‘Cosmoclimatology’ – tired old arguments in new clothes

The chief objection to the idea that cosmic rays influence cloudiness came from meteorologists who insisted that there was no mechanism by which they could do so. On the other hand, some atmospheric physicists concluded that observation and theory had failed to account satisfactorily for the origin of aerosol particles without which water is unable is unable to condense to make clouds.

I don’t think this is meant as a joke, and I don’t know if the article tries to make a point about classifying critics and supporters of his ideas as ‘meteorologists’ and ‘physicists’ (I’m a physicist). But that’s a tiny detail compared to the more substantial misconceptions embedded in this passage. There are plenty of ‘seeds’ in the air on which water can form, also known as cloud condensation nuclei (CCN). According to my old text book ‘A Short Course in Cloud Physics’ by Rogers and Yau (1989, p. 95 in Third edition): “Condensation nuclei of some sort are always present in the atmosphere in ample numbers: clouds form whenever there are vertical air motions and sufficient moisture”. The CCN tend to consist of mineral dust, sea salt, or sulphur-based matter.

I have serious misgivings concerning the following – vague yet false – statement put forward in the A&G article :

Attempts to show that certain details in the climatic record confirm the greenhouse forcing (e.g. Mitchell et al., 2001) have been less conclusive. By contrast, the hypothesis that changes in cloudiness obedient to cosmic rays help to force climate change predicts a distinctive signal that is in fact very easily observed, as an exception that proves the rule.

Again, no further qualifications or references. The irony is that Svensmark ignores (in addition to the lack of trend in GCR) the fact that the night-time temperature has risen faster than the day-time temperature, which I did pester him about on a Nordic Meteorology Meeting in Copenhagen in 2002. A journalist from Jyllands Posten present at the conference got the message, as my criticism was echoed in a news report the following day (“Klimaforskere i åben krig” [translation ‘Climate researchers in open war’], May 28, 2002): It’s tricky to explain how a warming caused by decreasing albedo would be stronger at the night-side (dark) of the planet.

Another newer puzzle is the surprisingly good correlation between low clouds and GCR (se figure below), since higher clouds (global mean cover ~13%) or middle clouds (~20%) which are not influenced by GCR, mask the lower ones (which represents between 28% and 30% of the globe). It’s indeed a surprisingly good fit between the two curves in the A&G article (reproduced below), considering the time structure of both the high-cloud, middle-cloud, and low-cloud curves, and the satellites cannot see the low-level clouds where there are higher clouds above blocking the view. The fact that the variations are small (~1% amplitude!) compared to the total area, suggest that the overlap/masking effect by the higher cloud must be very small for a high correlation to shine through the upper clouds. Even if the clouds hypothetically were completely determined by GCR, one would expect to see deterioration of the correlation if viewed from above due to the presence of higher clouds not influenced by GCR. Another issue is that the cloud data used in this analysis was only based on the infra-red (IR) channel, and a better analysis would include the visible observations too, but if the visible data are included, then the correlation is lower (private communications, Jørn Kristjansen).

Extracts of Figures 2 & 3 in Svensmark 2007

Page 2 of 5 | Previous page | Next page