I’ve seen this content before, on the website of Nir J. Shaviv, but this is the actual paper and it is more ‘formal’, both in content and in tone.
It has a lot of nice graphs and charts in it, but being a PDF it is harder to ‘lift one’ to put here as a teaser ;-) so you get to ‘hit the link’ to see them…
I particularly liked this bit from near the end, in the wrap up:
Our approach, based on entirely independent studies from astrophysics and geosciences, yields a surprisingly consistent picture of climate evolution on geological time scales. At a minimum, the results demonstrate that the approach is potentially viable, as is the proposition that celestial phenomena may be important for understanding the vagaries of the planetary climate. Pending further confirmation, one interpretation of the above result could be that the global climate possesses a stabilizing negative feedback. A likely candidate for such a feedback is cloud cover (Lindzen, 1997; Ou, 2001). If so, it would imply that the water cycle is the thermostat of climate dynamics, acting both as a positive (water vapor) and negative (clouds) feedback, with the carbon cycle “piggybacking” on, and being modified by, the water cycle (Nemani et al., 2002; Lovett, 2002; Lee and Veizer, 2003).
Recently, it was also shown by Ilya Usoskin of the University of Oulu, Nigel Marsh of the Danish Space Research Center and their colleagues, that the variations in the amount of low altitude cloud cover follow the expectations from a cosmic-ray/cloud cover link (Usoskin et al., 2004). Specifically, it was found that the relative change in the low altitude cloud cover is proportional to the relative change in the solar-cycle induced atmospheric ionization at the given geomagnetic latitudes and at the altitude of low clouds (up to about 3 kms). Namely, at higher latitudes were the the ionization variations are about twice as large as those of low latitudes, the low altitude cloud variations are roughly twice as large as well.
Thus, it now appears that empirical evidence for a cosmic-ray/cloud-cover link is abundant. However, is there a physical mechanism to explain it? The answer is that although there are indications for how the link may arise, no firm scenario, at least one which is based on solid experimental results, is yet present.
Although above 100% saturation, the preferred phase of water is liquid, it will not be able to condense unless it has a surface to do so on. Thus, to form cloud droplets the air must have cloud condensation nuclei—small dust particles or aerosols upon which the water can condense. By changing the number density of these particles, the properties of the clouds can be varied, with more cloud condensation nuclei, the cloud droplets are more numerous but smaller, this tends to make whiter and longer living clouds. This effect was seen down stream of smoke stacks, down stream of cities, and in the oceans in the form of ship tracks in the marine cloud layer.
The suggested hypothesis, is that in regions devoid of dust (e.g., over the large ocean basins), the formation of cloud condensation nuclei takes place from the growth of small aerosol clusters, and that the formation of the latter is governed by the availability of charge, such that charged aerosol clusters are more stable and can grow while neutral clusters can more easily break apart. Several experimental results tend to support this hypothesis, but not yet prove it. For example, the group of Frank Arnold at the university of Heidelberg collected air in airborne missions and found that, as expected, charge clusters play an important role in the formation of small condensation nuclei. It is yet to be seen that the small condensation nuclei grow through accretion and not through scavenging by larger objects. If the former process is dominant, charge and therefore cosmic ray ionization would play an important role in the formation of cloud condensation nuclei.
Further down the conclusion is also more strongly stated:
The implications of this link are far reaching. Not only does it imply that on various time scales were solar activity variations or changes in the galactic environment prominent, if not the dominant climate drivers, it offers an explanation to at least some of the climate variability witnessed over the past century and millennium. In particular, not all of the 20th century global warming should be attributed to anthropogenic sources, since increased solar activity explains through this link more than half of the warming.
Once again we have folks coming to the same conclusion, that this is a Water World, and global climate is driven by our place in the solar system and the galaxy, with natural modifications of the water cycle. Different approaches, from different scales and with different data, all showing the same thing.
Here Nir Shaviv looks at things from a galactic point of view and on a global scale with a hundreds of million years time scale. On the micro end, tropical thunderstorms are shown to be activated by daily heating, and quiet as the sun sets, their daily and very local cooling job done for the day. In between we saw that variations in lunar tidal effects on the oceans match a medium time scale of oscillations and that changes in ocean currents can explain the hysteresis seen during D.O. Events and Heinrich Events. At every scale we come to the same conclusion. It’s the water, Jim…
(For those not saturated with 1980s American cultural influence, the last line is a tortured play on the stock line from Star Trek where “Bones” would turn to Capt. Jim Kirk and say “He’s dead, Jim.” Done so often it became a cliché. So in this case it implies looking at the CO2 thesis and saying “He’s dead, Jim. (It’s the water)…” as often just after pronouncing ‘dead Jim’ we’d have an explanation of what / why…)