This is the second of three activities designed to investigate: Is Global Warming just natural variation? This activity provides an example of an "unnatural" variation by examining the extremely quick rise of CO2 levels in the atmosphere. It also introduces students to one of the processes that is central to the global warming controversy.
The alarm that signaled the beginning of the global warming and greenhouse effect controversy came from data that showed a dramatic increase over the past 35 years in the amount of CO2 in the atmosphere. These data provide the primary piece of evidence in the global warming controversy by showing that CO2 levels have risen by almost fifteen percent during this time. The cause of this increase is almost universally attributed to industrial pollution, especially the burning of fossil fuels to produce energy for first world countries. Because this increase is caused by the actions of people it is considered an unnatural variation. The data that is examined here comes from Mauna Loa, Hawaii, and is the longest continuous record of atmospheric CO2 levels. Inspection of this data shows it cycling up and down in tune with the seasons. This provides an example of natural variation within the overall pattern of increase.
This activity investigates the rising levels of CO2 as an example of "unnatural" variation. Students are asked to graph the data and then make some inferences through inspecting the graph.
A common confusion arises is between CO (carbon monoxide) and CO2 (carbon dioxide). An important difference is that carbon-monoxide is poisonous to humans while carbon-dioxide is not at all dangerous and is a common atmospheric gas. Confusing these two is particularly common when dealing with greenhouse effect because the increased levels of CO2 are associated with the burning of fossil fuels and the burning of fossil fuels are associated with pollution including CO. The important point is that CO2 is not pollution as the term is commonly used.
Another difficulty that arises is in understanding the units of parts per million that is used for atmospheric chemicals like CO2. One way to help with this is to provide examples. Here are several examples:
One part per million (ppm) is the same ratio as:
One part per billion (ppm) is the same ratio as
This data comes from: C. D. Keeling Scripps Institution of Oceanography University of California La Jolla, CA 92093
Examining the Mauna Loa CO2 recordMauna Loa is a mountain on the island of Hawaii. The data collected at Mauna Loa has shocked and amazed the world. It demonstrated conclusively that the amount of carbon-dioxide (CO2) in the atmosphere is rising, and rising quickly. Carbon dioxide is an invisible gas that is harmless to humans. It is different from carbon monoxide (CO), which can be harmful to humans and animals . In fact, we breathe out carbon dioxide every time we breath. Both carbon dioxide and carbon monoxide are produced by burning fossil fuels (gas, coal, and oil).
The Mauna Loa data set is the largest continuous record in existence of atmospheric carbon-dioxide. It covers 35 years. Unfortunately, this is still a very short time on the scale that climate is often studied, which can span thousands of years. One of the most arresting facts about the data is how fast the levels of CO2 is climbing. The speed of change is widely believed to unparalleled in the history of the earth and to be primarily caused by humans use of fossil fuels to generate electricity and power plans, trains, and automobiles.
The Mauna Loa data set is provided as an "unnatural" variation or a variation caused by human actions. In particular, the burning of enormous amounts of fossil fuels to provide energy for the Industrial and Modern ages is credited with producing these increases.
Here's what to do:
The data is provided in two forms:
- Thirty-five rows containing one year each of monthly CO2 measurements
- One long column containing all the monthly CO2 measurements.
The first form is better for graphing yearly averages and finding patterns in individual months. The second form is better for graphing the whole data set.
- Using the annual averages (first table of data), create a bar graph.
- Estimate how much the CO2 is rising each year.
- Based on the growth rate you found, how many years will it take before the amount of CO2 in the atmosphere has doubled?
- Using the long column of all the data (second form), create a line graph. This graph shows that the data isn't just uniformly rising.
- Describe the cycle or pattern that the data shows?
- How many months does it take for the pattern to go through one cycle?
- What is the cause of these cycles?
- (optional) Find out if the amount of change in the pattern is increasing over time.
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