
history. We now have a good
record of Earth’s paleoclimate from several sources, including
tree rings, the rock record,
fossils, and ice cores. Tree rings can give us a short-term record
(past several thousand
years) of past temperatures. Geologists can also piece together
the paleoclimate from the
rock record and fossils. For example, the occurrence of marine
limestones at A- Mountain in
Las Cruces tells us that, in spite of the arid climate and high
elevation today, this part of
New Mexico was once under an ocean. Animals live in distinct

3. climates on Earth, so their
fossils are good indicators of paleoclimate as well. For example,
the fossils of wooly
mammoths are commonly found in Michigan, indicating that the
climate in Michigan was
much cooler in the past. The chemistry of ice cores from thick
ice sheets, like those in
Greenland and Antarctica, provide detailed paleoclimate
records. The ice in the cores is
composed of many layers of snow and ice trapped over hundreds
of thousands of years. It is
these ice core records that have provided us with the most
detailed look at temperature
changes in Earth’s past (for example, the Antarctic ice cores are
~ 3 km long and record
Earth’s temperature over the past ~800,000 years).
Using these datasets, geologists have pieced together Earth’s
paleoclimate. We now know
that Earth has been both much warmer and also much cooler in
the past than it is today.
The Earth has clearly experienced natural fluctuations in
temperature over time. For
example, the Earth’s climate periodically cools significantly,
producing times of
glaciations or “Ice Ages” that have occurred every 40,000-
100,000 years during the past
two million years. These Ice Ages were periods of global
cooling, when glaciers advanced to
lower latitudes. During the last Ice Age, which peaked ~21,000
years ago, an ice sheet
extended from Greenland through Canada and into what is now
the northern U.S. This was
also a time of greater rainfall in the western U.S. and large
lakes were present in now-arid

4. regions, for example in Utah (Lake Bonneville) and New
Mexico (Lake Otero, now the
location of White Sands sand dunes!).
157
Figure 1. Variations in global temperatures over the past
800,000 years. The large drops in
temperature every ~100,000 years correspond with Ice Ages,
which are separated by warmer “inter-
glacial” periods. (from NASA)
Although much of Earth’s paleoclimate can be explained by
natural fluctuations, our
current climate is changing at an alarming rate. Overall, Earth’s
climate had been cooling
for the past ~50 million years, but in the past 100 years or so,
global temperatures have
increased dramatically (Fig. 2). This temperature increase is
happening rapidly, and is
occurring at the same time as concentrations of CO2 and
methane (greenhouse gases) in the
atmosphere are increasing at rapid rates. These increases are
linked, and likely caused by
human activities (increased burning of fossil fuels, increases in
agriculture, deforestation,
etc.). This global warming is an issue facing not only scientists,
who are trying to model the
future climate and searching for solutions to minimize the rise
in global temperatures, but

5. an issue that will impact all of us in our lifetimes, as we deal
with the changes (e.g.,
changes in weather patterns, extreme weather, sea level rise)
that come with it.
Figure 2. Variations in global temperatures over the past 1500
years. Note the rapid increases in
global temperature in the last ~100 years. (from NASA)
IMPACTS OF CLIMATE CHANGE
The impacts of a changing Earth climate are broad. Increases in
global temperatures cause
ice to melt and thus sea level to rise. These changes in turn
affect precipitation patterns;
some regions may get more rain, others may experience
drought. Extreme weather events
158
occur with greater frequency. All of these effects of a warming
planet will clearly affect the
human population of our planet – rising sea levels will displace
low-lying coastal
communities, farmers will need to adapt to changing
temperatures and amounts of rainfall,
and communities will be impacted by increased extreme weather
events (hurricanes,
tornadoes, heavy rainfall and subsequent landslides, etc.). We
will explore just two of the
areas affected by changing climate – glaciers and sea level – in

6. the past, present, and
future.
Glaciers
Glaciers are flowing bodies of ice that form from the
accumulation and compaction of
snow. They range in size from relatively small ice masses in
the valleys of mountain ranges
(Fig. 3) to massive ice sheets like those currently covering
Greenland and Antarctica.
Glaciers can be found everywhere from the poles to the equator
– as long as temperatures
are cold enough to maintain ice year round (high latitudes, high
elevation), glaciers can
form.
Figure 3. The retreating Schoolroom glacier, Grand Teton
National Park (photo: E. Johnson)
Although glaciers may seem like large, immobile features,
glaciers are actually in motion.
Snow falls, accumulates and compacts on the upper parts of the
glacier (zone of
accumulation), creating new ice (Fig. 4). Below snowline
(equilibrium line), the glacier
is melting (zone of wastage). This accumulation at high
elevation and melting at low
elevation results in the glacier flowing down slope. As glaciers
flow, they transport
sediment that is incorporated at the base of the glacier and
sediment that has fallen on top
of the glacier. This sediment is deposited in thick ridges on the

7. sides of the glacier forming
lateral moraines, and at the toe of the glacier in a terminal
moraine (Fig. 3).
159
Figure 4. Cross-section of a glacier. The equilibrium line (also
snowline) divides the zone of
accumulation from the zone of wastage (or melting).
Although glacial ice always flows downhill, glaciers as a whole
can either advance or
retreat. Glaciers advance when the amount of accumulation
(snowfall) is greater than the
amount of wastage (melting). In this case, the length of the
glacier increases and the toe of
the glacier advances. Glaciers retreat if the amount of wastage
is greater than the amount
of accumulation, and the toe of the glacier will move uphill and
the length of the glacier
decreases. If the amount of accumulation and wastage are equal,
the size of the glacier will
be constant. You can imagine then how increasing global
temperatures can affect glaciers:
higher temperatures shift the equilibrium line (snowline) to
higher elevation and thus
cause glaciers to retreat.

8. Glaciers also provide us with a look into the Earth’s past
climate through their deposits.
Geologists can map out the moraines left behind by glaciers and
estimate how much
glaciers have retreated or advanced in the past. What’s more,
we can use this information
to estimate past temperatures. The equilibrium line is a snow
line that is located about
halfway between the top of a glacier and the toe of a glacier
(Fig. 4). The location of this line
can tell us the elevation of the freezing point (0°C, or 32°F) on
any given glacier. By using
the elevation of the terminal moraine (at the toe/base) of a
retreated glacier and the
elevation of the top of the glacier we can estimate where the
equilibrium line was in the
past. Temperature varies with elevation by approximately
2°C/300 m (so, if you were
hiking up in the mountains, you would expect the temperature to
drop by about 2°C for
every 300 meters of elevation you climb).
Sea Level
Sea level fluctuates with the changes in Earth’s climate. In
times when the climate has
been cooler sea level was lower. For example, during the last
glacial maximum 21,000 years
ago sea level was ~120 m lower than it is today. When the
climate cools, the amount of ice
on Earth increases and sea level drops because water becomes
locked up as ice on land.
When the climate warms, ice on land (glaciers) melts, and sea
level rises. Warming global
temperatures have a double impact on sea level: not only does

9. more ice melt, but the ocean
waters warm and expand (warm water takes up a larger volume
than cold water),
increasing sea level even further.
160
The impacts of sea level rise and fall on coastlines depend on
the slope of the shoreline at
the coast. As illustrated in Figure 5, you can see that if sea level
were to rise one meter (the
upper-estimate of sea level rise by 2100), coastlines with steep
slopes or sea cliffs will not be
impacted as dramatically as those with low slopes.
Figure 5. The effect of a rise in sea level of 1 m on a coastline
with a steep slope (left) and with a low
slope (right). With a low slope, the new shoreline will move
farther inland.
NAME:_____________________________________
ASSIGNMENT PART ONE: PALEOCLIMATE AND
GLACIATION IN
THE TETON RANGE, WYOMING

10. 1. Use the map in the lab manual (see the color version in the
online version of the lab)
to look at the extent of the Teton Glacier.
a) Find the Teton Glacier on the topo map (also consult with
color images
provided in the intro presentation). What is the bottom elevation
of the
glacier?
b) What is upper elevation of the glacier?
c) What is the elevation of the equilibrium line (refer to Figure
4 and the text on p.
159)?
2. During the last Ice Age the Teton Glacier occupied the
valley labeled “Glacier Gulch”
on the map.
a) Find the ancient terminal moraine for the Teton Glacier,
which marks the toe of
the glacier in the past. Describe its location on the map. (HINT:
the moraine
sediment is commonly more heavily forested). What was the
bottom elevation of
the glacier?
b) Assuming that the ancient Teton Glacier extended up to the
top of the ridge

11. above the modern Teton Glacier, what was the approximate
elevation of the top
of the glacier?
c) What was the elevation of the equilibrium line?
3. The location of the equilibrium line in the past compared to
today can allow us to
estimate how temperature has changed over time.
a) What is the elevation difference between the two equilibrium
lines (past and
present) in meters? (remember that 1 ft = 0.3048 m)
b) Remembering that the equilibrium line is the height of
average annual freezing
temperature (0°C), what is the temperature change (in °C)
associated with this
change in the equilibrium line?
110°45'W110°46'W110°47'W110°48'W
43°
44'N
0 1 2 3 40.5 km
Contour interval = 80 ft

12. Topographic map of the Grand Teton area (portions of the
USGS Grand Teton and Moose 7.5' quadrangles)
Contour interval = 20 ft
163
NAME:_________________________________________
ASSIGNMENT PART TWO: MODERN AND FUTURE
GLACIAL
RETREAT
Answer the following questions using the Google Earth images
of the Coleman Glacier on
Mt. Baker, a volcano in the Cascade range of Washington.
These images appear on the
following page of the lab pdf file provided on Canvas.
4. The Google Earth images provided show a satellite image of
the Coleman Glacier
taken in August of 1993 and in July of 2013. Measured on the
image, the glacier
has retreated approximately 2.9 cm. The 300 m scale bar also
measured on the
image is 3.7 cm long. Using these values, about how far did the
glacier retreat from
1993-2013? (show your work and provide your answer in
meters)

13. 5. What is the rate (distance over time) of retreat of the
Coleman glacier over this time
period? (show your work)
6. The remaining Coleman glacier is about 4200 m long. If the
rate you calculated
above was to continue unchanged, in how many years might the
Coleman glacier
disappear? (show your work)
August, 1993
July, 2013
2001000 300 m
2001000 300 m
164
NAME:_________________________________________
ASSIGNMENT PART THREE: CHANGES IN SEA LEVEL
The following questions relate to changes in sea level in the
past and future around Florida.
7. Below is a graph showing monthly average sea level
observed in Key West, Florida

14. from 1913 through 2014. The line on the graph below shows
the
approximate average sea level rise over this time period.
8. Using the line drawn above, calculate the rate of sea level
rise in millimeter s
per year over this time period, in other words, the slope of your
line (recall that
slope, in this case, is change in sea level divided by the time
over which that change
occurred). Show your work.
165
NAME:_________________________________________
9. If the rate you calculated for the 100 years shown in the
graph continues, what is
the expected sea level rise for southern Florida 100 years from
now?

15. 10. Scientists have estimated that, globally, sea level could rise
by as much as one meter
by 2100.
a) How does this compare to what you calculated in #9?
b) What process could cause the rate of sea level rise to
increase in the future?
11. The map on the following page in the lab manual shows a
portion of southeastern
Florida. See the page after that in the online lab manual for
possible answers.
a) Sea level is expected to rise by as much as 1 m by 2100.
(NOTE: the contour
lines are shaded, and in centimeters where visible). Look at the
lines drawn on

16. the map, and give the letter of line that best represents the
position of the
shoreline if the sea level were to rise by 1 m.
b) How would this rise in sea level affect local infrastructure?
!
!
HOMESTEAD
FLORIDA CITY
80°10'W80°14'W80°18'W80°22'W80°26'W
25°
32'N
25°
28'N
25°
24'N
25°
20'N
25°
16'N
25°
12'N

17. 25°
8'N
0 5 102.5 km
Elevation
meters
0
0 - 0.4
0.4 - 0.8
0.8 - 1.2
1.2 - 1.6
>1.6
HOMESTEAD
FLORIDA CITY
80°10'W80°14'W80°18'W80°22'W80°26'W
25
°3
2'
N
25
°2
8'
N
25

18. °2
4'
N
25
°2
0'
N
25
°1
6'
N
25
°1
2'
N
25
°8
'N
0 5 102.5 km
Elevation
meters
0
0 - 0.4

19. 0.4 - 0.8
0.8 - 1.2
1.2 - 1.6
>1.6
A
B
C
D
167
NAME:_________________________________________
12. Use the contour map of Florida and the ocean floor on the
next page to answer the
questions below. See the page after that in the online lab to see
the shoreline
choices for both (a) and (c).
a) Based on the maps on the following pages, which of the
lines (A through E) best
shows the outline of the land during the last Ice Age when
global sea level was
about 130 meters lower than today?

20. b) Which side of the continental shelf offshore of modern
Florida has a steeper
slope, and how would this have affected prehistoric people
living near the
shoreline during the transition from the last Ice Age to modern
sea level?
c) Now, imagine that global warming continues un-checked
into the future. If ALL
of the ice on Earth were to melt, sea level could rise by ~80
meters! If glacial
melting continues into the future until sea level rises by 30 m,
where would the
shoreline be? Using the maps on the following pages of the
online lab handout,
which of the lines A through E best shows the position of the
Florida shoreline if
sea level rose 30 m above the modern level?
80°W
80°W
81°W
81°W
82°W
82°W

21. 83°W
83°W
84°W
84°W
85°W
85°W
86°W
86°W
30
°N
30
°N
29
°N
29
°N
28
°N
28
°N
27
°N

22. 27
°N
26
°N
26
°N
25
°N
25
°N
24
°N
24
°N
23
°N
23
°N
-3000
--2000
-1000
20
40

23. 40
40
100 km
-20
-140
20
20
-20
20
20
40
40
40
80°W
80°W
81°W
81°W

24. 82°W
82°W
83°W
83°W
84°W
84°W
85°W
85°W
86°W
86°W
30
°N
30
°N
29
°N
29
°N
28
°N
28

25. °N
27
°N
27
°N
26
°N
26
°N
25
°N
25
°N
24
°N
24
°N
23
°N
23
°N
-3000
--2000
-1000

26. 20
40
40
40
100 km
-20
-140
20
20
-20
20
20
40
40
40
A
B
C
E

27. D
169