Although greenhouse gases are essential to maintaining the temperature of the Earth, an excess of greenhouse gases can raise the temperature to dangerous levels. One of the most threatening greenhouse gases is carbon dioxide (CO2). The Mauna Loa atmospheric CO2 measurements constitute the longest continuous record of atmospheric CO2 concentrations available in the world. The following table shows the concentration of CO2 (in parts per million) at Mauna Loa, Hawaii, for three years.
Year CO2 (ppm)
1968...............................323
1999...............................368
2015...............................401
(a) Obtain the least-squares line that fits these data. (Let x = 0 correspond to 1968.)
(b) Estimate the concentration of CO2 in the year 2008. How does this compare with the actual reading of 386?
(c) If the trend continues, in what year will the concentration of CO2 reach 408 ppm?