ENV325 Lab Instructions
1. Carefully review the Grading Rubric for the criteria that will be used to evaluate your assignment before you
2. Go to http://learner.org/courses/envsci/interactives/carbon/carbon.html to open the carbon dioxide lab simulator.
3. Step 1 – Run the simulation twice to the years 2050 and 2100. The simulation is currently set at a 2% fossil fuel
increase per year. Run the simulation by clicking the green “Run Decade” Tab 4 times until you get to the year
2050, the data you need will be in diagram on the right, which shows the levels of carbon in each carbon “sink”
(terrestrial plants, soil, oil and gas, coal, surface ocean, and deep ocean). Record the carbon levels in each “sink”
at 2010, 2050, and 2100 in Table 1 on your Carbon Dioxide Lab Reporting Form and answer the subsequent
questions below the table the while thinking about how the model mimics real-life conditions. (*NOTE = total
carbon levels can be seen in the picture, those with a +number show the change since the original decade.
To get the total carbon level for these add the two numbers together, for instance soil is listed as 1800 +200
at year 2010, thus its total carbon soil is 2000 in the year 2010).
*Close the simulator between exercises to fully reset the parameters. This will help ensure accurate results.
4. Step 2 – In a best-case (but very unrealistic) scenario, imagine that scientists suddenly discovered an unlimited,
clean, and cheap fuel source that emitted no CO2 into the atmosphere, thus bringing fossil fuel use down to zero.
Reset the simulator and press the “NONE” button next to fossil fuel use to bring CO2 emissions to zero in the
simulator. Then run the simulation up to the year 2100 to see what happens. Record your data for years 2010,
2050, and 2100 in Table 2 on your Carbon Dioxide Reporting Form and answer the questions below the table.
5. Step 3 – So far we have considered only the impact of burning fossil fuels. But there are other human activities
that influence the carbon cycle. One major factor is deforestation and land use. Currently, land use (for example,
rice paddies) and deforestation outstrip reforestation by roughly 1 GT per year. If deforestation were to increase,
perhaps due to increased burning of rainforests, carbon would be transferred first from terrestrial plants to the
atmosphere and then through the rest of the carbon cycle. Reset the simulator (make sure to change fossil fuel use
back to 2.0% per year) and change the net deforestation rate to 1.6 GT per year and run the simulation to 2100.
Record the data for years 2010, 2060, 2080, and 2100 in Table 3 on your Carbon Dioxide Reporting Form and
answer the questions below the table. (NOTE* to change the deforestation and the fossil fuel use per year you
must use the green slider, typing the number into the box will cause the simulation to run improperly)
6. Step 4 – There are several important natural systems that may be affected by greenhouse warming as atmospheric
CO2 rises. Some of these systems may release even more CO2 into the atmosphere, speed up the warming, and
cause a positive feedback loop. A negative feedback loop would have the opposite effect and slow or reverse
climate change. Whether we experience positive of negative feedback effects is difficult to predict in such a
complex system, but a model for one feedback effect is included in the simulator: melting tundra. If the arctic
tundra were to melt as temperatures rise, its stored carbon would enter the system. Click on the lesson button at
the top of the simulator and then click feedback effects. To assume that 1/6 of the tundra will melt with increased
warming, click on the drop down box next to “melting tundra releases carbon” and choose 1/6. Now run the
simulation to 2100. Record the data for years 2010, 2050, and 2100 in Table 4 on your Carbon Dioxide Reporting
Form and answer the questions below the table. 7. When completed, save the Carbon Dioxide Lab Reporting Form as a Word document. No title page or headers are
necessary; however, any resources used to complete the questions should be listed in the reference section in APA
format. For information regarding APA samples and tutorials, visit the Ashford Writing Center, located within the
Learning Resources tab on the left navigation toolbar.