Meaningless? No. Why would I bring it up if it were meaningless?
The quotes from the IPCC come from the executive summary for policy makers. That portion is a political document for policy makers, not a scientific document. The science is often tentative in nature and the conclusions rarely ever state anything as being 100% proof. That is what the policy makers and politicians pretend to do afterwards. Having worked in policy development I understand the psychology behind this. One does not attempt policy change without accepting a set of presuppositions upon which to found one's actions. But these presuppositions are always limited in scope. They are meant to do something and not everything. So one rarely takes a global view on the outset.
The problem with the scenario building and generating policy on global warming is that it pretends to take a global view based on a limited set of presuppositions concerning origins. That will make for bad policy, in my opinion.
Scientists, too, are motivated by politics, personal concerns, worries and the like. There is nothing wrong with that so long as the debate does not sink to making speculative predicitions about future outcomes or unfounded claims. That is what the IPCC does as a document. From the 1990's to the most recent 2006 publication, the "predicitions" for future climate have slipped from being attempts at "modeling" based on extrapolations founded on a limited set of data, to "scenarios" that are presented as a means of providing limited illustrations of what could possibly happen in the most worst case situation. Climate is not a simple thing, nor is it an average thing. Nor do there exist robust models that can tell us what the world will look like in 100 years with any clear details.
The result of making dire predicitions to motivate social change is that what is reported on frequently in the press, what makes the headlines, what works people up, are the worst case "scenarios." The "worst case scenarios" presented in the IPCC are just that, the most extreme in terms of picturing what the future may possibly look like. But let me repeat this for you, it is an extreme picture, not to be read as being the most likely! That fact is actually mentioned in the IPCC report, so it is not a statement if imminent reality. Hence the reason why this research field remains active.
Neverthelesshese extreme scenarios have now become a form of public belief - now that they have repeated enough times. That is nothing new.
As for my claims, as I pointed out and you did not understand, I am suggesting that the debate is far from over. The evidence supporting only anthropogenic causes is incorrect: there are natural causes at work, as well, like the sun. The full impact of these natural forced of climate change are not clearly understood - and they have by far the greater effect on climate. For example, the debate concerning the impact of the sun lies in just how much a role it plays, be it 25% or 50% or 100%. The sun can't be controlled and so it changes climate whether we like it or not. The same goes for any other potential factor that contributes to climate change that lies beyond human activity.
And yes, I have been pointing out that a policy based on GHG reductions from only one sector of economic or human activity is a weak policy. Human contributions to existing inventory of global GHG's from natural sources is actually miniscule. Present modeling leaves out large portions of solar forcings; there is a neglect or misunderstanding of the considerable role of water vapour, there is incomplete knowledge concerning the role of high altitude clouds versus low altitude clouds. Accurate temperature records from the past are incomplete, as is the understanding for what always caused climate shifts. There is also incomplete knowledge concerning the present impact of GHG's in the atmosphere, and on how rapidly they are taken up through photosynthesis from both plants and marine life or dissolved by weathering.
And upon this people want to make absolute statements on human GHG production? That is my question.
