In the last part of the 20th century, scientists developed the theory that the planet was warming and the primary cause was the increasing amounts of carbon dioxide (Co2), which is the product of burning oil, natural gas, and coal (fossil fuels). Although many climatologists believe in the so-called greenhouse effect, there are many others who do not subscribe to this theory. There are three critical questions that need to be answered in order to resolve the issue.

a. Use whichever techniques you wish to determine whether there is global warming.

b. Use a graphical technique to determine whether there is a relationship between temperature anomalies and Co2 levels.