When assessing any study there are three questions you need to answer.

1. Why was the study done?

2. How was the stuidy done?

3. Do the principles behind the study have even the slightest idea of what they're talking about?

We should chill and enjoy the girl, which is probably her desire anyway.

The Venusian atmosphere is so high in CO2 for a few reasons. One is that there is essentially no CO2 bound into rocks, which is far from being the case on Earth. The reason for no CO2 in Venusian rocks is precisely because it's so hot and carbonate rocks are unstable at high temperatures.

The current theory about the evolution of the runaway greenhouse on Venus is that the water present, initially, on Venus in roughly the same amount as here became essentially all vapour, and H20 is of course a very good greenhouse gas; then solar ultraviolet split the water and the hydrogen rapidly escaped. Meanwhile, all the CO2 present in carbonates on Venus was turned into free gas.

If it happens here, it won't happen the same way - not quite. But there are several ways in which greenhouse warming could become uncontrollable. One involves the fact that CO2 makes ocean water more acid; we are not very far off the point where various marine plant organisms become unable to make their carbonate shells. This increases CO2 in two ways, direct and indirect. Direct; that CO2 in shells isn't in the water or the air. Indirect; that the plants presumably need those shells and without them will die - and therefore stop incorporating CO2 into their own tissues.

It is also known that tropical rainforests and deciduous forests sequester less CO2 the hotter it gets, because decomposition of leaf litter is faster and therefore CO2 is released into the air faster.

There is also the point that CO2 is not the only greenhouse gas. Methane is far better at it. There are very large reservoirs of methane in arctic permafrost which is beginning, already, to melt and release their methane during the summer, and there are also reserves of methane in deep-ocean sediments all over the place and in shallow-sea sediments in the Arctic, bound into clathrates which are not particularly stable. If the sediment on the bottom of the Gulf of Mexico, for example, becomes somewhat warmer then there is a potential for a sudden release of gigatons of methane - which would not only destroy a unique ecosystem but create a large, sudden spike in global warming - which would probably trigger similar releases elsewhere.

In short, there is a point, somewhere in the ever-upward curve of global temperature, where the system goes into uncontrollable positive feedback. Once that happens it may well be that it doesn't stop until the oceans have evaporated and the global temperature is several hundred degrees - in fact, it wouldn't stop there, because volcanoes wouldn't stop releasing CO2 and the high temperatures would start cooking it out of carbonates.

The ultimate result of this would not be a Venus-style hothouse. It would be worse - more greenhouse gas.

Nobody knows where that tipping point is. I would prefer my sister's great-grandchildren not to find out the hard way because Americans won't stop wasting fuel (and by the way giving a terrible example to emerging countries such as China).

And the word was made flesh, and dwelt among us at Hooters.

I see a typo. She needs some white out.

Fletcher,

You'd better head back to Pitcairn or to the bomb-shelter/ark/compound, your paranoia is showing. Your "data-points" do not a theory prove. You may as well talk about the radioactive isotopes in a volcano reaching "critical mass" and setting the world on fire. Tipping point, my ass. Get a grip, guy, and learn some science. Think cosmic, not comic.

Fletcher...

"uncontrollable positive feedback...much worse than a Venus-style hothouse"

You're bat-shit crazy dude.

What is Gerard's phrase? Intellectually insane?

twolaneflash:

Will an science honours degree from Cambridge University do?

I have seen some work (academic papers) on global climatology simulations, with some references to chaos theory. There appear to be three attractors in the system. One is Snowball Earth, stable on a historical (but not on geological) timescale - eventually it stops because CO2 is emitted by volcanoes and is not absorbed. One is a climate much like the one we have now, with maybe minor variations.

And one is Hell. That one is stable short of major astro-engineering effort.

If, by some luck, this happens AFTER we manage to colonise space, your descendants may well be some of those who terraform Earth.

Never mind, America, keep using twice as much fuel as any other country on Earth per capita, and wasting a good half of it on driving two-ton cars to collect a bottle of milk; something might turn up.

Yes, Fletcher, and you give away your real thoughts in your last paragraph, don't you? Not science, apparently.

The sister's descendants are an interesting angle as well. People with children often view legacy differently than those without them. Your playing the deep concern card rings a bit odd to me, who has four sons.

Your actual motives are leaking out all over the page, and you might wish to reflect on that.

Fletcher,

It's a sad comment that citing "academic papers" is no longer grounds to believe anything said, because it has become ever clearer that said "academics" are using methodology and data which are, to be charitable, suspect.

To use my own particular field of expertise (statistical model design): the simplest and most basic test to be performed on any predictive model is using t-1000 data to predict t-1 (ie. using large amounts of distant historical data to predict the recent past).

Not ONE climatological predictive model extant can predict yesterday's temperature with a satisfactory level of confidence. In many cases, the level of predictability is about the same as tossing a coin (50%). In fact, most of the models predict the same outcome almost without regard for the input data, which means that the weighting factors (the key to successful models) have been expanded and distorted to the point where the data itself has a value of 1.

Yet all these models have been designed by academics with impeccable credentials.

Why then, should we believe that their models are the result of anything other than an issue-driven agenda?

Fletcher,
That last line gave the whole game away...climate hysteria as a vehicle to bash America. You need to work on making your motive a bit more transparent.

Mr. Idiot:

"Playing the deep concern card" and regarding descendants; well, I mentioned my sister's descendants because I'm never going to have any for reasons that are none of your damn business.

As for the last paragraph - well, personally, I don't dive a damn whether Americans kill themselves through gross overeating and under-exercising, filling their food with chemicals for short-term profit or turning their cities' air into poison gas - not to mention handing terrorists billions of dollars to kill Americans (and others) with.

What I do mind is that Americans are setting a bad example for everyone else; as a small example the streets of Britain are filled with grotesquely large 4x4s. I am quite sure the fashion comes from across the pond. As another, the Chinese might well ask why they should restrict their economic growth when America already uses many times more fuel than they do - and they'd be right.

What I do mind is various American corporations not only trying to foist their Frankenstein food on us, but trying to make it impossible for us to tell that they are doing it - did you know that Monsanto are claiming in various court cases that labelling of food containing GM soya is against free trade treaties?

I could go on - but I won't, except to say two things. Americans' bad habits are a poor example for everyone else - and America's gluttony for oil in particular, and their actions to make sure it gets fed, and the money transfers resulting from it, make the rest of the world much more dangerous.

Thanks Fletcher. A considered and interesting response which I take up in some detail ">http://americandigest.org/mt-archives/006640.php> HERE.