QUESTION A1

In the last part of the 20th century, scientists developed the theory that the planet was warming and that the primary cause was the increasing amounts of atmospheric carbon dioxide (CO2), which are the product of burning oil, natural gas, and coal (fossil fuels). Although many climatologists believe in the so-called greenhouse effect, many others do not subscribe to this theory. There are three critical questions that need to be answered in order to resolve the issue.

 Is Earth actually warming?

 If Earth is warming, is CO2 the cause? There are greenhouse gases in the atmosphere, without which Earth would be considerably colder. These gases include methane, water vapour, and carbon dioxide. All occur naturally in nature. Carbon dioxide is vital to our life on Earth because it is necessary for growing plants. The amount of CO2 produced by fossil fuels is a relatively small proportion of all the CO2 in the atmosphere. 

The generally accepted procedure is to record monthly temperature anomalies. To do so, we calculate the average for each month over many years. We then calculate any deviations between the latest month’s temperature reading and its average. A positive anomaly would represent a month’s temperature that is above the average. A negative anomaly indicates a month where the temperature is less than the average. GLOBAL.xlsx stores the monthly data for temperature anomalies ( 0C) and the CO2 levels (ppm) in the atmosphere from Mar 1958 to November 2009. There are two issues in this discussion. First, is there global warming; second, if so, is carbon dioxide the cause?

 Is Earth actually warming? 

(a) Considering the temperature anomalies data over the data period 1958-2009, use a graphical technique to show whether there is global warming.

(b) Considering the average of the temperature anomalies, test to show that, on average, at the 5 percent level of significance, there is global warming. That is the mean temperature anomalies is positive (u > 0)?

 If Earth is warming, is CO2 the cause?

(c) Use a graphical technique to determine whether there is a relationship between temperature anomalies and CO2 levels. Interpret the results.

(d) Find the correlation between temperature anomalies and CO2 levels. Interpret the results.

(e) Calculate the least squares line between temperature anomalies and CO2 levels. Interpret the findings.

GLOBAL