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Greenhouse effect, CO2 heat in Watt/m2

Posted by Administrator (admin) on 8th February, 2010
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Modtran.  

On the illustration: 0 ppm CO2 corresponds to 230 W/m2. (One degree Celsius corresponds toapproximately 4-5 W/m2).

Almost half the CO2 heat effect at 320 ppm is achieved already at approximately 20 ppm CO2 concentration. Changes in CO2 concentration at higher concentration has only a modest effect. This is due to the fact, that the radiation frequencies CO2 is capable to absorb is almost fully absorbed already at small CO2 concentrations. Thus, the CO2´s heat effect is logarithmic declianing for an increasing CO2 concentration.

The first 20 ppm represent around 50% of the CO2 effect, and thereafter each doubling of CO2 concentration has equal effect. This effect of one doubling of CO2 effect is called “CO2-sensitivity”.

So IF all the atmospheres insulating effect id due to greenhouse gasses only, then we have a total greenhouse effect of CO2 equals 6 degrees Celcius . Then we can calculate roughly:

 

 

- because 3 + 4 x 0,75 = 6 degrees Celsius.

So a doubling of CO2 might result in around 0,75 degrees Celsius = the ”CO2-sensitivity”.

This is the basic principle, however quite different opinions on the CO2-sensitivity extists, mostly because some believes that just a little heat from CO2 (or any other heat source) could result in a far bigger heat deveoplment due to “positive feedback”, see: ’Positive feedbacks – the dangerous aspect of CO2 heat’.

 

IPCC suggests CO2-sensitivity (heat effect pr doubling of CO2 concentration) on 3 degrees Celsius. Lets try to apply this in the rough calculation:

 

 

12 + 4 x 3 = 24 degrees Celsius for the total CO2 effect inclusive positive feedbacks.

So at first glance, approximately no less than 24 degrees Celsius of insulating effect of the Earths atmosphere originates from the CO2 molecule incl. positive feedbacks – IF the IPCC CO2 sensitivity of 3 degrees Celsius is correct.

This actually has the consequence, that no less than 70% of the Earths insulating effect (33 degrees Celsius) should be result of CO2 incl. positive feedbacks from CO2.

So.. Without CO2 in the Earth atmosphere, there should be hardly water in the atmosphere even though the Earths surface is 70% water..)

 

James Hansen, leader at NASA/GISS speaks of CO2-sensittivity = 6 degrees Celsius

That is, one CO2 doubling = 6 degrees Celsius.

without any calculations, it sounds strange that on doubling of CO2 should equal the total CO2 greenhouse effect. A Very courageous theory indeed?

But lets calculate anyway: On doubling of CO2 = 6 degrees Celsius incl positive feedbacks. Using same calculations as above, the total CO2 incl positive feedback should give the Earths atmosphere a 48 degrees Celsius insulating effect which is more than the Entire Earth atmospheres insulating effect, 33 degrees Celsius. These numbers are obviously subject to intense debate and there are more aspects than mentioned here – but still, I have seen no satisfactory explanation yet.

Also see: ”Hotspot – The ’CO2-signature”, the central CO2-theory:

 

Last changed: 8th February, 2010 at 17:27:19

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