Posted: Apr 27, 2010 8:27 pm
Luis Dias wrote:FACT-MAN-2 wrote:
The science is telling us, with 95% probability, that earth's mean annual temeperture will be standing at somewhere between 2 and 7 or 8C above where it stood in the preindustrial era come the year 2100, which is indeed 90 years from today.
One should ponder a moment about the 95% statement. What does it really mean? Does it mean that there is a 95% chance that such phenomenon will in fact occur within 2100? No, it does not mean that. It means that if you take for granted all the axioms and assumptions from where such numbers were produced (if they were), and by "granted" I mean take them as "absolute truths", 100% true representations of the world, then there's 95% chance of this occurring.
So the scientists who stated the 95% confidence are dumber than you are, is that it? I rather think that's an unlikely situation. They've been at this for 20 years, how long have you been at it? They know exactly what the characteristics and attributes are of their analytical basis and they understand their veracity.
They openly state the fact that their predictions are based on estimates of emissions that will occur between now and 2100, and it is obvious that if those estimates prove to be wrong by what emissions actually do in reality between now and then, their predictions will not be achieved and something else will happen instead. In other words, if actual emissions exceed their estimates for them, mean annual temp in 2100 will be higher than what they've predicted; if they are lower, then the mean annual temp in 2100 will be lower.
There is simply no other way to handle this aspect of making a prediction. We dont know exactly what trajectory emissions will follow or exhibit, hence we have to estimate what we think they will follow, and that's done using historical emissions data, consensus economic forecasts, and other criteria that bear on what we might expect in terms of emissions. This then is then expressly stated as an assumption.
If you know of a better way to do this, I'm all ears.
As for any "axioms" that may be in play, I think either 1) there aren't any or 2) if there are they too are treated with copious amounts of good judgement or analyses that determine their force of relevance and meaning in the equation. Do you actually think these fellows are going to publish a report that makes a predition that can easily be shot down because any or all or some of its underlying "axioms" are less than credible? WTF kind of scientist would do that? None that I know of.
You make these assertions because you know we can't get into all those details here and so that makes them easy targets for claiming we have to take them (or the scientists are taking them) as "absolute truths" or "100% true representations of the world."
But the proof is in the pudding, a 787 airliner flies and flies well and predictably, which proves that any and all "axioms" and assumptions that underpin the science and engineering by which a 787 is built are indeed true representations of the world. In climate science, the modelers have managed to make very good predictions to date, which proves the validity of whatever "axioms" that may underly their science.
Luis Dias wrote:
But there's a problem here. These assumptions are called "models".
False. Models are mathematical representations of real phenomena. When run backward and the output they produce matches actual data, we can have a high degree of confidence that the output they produce when run forward does indeed represent what's going to happen.
You need to take modeling 101.
Luis Dias wrote:
So for one to utter these statements one must profess a 100% trust unto climate models, which is obviously silly. These models, in turn, have hundreds of smaller assumptions, some very easy and definite, some very hard to pin down, some even, are just values to keep the models "sane", that is, visually appealing, retrofitting nicely with the past and so on, with very little physics knowledge involved.
I repeat, you need to take modeling 101.
The models have been under development for 25 years or more. You talk like they were invented yesterday.
Luis Dias wrote:
So how much of trust should one impinge to these models? And is this trust even possible to define numerically? I don't think so.
It's pretty easy for an armchair commentator to make such pronouncements. The problem is they run counter to the conclusions reached by some 20,000 professional climate researchers and scientists and just about every climatologist on the planet. I trust you do know this.
To hear you tell it, we should just give up the whole endeavor and let it go at that and to hell with trying to learn what the future might have in store for us. Fortunately, others don't share this idea, they keep trying, they keep working.
Luis Dias wrote:
Finally there's the issue of averaging multi-model runs, as if they were "all equally good", after dismissing others because they gave too much warming or too little!
It isn't done this way and you should know better than to claim it is.
Luis Dias wrote:
After all of this, to still utter the silly proclamation of "95%" chance of this going to happen like X and Y without the multi-tonne weight of caveats annexed to it is disingenuous and misleading. Fortunately, science is catching up to this common sense basic notion. The next IPCC report will address this issue better than the one we have now, although I still think it won't address it fully honestly. If it did, we would be brought back to the early 90s conclusion, and that would be politically catastrophic, if we want to have any nation doing something "about it".
You're stating the obvious, which is, climate science gets better as time passes and more work is done. This can be expresed as gaining better resolution as time passes.
The idea is we work with what we have. It is true for example that if we had a temperature gauge located on every 2,500 square meters of the planet, including on the oceans and in polar regions, and these gauges were all identical and set up identically, we'd have little trouble meauring the temperature of the planet as a mean average, no problem at all. But we don't enjoy that kind of instrumentation, we only have partial coverage of the planet and are therefore required to develop and establish some very sophisticated ways of using the instrumentation we do have to obtain reasobaly accurate determination of the earth's mean annual temperture, aided now days by satellite measuring.
Exhaustive efforts have been made to determine a good paleo record of earth's temperature so that we have a reasonably accurate history from which to extrapolate the future. Is it perfect to the nth degree? No, of course it isn't. But it is good enough for what we're trying to achieve and it gets better with each passing year.
But here's the thing, we know from how much C02 is in the atmosphere right now that earth's mean annual temperature is going to rise over time, we know this as well a we know the sun's gonna come up in the morning. So the question becomes, how much is it going to rise? We can infer that from how much C02 is in the atmosphere too and the rate at which it is accumulating there. That's chemistry and physics and the known behavior of GHGs. These kinds of studies and analyses also point to a rise in earth's mean annual temperature in the same range the model predicts, somewhere between 2 and 7C degrees in the year 2100. Wow, whatta ya know, two completely different approaches yield essentialy the same results.
You appear to think you know better how all this should be done than the professionals who are actually doing the work. In that light, what would you propose as a better means of projecting future trends or events or expressing them or describing them? Or are you of the mind that we ought to just give it all up and stop trying?
I'm all ears.