El Nio 2017. Concern over the weather associated with El Nio has increased interest in the possibility

El Niño 2017. Concern over the weather associated with El Niño has increased interest in the possibility that the climate on Earth is getting warmer. The most common theory relates an increase in atmospheric levels of carbon dioxide 1CO22, a greenhouse gas, to increases in temperature. Here is a scatterplot showing the mean annual CO2 concentration in the atmosphere, measured in parts per million (ppm) at the top of Mauna Loa in Hawaii, each year from 1959 to 2016, and the global annual mean temperature (in degrees Celsius [C] from meteorological stations across the globe).

A regression predicting Mean Temperature from CO2 produces the following output table (in part).

Dependent variable: Mean Temperature R@squared = 89.5%
Variable Coefficient Intercept 9.786 CO2 0.013

a) What is the correlation between CO2 and Mean Temperature?

b) Explain the meaning of R-squared in this context.

c) Give the regression equation.

d) What is the meaning of the slope in this equation?

e) What is the meaning of the intercept of this equation?

f) Here is a scatterplot of the residuals vs. CO2. Does this plot show evidence of the violations of any of the assumptions of the regression model? If so, which ones?

g) Suppose CO2 levels reach 440 ppm in the future. What Mean Temperature does the model predict for that value?