Tuesday, July 22, 2014

Basic CO2 Forcing Issue


The Basic CO2 Forcing issue

Its always healthy to take a “birds perspective” of things, just to ROUGHLY get an idea of the situation.

Normally its believed that CO2 (incl feedbacks) is responsible for around 15% of the Earths Greenhouse effect. It cannot be much more since we live on a planet with a water surface and thus plenty of water in the atmosphere. So water (incl feedbacks) is responsible for the majority of Earths greenhouse effect.

The whole idea of global warming started because the Earth appeared around 33 K warmer (278 K) than “it should have been” (255K) given the Earths albedo.
So all greenhouse gasses incl. all feedbacks combined yields roughly these 33 K.

No news so far, I agree.

This ROUGHLY leaves around 15% of 33K to the CO2 forcing incl. feedbacks. That is around 5 K. Lets say 6 K to be conservative.

So as a ROUGH starting point we have around 6 K of warming from CO2 forcing incl feedbacks from CO2 in tha atmosphere.

Still not much new in this, so lets go a step further.

If you take a climate model like MODTRAN you will see that the forcing of the entire CO2 concentration (incl feedbacks) is typically around 9 – 10 times the forcing of one CO2 doubling incl. feedbacks.

So according to typical models, ONE doubling of CO2 should yield around a tenth of the forcing seen from the entire CO2 concentration in the atmosphere incl. feedbacks.

The entire CO2 concentration should have a forcing that matches roughly 10 doublings.

So as a starting point – the rough birds perspective – a new doubling og CO2 concentration from 400 ppm to 800 ppm should yield around one tenth of the 6 K warming we have from the entire CO2 concentration.

So a doubling should yield warming around 1/10 times 6 K = 0,6 K.

Something is wrong now.

IPCC suggests 3 K for just ONE new CO2 doubling. That is, today ONE doubling should have an effect incl. feedbacks of HALF the entire CO2 concentration.

This is a violation of the principle that each doubling has a similar effect.

James Hansen goes further, he suggests 6 K of forcing from jus ONE doubling of CO2. So one doubling today for some reason should match the effect incl. feedbacks from the entire CO2 concentration.

Also, some believe that we will have a global temperature rise of 2-4 K within year 2100.
But hardly any believe that we will have more than 600 ppm in year 2100. (even 600 ppm appear not realistic)
So with just HALF a doubling, we are supposed to see a 2-4K rise in temperature. This demands arounf 4-8 K warming effect from CO2 incl. feedbacks.
Again this demands that the next CO2 doubling incl. feedbacks has an effect around 10 times the other doublings incl. feedbacks.

The point.

As long as it is NOT explained why CO2 effect incl. feedbacks added to the atmosphere now should have an effect dramatically stronger than the CO2 already in the atmosphere, then any such claim fall.

You cannot claim that one doubling of CO2 now should have an effect that roughly matches the entire CO2 concentration in the atmosphere without very carefully explaining, documenting and justifying how this should be possible.
So far this obvious problem is not even mentioned when claiming dramatic forcing from CO2 incl. feedbacks.

See illustrations and more:



I will start with your ending - referencing Anthony Watts on anything. If you do that, there is a very high probability you are wrong. See my response about your previous submission for more details about Watts.

But, let's go back to the beginning of your submission when you say that CO2 is responsible for only 15% of the greenhouse effect. This is false it two ways. First, CO2 is responsible for about 1/3rd (33%) of the warming, but it is the principle driver because the main greenhouse gas is water vapor and that vapor wouldn't be there if CO2 wasn't raising the temperature in the first place. So, CO2 is actually the principle driver of the greenhouse effect. So, using your own math, the result of doubling CO2 would be about 1.5 degrees C. But, there are many other factors involved, most noticeably the water vapor. Another very major factor is what happens to cloud formation. Clouds are a negative feedback in the daytime by reflecting incoming sunlight, but a positive feedback at nighttime by trapping IR radiation leaving the surface. And, how does the cloud formation change with temperature and water vapor? It all becomes very complicated very quickly and the question of clouds is the wild card in this whole process.

In short, you tried to use a simple calculation to make a definite calculation for a very complicated system. The fact that your number does not agree with forecasted results is not surprising or controversial.

But, the bottom line is if you are going to rely on Watts for you information, you will always have problems. Garbage in, garbage out.

You did not prove man made global warming is not real.

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