# Trends in Carbon Dioxide Levels

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```					                                          Trends in Carbon Dioxide Levels

The CO2 level data given in Table 3 show average measurements taken at the Mauna Loa Observatory in Hawaii.
table 3
Year                  Approximate CO2 level
(ppm by vol.)
1870                          202
1900                          252
1920                          270
1930                          287
1960                          311
1965                          318
1970                          325
1972                          328
1974                          330
1976                          332
1978                          335
1980                          338
1982                          341
1984                          344
1986                          347
1988                          351

1. Construct a scatter plot of the data in Table 3.                     DIRECTIONS FOR TI-82/83
Prepare your horizontal axis to include the years 1870     o Clear all equations
to 2050. The vertical axis will represent CO2 levels       Ö EDIT
from 280 ppm to 600 ppm.                                   L1 = Date (year)
L2 = CO2 level (ppm)
2. Sketch the graph.                                       yo
Plots Off
Õ
yo
Plot1
ON
” Xlist=L1 Ylist=L2 Mark: +
q
ZoomStat

3. Calculate a linear regression for this data and record
the equation information.                                 Ö CALC LinReg(ax+b) ENTER ENTER
o Y1 ê Statistics EQ RegEQ
Y=                                                        s

4. Assuming the trend in your smooth curve continues       DIRECTIONS FOR TI-82/83
from 1990 to 2050, expand your window to include the       p
year 2050. This extrapolation is a prediction for the      Xmin = 1850
future, based on past trends.                              Xmax = 2060
Xscal = (2060-1850)/10
Ymin = 175
Ymax = 375
Yscl = (475-175)/10
s

<over>
Questions

You will make some predictions using the graph you have just completed. You will also evaluate these
predictions.

1. What does your graph indicate about the general change in CO2 levels since 1870.

2. Based on your extrapolation, predict CO2 levels for    DIRECTIONS FOR TI-82/83
a. the current year                               y
b. the year 2000                                  r
c. the year 2050                                  Value
Enter year

3. Does your graph predict a doubling for the 1870 CO2 level?

4. Which predictions from Question 2 are the most likely to be accurate? Why?

5. Describe factors that might cause your extrapolations to be incorrect.

6. What assumption is involved in making any extrapolation from known data?

7. Describe what the y-intercept value tells you about CO2 levels at year zero. Does this make sense? Explain.

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