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collect air flasks from sites around the world each week and measure the

concentration of carbon dioxide. An annual global mean of the CO₂

concentration is then calculated. The most recent data is in Source 1.

a) Use Excel to plot these data on a scatter chart with CO₂ (ppm) on the

y axis and year on the x axis.

b) Add a linear trend line

c) Find the equation of the linear trendline

d) Use this equation to find the mean growth rate of CO₂ in ppm/year

e) If CO₂ growth continues at this rate what will the global averaged CO2

concentration be in 2050?

f) Can you find a trendline that fits the data better? If so, what is the

equation of this new trendline?

g) What would the global average CO₂ concentration be in 2050 if it

continues to follow the equation you found in part f?

2. Source 2 contains a series of measurements of apparent width and

dip of a bedding plane in degrees. The outcrop width is 5 m.

a) Find the mean of the measurements of dip

b) Find the standard deviation of the dip measurements

c) Find the standard error of the dip measurements

d) Recalling that stratigraphic thickness = sin(dip angle) * (outcrop

width), use trigonometry to calculate the true width of the bedding plane.

(Hint: Use Excel to do the calculation but remember that the Excel

trigonometric functions require the angle to be in radians)

3. The data in Source 3 are the Arctic sea ice extent in millions of km²

every September from 1979 to 2021. Answer the questions below.

a) What is the mean sea ice extent over the observational record?

b) Plot a graph of the data in Excel.

c) Calculate the mean slope of the entire data record by using Excel to

fit a linear model to the data using a least squares methodology. What does

the slope tell you?

d) Using this model, in what year is the Arctic expected to be free of sea

ice in September?