Trees, CO2 Banks
Money doesn’t grow on trees.
Trees are good banks for the CO2
our cars produce.
CO2 is an important molecule in our atmosphere. Plants need CO2
to make sugar and then the other chemicals they need. As they grow they reduce
the amount of CO2 in the atmosphere. When we drive a car it burns
gasoline. The car engine converts the gasoline into CO2 . This
activity will help us explore the impact of cars and trees on the carbon levels
in the atmosphere.
How could you determine the CO2 a car produces when it burns a
gallon of gas? You could burn a gallon of gasoline in a car and collect the
exhaust. Then you could separate the CO2 from the other products. Finally
you weigh the CO2 . Scientists have done this analysis. They have
determined that on average one gallon of gasoline burns to produce 20
pounds of CO2. Why do
we say an average gallon of gasoline produces 20 pounds of CO2? All gasoline isn’t created equally. Some states
require additives. Gasoline has different octane ratings. Gasoline is really a
family of chemicals. These related chemicals are blended to make the gasoline
you put in your car. Some cars run efficiently. They burn almost all of the
gasoline into CO2 and water. The black smoke that comes out of
other cars is only partly burned.
Finding the carbon in a tree is the same issue.
Collecting all of the gas produced when the tree burns is a huge project. Even
weighing the tree is difficult. Foresters had this problem. They needed to know
how many tons of wood there are in a forest. They needed a set of formulas that
would help them find the answer quickly. They went out into the field and cut
down trees. They carefully weighed the different parts of the tree. Next they
analyzed the data and found formulas that fit the data. You can use those same
formulas to estimate the weight of trees in your community.
The formulas aren't simple. You could do the calculations with a scientific
calculator. If you did most of your class period would be spent carefully doing arithmetic
and you wouldn't have much time to explore the relationships. Science is really
the exploration. If you can get a computer to do the arithmetic you can exercise
your brain cells by exploring new ground. This new approach of using computer
models to help explore science questions is called computational science.
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