EARTH 103 - Module 3 Lab
Feedbacks (Q 1-4)
Open the climate model.
What happens if we start out with an Earth that is not in a steady state, so that E_in≠E_out? Use the slider
controls at the top to set the initial conditions so that the initial temperature is 0 instead of 15 (15 is the
default setting, so you have to change this).
QUESTION 1. What will happen? How will the temperature change over time? Think about how the Ein
and Eout will compare at the beginning — it will help to study the red curve in Fig. 4. On this graph, find
the approximate energy emitted at a temperature of 0°C and then compare this with the energy in value of
240 W/m2.
Remember to change the initial temperature to 0 before you run the model.
A) Eout > Ein — this will cause warming
B) Eout < Ein — this will cause warming
C) Eout = Ein — temperature will remain constant
QUESTION 2. Now, run the model and see what happens. What is the temperature at the end of the
model run (to the nearest 0.1 °C)?
QUESTION 3. Click on page 2 of the graph pad (click in the bottom left corner on the page turning icon)
in the model and study the Eout and Ein curves (labeled E Flux In and E Flux Out). Note that Ein remains
constant, but Eout changes. When it stops changing, what is the relationship between Eout and Ein?
A) Eout > Ein
B) Eout < Ein
C) Eout = Ein
QUESTION 4. Now change the initial temperature to 30°, run the model and see what happens. Is the
ending temperature the same (within 0.2 °C) or different (varies by more than 0.2°C) than what you found
in question 2 above?
A) Same
B) Different
Steady State 9 (Q5-15)
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Before you start this part, click on the Restore Everything button in the lower right of the model to return
the model to its original condition.
When you are done with each of the following, click on the Restore Everything button in the lower right
of the model to return the model to its original condition — this way, we will change just one thing at a
time.
You might want to run the model in it’s restored state between runs to remind yourself of what the results
look like.
QUESTION 5. If you increase the solar input by 10% (change the solar multiplier to 1.10), the new
steady state is
_________ °C
QUESTION 6. If you increase the solar input by 20% (change the solar multiplier to 1.20), the new
steady state is
__________OC
QUESTION 7. Based on your answer to questions 5 and 6, what effect does increasing the solar input
have on climate?
A) Increasing the solar input has a warming effect on climate
B) Increasing the solar input has a cooling effect on climate
C) Increasing the solar input has no effect on climate
QUESTION 8. Restore the model before you begin this question
If you increase the albedo by 10% to 0.33, the new steady state temperature is
____________°C
QUESTION 9. If you increase the albedo by 20% to 0.36, the new steady state temperature is
_______ °C (to nearest 0.1°C)
QUESTION 10. Based on your answer to questions 8 and 9, what effect does increasing the albedo have
on climate?
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A) Increasing the albedo has a warming effect on climate
B) Increasing the albedo has a cooling effect on climate
C) Increasing the solar input has no effect on climate
QUESTION 11. Restore the model before you begin this question
If you double the ocean depth to 200 m, the new steady state temperature is
_________oC (to nearest 0.1 oC)
QUESTION 12. If you treble the ocean depth to 300 m, the new steady state temperature is
__________oC
QUESTION 13. Based on your answer to questions 11 and 12, what effect does increasing the depth of
the ocean have on climate?
A) Increasing the depth of the ocean has a warming effect on climate
B) Increasing the depth of the ocean has a cooling effect on climate
C) Increasing the depth of the ocean has no effect on climate.
QUESTION 14. Restore the model before you begin this question
If you double the greenhouse gas concentrations by changing the CO2 multiplier to 2 (CO2 goes from
380 ppm to 760 ppm), the steady state temperature is
__________oC
QUESTION 15. Based on your answer to question 14, what effect does increasing the concentration of
carbon dioxide in the atmosphere have on climate?
A) Increasing the concentration of carbon dioxide in the atmosphere has a warming effect on climate
B) Increasing the concentration of carbon dioxide in the atmosphere has a cooling effect on climate
C) Increasing the concentration of carbon dioxide in the atmosphere has no effect on climate
Response Time (Q16-24)
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Restore the model before you begin this question
QUESTION 16. If you decrease the albedo by 10% to 0.27, the system will be forced into a new state.
We want to know how quickly it responds.
The new steady state temperature of the system is _____________°C (rounded to the nearest whole
number)
The response time of the system is ______________ years (rounded to the nearest whole number)
QUESTION 17. Restore the model before you begin this question
Turn on the solar switch and run the model. How much does the planetary temperature change over the
solar cycle (difference between peak and trough — measure this after the third peak)?
Change in temperature in one cycle _______________°C (answer to 3 decimal places e.g. 1.234)
QUESTION 18. Notice that the temperature peaks after the Solar Constant peaks. This time delay is
called a lag time. What is the lag time here in years?
The lag time is __________________ years (answer to the nearest 0.1 years).
QUESTION 19. What does the time lag suggest about the relationship between temperature and the solar
constant?
A) Increases in temperature drive increases in the solar constant
B) Increases in temperature drive decreases in the solar constant
C) Increases in the solar constant drive increases in temperature
D) Increases in the solar constant drive decreases in temperature
E) There is no relationship between temperature and the solar constant.
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Let’s explore the relationship between the concentration of CO2 in the atmosphere and the temperature.
Initially, the model is set up with a CO2 concentration of 380 ppm and we can change this using the CO2
multiplier — a value of 0.5 will half the CO2 to 190 ppm, and a value of 2 will double it to 760 ppm.
QUESTION 20. Restore the model before you begin this question
We know that our initial model with 380 ppm gives us a temperature of 15°C and we saw above that
when we doubled the CO2 to 760 ppm, we increased the temperature to 17°C, which means that we got a
2°C increase with a CO2 increase of 380 ppm. So, how much more CO2 do we have to add to get
another 2°C rise in temperature? Change the CO2 multiplier until we get a steady state temperature of
about 19°C, and find the CO2 concentration (CO2 total in the model, on graph 1) needed to get this
temperature.
CO2 Multiplier to result in a temperature of 19°C: _____________
CO2concentration (ppm): ___________ ppm
QUESTION 21. Now find the CO2 multiplier and concentration needed to get an additional 2° warming
— to 21°C.
CO2 Multiplier to result in a temperature of 21°C: : _____________
CO2 concentration (ppm): ______________ ppm
QUESTION 22. Which of the following summarizes your findings:
A) Each additional increase of 380 ppm results in a 2°C warming
B) Each additional increase of 760 ppm results in a 2°C warming
C) Each doubling of the CO2 (from 380 to 760 to 1520, and so on) results in a 2°C warming
QUESTION 23. Does the temperature still reach a steady state in each of these cases?
A) Yes
B) No
QUESTION 24. Based on your understanding of how CO2affects temperature, how much CO2 would
you need to get a final temperature of 25°C. Note: The model does not go this far. You will have to
calculate it based on your understanding thus far.
CO2 Multiplier needed to result in a temperature of 25°C: ____________
CO2 concentration (ppm): _______________ ppm
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Albedo (Q 25-27)
Restore the model before you begin this question
QUESTION 25. We know that during the last glacial maximum, around 20,000 years ago, the
atmospheric CO2 was about half of today’s value — 190 ppm, and we also know that the average
planetary temperature was about 6°C cooler than the present (i.e., around 9°C instead of 15°C). Next, just
change the CO2 multiplier to 0.5, halving the carbon dioxide concentration, which takes us to 190 ppm
CO2.
Run the model and find the steady state temperature.
Steady state temperature at 190 ppm = _________________ °C (answer to closest 0.1°C)
QUESTION 26. Now turn the Albedo Switch on and keep the CO2 multiplier at 0.5.
The steady state temperature at 190 ppm with albedo feedback (at time= 80 years): _______________°C
How much additional cooling was caused by this feedback mechanism?
______________°C
QUESTION 27. Turn the albedo switch off and increase the albedo to 0.6 while leaving the CO2
multiplier at 0.5. What is the steady state temperature?
Steady state temperature is _____________°C
Climate forcings (Q28-30)
You use a different model to do the following questions! Remember to change the model!
QUESTION 28. Use the table below to keep track of your findings as you move through this experiment.
Type one of the three choices in each box — poor, so-so, or good to respond to the question at the top of
the columns.
Forcing
Solar
Aerosols
Volcanoes
GHG
All Together
How well do model
results match the
sharp, small ups and
downs?
Poor So-so Good
Poor So-so Good
Poor So-so Good
Poor So-so Good
Poor So-so Good
How well do model
results match the
general trend of the
first 800 yrs?
Poor So-so Good
Poor So-so Good
Poor So-so Good
Poor So-so Good
Poor So-so Good
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How well do model
results match the
general trend of the
last 200 yrs?
Poor So-so Good
Poor So-so Good
Poor So-so Good
Poor So-so Good
Poor So-so Good
QUESTION 29. Of all the forcings, which is the most important in terms of matching the observed
temperatures in the most recent 200 years?
A) Solar
B) Aerosols
C) Volcanoes
D) GHG
QUESTION 30. Of all the forcings, which is the least significant variable in terms of matching the
observed temperatures in the most recent 200 years?
A) Solar
B) Aerosols
C) Volcanoes
D) GHG
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