Greenhouse gases are “real” the only issue is what the real sensitivity value is? Hansen and the IPCC think it is 3.0 degrees C per doubling and more current work supports that it is less that half that value (I agree with the half crowd). If the half group is right than the entire concept goes away!
The principle is :
Heat can only flow from a warmer place to a cooler place
The heat source is the sun. The sun irradiates the the Earth’s surface. As a first order principle, all of this heat has to return to space.
One of the things controlling the temperature is the efficiency of the atmosphere at returning the heat to space. If the atmosphere completely blocked the passage of heat, the earth’s surface would keep heating from solar radiation and get extremely hot. If the atmosphere provided no resistance to the passage of heat, the temperature would be cold.
Greenhouse gases are one of the factors which influence the atmosphere’s efficiency at returning the sun’s heat to the upper atmosphere, and thus help regulate the temperature of the atmosphere.
The heat source is the sun. Greenhouse gases are part of the thermostat. An increase in greenhouse gases will tend to raise…
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