...and yet again...

The devil is in the details (as it always is), or should I say the devil's in the methodology in this instance.

The single biggest factor in my remaining skeptical of this alleged groundswell of opinion is that I read too many public proclamations being made by organisations such as the United Nations, that cite an overwhelming majority of climate experts who agree that the upward change in mean global temperature is due to mankind. I find this misleading because:

1) there is no central registry of "climate experts" of which I'm aware, and if there is, I'd like to know who is responsible for the creation and maintenance of that list and the criteria upon which it is based. In order to have a majority, let alone an overwhelming majority, both sides in the discussion need to establish a mutually acceptable list of experts whose opinion we'll all accept;

2) in these broad pronouncements, there is no effort to reproduce the research, and thereby repudiate the science, of the primary investigators;

3) there is no attempt to attach weighting to the absolute value of each of the individual studies. To the contrary, there appears to be an underlying assumption that all research is of equal probative value;

4) far too many of the primary research efforts use correlative statistical methods, which as you must surely know, carry the least weight because of their inability to attach the element of causality;

5) there is no evidence that the bodies making these pronouncements have performed any statistical manipulations to exclude, or at the very least, minimise the impact of duplication of data, the funding source issue that you've correctly cited, or the impact of "me-too"-ism, a well-documented phenomenon to which any group of humans is susceptible.

In short, if I was sitting on your doctoral thesis committee and you handed in a report similar to the recent UN white paper on mean global temperature rise, I'd send you back to answer at least the few points that I've raised here, if not more, before I'd hear your defence of your thesis. My comment to you would be that what you'd put forth so far isn't particularly persuasive without stronger evidentiary material and analysis.

Now, onto the subject of whether the current trends are the result of these longer-term oscillations in mean global temperature that you refer to as "natural factors". I think you're missing the point on this. Many of the skeptics, scientist and non-scientist alike, believe that the current observations are in fact due to the "natural factors" of the planet. These "natural factors" fall into three general domains - that due to living things, such as trees, mankind, cows etc; that due to geological forces, such as volcanoes, plate tectonics, variations in mean planetary albedo etc; and that due to exoplanetary forces, such as orbital variations, mean solar output and galactic movement, etc. That has been the evidence on the table throughout this whole discussion.

This is a significant point - it's just not that these "natural factors" can cause change in mean global temperature, it's that they do cause change in mean global temperature. What the skeptics are waiting to hear is definitive proof that the activities of mankind are unequivocally causing the results that we're observing. The burden of proof, here, is on those who suggest that the causes of planetary warming are different from what has been identified through years of prior research, not on those who believe that 3+ Bn years of evidence represents persuasive proof.

When you speak of making political decisions, you're really talking about socio-economic decisions that have the power to stultify the progress of mankind and to my way of thinking, decisions of that magnitude ought not be rendered on incomplete, inaccurate or misleading information. Because of their impact they deserve to be made on facts, not speculation.

. . .and again

Not at all. Of course proper scientific procedure is the way to go, but there is a political decision to be made now, because - as you say - science cannot yet give us the necessary clarity on climate change.

My point about conspiracy theory is simply that it is unlikely that a disparate group of international scientists, whom you yourself say are inclined to disagree anyway, could organise such a world-wide scam as to promote a misleading notion of human-driven global warming as a means to gain funds. On the other hand a small and powerful group, such as the global oil industry, is capable of setting up an effective counter-campaign. I'd be surprised if they weren't.

Concerning natural factors being responsible for the current warming process, I understand that this has happened over the millenia, but I don't see anyone citing evidence that those factors actually ARE operating. Only that they can.

Which still leaves us with political decisions to make about observed global warming on the basis of insufficient scientific input.

And yet, then again...

"...smacks rather of an organised group whose aim is to counter the effects of the global warming consensus. Might such a group exist? It might. It might be funded by Exxon-Mobile...."

In other words, a global conspiracy of oil barons is attempting to despoil a consensus among those who notoriously fail to reach consensus, namely scientists? Further, when scientists eventually do fall into a consensus, often those consensus opinions have historically been wrong - steady-state universe; biological demise of the dinosaurs are but just a few of the more recent consensus opinions to fall into disrepute.

"...commentators - especially on the sceptical side - insist we know too little about how these work. Which means, in short, that we have NO EVIDENCE that natural causes are currently operating..."

But we do have evidence - credible evidence from ice cores, tree rings, fossil evidence, geological evidence. Evidence isn't the problem here - it's how all the evidence connects. What we don't possess is a broad overarching view of what all of the evidence means within the context of all of the other evidence.

"I am open to the suggestion that the search for funds distorts the direction of scientific research, as I am to the possibility that the nuclear fuel industry has a vested interest in promoting the global warming agenda - and yes, I remember the great K2 fiasco (which I never believed in). However, to suggest that the whole global warming movement is little more than a scientists' scam, as some have done, amounts to a vast conspiracy theory."

Hold on, I''m confused here - conspiracy theories are OK when they work for you as in your first paragraph, but not when they work against you as in the paragraph above? Rather than to rely on rhetoric and polemics to further the debate, I think the prudent course is to continue developing a better understanding of how what we know all fits together.

"My mental resources are limited, as is the world I live in, but I would opt for cautious action on the assumption that we are causing damage to our environment over sceptical inaction, which merely seems to be self-serving."

I think you can see that there are people and organisations who hold vested positions on both sides of this debate, and who therefore are self-serving. Ultimately, I think we have to let the facts lead the way and make decisions that are driven by solid science, rather than ones that are driven by a religious-like zeal to dominate the marketplace of free ideas..