## onsdag 8 september 2010

### Climate Sensitivity 0.5 C

Frank Lanser has a guest post on WUWT arguing that climate sensitivity (global warming from doubled CO2 concentration) is at most 0.5 C. I agree and have come to the same conclusion, using similar reasoning: The simple argument goes as follows:

Out of the present total warming effect of the atmosphere of 33 C, at most 15 % may be due to CO2, say at most 5 C (probably less).  Now, the warming effect of CO2 could well be logarithmic in its dependence on concentration,  and thus the effect declines with each doubling. With 10 doublings to reach the present level, each doubling would correspond less than 0.5 C, as a first crude estimate of total climate sensitivity including feedbacks.

Another crude estimate is to say that doubled CO2 may give a "radiative forcing" of 1% of
total incoming radiation with a corresponding 1% change of a total temperature drop of 33 C, that is 0.3 C, according to Fourier's Law, including feedbacks.

Yet another crude estimate is to say that a "radiative forcing" of 2 W/m2 would correspond to a 2% increase of the 120 W/m2 delivered from the Earth surface by convection/latent heat
under a temperature drop of 30 C, with a corresponding 2% increase of the temperature drop of 0.6 C , including feedbacks.

This is to be compared with IPCC's first crude estimate = 2 - 4.5 C, a factor 5 - 10 bigger. Climate alarmism is solely based on this factor 5 - 10, which lacks scientific rationale.

#### 2 kommentarer:

1. The initial estimate also lacks scientific support. So does the frequently mentioned number 33 degrees C. On another blog I saw the following engineering joke

"A researcher with a thermometer knows what the temperature is, A researcher with two thermometers is confused"

It makes sense actually, there is no universal "speedometer", no universal "energymeter", no universal "entropymeter" and so on. And the reason why there are no such things is because entities like speed, energy and entropy are theoretical constructs that depends on how you defined the system in the first place.

2. I think his name is Frank and not Fredrik.

I don't find it right now, but there has been another interesting guest blog at Watts where the sensitivity was estimated based on the satellite temperature measurements and ocean measurements. I think the result was similar to this estimate.

Pielke Sr argued that it would make more sense to measure heat content in the ocean surface instead of air temperature. By doing this we could get much faster and more reliable feedback on what is going on. I think the current result for the approximately last 5 years is that the earth has been losing energy, quite the opposite to what we could expect from the IPCC models.