muso wrote on Apr 16^th, 2010 at 1:26pm:


I believe!

I can tell whether it will be cold at dawn simply by checking out the cloud cover during the night. How about that? Clever, what?


Quote:


I am sorry, I can never follow non-deniers (nice?) when they switch from 'one variable' CO2 induced AGW  to climate change to sea levels and glaciers, to acidification, wild weather, future catastrophy through tipping point of no return already reached to desertification and back to mere warming.

At any rate, the only variable you ever talk about is CO2. You mention others only to discount them. You treat CO2 as if it was the 'one ring to rule them all'. For a topic like climate that is at least 'reasonably complex', this is monomania.


Quote:


What, do you want me to do your arguing for you now? I meet you half way - I wholeheartedly agree with the "At least that's what I think he's doing" bit. Fair enough?

muso wrote on Apr 16^th, 2010 at 3:30pm:



Do you think I'm humble too?

Soren wrote on Apr 16^th, 2010 at 2:26pm:


Which other variables have I discounted?

I think we've discussed all the variables.  What we're talking about is very specific - What are  the effects of increasing atmospheric greenhouse gases and clearing mainly tropical rainforest?

You stated that CO2 is 'just' a minor greenhouse gas. Well it isn't - it's the second most important greenhouse gas overall after water vapour , and we've already agreed that it doesn't matter how much water vapour we put into the atmosphere, because it will just drop out as precipitation.

In fact, most of the change that's occurring is happening in a specific part of the upper atmosphere. At that particular altitude, the air is very dry, and CO2 takes over as the most important greenhouse gas. So in terms of changing temperature, CO2 is the most important variable. It's actually more complex than that. Once you get really high in the atmospheric column, some of the re-emitted infrared is transmitted into space, but a fair proportion is also emitted towards the earth. It's a very subtle effect, but it is understood.


The main factor that controls water vapour concentration is temperature.  You've already agreed with that.

Therefore the next biggest greenhouse gas in terms of effect is CO2, followed by methane, then Nitrous oxide.  Do you agree with that?

What other variables are you interested in? All the heat ultimately comes from the Sun, and the temperature increase is determined by two main factors - the incoming heat from the sun, and the outgoing blackbody radiation from the Earth. These two factors control the heat balance.

I'm sure you've seen the attached figure before. It shows the extent of the forcings, including natural and anthropogenic.

Now the solar irradiance plus all the other factors combined have actually led to a slight net decrease in forcing as you can see from the figure.

The radiated longwave radiation has also decreased over the last few decades, and we know why. Why do you think that is?  

So nobody is saying that it's just CO2, except for the strawman that you have constructed.

I'm not sure if it was this thread or another, but somebody made the comment that the forcing equation might hold under laboratory conditions. Basically the radiative forcing equation only applies specifically to the atmosphere. I could explain how it's derived, or provide a link, but I doubt if it would be of any benefit to do so. It's dependent on the structure of the atmosphere at different altitudes. Let's leave it at that.

The fact that you believe that it only applies in a laboratory speaks volumes.  

To answer the question - how much of the warming was caused by anthropogenic greenhouse gases is a difficult one because of the amplifying effect of water vapour (as we've discussed ad nauseum)

If we take the total natural forcings, as I said before, you get a slight decrease over the last 50 years or so. So the actual warming contribution from anthropogenic greenhouse gases is a tad more than 100%.

We should also remember that a fair whack of the CO2 ends up in the ocean too. The effect we have seen takes that into account.

freediver wrote on Apr 15^th, 2010 at 10:07pm:

muso wrote on Apr 19^th, 2010 at 2:54pm:


I dunno - how about the most important one?

Quote:



But, you see, that's how the bloody thing works.

Water wapour is the most important, by the way, not just by a nose but by a level of magnitude. But somehow, with teh most impotrtant GHG there is a magical or banal balancing going on.
Not so with out evil progeny, CO2.
With the second most important GHG, there is no balancing, apparently, magical or banal. CO2 is rampant. Small it may be by comparison but golly, is it a loose cannon? It it is UNCONTROLLABLE, much like the human blight on this blue planet. CO2 has our evil disposition, don't you see. Other GHGs play ball, rub along, fall out of the sky on cue - but not our representative in the atmosphere. No, siree.  The human emissary in the atmosphere is as deadly as we are on this earth. CO2 is humanity writ GHG.

And so on, ad nauseum.
Muso, you are projecting.

You must admit, Mozz, that this 'I'm open, teach me' kinda stance is fairly recent. Until 5 minutes ago you knew it was all sorted.

Well, beware of the people who say they have the miriad variables sorted. They don't. Anybody who pretends that this complex issue is all settled is lying. There's a first rule of thumb for all of us.

Put forward a hypothesis, be passionate and argue for it, counter the doubters, present new explanations as the challenges arise - fine and honourable. Talk of wilful deception by those who cvhallenge and disagree, and you are on scientifically and ethically untenable ground.

AGW has been a crash or crash through case so far, and it has well and truly crashed. It cannot be revived in its pre-Copenhagen guise. That nonsense is dead.