Thanks for the response Eclipse,

Having read the articles/ and a fair sample of the threads that follow them, whilst these broadly support a positive feedback effect of low clouds (My reading indicates it has long been theorised, if not quantitatevly understood that low lying clouds have a warming effect, and high clouds have a cooling effect), they certainly also concede the complexity of the issue and that considerably more work needs to be done. I cannot see how anyone could read these articles and conclude that the role of clouds is well understood - see below quotations from each study:

http://pubs.giss.nasa.gov/docs/2000/2000_DelGenio_Wolf.pdf

"We not that our conclusions apply only to the role of low clouds in climate change. Middle and high clouds, which are not directly coupled to the surface, may be governed by different physics, and there is as yet no observational or theoretical basis for predicting the sign of their contributions to cloud optics feedback."

http://pubs.giss.nasa.gov/docs/1999/1999_Yao_DelGenio.pdf

"Increased ocean evaporation will cause cloud cover to increase in a warming climate. Many articles about greenhouse warming in the popular press (cf. Stevens 1997) make this assertion. Yet climate GCMs, right or wrong, almost unanimously predict that cloud cover will decrease with warming..."

"A physical basis for parameterizing cloud cover does not yet exist, so all such predictions should be viewed with caustion..."

"... observations of upward trends in cloudiness over the twentieth century which are restricted to a few midlatitude continental locations, should not necessarily be interpreted as evidence of a global negative cloud feedback..."

{Comment: from this article it seems models almost universally predict that cloud cover will reduce with rising temps, but the available observations (albiet very limited, indicate increased clouds over the warming period of the 20th century. Whilst we might have cause to doubt the observations, surely this equally gives us cause to doubt the models?}

http://pubs.giss.nasa.gov/docs/1998/1998_Tselioudis_etal.pdf

"we have explored only one part of the cloud optical thickness feedback issue. Midlevel and high clouds are subject to different dynamic and thermodynamic influences and have different radiation forcing, primarily in the longwave."

(continued)

"The study also illustrates that potential cloud feedbacks on climate are far more complicated than those predicted by simple adiabatic calculations, or by climate models using cloud schemes that rely on those calculations. The optical properties of the clouds are determined by a balance of water-forming and water depleting processes that depend on dynamical, thermodynamical, and microphysical conditions. The inclusion of interactive optical properties in GCM cloud scemes constitutes a large step ahead in the effort to understand and reslove this balance: the older versions of the GISS GCM cloud scheme produced changes of low cloud optical thickness with temperature that bear little resemblance to the observations."

If the links you provided reflect the current state of the science, then plainly the role of clouds is not well understood, contrary to what some have previously said/implied on this thread. Surely you concede, given the significant role that clouds have on the greenhouse effect, that this is a massive unknown variable in trying to predict future climate?

Nevertheless, I am keen to read more if you have any further links, particularly about the mid level and higher cloud effects.

Also, I am wondering why you described the assertion that cloud formation was dominated by cosmic rays, as silly. My reading indicates that there is considerable correlation between cosmic rays and cloud formation. I don't understand the mechanism, or the strength of the relationship, but my reading of the threads in your link didn't give me the impression that the idea was so easily disproved as to make the idea 'silly.' Such strong language about contrary theories, is rarely justified, so I'm wondering you feel so strongly. As that dullard, Pauline Hanson would have said: "please explain?"

Thanks again for the posts. I do appreciate your helpfulness.

It's silly because it was used by Martin Durkin's mockumentary to "disprove" global warming.

http://en.wikipedia.org/wiki/The_Great_Global_Warming_Swindle

It's silly because the theory relies on old solar data that was rather crude, and has since been refined.

As a former head of the IPCC writes (of the "Swindle")...

"6. Changes in the sun influence climate – TRUE. They cited the Maunder Minimum in the 17th century when no sunspots were observed, as a probable example. Solar influences are the main driver of global average temperature in the 20th century – NOT TRUE.

Changes in solar output together with the absence of large volcanoes (that tend to cool the climate) are likely to have been causes for the rise in temperature between 1900 and 1940. However, the much more complete observations of the sun from space instruments over the past 40 years demonstrate that such influences cannot have contributed significantly to the temperature increase over this period. Other possibilities such as cosmic rays affecting cloud formation have been very carefully considered by the IPCC (see the 3rd Assessment Report on www.ipcc.ch) and there is no evidence that they are significant compared with the much larger and well understood effects of increased greenhouse gases such as carbon dioxide."
http://www.jri.org.uk/index.php?option=com_content&task=view&id=137&Itemid=83

Kalin

This may help:

http://www.sciencemag.org/cgi/content/full/325/5939/460

Or, you could try this (explanation in layman's terms):

http://www.sciencemag.org/cgi/content/full/325/5939/376

If you can't get past the 'pay-wall', try this:

http://www.sciencedaily.com/releases/2009/07/090723141812.htm

I appreciate your earlier comments, but at the end of the day, OLO is just an "opinion" site where a lot of white noise is generated, from all quarters.

You should browse the topics/questions you're interested in at sites like RealClimate. You can even partake without word/post limits.

You can't 'judge' the science as in a court of law. It is not about guilty/not guilty, right/wrong, black/white - it is about weight of evidence (this is not to say 'consensus' can't be overturned by just one robust 'counter-argument' - it can, it just hasn't been provided).

We the concerned and responsible humans and environmentalists of the planet demand the United Nations immediately file charges of treason against the directors of the IPCC, NASA, NOAA the UK’s MET Office and Canada’s Dr. David Suzuki and MP Elizabeth May, for needlessly calling the world to war against a non-existent enemy, the “catastrophic” CO2 based Climate Change Theory, a.k.a. the Global Warming Theory now 23 years old.
We further command a special charge of treachery and betrayal be imposed upon the United State’s Al Gore for recklessly setting back humanity’s struggle to evolve as a more advanced and civilized species of Human Beings.
We have retreated thousands of years back to when it was thought human kind was the centre core of nature and was, as now, motivated only by fear and ignorance and superstition.
Together the people of the world can unite to see the transparency of the hysterical and fear based mentality of our society, to instead preserve this planet, not save and rescue it from a massive cultural error that has convinced our children that they will be suffering an imaginable death ( “life as we know it”-IPCC ) on a sick planet.
We further humbly surrender ourselves to the reality that Nature is in charge, not us and as a progressive society we will preserve, protect and respect this 4.5 billion year old planet at a point in history where we are enjoying our highest longevity rates and strive to cherish instead of fear the future of progress.

Ummm, what?

Nothing to see here anyone, move along, move along.