It is refreshing to finally see a thread on the topic of H2O even though it is introduced through the back-door (in the form of cloudiness).

But cloudiness is the high road to understanding: the albedo of the open ocean is essentially zero. The albedo of a low level stratocumulus blanket is up to 60. Plug those figures into the incoming radiation and see how the putative CO2 effects are dwarfed.

M’s original post, even includes references to phase changes of H20. How refreshing!.

remember that a cloud isn’t just a cloud: even the size of the droplets can significantly effect the albedo. No wonder climate modellers shy away from cloud physics when, for example, the collision of two drops is governed by the size of the impactees and can result in rain, lower albedo, or more smaller droplets which give higher albedo.

Although air is considered “saturated” when RHs reach or exceed 90%, clouds can still form at much lower RH’s as low as or even lower than 70% here. It depends on the amount and character of condensation nuclei present. The ECMWF model parameterization considers 50% RH as the level at which no clouds will be present .

But, of course, it’s even more complicated than that. The number of CCNs depends on all manner of things: industrialisation, wind strength, wave breaking, desperate inhabitants on the underside of melting icebergs pumping out DMS to save their little home. Even the presence of organics on the ocean surface can alter the number of CCNs by a factor of 1.5 (Tyree, Corey A.; Hellion, Virginie M.; Alexandrova, Olga A.; Allen, Jonathan O. Foam droplets generated from natural and artificial seawaters ), and that is a minor uncertainty. And, of course, lack of nuclei can mean no clouds form at all, with the expected albedo dropping from 60 to zero, remember (http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=11271). So a piece of ocean that should be reflecting 60% of the incoming radiation is reflecting none. How many watts/metre^2 is that? Over what area?

I can understand why clouds are parametised, understand but not approve.

JF

http://www.boston.com/bostonglobe/editorial_opinion/oped/articles/2008/01/06/br_r_r_where_did_global_warming_go/

One, I don’t think most policy makers are that aware of how dependent many of the “consensus conclusions” are on GCMs, so any comment about uncertainties in predictions based on the models would be way beyond what the scientists would present. They’re much more comfortable saying, “temperature is way up in the last 30 years, to levels not seen in the past 1K years, perhaps even 1M years, and the physics tell us its the CO2.”

It’s in Chapter 1 of AR4 so they did present it. There is a reason why there are still huge error bars on their predictions for what happens over the course of this century under the various future emission scenarios. I think you underestimate the intelligence of the average policy maker if you think they don’t notice the size of those errors bars and read a bit deeper than the executive summary to find out why they are still so large despite all the public money that has been poured into climate research in recent years. Most people like to know that they are actually getting value for money when large amounts of money are being spent after all.

The problem isn’t so much with what the scientists are doing with the modeling (Mann’s hockey stick is a bit of a red herring in that regard and is not really a core part of what is happening scientifically), in my opinion, but with what the environmentalists and journalists are doing with the key data, which is being presented to the general public in a highly skewed manner either to scare people into backing a tree hugging back to nature agenda or to come up with a sensational headline.

26 Steve McIntyre says:

January 6th, 2008 at 3:37 pm
In my opinion, no one has made a relevant comment on what struck me as the key issue in this post. [....]
There’s a very large issue here. AR4 says that Senior and Mitchell 1993 contains a “now classic” result – a result which is “unsettling” for GCMs. But this result was not mentioned in TAR – why not? Instead, TAR mentioned Senior and Mitchell 1993 in a different context. Did TAR have an obligation to report this “now classic” result?

To answer your question requires firstly a determination of what obligations were incumbent upon the IPCC and secondly whether or not the Senior and Mitchell 1993 result is encompassed within one or more of those obligations.

To determine what obligations the IPCC has, we must first see what the United Nations mandate authorized the IPCC to do when the IPCC was organized. The mandate said in part:

The IPCC does not conduct any research nor does it monitor climate related data or parameters. Its role is to assess on a comprehensive, objective, open and transparent basis the latest scientific, technical and socio-economic literature produced worldwide relevant to the understanding of the risk of human-induced climate change, its observed and projected impacts and options for adaptation and mitigation.

The WMO and other organizations made the determination a third of a century ago that human-induced climate change was being caused by anthropogenic emissions of greenhouse gases, and they led the members of the United Nations to organize the IPCC to assess the environmental risks which stem from such changes and how those risks can be mitigated. Is there anywhere in the mandate of the IPCC an authorization to assess “scientific, technical and socio-economic literature” which is not “relevant” to the understanding of the consequences of ” human-induced climate change” or is relevant to natural induced climate change?

Insofar as the results from Senior and Mitchell 1993 may be unable to support GCMs, how can such results be “relevant to the understanding of the risk of human-induced climate change” already assumed by international policy mandate and the IPCC to exist? In other words, is it even possible from the IPCC point of view for any literature whatsoever to be relevant to the IPCC mandate and assessments if and when such literature is inconsistent with and not supportive of the predetermined existence of “human-induced climate change?”

Does the IPCC literally interpret its legal mandate to mean that information contrary to a determination of human induced climate change as being not relevant to the purpose and mission of the IPCC?

It reflects my reading of the IPCC report and other discussions around that: It seems to be quite clear that clouds are an open question.

I have no special “in” on live discussions.