drankin said:
That's what the "experts" are for. If something is "scientific" a court can't make a valid decision? That's rediculous. This is done every day. What the experts have to do is lay out the facts to their most basic premises. They have to break it down and show their evidence. If a particular side cannot support their case as well as the other then you have a decision that represents it. Like I asked, "What more do you want?"
The problem is that "experts" are polarized now too. So depending on WHICH expert you pick, you know what he will say. This debate has come up several times here on PF already, but the SCIENCE of global warming is far less settled than proponents or opponents sometimes seem to claim: in other words, there is not such a thing as a complete and clear consensus in the scientific community as to what exactly happens, due to what causes and so on, like, for instance, in electrical engineering, just to take a silly example. That doesn't mean that there is nothing, either. But for the moment it seems that the "politically correct" word in climate science is to say that there will be global warming, caused by human effects. If you say that, you get grants, you get invited by politicians, tv-shows, and everything, while if you say the opposite, you are defending oil companies etc... From the moment that these issues get mixed into the position taken by a scientist (which is also a human being), one cannot count anymore on his neutrality. In other words, you won't find a NEUTRAL EXPERT. And so, according to how you set up your panel of experts, you can predict already what will be the outcome, but with a strong bias towards "global warming is humanly caused". Now, it is not because of this, that there is no such AGW ! But is not yet an indisputable scientific fact. It might not be there.
To prove a CAUSAL link implied by AGW, one needs to turn an OBSERVED correlation into a genuine cause-effect relationship. The observed correlation is that there is a slight increase in global temperature on one hand, and an increasing concentration of CO2 on the other. But one can find other correlations: there's a correlation between the increase in global temperature and the average processor speed of the sold personal computers over the year too.
Now, nobody is going to think that increased processor speed in PCs is causing global warming. There's a correlation, but not necessary a causal link. However, with CO2, it might. Then, one also has to indicate that this CO2 is *the cause* of human emission, and not the consequence of some global warming.
There are two ways to prove beyond scientific doubt that there is a cause-effect relationship in science, and neither has been achieved in AGW. The first one is an indisputable derivation of the relationship from well-known physical laws, which makes accurate predictions of the observed correlation, and which indicates the causality.
In other words, if one is able to model, using only known physical laws, precisely the warming of the Earth that results as a consequence of an increase of CO2, then one can assume that the cause-effect relationship is demonstrated and even understood as a function of the used laws. Well, to my knowledge, that has never been done in this case. There are a lot of computer models, but they all need "phenomenology" like cloud formation, soil response, vegetation response and all that, and on these things there's so much uncertainty that you can "warm" or "cool" as you like. This is not to say that this is not a good approach, but the problem is simply very complicated.
The other way is experimental: if you can arbitrarily VARY the cause, and the effect remains correlated, you've also shown a cause-effect relationship. In order to do so, you should, say, divide by 10 human CO2 emissions, and wait long enough to see the "glitch" in the global temperature. This is probably the kind of experiment we're tempting in the 21st century, by trying to cut back on CO2 emissions for 30 years, wait for 40 more years, and compile the data
So the two approaches to indicating a causal link have not been applied beyond doubt. So you can't yet state with scientific "certainty" that AGW is true. Scientifically, there are *indications*, like the prediction of SOME models, and the observed correlation of CO2 and warming. But none of this is yet at the stage where the relationship has been scientifically proved without any reasonable doubt, like it is, for instance, concerning the prediction of the next solar eclipse, or the prediction of the current that will flow in a given resistor when exposed to a certain voltage or anything of that kind.
However, does it mean that we have to *dismiss* AGW ? It certainly would be reckless to do so. After all, the scientific indications that one has seem rather to go in the sense of it. This is probably why many scientists take on this attitude. Moreover, behaving AS IF AGW is true is a good thing, because this might induce humanity to seriously reduce CO2 emissions, which is necessary in any case to perform the 21-century experiment. One needs to convince people of the reality of AGW in order for the scientific experiment to be conducted in the first place.
So, the good attitude as a scientist is to tell Bob in the street that AGW is true, and that he urgently needs to cut down on CO2 production. This will allow the global experiment to be performed. However, within the scientific community, one should keep a reserved attitude as should every scientist before his experiment has shown any definite result
