Modeling carbon dioxide concentration changes
Using a Model to estimate future carbon dioxide levels
and possible global warming
Introduction.
Watch this NASA video on the Carbon Cycle
Here’s a video related to some interesting aspects of the carbon cycle.
Figure 1. The blue dots are the monthly mean CO2 values measured at the
Mona Loa observatory since 1960. The red line is the 12 month running
average of these monthly means. Here’s a link to a larger image.
Part 1. The Data:
Reading the Graph of Figure 1 (see link above to access largerFigure 1)
Q1: Objective: How has the CO2 concentration changed over the recent past?
Read the graph of figure 1 to answer these questions (Ctrl-click on the image to enlarge
it). Using the 12 month running mean (red line) estimate the mean concentrations of CO2
in 1960, 1970, 1980, 1990, 2000? What are the decadal changes in CO2 over the 5
decades? For example the decadal change in the 1960s is (the 1970 value – the 1960
value). Record in the following table.
R. M. MacKay, Clark College Physics and Meteorology
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Modeling carbon dioxide concentration changes
Year
[CO2] (ppm)

1960
1970
1980
1990
2000
2010

[CO2] ppm
*******
1960s
1970s
1980s
1990s
2000s
Q2: From these estimated values is the rate of increase of CO (right column)2 :
Growing
staying about the same
decreasing
[circle one]
Discuss possible reasons for the behavior of atmospheric carbon dioxide concentration
levels over the past 50 years, especially the change in CO2 growth from the 1990s to the
2000s. The figures below and on the next page may provide some insight into these
question. Make sure your discussion touches on: Why did CO2 grow at a fairly steady rate in the 1980s
and 1990s? Why did CO2 grow so much over the decade from 2000 through 2009? What type of fuel has
become increasingly popular world wide? Compare and contrast the per capita fossil fuel emission
changes in the developed countries and developing countries. (70 words minimum)
Larger images
(left) http://cdiac.ornl.gov/GCP/images/global_co2_emissions.jpg
(right) http://cdiac.ornl.gov/GCP/images/countries_co2_emissions.jpg
R. M. MacKay, Clark College Physics and Meteorology
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Modeling carbon dioxide concentration changes
(Larger image at) http://cdiac.ornl.gov/GCP/images/per_capita_co2_emissions.jpg
(Larger image at) http://cdiac.ornl.gov/GCP/images/fuels_co2_emissions.jpg
R. M. MacKay, Clark College Physics and Meteorology
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Modeling carbon dioxide concentration changes
The simulation environment that we will use is a model based on the IPCC
parameterization of the impulse response function for carbon dioxide injected into the
atmosphere. See http://www.atmosedu.com/meteor/ejs/CO2SimulationEnvironment.pdf
for a more detailed description of our CO2 simulator. In the schematic above there are 4
major components of the of the global carbon cycle: Atmosphere, Biosphere, Surface
Ocean, and Deep Ocean. LS,HS, HD in the above figure are Low latitude surface ocean,
High latitude surface ocean, and High latitude Deep Ocean. K is the vertical diffusion
constant, q is the horizontal diffusion in the deep ocean, u is the mean upwelling downwelling velocity, and w is the horizontal advection velocity in the surface layer.
Q3: Aside from an explicit inclusion of human activity, what other important
component(s) to the carbon cycle is missing? Why has this component been omitted in
the Bern model designed to make projections of CO2 throughout this century?
R. M. MacKay, Clark College Physics and Meteorology
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Modeling carbon dioxide concentration changes
Part 2 Using JAVA CO2 Simulator observation for model calibration.
Objective: Download and use the JAVA CO2 simulator to estimate the terrestrial
sink needed to obtain the best fit between model simulated atmospheric CO2
concentrations and Mauna Loa CO2 observations.
Download and then open the JAVA CO2 simulator from
www.atmosedu.com/meteor/ejs/ejs_CO2C.jar
Details on the simulator and how to use it can be found at:
http://www.atmosedu.com/meteor/ejs/CO2SimulationEnvironment.pdf
Adjust the Terrestrial sink to achieve your best fit between model simulation and Mauna
Loa CO2 observations. Remember emissions from fossil fuels and land use changes are
provided as prescribed input into the simulation model estimated from current research.
Q4: What value of Terrestrial Sink gave your best fit between model and observations?
Terrestrial Sink (GtC/yr)= _______________
Q5: How does this agree with published estimates of 1.1+/- 0.8 (GtC/yr)? (see the
reference to the 2011 paper by Pan et al. (1))
Q6: Using the estimates of 1.1+/- 0.8 (GtC/yr) for the terrestrial sink, run three
simulations: Terrestrial sink =0.3, 1.1, and 1.9 (GtC/yr). Graph all three simulations on
the same axes and discuss your results. In your discussion include: The range of 2010
CO2 values obtained in 2010 for these three simulations.
Paste a copy of your graph here
Insert your discussion here
Q7: According to the data available at the DOE site
http://cdiac.ornl.gov/GCP/carbonbudget/2013/ the emissions from both fossil fuels and
land use change have uncertainties of +/- 5% and +/- 5 GtC/yr respectively. Assume that
some new research were to find that the terrestrial sink was 0.5 GtC/yr +/- 0.2 Gt/yr.
What influence would this information have on our assumed emissions from fossil fuels
and land use change?
R. M. MacKay, Clark College Physics and Meteorology
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Modeling carbon dioxide concentration changes
Q8: With the best fit what does the model predict for the year 2010 concentration
and total carbon emission. (read the output data table for these values)
Make sure to include units.
2010 concentration=_______________ 2010 total emission =________________
Part 3: Using the JAVA CO2 simulator for future projections.
Objective: Use the JAVA CO2 simulator mode in future projections mode to
estimate future levels of atmospheric carbon dioxide for different assumed emission
scenarios.
With the JAVA CO2 simulator open: 1) click the reset button; 2) select the radio
button for 2000 to 2100 simulation run; and 3) Use the best fit Terrestrial Sink value
from part 2.
Q10: Find an emission scenario that just
keeps CO2 levels from going above 450
ppm. You maximum CO2 concentration
for this run should be no larger than 450
and no less than 440 ppm. Paste both the
CO2 graph and the emission graph into
your report below for this scenario.
Comment on what had to be changed
and how soon it had to be changed, and
on the feasibility of this scenario (80
words minimum). You must change the
emission growth rate values from their
default values (business as usual) to values
that keep CO2 concentrations below 450
ppm for the duration of this century.
Negative values are also okay. Record
your new % increase per year values at
right
Q9: Your % increase per year values:
2013 to 2030= _____________
2030 to 2050= _____________
2050 to 2080= _____________
2080 to 2100= _____________
Is it possible to do this without decreasing
the 2013 to 2030 emission growth rate?
Past Graphs and insert comments here.
R. M. MacKay, Clark College Physics and Meteorology
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Modeling carbon dioxide concentration changes
Reset, check the 2000 to 2100 run radio button, and set Terrestrial Sink to Part 2 value.
Run a simulation with 2013 to 2030 growth rate =-100% (all other growth rates the same.
This is very unrealistic.
Q11: Paste both the CO2 graph and the emission graph for this scenario below.
Comment on the results of this scenario (70 words minimum). The idea here is that all
emissions are suddenly (and magically) cut to zero. but the year 2100 CO2 concentration
seems to stay above preindustrial level of 280. Why is this true? How long do you think
it will take for the emissions to get back to preindustrial levels*?
Paste Graphs and enter comments here.
*Actually in the present model the CO2 concentration will never get back to 280 because plate tectonics
have been omitted from the model so there is no way that carbon can be permanently removed from the
“permanent component” of the climate system in this model.
Reset, check the 2000 to 2100 run radio button, and set Terrestrial Sink to Part 2 value.
Q12: Run the three runs shown in the
table above and record the year 2030
and year 2060 CO2 values for each
simulation. Also record the BAU-half
and half – zero differences.
[CO2] in Year BAU
half
zero
BAU-half
half-zero
2030
2060
Table 2. 2030 and 2060 CO2 concentration for 3 different emission scenarios.
Q13: How do the 2030 concentrations for the three different scenarios of Table 2
compare with each other?
R. M. MacKay, Clark College Physics and Meteorology
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Modeling carbon dioxide concentration changes
Q14: How do the 2060 concentrations for the three different scenarios of Table 2
compare with each other?
Q15: T/F the predicted 2030 concentration depends very strongly on the assumed
emission scenario.
Q16: T/F the predicted 2060 concentration depends very strongly on the assumed
emission scenario.
Q17: A policy change aimed at limiting carbon dioxide in the atmosphere that is
implemented by a political agreement today will take ____________ years to result in
observable differences in the amount of carbon dioxide in the atmosphere.
a. 5 years
b. 10 years
c. 20 years
d. More than 20 years
Q18: Based on your answers above and any other potentially important factors, discuss
the political incentives and disincentives to proposing legislation to curtail carbon
emissions.
*Actually in the present model the CO2 concentration will never get back to 280 because plate tectonics
have been omitted from the model so there is no way that carbon can be permanently removed from the
climate system with this model.
Reset, check the 2000 to 2100 run radio button, and set Terrestrial Sink to Part 2 value.
Devise your best future emission scenario for estimating atmospheric carbon dioxide
concentrations for the rest of this century. Use a web based search and your intuition for
rationale in selecting your emission scenario. (explain your rationale 100 words
minimum)
Explain your rationale here.
Paste both the CO2 graph and the emission graph into your report for this scenario.
R. M. MacKay, Clark College Physics and Meteorology
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Modeling carbon dioxide concentration changes
Use the assumption that limiting atmospheric CO2 concentration to 450 ppm or below
will result in adaptable climate change as a benchmark to discuss to possible implication
of your emission scenario to our future climate. (100 words minimum)
Paste Graphs and enter comments here.
References
1. Yude Pan et al., A Large and Persistent Carbon Sink in the World's Forests
Science 333, 988 (2011)
2. Mauna Loa CO2 data from: http://cdiac.ornl.gov/GCP/carbonbudget/2013/
R. M. MacKay, Clark College Physics and Meteorology
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