Soren wrote on Jan 27
th, 2010 at 12:11pm:
That is, in a nuthell, the case against AGW.
ABout our current dispute:
Darwin, a warmerist, was giving me the 'nudge-nudge, wink-wink, know what I mean' about the Gulf Stream and balmy/freezing weather in England as somehow another ace against sceptic. he mentioned something about a rate of something or other being 6 %. To his boosterist mind that was in the general neighbourhood of proof. You gently shot him down indicating the uncertainty of atributing causality to a change at rate of 6 percent in the GS.
Not quite. I just gave a short discussion of the papers presented, which showed that even a 30% change was close to the uncertainty of measurement.
It's not the figure of 6% or 30% that's significant, it's whether or not we can tell if that figure is reliable or not, and that comes down to the precision of the measurement. Intuitively, it would make sense that a 30% change in the flow rate of the GS should have a significant effect in the weather in NW Europe, however if we are not capable of measuring it with any degree of confidence, we can't draw any such conclusion. The jury is still out on it. The most we can say is that it's 'quite possible'.
Quote:At this point I said that if a rate of change of 6 % in oceanic flows is not conclusive (it isn't), then....
I know what you said, but for a start, you're simplifying what I meant. I meant that a change of 30% is really not quantifiable using the techniques in the original paper. So it wouldn't matter whether it was 6% or 30% - you might as well say x percent, where we don't really know what that value is.
Quote:...a rate of change in atmospheric CO2 from 0.0280% to 0.0560% can hardly be accepted as conclusive demosntration of causality between that CO2 change and climate change (never mind for now that not all that change is antropogenuic CO2
There are several things that add up to a causal relationship. One is the basic underlying physics, the second is the accuracy with which we can determine the rise in CO2 level (very accurate) and the third is the confirmation in terms of measurements - the decreasing Long wave radiation as measured from orbit which demonstrates that more and more heat energy is being retained by the Earth's atmosphere. This is an effect called teh greenhouse effect, which is well understood.
Quote:Re parameters : apparently there is no evidence for CO2 causing past climate changes. It seems that increased CO2 levels followed, rather than caused, rises in temperature.
Once again soren, nobody is claiming that it's all one way** Heat the oceans and you release some CO2, cool the oceans and you absorb more CO2. It's a two-way relationship. The difference between the pre-industrial past and the present day is that there was nobody adding CO2 to the atmosphere at that time, and there were a lot more buffers, such as rainforests, that acted as a sink.
Quote:Human or other CO2 now causing global warming is a theory without historical precedence.
Incorrect. The Milankovich orbital changes in the Earth's orbit could not account for all the temperature changes during the ice ages and interglacials. The greenhouse gases (mainly CO2 and water) contributed to the effect and in fact dominated the effect.
It is correct to say that CO2 did not trigger the warmings in the last million years or so, but it definitely contributed to them. In fact it can be shown that greenhouse gas forcing was the dominant factor in the magnitude of the ultimate changes during these periods.
Quote:This is hardly surprising. Even doubling CO2 will not make it anything but a trace gas (still only 0.0560%). Relative to other greenhouse gases, it will still be a small player, regardless of the forcings and amplification which would have been active in the past as well. Yet, there is no past evidence of CO2 causing warming.
Again, you're ignoring the fact that different gases absorb IR radiation to different extents. Where it matters, water vapour and CO2 both absorb and re-emit IR radiation and contribute to the greenhouse effect in a quantifiable way.
You don't dispute that the Earth has a greenhouse effect - do you? That's what keeps the Earth at a much higher temperature than what it would be otherwise. That greenhouse effect is caused by well-known greenhouse gases.
** This very tired argument of "CO2 doesn't lead, it lags" is a classic strawman. It's a bit like saying that I have proof that men don't cause marriage, because I have proof that some women (probably most) actually lead men into marriage.
First you take a false statement. I'll emphasise it to make it clear.
All climatologists believe that men lead women into marriage.
Then I provide data to knock that hypothesis down in flames.
My sister plotted with her girlfriends to get her fiance to marry her
Therefore all climatologists are wrong!!!!
In fact, marriage is a two-way relationship, just like CO2 and temperature.
As the French say "L'homme propose, et femme dispose"