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Creating an
Earth System II

Creating an Earth System II:

The Greenhouse Effect

1. Greenhouse is Good

In the absence of an atmosphere, Earth’s surface temperature would be about –18°C, or 0°F, which is way too cold for life. Earth is habitable because of the ‘greenhouse effect’ -a slightly inaccurate term for the heating of Earth’s atmosphere due to the presence of greenhouse gases such as water vapor, carbon dioxide (CO2), methanes (CH4) and nitrous oxide (N2)). Greenhouse gases have just the right molecular structure to absorb infrared radiation that the Earth emits. It re-emits most of that infrared energy in all directions, warming the atmosphere to its comfortable average temperature of 15°C (60°F). So the greenhouse effect is a good thing.

(In a real greenhouse, it’s warmer inside because the structure prevents cooler outside air from mixing with the warmer air inside the greenhouse.) But an enhanced greenhouse effect can lead to global warming.   image courtesy EPA

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