When rstuart makes a political alliance with Pericles on defining subjects like the power of the Global Resreve Banks,then there are serious doubts about his intentions.These two have ganged up upon myself in ad hominem on my general discussion thread,'The Revolution in Europe has Begun' and not argued any logic I've presented.Rstuart has an agenda and it is not truth or integrity to benefit all humanity.

@RStuart,

<<It looks to me like you haven't taken the time at least come to grips with the basic science, preferring instead to take pot shots from the sidelines>>

"Pot shots"?
‘Twas more like a ruddy great barrage that brought down your mainsail (you're the one for pot shots... and maybe some whisky shots too!) .

380 ppm of CO2 (to borrow a line from Poirot) caused “a monumental departure from the previous state of affair” in just 100-200 years , yet 6000-7000 ppm took 25 mil years!

Unable to give an effective answer , you reverted to the classic believers rouse of telling the sceptic they just don’t understand, or asking them to look a little harder and they will surely see.


<< The science we are discussing here is pretty simple stuff compared to what they actually do to model climate. I don't understand it. It's not for lack of trying in my spare time. I suspect to understand it and get some confidence in what they are doing I would have to literally take time off for weeks, understand the equations they are using, design my own models, compare the output of the models to real world data sets… almost all people who study the climate think the models are accurate if not enough to remove all lingering doubts for me.>>

If you are that impressed with climate models . You would have been blown away by some of the financial modelling invented by quants in the pre-global financial crisis world. Everyone who used their models thought they worked wonders too -- till they lost their shirts.

Strangely enough, your climate models will have us losing our shirts too --- with the unilateral carbon tax and the like.

@SPQR,

The answer was in the questions I posed. You just didn't look.

Quiz answers, from http://en.wikipedia.org/wiki/Greenhouse_gas :

- The greenhouse effect of CO2 increases with the log of the concentration. Thus a 380 to 7000 isn't the 18 times increase. It's under a 4 times increase.

- The major greenhouse is water vapour, not CO2. The effect of CO2 is minor. In triggers a tiny rise in the temperature, which increases the amount of water vapour, which triggers another rise, which causes yet more water vapour to enter atmosphere and on and on.

Finally, the greenhouse effect depends energy from the sun being absorbed and re-radiated as heat. The sunlight passes through the greenhouse gases easily. The re-radiated infra-red doesn't, so it is trapped. Our planet has lots of dark green/brown/blue surfaces right now, so this absorb/re-radiate mechanism dominates.

OK, so with the physics in place it's time develop our climate model for snowball earth.

1. The 7000ppm CO2 has a fraction of the effect 400/7000 ratio implies because adding CO2 gets diminishing returns, and because CO2 isn't a strong greenhouse gas.

2. The major greenhouse gas, water vapour, is mostly absent because the seas are frozen and the air is cold.

3. The planet is a shiny white colour. The sun's energy isn't being absorbed and re-radiated back at a lower frequency, it is mostly being reflected at the same frequency and that frequency isn't a effected by CO2.

Put it all together and the wonder isn't that it took 25 million years to melt snowball earth. The wonder is it melted at all.

@SPQR: Unable to give an effective answer, you reverted to the classic believers rouse of telling the sceptic they just don’t understand

So you have learnt several things today. One is about snowball earth, another is you truly didn't understand, and finally how a person might go about testing if you are more interested in taking pot shots than engaging in the debate at hand.

@ RStuart,

Thank you for your climate science 101 tute –now we’ll tell you where you went wrong:

<< The greenhouse effect of CO2 increases with the log of the concentration. Thus a 380 to 7000 isn't the 18 times increase. It's under a 4 times increase.>>
The key point –which you seem intent on trying to redefine away – is that CO2 concentrations during the cold Neoproterozoic era were many times more than they are today.

<< CO2 … triggers a … rise in the temperature, which increases the amount of water vapour, which triggers another rise, which causes yet more water vapour to enter atmosphere and on and on>>
Except, there wasn’t a progressive warming as you imply. There might well have been “ at least two and possibly up to six 'snowball' phases between 750 million and 580 million years ago”

<<The planet is a shiny white colour. The sun's energy … is mostly being reflected >>
The planet MIGHT have been a shiny white ball if what occurred had matched the classic snowball Earth description. Except, we now know there was no all Earth encompassing snowball. And how do we know this? Because we are finding areas of the Earth that were never covered by ice during any of the ice periods. And because the climate models which you are usually very enamored with cannot produce a whole Earth snowball.In such models the tropics are left ice-free. And if the tropics are not a “shiny white colour ” they were likely to have been “lots of dark green/brown/blue” colours absorbing lots of energy.And why is that especially significant ? Because most of the sun energy falls on the tropics.

<< The major greenhouse gas, water vapour, is mostly absent because the seas are frozen and the air is cold>>
Your wording here is (deliberately) misleading. Cold air is not devoid of water vapour.
And the same volcanic activity which is thought to have released the CO2 would have released huge volumes of water vapour : http://en.wikipedia.org/wiki/Volcanic_gas

@SPQR: The key point –which you seem intent on trying to redefine away – is that CO2 concentrations during the cold Neoproterozoic era were many times more than they are today.

No, the key point is the greenhouse effect of the CO2 was less than 4 times, and that is 4 times of "not much" because CO2 isn't the strongest greenhouse gas. We are discussing physics here, not morals or ethics. You can not refine the physics of a gas away. It is what it is - hard, real and unchanging.

@SPQR: Because we are finding areas of the Earth that were never covered by ice during any of the ice periods.

Your original query was: if there was a snowball earth, how come it took 25 million years to melt. I am answering that. We both agree snowball earth theory is somewhat speculative, the degree it to which it happened under debate, that includes the thing you are taking exception to: that they lasted 25 million years. The point you are making here is if you vary your original question and the earth wasn't really a snowball, or it didn't last 25 million years, then my answer may not apply. Your probably right, but I do not have the time nor inclination to address every scenario you dream up.

@SPQR: Your wording here is (deliberately) misleading. Cold air is not devoid of water vapour.

No, my wording was spot on accurate. The amount of water vapour the air can hold varies with temperature. It's an exponential relationship, which roughly translates to the air holding bugger all until it gets to 0C, then going up rapidly thereafter with increasing temperature. http://en.wikipedia.org/wiki/Vapour_pressure_of_water

@SPQR: And the same volcanic activity which is thought to have released the CO2 would have released huge volumes of water vapour

Irrelevant. What happens when the hot water vapour from the volcanoes hits the air? It cools obviously, and as soon as it does the vapour pressure law quoted above means it condenses out.

@RStuart,

<<We are discussing physics here, not morals or ethics.>>
No. One of us is using physics to hype "the greatest moral” crusade of our time ---And, it certainly ain’t me!

<< the key point is the greenhouse effect of the CO2 was less than 4 times, and that is 4 times of "not much">>
However you might try to reframe it. If an increase of CO2 from “ pre-industrial … 280 ppms to 379 ppm in 2005” resulted in an increase in global temperature (more than IC over the continents),the worldwide retreat glaciers, the extensive loss permafrost & sea ice , and worldwide expansion of deserts. And had the strongest impact on the higher colder latitudes.[and according to this it did: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf] It is entirely reasonable to have expected the higher levels of Neoproterozoic CO2 to have had a greater impact.

<< Your original query was: if there was a snowball earth, how come it took 25 million years to melt. I am answering that>>
No , if you care to go back and read it (and you could benefit from reading it multiple times!). It said, it was incredible that it took 25 million year for such high levels of CO2 to melt a SNOWBALL EARTH. BUT (and this was the part you missed) given that evidence is now coming in that there was NO whole Earth encompassing ice sheet, it is even more incredible it took 25 million year to heat up!

<<No, my wording was spot on accurate. The amount of water vapour the air can hold varies with temperature>>
Your original wording : “water vapour, is mostly absent because the seas are frozen and the air is cold.” Plays on the (false) image of as solid snowball Earth with worldwide Antarctic conditions.Given what we are now finding there was likely to have been a variety of climate zones on Neoproterozoic Earth. Water vapour is likely to have been a lot more prevalent than you allow for.

<< when the hot water vapour from the volcanoes hits the air? It cools >>
Ditto previous point.