# People Changing the Atmosphere

Discussion:

Although students may understand the cause and effects of global warming due to the greenhouse effect, many may not establish the connection between their own behavior and its impact. By keeping a "CO2 Journal," each student establishes this connection, while simultaneously discovering what he or she can do to reduce global warming.

Objectives:

- illustrate an application of basic mathematics.
- connect individual behavior to a global issue.
- increase understanding of ways to reduce the greenhouse effect.

Materials:

- copies of worksheet (one per student).
- Determine a period of time (about one week) over which the students will measure their CO2 production.
- During the sample time, students should record their daily transportation, home energy, and waste behaviors. Totals for the week are entered on the worksheet. Some of this information can be obtained from home utility bills, car and school bus odometers, and maps.
- Students should calculate an estimate of their direct carbon dioxide emissions. It is important to recognize this as only an estimate. The arithmetic assumes many things: that all members of the household are using energy equally, that production of the electricity uses an average ratio of fossil fuels to nuclear and renewable sources, etc. How can we get more accurate numbers?
- Total the emissions from different sources to get a weekly estimate.
- Multiply the weekly estimate by 52 to find the amount of CO2 produced in a year.
- Multiply the annual total by two to reflect indirect production of carbon dioxide. These indirect emissions include everything from the energy needed to make their pencils to the fuel used to bring groceries to the supermarket. Typically, ones indirect production of CO2 is roughly equal to ones direct production.
- Student totals will be above the global average of 9000lbs of CO2 per person per year. But even if they are less than average, this might not be good enough to stop global warming. Many experts think that stabilizing the climate may require a 50% reduction in global emissions of CO2. By examining the worksheet, students should be able to find ways to cut down: finding more efficient ways to get around; using less electricity, gas, and oil; and recycling more.
- Ask the students to aim for a 20% reduction in their emissions, and have them figure out what steps they could take to meet that goal.

Method:

Going Further:

- Students may graph their CO2 production by source.
- Determine what effects renewable energy sources such as solar and hydroelectric power would have on CO2 production.

```                               Carbon Dioxide Journal

Transportation
By Car:
a) Miles travelled during the week:     ________
b) Miles per gallon of that car:        ________
c) Gallons of gasoline used (a/b):      ________x 22
lbs/gal = ______ lbs CO2

By Bus:
a) Miles travelled during the week:     ________x 0.7
lbs/mile= ______ lbs CO2

Train or Subway:
a) Miles travelled during the week:     ________x 0.6
lbs/mile  = ______ lbs CO2

Home Energy-check your family's utility bills

Electricity:
a) Kilowatt-hours of electricity
used in a month:         ________
b) kWh used in a week (a/4):      ________
c) kWh used per person
(b/# of people in household): ________x 1.5 lbs/kWh
= ______ lbs CO2

Natural Gas
a) Hundreds of cubic feet of gas (ccf or therms)
used in a month:         ________
b) Therms used in a week (a/4):   ________
c) Therms used per person
(b/# of people in household): ________x 11 lbs/therm
= ______ lbs CO2

Heating Oil
a) Gallons of heating oil
used in a month:         ________
b) Gallons used in a week (a/4):  ________
c) Gallons used per person
(b/# of people in household): ________x 22 lbs/gal
= ______ lbs CO2

Waste
a) Pounds of trash thrown away:   ________x  3 lbs/lb =
______ lbs CO2
b) Pounds of trash recycled:      ________x  2 lbs/lb =
______ lbs CO2

TOTAL============

a)           Total of daily direct CO2 emissions:
__________ lbs

b)   a x 365 =    Total annual direct CO2 emissions:
___________lbs

c)    b x 2  =    Total annual CO2 emissions:
___________lbs

Global average: 9,000
lbs
```