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You are here: Experts > Science > Environmental Issues > Global warming/Climate Change > CO2
Expert: David B. - 10/26/2009
Question
We are teaching our primary and secondary students about Climate Change, and of course we hear a lot about tons of CO2 being released into the air.
I haven't found anyone to explain how CO2 is measured---I can't imagine that carbon and oxygen could possibly weigh so much. Is it measured based on the weight of fossil fuels being burned? Or what? Thank you very much.
-Laura
Answer
Hi Laura,
The specific techniques of measuring CO2 are not my expertise, but hopefully my limited knowledge will be of some use.
There are of course estimates out there of the amount of fossil fuels being burned, but the concentration of CO2 in the atmosphere is measured directly and continuously by hundreds of monitoring stations around the world.
The oldest and most famous of these is the "Keeling curve" from the Mauna Loa observatory in Hawaii. Basically Dr. Keeling took a sample of air then used a technique called mass spectroscopy to find the concentration. It basically involves emitting radiation through the sample and measuring how much got absorbed, then comparing this absorbance % to a control. It is a bit interesting that the very property that makes CO2 significant as a greenhouse gas is the property used to measure its concentration.
Measurements can also be taken from satellites, again using the properties of CO2's radiative absorption. The most notable of these satellites is NASA's Aqua. There is also a Japanese satellite named Ibuki; NASA had planned to launch a similar craft this February, but unfortunately the launch failed and it never reached orbit.
Good luck with your unit on climate change. I have some experience in explaining science to elementary school students, so if you have any other questions feel free to contact me again.
Regards,
David Brooks
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