This assignment has two parts, word document and an excel spreadsheet.
Word doc
This assignment has two parts, word document and an excel spreadsheet.
Word document
Homework #5: The Carbon Cycle
Due Date
Sunday, March 17th by 10:59pm PT
Part 1: Overview of the Carbon Cycle
The carbon cycle is a complex system with interactions between the different components of the Earth System. In this homework, you will learn how carbon is moved between the different reservoirs naturally, and how human activities are changing the cycle.
Volcanic eruptions (0.6 GT/year)
Dissolution of atmospheric carbon in surface ocean (90 GT/year
Photosynthesis on land (110 GT/year)
Release of carbon from surface ocean to atmosphere (90 GT/year)
Leaf fall to soil (60 GT/year)
Uptake of carbon from surface ocean by ocean life (10 GT/year)
Respiration from life on land (i.e., plants, 50 GT/year)
Downwelling (mixing) from surface to deep ocean (96.2 GT/year)
Respiration from soil (59.4 GT/year)
Upwelling (mixing) from deep ocean to surface ocean (105.6 GT/year)
Runoff of soil to surface ocean (0.6 GT/year)
Dead ocean life sinking to deep ocean (10 GT/year)
Deposition of sediment from deep ocean to rock (0.6 GT/year)
1.The diagram above shows the reservoirs of the carbon cycle with the mass of carbon in Gigatons. Using PowerPoint or the “Draw” feature in Microsoft Word, draw labelled arrows between the relevant reservoirs to represent the sinks and sources listed in the table above. Save your PowerPoint slide as an image (watch the tutorial video if you need help) and insert the image in the space below. (13 points)
2. [Insert your completed carbon cycle diagram here. ]
3.Ignoring the solid Earth, which of the reservoirs has the longest residence time and which has the shortest residence time? What are the residence times of carbon in each of these? (4 pts)
Longest
Reservoir:
Residence time:
Shortest
Reservoir:
Residence time:
4.Your diagram currently represents how the carbon cycle operated before humans started affecting the atmosphere. Is the carbon cycle at a steady state today (as in the year 2024)? How do you know? (2 pts)
5.What extra arrows would you need to draw on the diagram to represent human activities that affect the carbon cycle? Where would they flow from and to? Describe at least two. (2 pts)
6.What effect do you think these additional fluxes will have on the size of the different carbon reservoirs? (2 pts)
Part 2. Interactive Carbon Cycle Simulation for “Business as Usual”
In this step, you will use an online carbon cycle simulation to observe how human activities are impacting the flux of carbon through the Earth System. You will need to “ESS15_W24_HW5_CarbonCycle.xlsx” file and this link for the website.
1.For the first simulation, you will use the lesson Carbon Cycle and keep the parameters of fossil fuel use and net deforestation at their pre-set values of 2%/yr and 1 GT/yr, respectively.
This simulation will show you what the future carbon cycle will look like if we continue the “business as usual” pathway of using fossil fuels and deforestation at our current global rates.
Familiarize yourself with the carbon system diagram on the right. The main reservoirs of carbon are labeled, and their initial sizes are shown. For example, in year 2010, the size of the terrestrial plants carbon reservoir is 700 GT and the size of the atmosphere is 720 GT. As you progress through each decade of the simulation, these values will change, and we will keep track of this information in our spreadsheet.
Begin the simulation by clicking the green “run decade” button.
At each decade interval, fill in the corresponding data table in the Excel spreadsheet. Complete the simulation through the year 2120. (5 pts)
*Hint: the sizes of the soil, ocean surface, and deep ocean reservoirs do not change, but rather show the +XX GT change. In your table, start with their initial values for 2010, and then add formulas for the following decades. For example, with the surface ocean you can do: = 1000+XX, or deep ocean: =38000 + YY where XX and YY are the respective increases in those reservoirs per decade of the simulation. This way the math is done for you automatically on your Excel table.
2.Using the collected data, make a plot of the different reservoir sizes in GT (atmosphere, surface ocean, deep ocean, soil, and plants) from 2010 to 2120. Put the deep ocean on a secondary y-axis (watch this video for help). Insert your figure below. Be sure to include appropriate axes labels and units, a legend, and a title. (5 pts)
3.Calculate the rate of change in the size of each of the reservoirs from 2010 to 2120.
where t is the current time step (ex: year 2030) and t-1 is the previous time step (ex: year 2020). The atmosphere’s rate of change is started for you.
Make a figure for the rate of change for each reservoir and insert your figure below. Be sure to include appropriate axes labels and units, a legend, and a title. (15 pts)
4.What do you observe in the rate of changes in the different carbon reservoirs over time? Are they all the same? Or do some change more/less than others? In at least one paragraph, discuss your observations. (5 pts)
5.Calculate the amount the carbon emissions (in percent) that end up in each reservoir for each decade. This can be done by first determining the change in the reservoir’s sizes after each decade. Then divide these values by the total emissions of carbon at the time step (column G, “Smokestack”). For example, if the atmosphere changed by 10 GT and the total emissions were 100 GT, the percent of the total emissions that ended up in the atmosphere at that time step would be 10%. Remember that Excel acts as a calculator, so you can type formulas in a cell and drag!
Make a graph of the results and insert your figure here. Be sure to include the appropriate axes labels and units, a legend, and a title. (15 pts)
6.What do you observe about where carbon ends up in the Earth System through time in this scenario? Do all the reservoirs “accept” the same amount of carbon or are some different? Is the amount of carbon ending up in each reservoir the same at every time step or does it change? In at least one paragraph, discuss your results. (5 pts)
Part 3. Interactive Carbon Cycle Simulation for a “Drawdown” Scenario
1.For the second simulation, you will change the lesson to “Curb Emissions” and reduce the parameters of fossil fuel use and net deforestation at to -4%/yr and -4 GT/yr, respectively.
Press “RESET” to set these parameters. This simulation will show you what the future carbon cycle will look like if make drastic cuts to our carbon emissions by stopping fossil fuel use and deforestation. Begin the simulation by clicking “run decade”. At each decade interval, fill in the corresponding data table in the Excel spreadsheet. Complete the simulation through year 2100.
Using the collected data, make a plot of the different reservoir sizes from 2010 to 2100. Insert your figure below. Be sure to include appropriate axes labels and units, a legend, and a title. Put the deep ocean on the secondary y-axis (10 pts)
2.Compare and contrast the differences in the carbon reservoirs with this curb emissions scenario and the “business-as-usual” scenario. (5 pts)
3.Continue running the curb emission scenario out into the far future (2500). You do not need to record the data. While you do this, pay attention to the different reservoir sizes and to the atmospheric CO2 concentration. Describe what happens to carbon in the Earth System in the future. Where does the carbon that had been emitted to the atmosphere prior to 2010 end up? Is this a slow or fast process? (5 pts)
4.From what you have witnessed in this “curb emissions” scenario, explain the concept of “climate inertia”. Use the internet if you need to and cite your sources (links are acceptable). (5 pts)
5.With the concept of “climate inertia” in mind, why is it important that we begin curbing carbon emissions as soon as possible? (2 pts)
6.In one paragraph, summarize what you learned from this homework activity. (2 pts)