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Elementary Science Education


Global Warming, Climate Change

There are many people who still deny climate change/global warming. Can such denial stand up to evidence and rational reasoning?

For understanding global warming a key observation, which can be easily demonstrated, is the following. Given a constant heat input, a body does not get indefinitely hotter. Its temperature rises and then levels off at point where it gives off heat at a rate equal the rate of energy input. This can be demonstrated by putting a pan of water over a candle flame and measuring the temperature of the water over time. Expand this idea to the basic concept: The temperature of any body is a balance between incoming energy and outgoing energy. “Any body,” includes the whole Earth; the average temperatures experienced on Earth, despite all the perturbations, come down to a balance between the the rate of energy input, solar energy from the sun, and the rate of energy output, heat radiation from the Earth into  outer space.

How might this balance be upset in a way to raise the temperature? Reflect again on the pan of water over the candle flame. One might increase heat input, but in terms of the Earth, the sun provides a constant energy input that can’t be adjusted. A second possibility is to put additional insulation around the pan to reduce the rate of energy output. This can be demonstrated and one will observe that temperature rises to a new level. 
Here is the crux. CO2 absorbs outgoing heat radiation from the Earth. (It does not effect incoming solar (light) energy.) The amount of CO2 in the atmosphere is effectively the amount of insulation around the Earth. Are we changing the amount of CO2 in the atmosphere? Yes, the unavoidable waste product of burning fuels is CO2, and much of this CO2 is accumulating in the atmosphere leading to a sharp increase.  (see Increasing temperatures due to this increasing insulating effect of CO2 are unavoidable. The only questions are in the timing, degree, and effects  of temperature increases. There are numerous observations that show they are already occurring (
Bernie Nebel

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