Name: ________________________
Earth Science
Date: ____________
Landscapes Unit
Antarctic Sea Ice
Objectives
1. Students will construct graphs of the extent of sea ice over time.
2. Students will use technology to analyze data and draw conclusions
about natural phenomena in the Antarctic
3. Students will compare the graphs and charts of the extent of sea ice
over time between Antarctic and the Arctic
4. Students will explain the factors that affect Antarctica’s climate
Background Information
Frozen water is found in many different places on Earth. Snow
blankets the ground at mid and high latitudes during winter. Sea ice and
icebergs float in the chilly waters of polar oceans. Ice shelves fringe lands in
Earth’s polar regions. Glaciers and larger ice sheets move slowly over land in
polar regions. Glaciers are also found on high mountaintops around the
world. The soils of polar regions, called permafrost, are filled with frozen
water. Together, these different types of frozen water are known as the
Name: ________________________
Earth Science
Date: ____________
Landscapes Unit
Earth’s cryosphere. Approximately three-quarters of the world’s fresh water
is frozen in the cryosphere.
Some parts of the cryosphere, such as snow and the ice on ponds and
lakes in mid-latitude locations, are only around during winter months. Other
parts of the cryosphere, such as glaciers and ice sheets, stay frozen yearround and, in fact, can stay that way for tens of thousands or even hundreds
of thousands of years. Some of the ice in the ice sheet that covers most of
the continent of Antarctica has been there for nearly a million years.
Sea Ice
Sea ice is frozen seawater. It can be several meters thick and it moves
over time. Although the salts in the seawater do not freeze, pockets of
concentrated salty water become trapped in the sea ice when it first forms.
The pockets of salty water can work their way out of the sea ice over a few
years. During the summer months much of the sea ice melts and during the
winter months it forms again. Some sea ice stays around all year long.
The Arctic Ocean has a large amount of sea ice floating at its surface,
especially in winter. Sea ice is very important for the people and animals
that live in the Arctic region. Animals like polar bears live on the sea ice and
find their food in the surrounding and underlying ocean. Marine life exists
under the Arctic sea ice too. Over the past few decades, more and more of
the sea ice has been melting in the summer as Earth’s climate warms.
Scientists predict that with continued rates of global warming there will be
no sea ice in the Arctic in the summer months by the end of the 21st
century. Ice thickness has also been decreasing.
In the South Polar Region, there is evidence that sea ice is important
for the breeding cycle of certain penguin species. Emperor penguins breed
on sea ice. One of the most northerly colonies of Emperor penguins, the one
where the documentary “March of the Penguins” was filmed, has declined
over the past few decades, probably because of warming temperatures,
which cause the sea ice to melt and break apart earlier in the spring, before
the chicks are ready to fledge. Melting sea ice might have some benefit to
Adelie penguins. Adelie penguins build nests made of pebbles on land. In
search of food, they travel over sea ice that is attached to the shore, called
fast ice, to get to the ocean, and then bring seafood back to their hungry
chicks on land. With less sea ice, the journey to the ocean to find food
becomes shorter. However, Adelie penguins are adapted to the cold
conditions. The benefit of a shorter trip to the ocean is overshadowed by the
harm of warmer temperatures. In the northern part of the Antarctic
Peninsula, the warmest part of Earth’s coldest continent, the Adelie penguin
colony is declining rapidly. In this area sea ice used to be common, but now
is absent even in winter. The penguin nests made of rocks on the Antarctic
Peninsula have been abandoned. The warming climate has restricted the
Adelie penguins to colder areas further south.
Name: ________________________
Earth Science
Date: ____________
Landscapes Unit
A rise in sea levels is one of the most well-known consequences of
global warming. There are two ways that higher temperatures cause higher
sea level: (1) melting ice sheets and glaciers and (2) thermal expansion of
seawater.
How much is sea level rising?
Since 1900, sea level has risen between 1 and 2 millimeters per year
(10-20 cm or 3.9-7.9 inches per century) on average. During the preceding
3,000 years, scientists estimate that sea level was almost constant, rising at
a rate of 0.1 to 0.2 mm per year.
Scientists use averages from a large number of tide gauges around the
globe to estimate global average sea level. Since 1992, global sea level has
been observed using satellite data too, with more accurate results than tide
gauges (according to the Intergovermental Panel on Climate Change AR4
report). Satellite measurements show a rate of sea level rise of 3 mm per
year, far more than the tide gauges. Some scientists suspect that the
satellite is incorrectly calibrated. Others suspect that the difference may be
because the satellite measurements cover much of the globe while tide
gauges are near coastlines.
Change in global sea level in the future is predicted to occur at a faster
rate. The amount of sea level rise depends in large part on the amount of
warming. According to the IPCC Forth Assessment Report (2007) by the
mid-2090s global sea level may be 22 to 44 centimeters above its 1990 level
and rising at about 4 mm per year.
Sea Level Rise Due to Melting Ice Sheets and Glaciers
There is between 24 and 30 million cubic km of ice on land. About
90% of this ice is in Antarctica. Most of the rest is in Greenland and a tiny
fraction is locked up in mountain glaciers elsewhere.
As global temperatures have risen, some of this ice has begun to melt.
And as ice melts, meltwater flows into the ocean, gradually raising sea
level. Of course, each year the amount of ice on land changes with the
seasons, but overall global warming has begun to disturb this equilibrium.
Melting has outpaced snowfall, and the loss of ice has been greatest on
mountain glaciers in the mid-latitudes and tropics and on the Greenland ice
sheet. The Antarctic ice sheet seems less disturbed, however there’s
evidence that the rate of ice flowing towards the ocean has increased.
Melting ice can produce a positive feedback loop - darker areas (especially
oceans, but also land) beneath the high-albedo snow or ice absorb more
light than the bright snow or ice had done, and thus warm still further,
melting more snow and ice. This will be further discussed in the next week
of the course.
Name: ________________________
Earth Science
Date: ____________
Landscapes Unit
Melting ice can alter the salinity of seawater as freshwater is added to
the ocean. Changes in salinity alter seawater density, which can change
major ocean currents that transport heat through the ocean driven by the
currents, stimulating more climate change.
Complete melting of glaciers and ice sheets would raise sea levels
worldwide almost 70 meters (230 feet) above current levels. 7.2 meters of
this rise would be from the Greenland ice sheet, while 61.1 meters of this
rise would be from the Antarctic ice sheet. Melting glaciers would add
another half of a meter.
For some perspective on all this melting ice, consider this: sea level
has risen about 120 meters since the last glacial maximum approximately
20,000 years ago when ice covered large parts of the Northern Hemisphere
and wooly mammoths roamed the Earth.
Standards
New York State
STANDARD 1—Analysis, Inquiry, and Design
Students will use mathematical analysis, scientific inquiry, and engineering design, as appropriate, to
pose ques- tions, seek answers, and develop solutions.
STANDARD 2
Students will access, generate, process, and transfer information, using appropriate technologies.
2.1b
The transfer of heat energy within the atmosphere, the hydrosphere, and Earth’s interior results in
the formation of regions of different densities. These density differences result in motion.
2.1i
Seasonal changes can be explained using concepts of density and heat energy. These changes
include the shifting of global temperature zones, the shifting of planetary wind and ocean current patterns,
the occurrence of monsoons, hurricanes, flooding, and severe weather.
2.2c
A location’s climate is influenced by latitude, proximity to large bodies of water, ocean currents,
prevailing winds, vegetative cover, elevation, and mountain ranges.
Hypothesis – What is the relationship between the extent of sea ice and
time in years for Antacrtica?
Independent Variable
Procedure
1. Go to Mr. Mac’s Science Classes
2. Click on “Earth Science.”
3. Click on “Changing Climate e-Portfolio.”
Dependent Variable
Name: ________________________
Earth Science
Date: ____________
Landscapes Unit
4. Click on “Antarctic Sea-Ice Data.”
5. Construct a graph using Microsoft Excel. Follow the instructions below:
a. Open up the “Antarctic Sea Ice Data” using Microsoft Excel.
b. For your assigned month or months, highlight the data and click
on “Charts.”
c. Select “X Y (Scatter).”
d. Select “Smooth Marked Scatter.”
e. Once your graph has been created, select “Chart” to move chart
to new sheet and label it by month.
f. “Add Trendline” by clicking on one of the points on the graph,
and right click on a particular point.
g. Make sure your graph is labeled by month, and scale your graph
so that the y-axis maximum is set to 20, and y-axis minimum is
set to 0.
6. Save as a PDF file and upload your completed graph to Google Docs,
make sure you load it using your name and the date assigned.
7. Share with everyone in class. Find your block and share with the class.
Analysis and Conclusion
1. What makes up the cryosphere?
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
2. How much would sea levels rise if all the glaciers and ice sheets on our
planet melted? How much of it would be from Antarctica itself?
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
3. Based on the data and graph on the extent of sea ice, what pattern or
trend do you notice?
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
Name: ________________________
Earth Science
Date: ____________
Landscapes Unit
4. Give a scientific explanation for the trends that you observed in your
graph.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
5. Compare your graph to others, what pattern or trend do you notice?
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
6. Give a scientific explanation for the trends that you observed in
comparing the graphs from other groups.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
7. Based on the data and graphs from the entire class, what is your
conclusion? Does it agree or disprove your hypothesis? Explain.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
8. Explain why you think conditions would be different from sea ice data
taken from the Arctic.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
Name: ________________________
Earth Science
Date: ____________
Landscapes Unit
Links
 Antarctic Sea Ice animation
https://spark.ucar.edu/video/sea-ice-extent-maps-animate-antarctic
 Antarctic Sea Ice interactive
https://spark.ucar.edu/longcontent/sea-ice-extent-maps-compareantarctic