Anthopogenic Global Warming Myth or Real ?

[Hindmost]

Warmers are pretty much CO2 freaks. It goes in line with their little dainty carbon footsyprints, schemes for social control and taxation, and unscientific, gullible beliefs. Also a strong anti industrial sentiment.

Environmentalism-The New Religion.

Perfect strawman...this type of post marginalizes all your arguements.

A person can logically accept the scientific data of CO2 and global warming without "dainty carbon footsyprints" and "schemes for social control." There is nothing unscientific about CO2 and the probability of warming. Rhetoric and ridicule won't cancel it.

I startup nuclear power plants--kinda eliminates that anti industrial sentiment.

glenn

http://www.snowballearth.org/end.html

 

[DogB]

True, but palaeoclimatic data is relevant today, because things that were happening then are happening now. That includes increasing CO2, decreasing albedo, and melting permafrost. It takes sophisticated techniques and equipment to separate out the individual effects but it can be done with fair accuracy. The combined impact is easier to detect.

I’m afraid you’ll have to excuse me if I remain a little sceptical about our ability to tease out the effects of CO2 in a temperature rise a thousand years ago.

To get a good prediction of what's likely to happen in current circumstanes we need to stick to the fairly recent past - the last few hundred thousand years or so. Climate history is pretty regular over that timescale, the Sun has remained much the same as have Earth's orbital and rotational features, and continents haven't moved significantly. CO2 has stuck to a small range, ~180-310ppm.

Far from playing a minor role in explaining the ice-age cycle, CO2 was the star. The Milankovich cycles - regular oscillations in the Earth's orbit and axial tilt - don't provide enough energy to explain deglaciation, even with the positive albedo feedback. So scientists were stumped. The signal is obvious in the data, but the mechanism remained obscure.

Until it was recognised that warmer oceans hold less CO2. As oceans warmed they released CO2; as they cooled, they absorbed it. The mystery positive feedback. Work the numbers and sure enough, problem solved.

Okey dokey, here we go. Let me know where we differ.

Something (probably Milankovich cycles) trigger a warming event. Temperature begins to rise independently of CO2 levels. At a very early stage this warming would cease if it we not for the effects of CO2. The mild warming event causes the oceans to begin outgassing and the mild event is amplified.

You should be happy up to this point. I am too. I have absolutely no problem with this side of the equation either.

At some later date something (presumably the same thing that made it warm in the first place) triggers a cooling. This is the point. The CO2 is still up there. The positive feedback loop is in full swing and yet it still cools. The CO2 which materially effected the warming now is powerless to stop the cooling.

Help me. Explain how this could be so. If the trigger event is strong enough to overwhelm the greenhouse effect then why invoke CO2 at all.

If someone could just give me a simple, logical answer to this question I’d go away and darken your door no longer.

My sceptical side (which is pretty much the only side I've got) doubted that we could materially affect climate, but I never doubted the science. I just didn't think it would amount to much. (I was raised in the post-Enlightenment science tradition that big changes happen gradually and that Mankind should get over itself.) Since then (well over thirty years ago) I have seen it have a material effect on climate.

I’ve seen climate change. I’ve seen greenhouse emissions rise. The link seems logical yet logic doesn’t always work in science. I still wait for my personally acceptable level of proof. I’m glad you’ve reached yours.

When the nights draw in I enter my nocturnal phase .

I too, do my best work in the dark.

 

[DogB]

It's not important what proportion is directly attributable to CO2, as opposed to CO2 and feedbacks. The crucial point is that CO2 is the initial cause of current global warming.

But surely that's the point. Without being aware of the level of influence of CO2 how can we make such a claim?

We'll all look pretty stupid if we work for 50 years to reduce CO2 levels and then find it was the methane all along.

 

[a_unique_person]

Thank you both.

I do pick at this document but I find it just a bit superficial. It’s wonderful discussion of the history of the hypothesis but it’s less useful as a discussion of the current state of play.

He does include a bibliography, http://www.aip.org/history/climate/bib.htm if you want to go the source documents. Much of it is historical, but a lot of it is the basic science.

 

[Spud1k]

A neat summary statement but let me ask one question - can you give me an exact figure as to what percentage of the current greenhouse effect is caused by CO2?

Of the top of my head I've seen figures from about 5% up to about 25%. What's your thoughts?

The last IPCC report (which is a culmination of lots of other previous work by many groups) puts the warming influence of recent changes to CO2 concentrations as between 1.49 and 1.83 watts per square metre (I refer to figure SPM.2). This compares to about 0.48 for methane, 0.16 for nitrous oxide, 0.34 for halocarbons, 0.35 for tropospheric ozone, 0.07 for stratospheric water vapour, 0.1 for black carbon on snow, 0.01 for contrails and 0.12 for natural changes in solar irradiance. That means CO2 accounts for about half of the warming since pre-industrial times. There are also a bunch of anthropogenic cooling effects that subtract about 1.45 from this total (although the error bars on that are admittedly huge). This makes the net forcing that has been responsible for current temperature rises to be somewhere around 1.6 Wm^-2, so if we were to do nothing but somehow reduce CO2 concentrations back to pre-industrial levels, that would pretty much cancel out all of the other effects.

 

[TrueSceptic]

Thank you both.

I do pick at this document but I find it just a bit superficial. It’s wonderful discussion of the history of the hypothesis but it’s less useful as a discussion of the current state of play.

What do you mean by the "current state of play"? The basic science hasn't changed, just the arguments used by "sceptics" (even if they're old arguments being recycled).

 

[Pixel42]

At some later date something (presumably the same thing that made it warm in the first place) triggers a cooling. This is the point. The CO2 is still up there. The positive feedback loop is in full swing and yet it still cools. The CO2 which materially effected the warming now is powerless to stop the cooling.

Help me. Explain how this could be so. If the trigger event is strong enough to overwhelm the greenhouse effect then why invoke CO2 at all.

If someone could just give me a simple, logical answer to this question I’d go away and darken your door no longer.

This is my understanding, though I'm not an expert so I could be wrong:

Following the initial warming trigger, the positive feedback as the oceans and permafrost warm and release CO2 accelerates the warming until an equilibrium is reached. In the absence of any new external warming trigger no further warming then occurs, the CO2 level and the temperature remain constant.

If whatever caused the initial warming trigger then reverses cooling begins. As the oceans and permafrost cool they reabsorb the CO2 they previously gave up, which accelerates the cooling. So a positive feedback during a positive external forcing becomes a negative feedback during a negative external forcing.

 

[Spud1k]

So a positive feedback during a positive external forcing becomes a negative feedback during a negative external forcing.

Actually, a negative effect in response to a negative forcing is still a positive feedback. A negative feedback is something that works in the opposite direction to a forcing in either direction. Sorry, but my pedantic streak refused to let that one slip.

 

[Pixel42]

Actually, a negative effect in response to a negative forcing is still a positive feedback. A negative feedback is something that works in the opposite direction to a forcing in either direction. Sorry, but my pedantic streak refused to let that one slip.

I sit corrected

 

[a_unique_person]

What do you mean by the "current state of play"? The basic science hasn't changed, just the arguments used by "sceptics" (even if they're old arguments being recycled).

It has been consistent all along, unlike the denier crowd that clutches at every new paper that comes along.

Exhibit A. G&T.

Exhibit B. Miskolczi http://met.hu/doc/idojaras/vol111001_01.pdf

A prize to the person on JREF who picks the biggest hole in the paper.

What is interesting is the number of people on the blogosphere who will swear that the IPCC is all rubbish, partisan, communist, etc, but will say that such a paper Miskolczi is makes perfect sense to them. However, when you read the blogs, there are numerous questions about assertions made in the paper that he has to get back to them about.

 

[lomiller]

At some later date something (presumably the same thing that made it warm in the first place) triggers a cooling. This is the point. The CO2 is still up there. The positive feedback loop is in full swing and yet it still cools. The CO2 which materially effected the warming now is powerless to stop the cooling.

Help me. Explain how this could be so. If the trigger event is strong enough to overwhelm the greenhouse effect then why invoke CO2 at all.

Where you are going wrong is your understanding of how feedback operates. Positive feedback cuts both ways, it enhances a cooling effect as much as it enhances a warming effect. The easiest way to look at positive feedback is as an amplifier, whatever forcing occurs is made larger it takes a small positive forcing and makes into a big positive forcing, or it takes a small negative forcing and turns it into a big negative forcing.

Because climate is not a linear system there is hysteresis thrown in the mix, which means there will be a tipping point on the way up and on the way down that needs to be reached before the system moves rapidly towards another stable equilibrium. Just as in the case of positive feedback this applies equally in both directions.

 

[Spud1k]

It has been consistent all along, unlike the denier crowd that clutches at every new paper that comes along.

Exhibit A. G&T.

Exhibit B. Miskolczi http://met.hu/doc/idojaras/vol111001_01.pdf

A prize to the person on JREF who picks the biggest hole in the paper.

Good grief, that's a veritable block of Swiss cheese that one... so many holes to choose from...

The most glaring one is that trying to sell a 1D equilibrium model over 3D dynamical models is nothing short of comical when the system they are modelling is both 3D and highly dynamic.

But my favourite hole is that their basis of model validation is simply that it replicates current conditions, which given that that it is a purely parametrised model, is hardly a major achievement. When they then try changing something and the model doesn't hold or give the expected results, they come to the conclusion that changes are impossible rather than consider the very real possibility that the model may simply not work.

 

[lomiller]

Actually, a negative effect in response to a negative forcing is still a positive feedback. A negative feedback is something that works in the opposite direction to a forcing in either direction. Sorry, but my pedantic streak refused to let that one slip.

Not pedantic at all I think. One of the biggest problems I see people have when looking at this is that they assume positive feedback equates to positive temperature.

 

[a_unique_person]

Good grief, that's a veritable block of Swiss cheese that one... so many holes to choose from...

The most glaring one is that trying to sell a 1D equilibrium model over 3D dynamical models is nothing short of comical when the system they are modelling is both 3D and highly dynamic.

But my favourite hole is that their basis of model validation is simply that it replicates current conditions, which given that that it is a purely parametrised model, is hardly a major achievement. When they then try changing something and the model doesn't hold or give the expected results, they come to the conclusion that changes are impossible rather than consider the very real possibility that the model may simply not work.

It's interesting. McIntyre is quite happy to host a topic of over 1,000 posts, while not actually taking part in the discussion. http://www.climateaudit.org/phpBB3/viewtopic.php?f=4&t=161&st=0&sk=t&sd=a&start=20#p2939

He's not endorsing it, but he's happy to muddy the water. In the end, that's all that has to be done.

 

[TrueSceptic]

It's interesting. McIntyre is quite happy to host a topic of over 1,000 posts, while not actually taking part in the discussion. http://www.climateaudit.org/phpBB3/viewtopic.php?f=4&t=161&st=0&sk=t&sd=a&start=20#p2939

He's not endorsing it, but he's happy to muddy the water. In the end, that's all that has to be done.

Whatever else some of us might think about McIntyre, he's not an idiot. He doesn't do science; he does stats.

He's quite happy to provide a forum for others to argue sciency stuff, although he takes pains to keep things on topic and he quashes the fantasists. He knows that they hurt his credibility.

Back to the current topic. Misapplication of Kirchhoff's Law seems to be the basis of this paper.

 

[mhaze]

...The most glaring one is that trying to sell a 1D equilibrium model over 3D dynamical models is nothing short of comical when the system they are modelling is both 3D and highly dynamic......

Considering that a hundred examples can be easily made to the efficacy of one dimensional models in physical systems, and another hundred of the needless complexity of the general category of 3D models in given situations, your argument is flat incorrect. Seems like an odd leap to lump a use of the virial theorum with "one dimensional" , to boot.

What you've left out of your comment and which misrepresents the two means of looking at phenomena is the restrictions and/or limitations placed on the utility of the results by those making (whichever) respective argument.

Thus your critique as phrased may be considered laughable nonsense. I suspect that Miskolczi discussion is quite beyond JREF, it is quite technical.

 

[CapelDodger]

At some later date something (presumably the same thing that made it warm in the first place) triggers a cooling. This is the point. The CO2 is still up there. The positive feedback loop is in full swing and yet it still cools. The CO2 which materially effected the warming now is powerless to stop the cooling.

Help me. Explain how this could be so. If the trigger event is strong enough to overwhelm the greenhouse effect then why invoke CO2 at all.

You misunderstand what a positive feedback is. It isn't a warming feedback, it's a feedback which amplifies the forcing.

As the oceans cool they absorb CO2, thus amplifying the Milankovich cooling by removing it from the atmosphere.

If someone could just give me a simple, logical answer to this question I’d go away and darken your door no longer.

No need to be a stranger .

 

[CapelDodger]

If whatever caused the initial warming trigger then reverses cooling begins. As the oceans and permafrost cool they reabsorb the CO2 they previously gave up, which accelerates the cooling. So a positive feedback during a positive external forcing becomes a negative feedback during a negative external forcing.

It remains a positive feedback. Let's not reinforce confusion .

 

[CapelDodger]

Actually, a negative effect in response to a negative forcing is still a positive feedback. A negative feedback is something that works in the opposite direction to a forcing in either direction. Sorry, but my pedantic streak refused to let that one slip.

I've made the mistake of responding from the top instead of reading from the top beforehand .

 

[CapelDodger]

Whatever else some of us might think about McIntyre, he's not an idiot. He doesn't do science; he does stats.

What McIntyre mostly does is keep himself in the limelight.

He's quite happy to provide a forum for others to argue sciency stuff, although he takes pains to keep things on topic and he quashes the fantasists. He knows that they hurt his credibility.

And in the process has become an icon in a small world. As you say, no idiot. Anyone who can leverage an invitation from Inhofe to McIntyre's current status has a mind to be reckoned with. He's not a force to be reckoned with, of course.