EARTH SYSTEM SCIENCE
WRITING ASSIGNMENT #8 - TRACKING EVIDENCE OF GLOBAL CHANGE
Your assignment this week is slightly different than that of the previous weeks. Instead of downloading images, this week we will download actual data from the Carbon Dioxide Information Analysis Center (CDIAC) at Oak Ridge National Laboratories in Oak Ridge, Tennessee. As was presented in the Internet exercise for this week, CDIAC is the primary clearinghouse for data on atmospheric carbon dioxide concentrations. In particular, data representing actual CO2 measurements are available for download from these sites. Our task this week is to download those data and parse them into a spreadsheet. then, we can create our very own customized plots of atmospheric CO2 levels.
YOUR ASSIGNMENT FOR THIS WEEK:
Here's what to do:
EXERCISE 1:
1. Go to the CDIAC site by clicking the button at the bottom of the page.
2. From the CDIAC Home Page, click on the "TOP TEN" button..
3. Click on the link for "Trends - A Compendium of Data on Global Change ".
4. Click on "Carbon Dioxide and Carbon Isotopes". Then click on "Atmospheric CO2 records from sites in the SIO air sampling network ".
5. Click on the link for Mauna Loa, Hawaii data. At the top of the page, click on the "Digital Data" link. You will see a very large table of data arranged by year (rows) and months (columns). Go to the "EDIT" function on the menu bar at the top of the screen. Select "Edit" and "Select All". You will see the data highlighted. Now, return to "Edit" and "Copy".
6. Locate Microsoft Excel on your computer and start the software. Once Excel is running, select the "Edit" function from the Excel menu bar, then select "Paste". The data from CDIAC will be dropped into your spreadsheet. However, these data are all located in a single column (column A) of the spreadsheet and are not usable in this form. What we need to do is move each of the data entries to a single cell of the spreadsheet. This process is called "parsing" and is accomplished in Excel by going to the "Data" heading on the menu bar. Under the "Data" heading, select "Text to Columns". You will see a dialogue box which will ask you questions regarding the specific methods you want to use for parsing the data.
7. Under the "Original Data Type" select the radio button for "Delimited". Next, scroll the data preview screen to row 13 (this should show the months of the year). Now click "Next" at the bottom of the dialogue box. A new dialogue box appears asking what kind of delimiters are in the data. A delimiter is a symbol which separates individual data entries. This symbol may be a tab, space, comma, etc. Our data are delimited by spaces, so check the "Space" box. When you check the "Space" box, you should also check the "Treat consecutive delimiters as one" box. In the data preview, you will see the data arranged in nice columns. Click "Next".
8. At the next dialogue box, click "Finish" and the data will be parsed into the spreadsheet!
9. Notice that the text headers at the top of the data set will be parsed as well, which makes them rather unreadable, but we don't need them, so it's not a worry.
10. Now, we want to make a graph of these data. At the bottom of the Excel screen you will see a series of page tabs (labeled "Sheet1", "Sheet2", etc.). Click on "Sheet2". You will see a new spreadsheet page. This is the page where we will make our graph. From the "Insert" command on the menu bar, choose "Chart" and "on this sheet". The upper left cell will begin to blink. Go up to the cell and drag the lower right corner across the page until you have a size that you like. When you release the mouse, a dialogue box appears and asks for data you wish to chart. Click the "Sheet1" tab at the bottom of the screen. This returns you to the CDIAC data. Now, click on the year "1959" and drag to the bottom of the column (1996). Next, press the Cntrl Key and select the column "Annual", again beginning with 1959 and extending to the bottom of the column. Click "Next" on the dialogue box.
11. you are now asked to choose the type of plot. Choose "Line" and hit "Next".
12. You are asked to choose a specific type of line plot. Choose "4" and hit "Next". You will see another dialogue box. Where is shows "Use First blank Column(s) for (X) Axis Labels" make the number 1 and hit "Next". When it asks for a legend, select "No", then "Finish". you should then see your chart. Notice that there is a big dip in 1963 - this is because the data for that year are missing. To avoid seeing this point, double click on the Y-axis and then double click the Y-axis again. You should see a dialogue box with several page tabs at the top. Select "Scale", then set the minimum to 300. Now you can see the data representing the yearly increment in CO2 clearly.
To complete your assignment for this week, submit your spreadsheet and graph with the answers to the following questions via e-mail to Dr. Boss.
QUESTIONS TO ANSWER:
1. How much has the atmospheric CO2 concentration changed since 1959 in ppmv? What percent increase over the starting value is this? How much (on average) has CO2 increased each year? Does the rate of rise in CO2 appear to be decreasing? Why or why not?
2. Compare your graphic to those on the CDIAC website by going back to the site and clicking on the Mauna Loa "Graphics" link. How do your data differ from those on the website? What is the source of this difference?
3. When is CO2 at Mauna Loa at its lowest level? When is it at its highest? What process(es) cause the Mauna Loa data to be oscillatory?
4. Why was Mauna Loa chosen as the original site for these measurements?
5. Examine the graphic associated with the data from the Siple Station Ice Core (Antarctica). What does the average pre-industrial CO2 level appear to be? How much has CO2 increased since pre-industrial times (in ppmv)? What percent increase is this?
6. If you wanted to calculate the total quantity of CO2 (in, say, petagrams) that this increase represents, what would you need to know?
CO2 INFORMATION ANALYSIS CENTER
