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These activities will introduce your students to polar oceanography and how events
that occur in oceans thousands of kilometers away affect them and the mid-latitudes.
The students will also explore how conditions are changing in the polar
regions and the possible impacts upon life in the United States and other mid-latitude
nations. Are you ready for a "cool" experience? I mean a really
cool experience? In honor of the International Polar Year, we're going to focus
in on polar oceanography. Odds are you live in "the mid-latitudes,"
a geographic region between about 23.5° and 66.5° latitude. According
to the U.S. National Weather Service, much of the world's population lives in
the mid-latitudes. Since the mid-latitudes are removed from polar regions by thousands
of kilometers, you may wonder "What is the value of studying the oceans at
the top or bottom of the world? and how might events in that region affect us
here in the mid-latitudes?" Consider this fact: Over 70 percent of
our planet's surface is covered by water. Water by its nature has a high heat
capacity, meaning it can absorb, store and release tremendous amounts of energy.
Much of this energy is exchanged with the lower atmosphere, creating a strong
connection between the two and making world climate largely dependent upon the
ocean and currents running within it. 
PART I: A VIRTUAL VISIT TO THE TOP OF THE WORLD
Distribute "Worksheet:
A Virtual Visit to the Top of the World" (and make the reference sheets
"U.S. Map," "Images
from the Arctic" and "North
Pole Weather Data From 2007" available as handouts or overheads if your
class does not have Internet access).
Ask students to ponder what it
would be like to visit the "top of the world." Ask them to respond to
the worksheet questions, which are designed to generate class discussion. Have
your students record their responses and questions raised on the handout.
Consult the key
for answers and additional guidance for the Virtual Visit Worksheet.
Remind the students of their overall goal to understand polar oceanography.
Ask students to summarize the main ideas explored thus far by creating a concept
map or an outline.
PART II: EXPLORING GLOBAL OCEAN CURRENTS
The first part of this lesson introduced you to the conditions experienced
at the "top of the world," establishing that the Arctic Ocean underlies
the ice surrounding the North Pole. We know that conditions experienced in the
Arctic (and Antarctic) are quite different from those experienced where most people
live. To begin to look for connections between these two diverse regions located
thousands of kilometers apart, we will conduct a series of experiments designed
to explore the connections between three major Earth systems: the atmosphere,
the hydrosphere and the cryosphere.
Provide students the definitions
of "atmosphere," "hydrosphere," "cryosphere" and
"biosphere": - Atmosphere: gaseous envelope surrounding our
planet, thickest near the surface
- Hydrosphere: water covered portion of
Earth
- Cryosphere: portions of Earth covered in frozen water
- Biosphere:
portions of Earth where life occurs
Provide students the lab instructions
"Lab: Investigating
Convection" and review safety procedures. - This lab experiment
will take one 45-minute class period.
- Students need to be encouraged to
see the oceans as a fully inter-connected system (as well as having connections
to the other major spheres noted earlier).
Provide students the lab
instructions "Lab:
Investigating Density Currents" and review safety procedures. PART
III: OCEAN CURRENTS AND COASTAL CLIMATES
Do ocean currents affect
coastal climates?
The resources below enable you to access climatic
data for two communities: St. Mawgan, England, and Daniels Harbour, Newfoundland,
Canada. Both communities are located near 50°N latitude. St. Mawgan is situated
on the southwestern coast of England along the eastern shores of the Atlantic
Ocean. Daniels Harbour is located in Newfoundland near the western shores of the
Atlantic Ocean. Follow the instructions below to collect climate data, process
them and then finally analyze the data.
Collect the climate data: Process
the data: - Use the data provided to create a temperature
– time graph. Scale your x-axis in months from January to December. Select
an appropriate scale for your temperature (y-axis). Plot both sets of data on
the same graph.
- Analyze the graph you produced by comparing the temperature
patterns in the two cities. Write a brief summary comparing and contrasting the
patterns for each location.
Analyze the data: PART
IV: EVIDENCE OF CHANGE IN THE ARCTIC
Next, let's return to the
Arctic and search for evidence of change. We will ask the question: Are climatic
conditions changing in the Arctic and if so, how might these changes affect ocean
currents?
- Study the graph "Arctic
Temperature (1900-2003)." This graph depicts observed air temperature
patterns in the Arctic since 1900. Describe the observed pattern from data collected
over the past century.
- If the warming trend that began in the 1960's were
to continue, how might this affect the existing Arctic ice pack?
- (Note:
This step requires Internet access) Using the link below, you can study the Arctic
Ocean currents in detail. If significant melting of Arctic ice were to continue,
what changes can be expected in ocean current patterns? Hint: Think about how
sea water density is changed by the formation of an ice cap and how that affects
ocean currents. Woods
Hole: Arctic Ocean Circulation Primer
Teacher Answer: The
melting ice is adding fresh water to the Arctic Ocean. This lowers the salinity
of the "open ocean" waters in that region. Since the water is less dense,
its tendency to sink (due to extreme density) is reduced or eliminated.
- If ocean water were to stop sinking in the Arctic, would that affect surface
ocean currents in the mid-latitudes and tropics? Explain.
Teacher
answer: Think of the entire ocean current system as a giant conveyor belt. If
one part of the belt breaks down, the balance of the belt elsewhere will be significantly
changed. - If surface currents in the Arctic were
to carry "fresher" (less saline) water to mid-latitude ocean waters,
how might this affect the Gulf Stream and other ocean currents like it?
Teacher
answer: Fresher water carried to the mid-latitudes would eliminate the distinction
between the Gulf Stream and the surrounding "open ocean" waters. In
other words, the Gulf Stream is essentially floating on denser ocean waters as
it carries warm water (and its energy) away from the Equator and towards the North
Pole. If the density difference becomes minimal (or non-existent), the current
will cease to have a recognizable identity -or in simple English - "no more
Gulf Stream!" Some scientists believe this could happen over a very short
period of time and may in fact be what happened during the "little ice age"
that deeply impacted Europe and parts of North America.
To summarize
this topic, distribute the article "Changes
at Poles Drive Global Warming."
Alternatively, students may watch
the online video, "Polar
Warming."
Hold a full class discussion to summarize the main
ideas presented within the activity: - Are all ocean currents
connected? (Answer: Yes.)
- Why does Arctic sea water subside or sink? (Answer:
It is quite dense.)
- How might further warming in the Arctic affect deepwater
ocean currents originating in the Arctic? (Answer: They will not be "powered"
by subsiding surface waters.)
- Acknowledging that the Antarctic is much
colder than the Arctic, will warming necessarily result in extensive melting of
ice in that region? (Answer: No, at least not yet.) What other climate changes
may occur in the Antarctic as warming occurs? Hint: Recall the Arctic (and Antarctic)
are "frozen deserts", experiencing minimal precipitation annually. It
is in a sense, "too cold to snow". If warming were to occur, how might
conditions change? (Answer: If excess warming were to occur, snowfall might increase
and this would provide "negative feedback" to the original warming.
- What
evidence can be cited to demonstrate a strong connection between the oceans and
air temperature? (Look at the influence of oceans on the coastal climate of the
U.S. west coast and Western Europe, both of which have prevailing winds flowing
from the ocean to the landmass.)
- Use the NewsHour article "Changes
at Poles Drive Global Warming" to highlight key points and to emphasize
relationships between major Earth systems (atmosphere, cryosphere, hydrosphere
and the biosphere). (To print article see top right-hand corner of Web page.)
PART I:
Distribute the article "Polar
Year Explores How Earth Systems Interact."
Ask students to define
"International Polar Year" and create of list reasons that research
at the poles could be relevant to their lives. Ask students to describe the Arctic's
physical environment and the reasons why it is so different from the environment
students experience in the mid-latitudes.
PART II:
Distribute
"Extension Activity: Exploring Global Ocean Currents". Students
will need Internet access to complete this activity. PART III: 1.
Much of the observed difference between the temperature patterns can be attributed
to prevailing winds and the influence of the Atlantic Ocean and the (warm) Gulf
Stream (also known as the "North Atlantic Drift"). How might the climate
change in England if the Gulf Stream were to "collapse"? If this change
were to occur, what else or what other systems would be affected? Explain.
2. Use the Web site http://www.worldclimate.com
to explore climatic data worldwide. Ask students to identify coastal cities on
divergent coastlines with equivalent latitudes and explore differences in their
climatic patterns using what they know about wind and ocean currents. PART
IV: 1. Have students research causes of global climate change and
actions that may arrest the current warming trend. Encourage students to consider
the societal and economic implications of any remediation they propose. (Ask students
whether a push to produce alternative fuels, such as ethanol, will reduce carbon
dioxide emissions. Because ethanol is also a hydrocarbon, it won't reduce
emissions. Other strategies may cost more. The NewsHour Extra lesson plan
"Alternative Fuels and Alternative Cars" is available.
2. Ask students to prepare a poster illustrating what they have learned, detailing
the changes that may result from continued global warming in polar regions and
on biotic communities living within. (Issues addressed may include climate change
in their region; changes in flora, fauna, crops and growing seasons - some of
which can be anticipated and some of which can not. In other words, global change
could bring about some surprising changes.) |
