[cogitator]

However I most certainly give CO2 variation its due, (i.e.direct radiative effect of 0.2oC per each doubling of atmospheric concentration) as you well know.

Based on somewhat exhaustive Web research, the accepted direct radiative forcing from doubled CO2 is ~0.9 C. (globally). You and a couple of others attempt to distinguish between surface warming and total global warming; I can't pursue that with sufficient detail to determine if that discrimination is a valid approach.

I just happen to hold that other factors such as Solar activity mentioned above in #3, #6, & #7 impact earth's climate swamping out that of any very small contribution of anthropogenic CO2 accumlations in the atmosphere over natural variations due to external factors affecting cloud cover as well as direct irradiation.

And while we disagree on the relative sizes of each forcing, we agree that cloud effects are the dominant uncertainty (as I also agree with FR "palmer"). This agreement underscores your final comments here. The problem I perceive is that cloud cover could be a significant positive feedback, a minor positive feedback, no feedback either way, a minor negative feedback, or a significant negative feedback (and it sure would be NICE if it was the last). So a range of possibilities must be evaluated and a risk-analysis based on those possibilities must be formulated. Those who are risk-averse to the possibility of irreversible major climate effects (I put myself in that category) would favor more rapid and dramatic action than those who are less risk-averse.

[ancient_geezer]

Based on somewhat exhaustive Web research, the accepted direct radiative forcing from doubled CO2 is ~0.9 C.

I rather doubt that, as that "~0.9 C." figure is a climate sensitivity factor assuming an aprior existance of empirically unconfirmed atmospheric feedback operating on direct radiative forcing, and is not the value of direct radiative forcing which is solely of function of the Stefan-Boltzman relation.

Given:

The temperature of the Earth's surface with an atmosphere is           288^oK (+15^oC).
and the blackbody temperature of the Earth without atmosphere at  254.3^oK (-18.7^oC)

One may apply the Stefan-Boltzman relation:

E=sT⁴

where:

E = total amount of radiation emitted by an object per square meter (Watts m^-2)
s is a constant called the Stefan-Boltzman constant = 5.67 x 10^-8 Watts m^-2 K^-4
T is the temperature of the object in K

to determine the total GHG direct radiative forcing necessary to maintain the atmosphere/surface greenhouse temperature at the current 288^oK surface temperature of the earth.

Under constant albedo conditions (CO₂ does not contribute to earth's albedo) The total flux at the Earth's troposphere/surface system due to greenhouse factors is:

Flux (E₂₈₈) at the Earth's surface with atmosphere               = 5.67*10^-8(288^oK)⁴ = 390.08 w/m²
Blackbody flux (E₂₅₅) without atmosphere                          = 5.67*10^-8(254.3^oK)⁴ = 237.12 w/m²
==================================================================
                                                                                                            difference = 152.96 wm²

Given the (natural + anthropogenic) CO2 contribution is 3.502% of total greenhouse warming. The total radiative flux expressed in the thermal heating capacities of CO₂ must of necessity be less than:

0.03502*152.96 w/m² = 5.357 wm²

However, CO₂ IR flux at the surface from CO2 concentrations in the atmosphere is less than half that total CO₂ contribution of 5.357wm² for the system as a whole. More than half of CO₂ radiant forcing is emitted and/or scattered by clouds & dust upward to be lost to atmospheric heating and space rather than contributing towards global warming at the surface. It must be remembered that heat flow is from hotter regions to cooler from atmosphere to to the surface. Any change at surface due to CO2 concentration must be driven by a comensurately higher temp in the atmosphere.

The amounts of direct radiative heating contributed by atmospheric CO₂ used by the IPCC are allocated as follows:

Re-cycling of Infra-Red Energy

According to Dr Hugh Ellsaesser's IPCC submission, "The direct increase in radiative heating of the lower atmosphere (tropopause level) due to doubling CO2 is 4 wm^-2. At the surface it is 0.5 - 1.5 wm^-2". Schlesinger & Mitchell (1985), estimated this surface flux at 2 wm^-2. Thus, depending on the model, or modeler, the estimates for increased surface flux following a CO2 doubling, varies between +0.5 and +2 wm^-2. An above-averaged figure of +1.5 wm^-2 will be assumed here for purposes of analysis and comparison.

At the current surface temperature (288^oK) Doubling the atmospheric CO2 concentration from 340ppmv can only add 1.5w/m² at the surface for a total surface radiative forcing of

390.08+1.5 = 391.58wm²

providing a maximum

(391.58/5.67*10^-8)^0.25-288^oK = 0.277^oK (C)increase in surface temperature for a doubling of atmospheric CO₂ concentration.

 

Q.E.D:

"the direct radiative effects of doubled CO2 can cause a maximum surface warming [at the equator] of about 0.2 K, and hence roughly 90% of the 2.0-2.5 K surface warming obtained by the GCM is caused by atmospheric feedback processes described above."
--- "Increased Atmospheric CO2: Zonal and Seasonal Estimates of the Effect on the Radiation Energy Balance and Surface Temperature" (V. Ramanathan and M. S. Lian), J. Geophys. Res., Vol. 84, p. 4949, 1979.

 

And while we disagree on the relative sizes of each forcing, we agree that cloud effects are the dominant uncertainty (as I also agree with FR "palmer").

That's good of you especially considering that the UN/IPCC modellers consider cloud cover to be unchanging and not a forcing at all.

The problem I perceive is that cloud cover could be a significant positive feedback, a minor positive feedback, no feedback either way, a minor negative feedback, or a significant negative feedback (and it sure would be NICE if it was the last).

Certainly a consideration which just underscores that the atmospheric feedbacks on which that 0.9^oC climate sensitivity factor you have quoted is rooted in is essentially a WAG with no empirical confirmation.

The "feedback" in thermal terms is not the issue in what the Svensmark research is indicating. Cloud cover variation due to modulation of cosmic ray flux is an induced external factor not a thermal feed back.

In point of fact any thermal feedback in operation would multiply the thermal effects due to cloud cover variation in just the same operating modes and to the same degree as is presumed to be acting on CO₂ induced thermal increases. Heat is heat regardless of what it is attributed to. 1watt per square meter change in CO2 forcing at the surface is just the same as 1 watt per square meter change at the surface from thermal forcing due to varitation in cloud cover.

So a range of possibilities must be evaluated and a risk-analysis based on those possibilities must be formulated. Those who are risk-averse to the possibility of irreversible major climate effects (I put myself in that category) would favor more rapid and dramatic action than those who are less risk-averse.

Tell me does that risk assessment factor and risk-aversion include the risk of no essential result in whatever costly "rapid and dramatic action" you would impress upon the rest of us? In fact does that risk assessment factor include that anything done to decrease warming operates against those natural factors in the works headed in the the opposite direction?

I for one expect that mankind has much more to worry about in adjusting to ice-ages than it does in any global warming scenario under the current geophysical factors in place limiting warming that this Earth may undergo in the geological short term.

 

 

Ice Ages & Astronomical Causes
Brief Introduction to the History of Climate
by Richard A. Muller

Origin of the 100 kyr Glacial Cycle

Figure 1-1 Global warming (NOAA land and ocean temperatures)

Figure 1-2 Climate of the last 2400 years (GISP2)

 
Figure 1-3 Climate of the last 12,000 years (GISP2)

Figure 1-4 Climate of the last 100,000 years (GISP2)

Figure 1-5 Climate for the last 420 kyr, from Vostok ice

[ancient_geezer]

Based on somewhat exhaustive Web research, the accepted direct radiative forcing from doubled CO2 is ~0.9 C.

Since the forcing from doubled CO2 is about 1.5 watts per square meter surface thermal flux at the surface according to UN/IPCC global climate modelers. That would be about 0.9C climate sensitivity per 1.5 watts per square meter change in thermal forcings.

 

Re-cycling of Infra-Red Energy

According to Dr Hugh Ellsaesser's IPCC submission, "The direct increase in radiative heating of the lower atmosphere (tropopause level) due to doubling CO2 is 4 wm^-2. At the surface it is 0.5 - 1.5 wm^-2". Schlesinger & Mitchell (1985), estimated this surface flux at 2 wm^-2. Thus, depending on the model, or modeler, the estimates for increased surface flux following a CO2 doubling, varies between +0.5 and +2 wm^-2. An above-averaged figure of +1.5 wm^-2 will be assumed here for purposes of analysis and comparison.

 

The observed variation of lower level cloud cover effects a 1.4 watt per meter change in surface thermal flux across a five year period of 2% clearly as a result of cosmic ray modulation.

 

The UN/IPCC assigns 1.5 watts to CO2 doubling rather than lower cloud cover variation which it presumes to be zero change in its models.

Hmm doesn't leave much in the Earth's radiative balance for CO2 increases, taking into account the effects of changing solar activity throughout the period since the industrial revolution does it?

Looks like the UN/IPCC modelers have a lot of reprogramming adjusting for solar activity effects on cloud cover to rebalance the thermal factors to me.