Is Human-Generated Carbon Dioxide Escalating the Greenhouse Effect?

Overview

Objectives/Goals Although it is known that CO2 absorption of infrared radiation emitted from the Earthâ##s surface traps heat inside the atmosphere, and that this greenhouse effect has been keeping the Earth at a livable temperature for millions of years, the great debate about human generated C02 goes on. Has the tremendous increase in CO2 caused by humans escalated the greenhouse effect? Is CO2 the most significant greenhouse gas that humans are creating? My experiment attempts to determine if increased CO2 increases infrared absorption, and therefore increases global temperatures. Methods/Materials I sealed the ends of a PVC pipe with plexiglass windows, and drilled holes near the ends of the pipe in order to attach two hoses. One of the hoses delivered CO2 from a C02 canister with a pressure release valve, and the other connected to a pressure gauge. I sealed all joints with epoxy glue or hose clamps. I pointed a heat lamp, which has a variable transformer to regulate intensity, through one end of the pipe, and a wide-range infrared detector with amplified signal, through the other end. First, I measured the voltage output when the heat lamp and detector were turned on, to determine the steady baseline voltage. Then, I opened the valve on the C02 canister, noted the increased pressure in the pipe, and then noted the change in the baseline voltage. Results For an increased pressure of about 15 pounds, I detected an average drop in the voltmeter reading of about 0.1 milivolts. The effect of adding CO2 was greatest when I ran the experiment for the first time after airing out the pipe. Then, as I added more C02, there continued to be decreased voltage, but the drops were not as significant. I repeated the airing out and repressrising sequence several times and noted the same results. Conclusions/Discussion My calculations determined the percent extra absorption to be approximately 0.12%, per pound, per square inch increase in the amount of CO2. Since this figure is based on a 0.1 milivolt change, I think it would be beneficial to improve the signal-to-noise ratio of my experimental apparatus. This will be the focus of continued research on this topic.

Competition history

• CSEF 2007 Physics & Astronomy · Entry J1606

Resources

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