Language and argumentation in the climate debate
Watched some more discussions and debates about man-made climate warming. My initial conclusions are unchanged (we don't know if it's man-made). There are several aspects of this debate that to me quite obviously indicate that the issue is not settled, in part because it's too technically complicated, in part because it's politically driven.

During the debates, the supporters of man-made warming routinely conflate the three statements: 1) the mean temperature is globally rising, 2) proportion of CO2 has grown in the atmosphere since 1750, 3) the main cause of the warming is the man-made portion of CO2. If someone does not support 3), the opponent argues as if 1) and/or 2) were automatically rejected together with 3). If someone agrees with 1), it is assumed that one also must agree with 2) and 3). The language used for discussion ("climate change", "CO2 pollution", etc.) is never precise enough to distinguish 1), 2) and 3). This conflation of terms is mostly done by proponents of man-made warming, in order to avoid technical discussions on how high is the actual effect of man-made portion of CO2 on climate.

The often-cited "scientific consensus for (man-made) climate change" is another case when two notions are routinely conflated: 1) a hypothesis that the majority of scientists currently assume in their published research, 2) a theory that is finally accepted because it is mathematically and experimentally proved correct. Opponents of man-made warming say that the "97% scientific consensus for climate change" is meaningless because it is incorrect to arrive at 2) by consensus. Supporters of man-made warming say that most scientists assume that CO2 emissions affects climate, i.e. they refer to situation 1) when they say "consensus".

The probabilistic nature of climate predictions is interpreted by opponents of man-made warming as the impossibility of any predictions. ("The climate is a chaotic system and cannot be predicted.") On the other hand, the proponents of man-made warming take predictions of probabilistic models as the truth (rather than probability). The word "probability" is being used ambiguously: as "chances that the results are correct" and as mathematical probability of predicted climate values.

Congressional testimonies are useless as source of information, because they are conducted as adversarial debates where both sides are trying to discredit the persons making the testimonies. For instance, a meteorologist who does not support man-made warming was then asked about his religious views and about his views on evolution and creationism, in order to discredit him as a scientific expert. In a short discussion that followed, the two meanings of the term "theory of evolution" were conflated: 1) species are observed to change and to have changed in the past, and 2) all life on Earth was created from non-living matter by random selection.

An important factor missed by non-academic participants in the debates is the provisional nature of results reported in academic research. Most research papers are inconclusive: they give at best a partial evidence for some hypothesis. A research paper would typically advance a new hypothesis and test a few of its implications, showing that some observations are better explained by this hypothesis than by previous ones. Later, the new hypothesis might be rejected because other implications (not initially considered) make it incompatible with evidence, or because the author is busy publishing new papers with new hypotheses that appear more exciting. So it is a bad idea to base policy decisions on any statements taken from a cutting-edge research publication that advances a new hypothesis.

One scientist (a supporter of man-made warming) said that the reason scientists support it is that no other explanations were found to work. ("It took 25 years to examine alternative explanations, but we found none. The sun is as warm as it was before; the oceans did not change; etc.") So only the CO2 hypothesis is left for consideration. Now, this might sound convincing. However, this is a clear red flag for me. It means, they actually do not know at all what causes the current warming - none of their models work, or else they won't be looking for alternative explanations. (That scientist also does not mention the sun spots / cosmic rays / clouds argument, which is advanced by some scientists as the explanation. But let's assume that this also doesn't work.) So to me it's clear what is happening: they have no model that describes climate (retroactively) in a precise enough manner to talk about fraction of degree warming. This is a problem because grant money will not be coming unless you demonstrate a lot of research activity, and nobody will do research on your failing models. However, the man-made CO2 hypothesis is politically expedient and brings grant money. So scientists will be naturally driven to publish papers that assume the man-made CO2 hypothesis and then study its implications. This is a safe way of getting funded while publishing a scientifically correct (if inconclusive) paper.

Non-academic supporters of man-made warming do not generally understand the effects of political pressure on academic research. Scientific journals will accept for publication any number of harmless and inconclusive papers on any subject, as long as this brings grant money to everyone. A bureaucratic organization tasked with fighting a problem X will never conclude that its work is done because problem X is solved or became unimportant - on the contrary, the organization will try to expand the scope of its activities as much as possible. In many cases, organizations redefine the meaning of "problem X" in order to expand their scope, even after the original problem went away. Academic funding bodies have a huge budget that needs to be spent, also to avoid diminishing the scope of their activities. So they cannot suddenly stop funding the man-made CO2 hypothesis even if some research papers were to prove conclusively that man-made CO2 does not affect climate or, say, causes cooling. The academic funding bodies have all the incentives to continue funding research on adverse climate effects of man-made CO2, even if there aren't any such effects.

Supporters of man-made warming invoke the authority of science as if scientists were incorruptible and correct by definition. At the same time, opponents of man-made warming don't necessarily have a convincing scientific explanation.

We will be unable to make up our minds on the basis of non-technical information we can get. The IPCC (the commission for climate change) publishes reports that are curious in the way they are written. The technical parts are quite impenetrable: the scientists do not bother in the least to make their arguments clear to laypeople - or even to non-meteorologists. They fill hundreds of pages talking in their own jargon about complicated technical arguments advanced by other research papers about the details of chemical reactions in the soil, radiation transfer in various layers of the atmosphere, and so on. This is the kind of almost unreadable prose that scientists will happily produce in any quantity. It is very hard to find there a plain statement to the effect that "CO2 does X and Y to climate" or "alternative explanation Z does not work because Q". However, the policy conclusions in the IPCC reports are as clearly alarmist as possible.

My conclusions: 1) They have no incentive whatsoever to make their science arguments clear, and they don't. An IPCC publication is not peer-reviewed - it is panel-approved, i.e., the authors themselves (after lengthy discussions) agree on the text, and that's enough. (Non-academic people often don't understand the difference.) 2) The IPCC has an incentive to make alarmist predictions regardless of science, and they even say it explicitly in one of the reports. (The quote was, "Unless we talk about an impending catastrophe, nobody will take this seriously enough to make policy decisions." I downloaded the IPCC reports, and I'd like to find that quote...) It's not science.