Expert: Philip Stahl - 4/7/2009

Question
Where do the green house trap its energy?

Answer
Hello,

Your question is somewhat unclear, so if my answer is not what you expected, you may have to revise the wording of your question.

I am going to assume you mean the Earth acting as a "greenhouse" in terms of the greenhouse effect. In this case, the energy (mainly solar, via infrared electro-magnietic waves or heat) is trapped in the Earth's atmosphere.

The energy components of assorted greenhouse gases are typically given in terms of two data markers: the duration (t) of the gas in the Earth's atmosphere, and the forcing value (F), a measure of the power delivered in watts per square meter.

The following values are for the current greenhouse gases found in our atmosphere:

Carbon Dioxide: t >100 years,  F ~ 1.3 to 1.5 W/m^2

Methane: t ~ 10 years, F ~ 0.5 to 0.7 W/m^2

Tropospheric Ozone: t ~ 10-100 days,  F ~ 0.25 to 0.75 W/m^2

Nitrous Oxide: t ~ 100 years, F ~ 0.1 to 0.2 W/m^2

Perfluorocarbon Compounds: t  >1000 years, F ~  0.01 W/m^2 (Including SF6)


In terms of both criteria, you can see that carbon dioxed (CO2) delivers most of the forcing component and for the longest time, with methane a close second. (The data are from the National Research Council Data Report from 2000)

Using these inputs, the IPCC's GCM  (General Climate model) has arrived at its prediction of an Arctic air temp. increase of +5 C by 2100.

It should also be added here, that as the polar caps melt, much more energy will be input to the oceans raising their temperatures - since the ice caps will no longer be effectively able to reflect most solar radiation back into space.  Thus, oceans will also absorb more as the atmosphere does as well. In terms of conditions on the Earth, it will somewhat resemble living in an apartment with a fiercely hot (T ~ 40 C) environment outside, and your thermostat suddenly breaks. The temperature inside the apt. will quickly rival what's outside.

Hope this helps!