Download Climate Change Lecture Notes

Climate Change Lecture Notes (Topic 12A) – page 1
Climate Change Lecture Notes
Learning Outcomes for the Climate Change Unit
1. Students can list observations which suggest that the world is warming, and explain how
or why the evidence indicates that the world is warming.
2. Students can describe how visible and infrared electromagnetic waves interact with the
atmosphere and the surface of the Earth, and explain how this warms the planet (i.e.,
explain the greenhouse effect).
3. Students can identify the major ways in which human actions are affecting the average
temperature of the Earth, and how and why they affect the temperature of the Earth.
4. Students can describe how the ocean redistributes heat between the Equator and the
Poles.
5. Students can identify the major ways in which the ocean affects the average temperature
of the Earth, and explain how and why the ocean affects the average temperature of the
Earth.
6. Students can describe and explain how and why the amount of clouds in the atmosphere
affects the average temperature of the Earth.
7. Students can describe the major ways in which the warming of the Earth’s oceans and the
increased levels of carbon dioxide in the ocean will affect ocean life and humans, and
explain why the changes in the temperature and chemical composition of ocean water
will have these impacts.
8. Students can describe the thermohaline circulation (THC) and what causes the THC, and
explain how and why the THC affects the overall temperature of the Earth and the
climate at the Poles.
9. Students can describe how ocean life “permanently” removes carbon dioxide from the
ocean and atmosphere, and discuss how changes to the ocean environment would affect
the rate at which life removes carbon dioxide and the implications for the overall
temperature of the Earth.
Climate Change Lecture Notes (Topic 12A) – page 2
Climate vs. Weather
In this class we focus on climate, not weather. Climate is the long-term average of weather
conditions (what the weather is usually like). For example, Southern California has a warm, dry
climate. This does not mean that it is always warm (we have our cooler days) or that it does not
rain in Southern California; it means that our weather is warm most of the time and that rain is
less common here than elsewhere. Another way to think about it: weather is what conditions are
like a particular day, climate is what conditions are typically like over a season or a year.
Which of the following are examples of climate? Which are example of weather?
During January through March of 2013, California received only 26%
of normal amount of rain that in usually gets during these months.
The highest temperature recorded in Los Angeles County was 80oF
yesterday.
In March of 2012, nearly 80% of places where temperature
measurements are regularly recorded in the United States
were much warmer than normal (far above average) for March.
This afternoon there is less than a 10% chance of rain.
Climate Change Lecture Notes (Topic 12A) – page 3
Electromagnetic Waves (“EM waves”)
Electromagnetic waves are “disturbances” (ripples, wiggles) in the electromagentic fields
surrounding electrically-charged particles like electrons and protons. Electromagnetic waves
are named for the “size” of the disturbance (“wiggle”). Fast-wiggling, small disturbances are
called “high frequency, short-wavelength” EM waves, and slow-wiggling, large disturbances
are called “low frequency, long-wavelength” EM waves. The collection of all of the different
kinds of electromagnetic waves is called the electromagnetic spectrum.
273 K
Examine the chart above. Notice the arrow pointing the wavelength row.
Courtesy
of NASA
Give examples of short-wavelength EM waves: _____________________________________
Give examples of long-wavelength EM waves: ______________________________________
Each kind of atom and molecule emits (“sends away”), reflects, and absorbs certain specific
kinds of electromagnetic waves, because each kind of atom and molecule has its own unique
number and arrangement of electrons and protons. If an atom or molecule cannot emit, reflect,
or absorb a certain kind of electromagnetic wave, then these waves go through these atoms and
molecules! In other words, these atoms and molecules are “transparent” to this kind of
electromagentic wave.
Think about your own observations and experiences as you answer the next 3 questions:
Visible light cannot go through most substances.
What substance(s) can visible light go through?
______________________
What substances can X-rays go through?
_______________________
What substances absorb and thus block X-rays?
_______________________
Climate Change Lecture Notes (Topic 12A) – page 4
You cannot “see” all kinds of electromagnetic waves (EM waves) because the rods and cones in
your eyes are tuned so that they only send a signal to your brain when they pick up certain
specific kinds of EM waves: visible light (red, orange, yellow, green, blue, violet). Even if you
cannot see EM waves, they can still affect you: the atoms and molecules of your body can absorb
them.
Electromagnetic waves are created when electric objects like atoms and molecules move (e.g.,
wiggle). Since the atoms and molecules of objects are always moving, objects are constantly
emitting (sending away) energy in the form of EM waves. Of course, the warmer an object is, the
more energy it can and does emit.
A temperature of 273 K is about 0oC, the freezing point of water.
Refer to the chart on the previous page.
What kind of light does an object emit if it has a temperature of 0oC?
_________________
When it is dark, you cannot see most objects because there is no visible light reflecting off them
and into your eyes. If an object emits visible light, on the other hand, you can see it in the dark
because it creates visible light. Consider your own experience:
Does room-temperature wood emit visible light?
_________________
Does burning wood emit visible light?
_________________
Wood typically burns at a temperture of about 232oC. Based on this information and your
answers to the questions above, why don’t most ordinary objects (like those in the room around
you right now) emit visible light? How could you get the objects in the room around you to emit
visible light?
What kind of EM waves do most objects in the room around you right now emit? ___________
If an object absorbs EM waves, the object will get (A)_______________________.
If an object emits (sends away) EM waves, the object will get (A)_______________________.
Hot objects emit (B)___________________ EM waves (“heat”) than cold objects.
Very hot objects can emit (C)___________________ EM waves,
but objects at room temperature or colder emit (C)___________________ EM waves.
Very cold objects (D)___________________ emit EM waves (“heat”).
A: warmer, colder
B: more, fewer
C: visible light, infrared
D: do, do not
Climate Change Lecture Notes (Topic 12A) – page 5
Greenhouses
What is a greenhouse? Why is it called a “green” house?
What happens to visible light when it hits glass?
What happens to infrared “light” when it hits glass?
W
in
ds
hi
eld
Car Seat
What happens to the heat emitted as infrared “light” by the car seat?
Where is the car seat receiving heat from?
In other words, what kinds of EM waves are hitting it and what are emitting them?
The car seat is warmer because it is surrounded by windows.
Why would the car seat be cooler if there were no windows?
Climate Change Lecture Notes (Topic 12A) – page 6
ACTIVITY:
Greenhouse Gases and the Greenhouse Effect
Greenhouse gases only absorb infrared light;
other kinds of light pass through them.
The Sun emits mainly
e
visibl
Explain how the greenhouse effect works
by filling in the spaces below.
Atmosphere
(A)________________________ light
which (B)_________________________
the nitrogen and oxygen in the atmosphere
and (B)_________________________
the greenhouse gases in the atmosphere like ____________________________________ .
The sunlight (B) _________________________ the surface of the Earth,
making the surface of the Earth warmer, both the land and the ocean.
The warmer they get, the more heat the land and ocean send away
as (A) _________________________ light.
This light (B) _________________________ the nitrogen and oxygen in the atmosphere
but (B) _________________________ the greenhouse gases in the atmosphere,
making the greenhouse gases warmer and thus warming the atmosphere.
The warmer the atmosphere gets, the more heat the atmosphere sends away
as (A) _________________________ light. About half is sent out into space,
and about half is sent back to the surface of the Earth, making the Earth warmer.
Possible Answers
A: x-rays, ultraviolet, visible, infrared
B: goes through, is absorbed by, is reflected by
The Earth is warmer because it is surrounded by greenhouse gases.
Why would the Earth be cooler if there were no greenhouse gases in the atomsphere?
If there were no greenhouse gases in the atmosphere, what would the Earth be like?
CHECK YOUR ANSWERS WITH YOUR INSTRUCTOR
Climate Change Lecture Notes (Topic 12A) – page 7
Global Warming
Aside from direct temperature measurements, what other observational evidence is there that the
world has been and is getting warmer? How or why do these observations suggest that the world
is getting warmer? In each case, explain your reasoning.
Glaciers and Ice at the Poles: There is ___________________ ice than there was in the past.
This observation supports the idea that the world is getting warmer,
because in a warmer world, the ice would ___________________________________.
Sea Level: Sea level is ___________________________ than it was in the past.
This observation supports the idea that the world is getting warmer,
because in a warmer world, the ocean water would ____________________________,
and there would be ___________________________ water in the ocean
since melting ice __________________________________ would flow into the ocean.
Organisms’ Behavior: Plankton are blooming ___________________________ in the year.
Warmer water makes it seem there is more sunlight (when there is not). They reproduce
when there is more sunlight because they can make more food (_____________plankton)
or find more food (_________plankton).
What is currently the best idea that explains why the world has warmed over the last 100 years or so?
In other words, what idea is best supported by the observational evidence that we currently have?
What alternative ideas are well-supported by the evidence?
If an idea is well-supported by the evidence,
do scientists call the idea a hypothesis or a theory?
Where does a large amount of our carbon dioxide pollution go each year?
Climate Change Lecture Notes (Topic 12A) – page 8
Why can the ocean keep absorbing more and more carbon dioxide pollution
without becoming saturated? (In other words, why isn’t the ocean “full”?)
South
Pole
Equator
North
Pole
Thermohaline Circulation (THC)
The thermohaline circulation is a convection cell.
Explain the motion of the water in the THC.
The circulation is started by water sinking down from the surface of the ocean to the bottom.
Water sinks at the (A)_____________________________________ during the winter because
it has a (B)_______________ density due to BOTH the temperature and salinity of the water.
During the winter, the climate is very (C)____________________ at this location.
When seawater freezes into ice, the salt is “rejected” by the ice,
so seawater which does not freeze gets (D)_________________________ in the winter.
As the sinking water spreads across the bottom of the ocean, the water above is lifted upwards.
At the surface, water moves to the (A)______________________ to replace the sinking water.
A: Tropics, Mid-Latitudes, Poles
B: high, low
C: warm, cold
D: saltier, less salty
Only a small amount of water sinks to the bottom of ocean each year in certain special places
where the water gets very cold and very salty. The water takes over 1000 years to go all the way
around the thermohaline circulation one time.
Explain how the thermohaline circulation affects the climate of the planet.
The thermohaline circulation helps the ocean absorb more carbon dioxide from the atmosphere.
The sinking water is filled with carbon dioxide that it absorbed from its recent contact
with the atmosphere. The rising water, though, sank 1000 years ago when there was
much (A)_________________ carbon dioxide in the atmosphere,
so it has (B)___________________________ carbon dioxide dissolved in it.
Therefore, the rising water has (B)____________________________ room to absorb
more carbon dioxide from our modern, carbon-dioxide-rich atmosphere.
This (C)____________________ the strength of the atmosphere’s greenhouse effect
and therefore (D)____________________ the planet.
A: more, less
B: lots of, very little
C: increases, reduces
D: warms, cools
Climate Change Lecture Notes (Topic 12A) – page 9
The Biological Pump
Ocean life helps remove carbon dioxide from the surface of the ocean and send it into the deep
ocean. In other words, biology helps “pump” carbon dioxide down deep.
CO2
Phytoplankton remove carbon dioxide from ocean
water so that they can make food for themselves in
a process called ____________________________.
They also use carbon to make shells. For example,
________________ carbonate shells require lots of
carbon. Thus, phytoplankton (A)_______________
the amount of carbon dioxide in ocean water,
O2
CO2
O2
CO2
Bodies
Sink
which allows the ocean to absorb more carbon
99% Dissolved,
Decomposed,
This (B)____________________ the atmosphere’s greenhouse
Eaten
CO2
dioxide from the atmosphere.
effect and therefore (C)____________________ the planet.
However, most of the carbon absorbed by
1%
Become
Sediments
CCD
phytoplankton ends up back in the water when the
dead remains of ocean life, fecal matter, and other
forms of organic matter are dissolved by _______________________ or decomposed by
_________________. When organic matter is dissolved or decomposed, the carbon in it
is released back into the ocean water. This keeps the ocean water “full” of carbon dioxide and
therefore the ocean (D)__________________ absorb more carbon dioxide from the atmosphere.
About _____% of the dead and decaying material does not get dissolved or decomposed before
reaching the bottom and becomes sediments on the ocean floor. In other words, _______% of
the carbon dioxide absorbed by phytoplankton eventually goes back into ocean water and thus
does NOT help reduce our carbon dioxide pollution.
The sediments are mainly composed of (E)____________________________________.
The small amount of carbon in these sediments is never released back into ocean water
and is ocean life’s contribution to reducing our carbon dioxide pollution.
A: increase, reduce
B: increases, reduces
C: warms, cools
D: can, cannot
E: fecal matter, food molecules, mucus, shells
Climate Change Lecture Notes (Topic 12A) – page 10
The Earth’s Climate: Important Influences
Sunlight
The amount of sunlight and where it falls changes
due to variations in the Earth’s orbit and tilt (“Milankovitch cycles”).
Plate Tectonics
Creates Volcanoes
● Warm the planet over the long term: ________________________________ come out
of volcanoes. They are ___________________________________________________.
● Cool the planet over the short term: ________________________________ comes out
of volcanoes. It blocks ____________________________________.
Changes Wind & Rainfall Patterns:
Mountains rise and block winds.
Land and ocean have different temperatures due to their different heat capacities
so as continents move, winds shift and blow in different directions.
Changes in Ocean Circulation (including the thermohaline circulation)
Changes in amount of sunlight reflected and absorbed:
continents move: in some positions, ice and snow can build up
Climate Change Lecture Notes (Topic 12A) – page 11
The Ocean & the Climate of the Earth
North
90 N Pole
o
Ocean Currents
60o N
Asia
o
30 N
Sketch the gyres in the Pacific Ocean
into the map on the right.
Americas
Label the boundary currents as “warm” or “cold”.
0o
The boundary currents
Equator
Austrailia
____________________ the Equator
30o S
and ________________________ the Poles.
60o S
Possible Answers: warm, cool
90o S
Thermohaline Circulation
South
Pole
How does the thermohaline circulation affect the overall climate of the world?
Explain why it has these effects.
Heat Capacity
_______% of the Earth is covered by the water in the ocean,
and water has a (A)_____________________ heat capacity.
This means that during periods of global warming when the Earth is gaining heat
the ocean warms (B)_______________________ than the land, so the ocean makes
the Earth warm more (C)_______________________ than it otherwise would.
It also means that during periods of global cooling when the Earth is losing heat
the ocean cools (B) _______________________ than the land, so the ocean makes
the Earth cool more (C)_______________________ than it otherwise would.
A: high, low
B: faster, slower
C: quickly, slowly
Climate Change Lecture Notes (Topic 12A) – page 12
The Atmosphere
Greenhouse Gases
Greenhouse gases like ________________________________________________
absorb _______________________ light from the _________________________,
causing them to warm up and preventing the light’s energy from escaping into space.
Clouds
Clouds reflect
(A)____________________________ light
from the Sun, sending it back into space.
Cloud
Cloud
This (B)________________________
the surface of the Earth by preventing it from
being warmed by sunlight in the first place.
Clouds absorb (A)____________________________ light from the Earth.
As a result, the clouds (B)______________________________,
and begin to send more (A)_____________________ light back to the surface of the Earth.
This (B)________________________ the surface of the Earth.
A: infrared, visible, ultraviolet
B: warm(s), cool(s)
Dust
Dust absorbs or reflects sunlight, preventing it from reaching the surface of the Earth.
Thus, dust ________________________ the surface of the Earth.
The ocean affects the amount of greenhouse gases, clouds, and dust in the atmosphere.
How does the ocean affect the amount of each one?
Greenhouse Gases
Clouds
Dust
Climate Change Lecture Notes (Topic 12A) – page 13
Climate Change and Ocean Life
Consider what you have learned about how the temperature of ocean water affects the amount of
life in the ocean. How and why will global warming – the warming of the ocean – affect the
amount of life in the ocean? In other words, will there be more life in the ocean or less? Which
organisms will benefit? Which organisms will suffer? How? Why?
As the world warms, there will be (A)_____________________ phytoplankton in the ocean,
because it is (B)___________________________ for them to survive in warm water.
Phytoplankton need __________________________ and __________________________
for _____________________________________________________________________.
It is (B)_______________________ for phytoplankton to obtain sunlight if the surface water
is warm, because it is (B)___________________________ for them to float.
It is (B)______________________ for phytoplankton to obtain nutrients if the surface water
is warm, because it is (B)____________________________________ for
(C)__________________ to bring up nutrients from the thermocline below.
As the world warms, there will be (A)________________________ fish in the ocean,
because ______________________________________________________________.
A: more, fewer
B: easier, harder
C: waves, upwelling
If global warming reduces the amount of life in the ocean, will reduction in the amount of life
help warm the Earth or will it help cool the Earth? Why?
Fewer phytoplankton in the ocean will lead to a __________________________ Earth.
Phytoplankton absorb _____________________________________ from ocean water,
which allows the ocean to absorb more from the atmosphere.
It is a ____________________________________________________________ gas,
so if it stays in the atmosphere, it helps _____________________________ the Earth.
How and why will extra carbon dioxide in ocean water affect the amount of life in the ocean?
Which organisms will benefit? Which will suffer? How? Why?
There will be _______________ life in the ocean. When carbon dioxide enters ocean water,
it _____________________ the pH, making the water more ______________________ and
thus dissolves shells made of _________________________________________________.
These algae and animals will grow more slowly and be more vulnerable to predators,
so the animals who eat them will have less to eat.
Climate Change Lecture Notes (Topic 12A) – page 14
Past Changes in Climate
Earth’s Climate has been unusually stable for the last 10,000 years.
Changes in temperature have been small (1-2oC, 2-4oF), but the small variations during the
“Medieval Warm Period” and the “Little Ice Age” had significant effects.
Give an example of a well-known, small change in climate due to changes
in the ocean that has a significant impact on California’s economy.
______________
Natural, large climate changes can happen quickly (over decades)
because of changes in winds and ocean currents.
Climate Change Lecture Notes (Topic 12A) – page 15
An Example of Global Warming leading to a change in Ocean Currents
and the Effect on the Climate of Europe
Why did the thermohaline circulation shut down about 12,500 years ago?
The thermohaline circulation is caused by
(A)_____________________ and
(B)_____________________ water
Ice Sheets
16,000 years ago
sinking at the Poles. Surface water moves
towards the Poles to __________________
Mississippi River
the water which sank.
(B)__________________ water from melting glaciers on land went into the North Atlantic,
so the water stopped sinking because its density was too (C)________________________.
Did the shutdown of the THC circulation
warm or cool Europe? Why?
Ice Sheets
12,500 years ago
The shutdown of the THC
(D)______________ the climate of Europe,
St Lawrence River
because (A)______________ surface water
stopped coming north.
Why did the thermohaline circulation eventually start again?
Equator
As the climate cooled, seawater began to freeze into ice,
North
Pole
which made the water (B) _____________________ again and
thus its density (C)__________________ enough to sink again.
Did the thermohaline circulation starting again warm or cool Europe?
Why?
The climate (D)________________________,
because (A)_____________________ started coming north again to replace the sinking water.
A: warm, cold
B: fresh, salty
C: high, low
D: warmed, cooled
Climate Change Lecture Notes (Topic 12A) – page 16
Is Global Warming Bad? Why or Why not?
People who live near the Poles
People who live near the Equator
People who live near the Coast
Shipping & Mining Resources in the Arctic
Will it really be “Global” Warming?
If the Earth’s climate continues to warm, the ice sheets on Greenland will melt,
and the thermohaline circulation could shut down. Why?
Greenland
Ice Sheet
Will this cause Europe to get warmer or colder? Why? Explain your reasoning.
Climate Change Lecture Notes (Topic 12A) – page 17
Climate Change Review Quiz
1. What kind of “light” do not-very-hot objects emit?
a. X-rays
b. Ultraviolet
c. Visible
d. Infrared
2. “Greenhouse gases like carbon dioxide absorb visible light.”
a. True
b. False
3. Does the thermohaline circulation warm or cool the world overall?
What is the primary way that the thermohaline circulation affects the overall climate of the Earth?
a. Warms: warms the surface of the ocean
b. Warms: increases the greenhouse effect
c. Cools: cools the surface of the ocean
d. Cools: reduces the greenhouse effect
e. No Overall Effect: warm and cold water just switch places
How or why does the motion of the water in the thermohaline circulation produce
these effects?
Why does the water rising upwards
in the thermohaline circulation have
such low levels of carbon dioxide?
Climate Change Lecture Notes (Topic 12A) – page 18
4. Phytoplankton help clean up our pollution by absorbing carbon dioxide,
and using it for a purpose which makes it less likely for the carbon dioxide
to end up back in the ocean and/or atmosphere where it can cause harm.
Which use makes it most likely that the carbon dioxide will be
“permanently” removed from the environment and no longer able to cause harm?
a. Breathing
b. Decomposing
c. Dissolving
d. Photosynthesis
e. Respiration
f. Shells
Where does the carbon go? Where is the carbon “permanently stored”?
Which of the following add carbon dioxide to ocean water and prevent the ocean
from absorbing more from the atmosphere?
a. dead bodies and wastes condensing into marine snow
b. decomposing of dead bodies and wastes by bacteria
c. dissolving of dead bodies and wastes by ocean water
d. photosynthesis by phytoplankton
e. precipitation of dead bodies and wastes into sediments
5. How do clouds affect the Earth’s climate?
a. Warm the Earth
b. Cool the Earth
c. Warm the Earth in some ways, and cool the Earth in other ways
d. Clouds do not have a significant impact on the temp. of the Earth
Explain.
6. Aside from releasing greenhouse gases by burning fossil fuels and forests,
how do humans have a major impact on the Earth’s climate?
a. Adding Dust (“Aerosols”) to the Air
b. Breathing
c. Filling in Wetlands
d. Ocean Pollution Kills Phytoplankton