GEOL+1301+-+Lab+09+-+Glaciers+and+Climate
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1301
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Geology
Date
Dec 6, 2023
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Uploaded by ashleybramlett
GEOL 1301
Lab 09
Glaciers and Climate
This lab activity follows an online lab made available on the
Science Education Resource Center at Carleton College
website (
http://serc.carleton.edu/eslabs/index.html
).
The lab
has been developed with support from the National Science
Foundation (NSF), the National Aeronautics and Space
Administration (NASA), the National Oceanic and
Atmospheric Administration (NOAA), the National
Association of Geoscience Teachers (NAGT), and the
Technical Education Research Center (TERC).
Please upload
your completed lab on Canvas.
Go to the following website:
http://serc.carleton.edu/eslabs/cryosphere/lab_overviews.html
On the left side of this website, you find a navigation panel to
different parts of the lab.
You will answer questions from
Labs 1A, 1C, 2A, 2B, and 4A for this exercise, but feel free to
explore all parts of the “Climate and Cryosphere” section.
°
Lab 1A: Getting to Know the Cryosphere
Study the image below, which you also find on the website of
Lab 1 (
http://serc.carleton.edu/eslabs/cryosphere/lab1.html
),
and read through the introduction to Lab 1 on that website.
Name all the parts of the cryosphere.
Describe the similarities or differences between the time
scales at which the following components of the cryosphere
change: snow, glaciers, ice sheets.
Snow, ice, frozen ground and permafrost, glaciers, ice shelves and icebergs, sea ice
Snow, glaciers, and ice sheets exhibit varying time scales of change. Snow undergoes short-term fluctuations, responding to
seasonal and even daily weather patterns. Glaciers, larger ice masses, evolve over decades to centuries, influenced by climate
trends. Ice sheets, the most extensive ice masses, experience changes over millennia, reflecting long-term climate shifts. While
all are sensitive to climate, the key distinction lies in the magnitude and duration of their responses to environmental factors.
°
Cut out and tape together the cryosphere map that is found at
the end of this lab document (you can also look for an image
of what the completed “globe” should look like on the Lab 1A
website, http://serc.carleton.edu/eslabs/cryosphere/1a.html).
This globe shows the distributions of snow, ice, etc. averaged
over several decades.
Answer the following questions (some
of which you also find on that same website):
What parts of the cryosphere are
only found near the poles?
On December 26, 2000, there were reports of ten to twenty
inches of snow across the Texas panhandle, including nearly
twenty inches in the city of Amarillo. Why doesn't the map
show snow in Texas?
Where in North America do you find glaciers and ice caps?
To which latitude does sea ice extend in the northern
hemisphere?
Ice sheets
The map shows average snow cover, not individual snow events
-Mainly On the northwest coast; aka NW America and Canada
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To which latitude does sea ice extend in the southern
hemisphere?
Where do you find glaciers close to the equator?
Why do you
find them there?
°
Lab 1C: The Changing Cryosphere
Watch the satellite data-based NASA video “Tour of the
Cryosphere” on the website for Lab 1C
(http://serc.carleton.edu/eslabs/cryosphere/1c.html), then
answer the following questions.
What is happening or has happened in the recent past to the
ice shelves of Antarctica?
What is happening to sea ice coverage in the Arctic Ocean?
45ºN
55ºS
Glaciers near the equator are found in high-altitude tropical mountains. Examples include those in the Andes in South America,
East African mountains, and Papua New Guinea. Despite their proximity to the equator, these regions have elevations that
support glacial ice due to their extreme height, allowing for lower temperatures at higher altitudes, where accumulation of snow
exceeds melting.
As temperatures increase, we are seeing more melting ponds which are forcing their way into
cracks—weakening ice shelves. Recently, the Larsen B ice shelf collapsed within 5 weeks of
this persistence.
Arctic sea ice has been experiencing a decline in coverage over the past few decades. The extent of sea ice, especially during the summer months, has been decreasing, primarily due to global
warming and rising temperatures in the Arctic region. Warmer temperatures lead to the melting of ice, reducing both the thickness and expanse of Arctic sea ice. This trend has significant
implications for the Arctic ecosystem, wildlife that depends on sea ice, and global climate patterns.
Explain the “chain reaction” that is described in the video.
Where do most icebergs in the North Atlantic come from?
What is currently happening or has recently happened to the
Jakobshavn Glacier in Greenland?
°
Lab 2A: Sea Ice and Ocean Currents
Go to the website for Lab 2A
(http://serc.carleton.edu/eslabs/cryosphere/2a.html), then
answer the following questions.
The chain reaction of sea ice in the Arctic is interconnected with climate processes. As temperatures rise due to
global warming, Arctic sea ice undergoes several interrelated changes:
Warmer Temperatures: Global warming leads to higher temperatures in the Arctic, causing the ice to melt.
Reduced Ice Cover: Warmer temperatures result in decreased ice cover, especially during the summer
months. This reduction exposes darker ocean water, which absorbs more sunlight, further amplifying the warming
effect.
Positive Feedback Loop: As ice melts, the Earth's surface becomes less reflective (lower albedo), absorbing
more solar radiation. This creates a positive feedback loop, contributing to additional warming and ice melt.
Glaciers in western Greenland
.
The Jakobshavn glacier has thinned and the front has retreated— in fact the flow rate had
doubled from 1997-2003.
At what temperature does ocean water freeze?
What is a “brinicle” (watch also the video “Frozen Planet: Icy
Finger of Death” on the website to answer this question)?
Go to the “Ocean Circulation” animation on the website, use
the temperature slides, and describe what happens to the
ocean water as sea ice forms.
°
Lab 2B: Sea Ice Thickness
Go to the website for Lab 2B
(http://serc.carleton.edu/eslabs/cryosphere/2b.html), then
answer the following questions.
How is sea ice thickness related to age?
28.8ºC
In the frigid waters of polar environments, particularly in places like the Antarctic, a remarkable
phenomenon known as a brinicle, or "icicle of death," can be observed beneath sea ice. This unique
structure forms as a result of the freezing of seawater to create sea ice. During this process,
highly concentrated, supercooled brine is left behind in channels within the ice. Due to its extreme
cold and high salinity, this brine is denser than the surrounding seawater, causing it to flow
downward through small channels. As it descends, it freezes the less salty seawater around it,
forming a descending tube of ice that resembles an underwater icicle.
As the the weather gets colder, the saltwater (salt ions and water molecules) gets pushed below as water molecules are forming
freshwater ice.
The thickness of sea ice is closely related to its age, forming a crucial aspect of the dynamic process of ice development and decay. Newly formed sea ice,
known as first-year ice, is generally thinner and more vulnerable to melting and breaking compared to multi-year ice. As sea ice survives multiple melt seasons,
it thickens and transforms into multi-year ice, which can withstand higher temperatures and mechanical stresses. The relationship between thickness and age
is a key indicator of the resilience of sea ice. Climate change has amplified the significance of this relationship, as the Arctic, for instance, has witnessed a
decline in the extent of older, thicker ice due to warming temperatures and increased melting during the summer months.
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Study the figure below (which is also shown on the website),
which shows sea ice coverage and thickness in the Arctic
Ocean as an average for February for the years 1985-2000 on
the left and for February 2008 on the right.
Describe the
differences between the two images, and explain what they
mean.
°
Lab 4A: Glacial Ages
Go to the website for Lab 4A
(http://serc.carleton.edu/eslabs/cryosphere/4a.html), then
answer the following questions.
From the image below (which you also find on the website),
infer the typical time scale on which glacial periods occurred
during the past 1 million years.
The sea ice on the right is generally younger than the sea ice on the left—indicating
melted ice and the formation of new ice.
100,000 years
⊥
Timescale:
Read the section about Milankovitch Cycles.
What are the
three aspects of the Earth’s orbit that change over time, and at
what time scales are they changing?
°
Cryosphere Map:
The three primary aspects of Earth's orbit that change over time are eccentricity, axial tilt (obliquity), and precession.
Eccentricity refers to the shape of Earth's orbit around the Sun, oscillating between more circular and more elliptical
shapes over cycles lasting approximately 100,000 years. Axial tilt, or obliquity, pertains to the tilt of Earth's axis
concerning its orbital plane, fluctuating between about 22.1 and 24.5 degrees roughly every 41,000 years.
Precession involves the gradual shift in the orientation of Earth's axis, creating a circular motion like a spinning top,
with a cycle lasting approximately 26,000 years. These cyclic variations in orbital parameters influence the
distribution and intensity of solar radiation reaching Earth, contributing to climatic changes on geological timescales.
1
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