Calibration of the relationship between contemporary environmental values (sea-surface temperature) and proxy data (percentage of Globegerina in surficial sediments) permits us to estimate the past temperature when proxy data were deposited. The line in the graph of sea-surface temperature versus Globegerina percent (below) is described by two points (X,Y) 0,0 and 40,20 (Globegerina %, oC ). A fossil sample contains 25% Globegerina, what was the sea-surface temperature at the time (and place) that sample was deposited?
The transfer function for this problem is of the form Y = bX + c where
Therefore, the transfer function is Y = 0.5 * X + 0
(past Sea Surface Temperature equals ½ of the Globegerina percent)
For example, for 25% Globegerina the sea-surface temperature is 12.5 oC
12.5 oC = 0.5 * 25 + 0For the following five calibrations sets, defined by points 1 & 2, calculate the transfer function (Y = bX + c) by first finding the slope of the line (b) and the Y-intercept (c). Then, calculate the past temperature implied by the percentage of Globegerina in a fossil sample. Hand in a table showing the five pairs of points, b, c, the calculate temperature, and your calculations.