**Task:** Reconsider the problem of the assignment on rising atmospheric CO$_2$ levels. Using the data you already downloaded for the assignment, now fit a quadratic curve to the data by regression. Since the derivative of a quadratic function can be hand-computed, you would then be able to estimate the rate of change of the regression fit and address the earlier assignment task: provide a policy-maker with a "yes or no" answer on whether the *rate of increase of CO$_2$* is increasing.