This previous paper by Gerald Marsh shows quite clearly that over the period 1984 - 1994 the anomaly in low cloud fraction tracked the anomaly in total solar irradiance much more tightly that the anomaly in >13GeV cosmic ray flux (Figure 7).

http://arxiv.org/ftp/arxiv/papers/0905/0905.469...

Ouch!! Figure 1 is from Briffa et al.

I find it very hard to accept the argument that variations in cosmic ray flux are sufficiently strong to cause such major changes in albedo.

What we really do know about the gross relationship between Bond albedo, the solar constant and the greenhouse effect is well known and is as follows:

The net power deposited in the terrestrial atmosphere and surface depends on the solar irradiance and the Earth's short-wavelength (0.15–4.9 microns) albedo

Pin=CRe^2(1-A)

where C is the solar constant (adjusted for the Sun-Earth distance, i.e. TSI), Re is the Earth’s radius, and A is the short-wavelength Bond albedo (the amount of sunlight reflected back to space by the atmosphere and surface of the Earth). Subsequently, the short-wavelength, incoming power is re-radiated back into space at thermal or long-wavelengths (peaks near ~10–15 microns), where

Pout=4Re^2σTtoa^4

where σ is the Stefan-Boltzmann constant and Ttoa (~255 K) is the effective temperature of the Earth (defined with unit emissivity). Ttoa is a physically averaged long-wave emission temperature at about 5.5 km height in the atmosphere (this “top of the atmosphere’’ or “toa’’ temperature depends on wavelength and cloud cover; altitudes from 0 to 30 km contribute to this emission). One can relate that temperature to a more relevant global climate parameter like the globally averaged surface temperature Tsurf by introducing a greenhouse forcing parameter G [W/m2], which is defined as the difference between the emission at the surface and the top of the atmosphere (OLR). The forcing G increases with an increasing concentration of greenhouse gasses. After Raval and Ramanathan (1989), one can define the normalized greenhouse effect g as g=G/σTsurf^4. Then the outgoing power can be written as

Pout=4Re^2σ(1-g)Tsurf^4

If the planet is in radiative equilibrium, Pin=Pout, then we have

Tsurf^4=C(1-A)/4σ(1-g)

This means that the Bond albedo, together with solar irradiance and the greenhouse effect, directly controls the Earth’s temperature. Global warming would result if either A decreased or g or C increased.

How are changes in cosmic ray flux which may or may not have a big effect on nucleation of low cloud going to overcome the enormous power of the total solar irradiance (C) (or TSI) to vary albedo - which is controlled simply via OLR = C(1-A)/4.

This is especially puzzling in a warm state interglacial world where there is a lot of photautotrophic biological activity going on, busily pumping oodles of Cloud Condensation Nuclei (CCN) into the lower troposphere?

In my view, for any fixed value of C (TSI), the relationship between Bond Albedo and surface temperature is a big lazy S type curve with only a relatively small zone of (linear) inflection at any metastable state where the albedo may be stabilized by the supply of CCN (presently biogenic and anthropogenic in my view).

For those familiar with a sort of extended Miskolczian nomenclature it looks something rather like this:

http://jump.fm/IOWFF

I think we have to be very, very careful with the use or misuse of ice core 10Be data as a supposed proxy for cosmic ray flux because it has been shown that it is very much a function of the overall dust content of the ice and should probably be normalized against sulfate content at the very least due to volcanic dust flux.

Simple variation in TSI is the most likely cause of glacial Terminations.

I too suspect that CRF effect will not be adequate despite the correlations (and the correlations below are similar enough). Am currently writing up an analysis whereby response to periodic fluctuating forcing is amplified, and this could be due achieved by biotic factors too. I need to get it finished first.

David,

Their view that "the sensitivity of the climate to CO2 cannot be as low as suggested by these results because low sensitivity cannot explain the large glacial-interglacial transitions” is founded on the logical fallacy of arguing the consequent; and isn't scientific as well.

The scientific approach would be to note their observations, conclude the theory is wrong, and go back to the drawing board.

I could offer alternative explanations but prefer not to, at this point in time, because it's too early to introduce facts that will cause a fundamental shift in the scientific paradigm, that established by Charles Lyell two centuries ago.

Other factors can account for GIGs.