Antarctic Ice Sheet Collapse

[brennan]

Independant think tank?

Climate scientists from NASA, Stanford University and Princeton dismissed Singer's most recent report on global warming as "fabricated nonsense." Singer admits accepting $10,000 from Exxon.[27]

Thanks for the reference. Talk about your known hack. I particularly liked this bit on his expertise about climate and weather:

Spoiler :

Dr. S. Fred Singer debated Carl Sagan on the impact of the Kuwaiti petroleum fires on the ABC News program Nightline. Sagan said we know from the nuclear winter investigation that the smoke would loft into the upper atmosphere and that he believed the net effects would be very similar to the explosion of the Indonesian volcano Tambora in 1815, which resulted in the year 1816 being known as the year without a summer, in massive agricultural failures, in very serious human suffering and, in some cases, starvation. He predicted the same for south Asia, and perhaps for a significant fraction of the northern hemisphere as well as a result. Singer, on the other hand, said that calculations showed that the smoke would go to an altitude of about 3,000 feet and then be rained out after about three to five days and thus the lifetime of the smoke would be limited.[16] In retrospect, we now know that smoke from the Kuwait Oil Fires dominated the weather pattern throughout the Persian Gulf and surrounding region during 1991, and that lower atmospheric wind blew the smoke along the eastern half of the Arabian Peninsula, and cities like Dhahran, Riyadh and Bahrain experienced days with smoke filled skies and carbon fallout.."[17]

People who stick out for disagreeing with the actual experts tend to deserve their label as hacks.

Go right ahead and show me the scientific credentials of the others. I'm really not daunted by this first attempt.

As Basketcase would say, the science stands up on its own. Unfortunately you need a modicum of understanding to understand what that actually means.

 

[skadistic]

Independant think tank?
Thanks for the reference. Talk about your known hack. I particularly liked this bit on his expertise about climate and weather:

Spoiler :

Dr. S. Fred Singer debated Carl Sagan on the impact of the Kuwaiti petroleum fires on the ABC News program Nightline. Sagan said we know from the nuclear winter investigation that the smoke would loft into the upper atmosphere and that he believed the net effects would be very similar to the explosion of the Indonesian volcano Tambora in 1815, which resulted in the year 1816 being known as the year without a summer, in massive agricultural failures, in very serious human suffering and, in some cases, starvation. He predicted the same for south Asia, and perhaps for a significant fraction of the northern hemisphere as well as a result. Singer, on the other hand, said that calculations showed that the smoke would go to an altitude of about 3,000 feet and then be rained out after about three to five days and thus the lifetime of the smoke would be limited.[16] In retrospect, we now know that smoke from the Kuwait Oil Fires dominated the weather pattern throughout the Persian Gulf and surrounding region during 1991, and that lower atmospheric wind blew the smoke along the eastern half of the Arabian Peninsula, and cities like Dhahran, Riyadh and Bahrain experienced days with smoke filled skies and carbon fallout.."[17]

People who stick out for disagreeing with the actual experts tend to deserve their label as hacks.

Go right ahead and show me the scientific credentials of the others. I'm really not daunted by this first attempt.

As Basketcase would say, the science stands up on its own. Unfortunately you need a modicum of understanding to understand what that actually means.

Yup keep up those ad hominem attacks.

You read that right people. If you dare to offer a different opinion is science you are a hack.

http://www.heartland.org/NewYork08/newyork08.cfm

* No corporate dollars were used to help finance this conference.

* The Heartland Institute has 2,700 donors, and gets about 16 percent of its income from corporations.

* Heartland gets less than 5 percent of its income from all energy-producing companies combined. We are 95 percent carbon free.

And let me further add to the record:

* The honoraria paid to all of the speakers appearing at this conference add up to less than the honorarium Al Gore gets paid for making a single speech, and less than what his company makes selling fake carbon “off-sets” in a week.

* It is no crime for a think tank or advocacy group to accept corporate funding. In fact, corporations that fail to step forward and assure that sensible voices are heard in this debate are doing their shareholders, and their countries, a grave disservice.

But hey its ok for scientists to take money for grants that "prove" global warming right?

We have with us, tonight and tomorrow, more than 200 scientists and other experts on climate change, from Australia, Canada, England, France, Hungary, New Zealand, Poland, Russia, Sweden, and of course the United States.

They come from the University of Alabama, Arizona State, Carleton, Central Queensland, Delaware, Durham, and Florida State University.

From George Mason, Harvard, The Institute Pasteur in Paris, James Cook, John Moores, Johns Hopkins, and the London School of Economics.

From The University of Mississippi, Monash, Nottingham, Ohio State, Oregon State, Oslo, Ottawa, Rochester, Rockefeller, and the Royal Institute of Technology in Stockholm.

And from the Russian Academy of Sciences, Suffolk University, the University of Virginia, Westminster School of Business (in London), and the Wharton School at the University of Pennsylvania.

I guess all those people are hacks too. huh?

No "experts" there. All hacks.


Intellectual honesty. You should try some.

 

[Erik Mesoy]

Independant think tank?
Thanks for the reference. Talk about your known hack. I particularly liked this bit on his expertise about climate and weather:
<long spoiler removed>
People who stick out for disagreeing with the actual experts tend to deserve their label as hacks.

Go right ahead and show me the scientific credentials of the others. I'm really not daunted by this first attempt.

As Basketcase would say, the science stands up on its own. Unfortunately you need a modicum of understanding to understand what that actually means.

Yup keep up those ad hominem attacks.

An ad hominem attack is when someone says something like "Person X is wrong because Person X is ugly". Please point out the ad hominem, because I don't see it. All I see is "This guy is wrong because he doesn't know what he's talking about, and here are examples of him not knowing what he's talking about", which is perfectly legitimate.

Intellectual honesty. You should try some.

Pot. Kettle.

 

[skadistic]

An ad hominem attack is when someone says something like "Person X is wrong because Person X is ugly". Please point out the ad hominem, because I don't see it. All I see is "This guy is wrong because he doesn't know what he's talking about, and here are examples of him not knowing what he's talking about", which is perfectly legitimate.

This guy is wrong because he is a hack. "People who stick out for disagreeing with the actual experts tend to deserve their label as hacks." That wasn't very hard to miss. But hey I'm sure all the other people who are participents in that study are hacks too. Nope not a single scientist in there. Speaking of scientists What does the Dr. in Dr. S. Fred Singer stand for again?


But scientists can't ever be wrong can they? Even when they are experts right? Just like the "experts" are right about global warming.... er I mean global climate change now. They can't possible be wrong can they? No they can't. Only those who don't agree are wrong........

Pot. Kettle.

So witch are you and witch is brennan?

 

[Erik Mesoy]

This guy is wrong because he is a hack. "People who stick out for disagreeing with the actual experts tend to deserve their label as hacks." That wasn't very hard to miss.

I'll have to check with brennan to be sure, but I'm strongly under the impression that "hack" is here used as a shorthand indicating, among other things, that Singer doesn't know what he's talking about.

But hey I'm sure all the other people who are participents in that study are hacks too. Nope not a single scientist in there. Speaking of scientists What does the Dr. in Dr. S. Fred Singer stand for again?

It stands for something like "I have a degree". The question isn't whether he's a scientist (that way lies the appeal to authority fallacy), but whether he's a climatologist or the like (legitimate authority). And his degrees are in physics and electrical engineering.

But scientists can't ever be wrong can they?

Yes, they can. This is a strawman.

Even when they are experts right?

This is another strawman. What I'm arguing, and that I think brennan is arguing (brennan, can you confirm?), is that the experts in the relevant field(s) are greatly more likely to be right than wrong about global warming, and also that they are more likely to be right about global warming than experts in other fields, who for the purposes of this discussion it would be easier to refer to as "non-experts".

<snip extended strawmannery>

So witch are you and witch is brennan?

That makes no sense.

 

[brennan]

No, this guy is wrong because he is wrong.

BTW The irony of people who call supporters of a well established and well supported scientific theory 'alarmists' and then attacking their critics for 'ad hominem attacks' is quite delicious.

That entire article is an ad hom on the consensus; It makes absolutely no effect to address issues.

The science of global warming critics is suspect at best. As is shown repeatedly on these threads.

Scientists are paid grants by funding bodies who are interested in scientific content: they get paid for demonstrating that they are conducting and publishing good solid science. Hacks get paid by Corporations for conducting flawed research (that will never be published anywhere reputable) in order to support corporate lobbyists. This guy is a hack. When he was paid by Phillip Morris he said passive smoking was junk science, now he's paid by a bloody great oil corporation he says global warming ain't down to humans. His credibility is zero and his research on a variety of issues is demonstrably incorrect.

Let's look at the report you linked to shall we?:

Foreword
The IPCC is pre-programmed to produce reports
to support the hypotheses of anthropogenic warming
and the control of greenhouse gases

Yup, that's an analysis of the science all right; and these guys attack us for ad homs?

Preface
Before facing major surgery, wouldn&#8217;t you want a
second opinion?
When a nation faces an important decision that
risks its economic future, or perhaps the fate of the
ecology, it should do the same.

That's right, they want to be considered plausible because they disagree with the consensus. There's no attempt to present a scientific, evidence based argument yet, they just want you to think of them as the good guys. Remind you at all of 'teach the controversy'?
The preface then embarks on a lengthy character assasination of the IPCC including fabulous red-herrings like this:
"While we are often told about the thousands of scientists on whose work the Assessment reports are based, the vast majority of these scientists have no direct influence on the conclusions expressed by the IPCC. Those are produced by an inner core of scientists, and the SPMs are revised and agreed to, line-by-line, by representatives of member governments. This obviously is not how real scientific research is reviewed and published." ...and tell us, how many of these scientists actually object to the IPCC's assessment of their work...? Is it none perhaps?

I was going to comment upon the science, but was unable to find any. The main body is 100% full of assertions "correlation is poor" with no attempt at proper analysis, and the sort of 'yeah but' arguments BaskeCase makes.

If these guys were to try to publish a paper like this in a journal their careers would be over.

Edited to remove odd formatting.

Erik: A Hack gets his label because his work is demonstrably false/unreliable and because he obviously has an agenda, usually attributable to his financial backing. For all I know this guy knows exactly what he is talking about, but he just says what he needs to to get his paycheck. All that is important is that his work is wrong. And the piece Skadistic linked to actually contains bugger all science.

Edit 2: to clarify: brennan is actually a tea-cosy

 

[skadistic]

I'll have to check with brennan to be sure, but I'm strongly under the impression that "hack" is here used as a shorthand indicating, among other things, that Singer doesn't know what he's talking about.You're right how could someone in a field of science know what hes talking about......

It stands for something like "I have a degree". The question isn't whether he's a scientist (that way lies the appeal to authority fallacy), but whether he's a climatologist or the like (legitimate authority). And his degrees are in physics and electrical engineering.Yup no physicist would ever understand climate. They have no overlap at all...........


Yes, they can. This is a strawman.Wait so pointing out scientist can be wrong is a strawman now. Wow.

This is another strawman.So experts being wrong is a strawman? Incredable. What I'm arguing, and that I think brennan is arguing (brennan, can you confirm?), is that the experts in the relevant field(s) are greatly more likely to be right than wrong about global warming, Ok so when experts disagree with the "consensus" they are more likely wrong or right?and also that they are more likely to be right about global warming than experts in other fields, who for the purposes of this discussion it would be easier to refer to as "non-experts".Right so only the ones who are climantologists and agree with the alarmists are right. Gotcha.

<snip extended strawmannery>

That makes no sense.

Sure it does. Maybe you should get an expert to explain it to you. But make sure he is in the "consensus" so you know he is right.

 

[brennan]

Have you got any science you'd like to discuss, or are you going to carry on bleating about ad-hominems?

 

[skadistic]

No, this guy is wrong because he is wrong.Really? Is it because you looked at his data or because he isn't in the "consensus" What about all the others who are experts that agree with him?

BTW The irony of people who call supporters of a well established and well supported scientific theory 'alarmists' and then attacking their critics for 'ad hominem attacks' is quite delicious.Except its not well established or well supported. Unless you think there is a "consensus".

That entire article is an ad hom on the consensus; It makes absolutely no effect to address issues.Right because the "consensus" is all that matters and every one out side of it is a hack.

The science of global warming critics is suspect at best. As is shown repeatedly on these threads.The science of global warming as man made is suspect at best as shown in these threads. BUt thats all from hacks outside the "consensus" so it doesn't matter.

Scientists are paid grants by funding bodies who are interested in scientific content: Yeah There is no political tilt at all in funding. I bets much easier to get a grant that says you will show there is global warming then isn't.they get paid for demonstrating that they are conducting and publishing good solid science.So all the global warming studies that show its mans fault are pure science and with out fault. Hacks get paid by Corporations for conducting flawed research So anything outside of the consensus is a hack and uses flawed science. Gotcha.(that will never be published anywhere reputable) in order to support corporate lobbyists.So despite getting the funding after the study..... This guy is a hack. Right because he disagrees with you we get it.When he was paid by Phillip Morris he said passive smoking was junk science,And so did others. now he's paid by a bloody great oil corporation he says global warming ain't down to humans. Man did they pay a lot too. Yup its all those evil corps. Governments never have an agenda when giving out grants do they. Nope never ever would that happen.His credibility is zero and his research on a variety of issues is demonstrably incorrect.His creadability is zero because hes a ahack beacuse he doesn't follow your agenda.

Let's look at the report you linked to shall we?:
Yup, that's an analysis of the science all right; and these guys attack us for ad homs?So the study is wrong? How exactly?
That's right, they want to be considered plausible because they disagree with the consensus. There's no attempt to present a scientific, evidence based argument yet, they just want you to think of them as the good guys. Remind you at all of 'teach the controversy'?So what exactly is wrong with the study? Where exactly is it wrong because it was bought for by the evil corps?
The preface then embarks on a lengthy character assasination of the IPCC including fabulous red-herrings like this: Wait are complaining about the "hack" saying you side isn't 100% correct?
"While we are often told about the thousands of scientists on whose work the Assessment reports are based, the vast majority of these scientists have no direct influence on the conclusions expressed by the IPCC. Those are produced by an inner core of scientists, and the SPMs are revised and agreed to, line-by-line, by representatives of member governments. This obviously is not how real scientific research is reviewed and published." ...and tell us, how many of these scientists actually object to the IPCC's assessment of their work...? Is it none perhaps?Perhaps or perhaps Kevin Trenberth thinks the IPCC overstepped its findings and claimed things it shouldn't have.

I was going to comment upon the science, but was unable to find any. The main body is 100% full of assertions "correlation is poor" with no attempt at proper analysis, and the sort of 'yeah but' arguments BaskeCase makes.NO attempt? So you have read the whole study and just the released summery? Where did you find that?

If these guys were to try to publish a paper like this in a journal their careers would be over.Right because those who are against the "consensus" find it hard to get funding.

Edited to remove odd formatting.

Erik: A Hack gets his label because his work is demonstrably false/unreliable and because he obviously has an agenda, usually attributable to his financial backing. For all I know this guy knows exactly what he is talking about, but he just says what he needs to to get his paycheck. All that is important is that his work is wrong. And the piece Skadistic linked to actually contains bugger all science.Yup being wrong makes one a hack. I guess Hawking is a hack too since hes been wrong. And remember only corps have agendas when they back something but never governments or the UN.

Edit 2: to clarify: brennan is actually a tea-cosy

Summery: Any one who doubts global warming is man made is a hack.

 

[skadistic]

Have you got any science you'd like to discuss, or are you going to carry on bleating about ad-hominems?

I don't know I guess scientific conclusions by scientists aren't science enough. Maybe I should bring up some other experts so you can call them hacks because they don't agree with you.

 

[brennan]

Perhaps you'd like to show me what part of the study you linked to counts as proper scientific analysis?

For example when they state that correlation between temperatures and CO2 levels is poor, what method of analysis did the use, what study did they cite? The answer is they didn't and there wasn't. It's just an assertion, and from what I saw that is the modus operandi of the entire piece, that and the presentation of red-herrings like your comment on La Nina in the science forum.

That isn't science my deluded friend. Neither is commenting on the alleged political agenda of the IPCC, which is what half the 'study' is. Neither is making cracks about Al bloody Gore.

 

[skadistic]

Perhaps you'd like to show me what part of the study you linked to counts as proper scientific analysis?

For example when they state that correlation between temperatures and CO2 levels is poor, what method of analysis did the use, what study did they cite? The answer is they didn't and there wasn't. It's just an assertion, and from what I saw that is the modus operandi of the entire piece, that and the presentation of red-herrings like your comment on La Nina in the science forum.

That isn't science my deluded friend. Neither is commenting on the alleged political agenda of the IPCC, which is what half the 'study' is. Neither is making cracks about Al bloody Gore.

I guess you don't understand what a summery is.

So its ok to call those who disagree with the IPCC hacks and bought and paid for by the evil corps but to question the motives of the IPCC is a red herring.

Everything that is against your global warming.... er climate change is a hack and a red herring.

Showing that weather changes = red herring
Pointing out that its colder in a big portion of the northern hemisphere = red herring
El nina = red herring
El nino = red herring
Pointing out that the ICPP has a political agenda = red herring
Anything other then towing the global warming.....er climate change = red herring

Splendid! Enjoy that coolaid

 

[Erik Mesoy]

I am going to wait for a reply that isn't mostly inside a quotebox, and doesn't consist largely of strawmen and equivocation, and preferably contains a couple of continuous paragraphs instead of line-by-line contrarian remarks before I say anything more, because otherwise I might say something overly snide.

 

[ainwood]

Moderator Action: Proper debate, please people.

 

[BasketCase]

Yeah.

Stop the presses. Erik Mesoy and I actually agree on something.

Time for CAKE.

I say that the nonlinearity is on my side, and it's the first increases that are by far the most important, and the later ones are less important. If we increase the CO2 concentration on Earth to double what it is now, the degree to which we are screwed, I say, will increase more than it will increase by our increasing the CO2 concentration by the same amount again afterwards (another 50%).

Okay, we seriously got our wires crossed here.

I agree completely with the above, Erik--that is the whole point I was trying to make. The first time you add X cubic kilometers of CO2 is when you get the most warming. If you add X again, you'll get less. Add X a third time, and you get less than the second time. Right?

You've got it perfect. Here's where you went wrong, and actually it's a minor detail: the non-linear progression must include the CO2 that was already there to begin with. Before humans came along and messed up the system, the planet's atmosphere had something like 200 parts per million of CO2 in it. Add another 200 parts per million, and you'll get less warming than that first 200 ppm was producing.

As we humans dump more and more greenhouse gases into the system, we are contributing to the problem at a slower and slower rate.

Something the Earth hardly ever does. If the planet were capable of a positive-feedback "runaway" we would have seen one.

That's complete crap. I might as well say: "If the galaxy were capable of harboring other sentient life, we would have seen some."

Bad example--we can't see the entire galaxy. We can see the entire Earth, and our skills at geology and archaeology give us a pretty complete picture of how the planet's environment has changed over the eons. We can estimate past CO2 concentrations from ice cores; we can see sudden changes in the planet's climate (and this has happened many times) from changes in sediment composition and layering, as well as sudden changes in the fossil records. When 90% of all the planet's species die off, it's clearly visible in the fossils we dig up.

There have been many periods in Earth's history where CO2 concentrations were much higher than today--during which positive-feedback runaways did not occur.

Now, there are a large number of potholes to watch out for here. Our view of the Earth's climate history is definitely not perfect. Maybe a climate hiccup occurred and we simply haven't found evidence of it yet. Maybe the complexity of the system prevented hiccups that were supposed to happen.

Those caveats do not mean the entire idea should be discarded as false. If you're not sure, you can't say "false". YOu have to say what BasketCase says:


And BasketCase says "undecided".


I am not sure if human beings are causing global warming.

 

[Berzerker]

Hey Brennan, did you read your link about Sagan and Singer? Singer was right and Sagan was off the wall...

Sagan

he believed the net effects would be very similar to the explosion of the Indonesian volcano Tambora in 1815, which resulted in the year 1816 being known as the year without a summer, in massive agricultural failures, in very serious human suffering and, in some cases, starvation.

Singer

Singer, on the other hand, said that calculations showed that the smoke would go to an altitude of about 3,000 feet and then be rained out after about three to five days and thus the lifetime of the smoke would be limited.

Compare

In retrospect, we now know that smoke from the Kuwait Oil Fires dominated the weather pattern throughout the Persian Gulf and surrounding region during 1991, and that lower atmospheric wind blew the smoke along the eastern half of the Arabian Peninsula, and cities like Dhahran, Riyadh and Bahrain experienced days with smoke filled skies and carbon fallout..

Why did you post that to discredit Singer?

 

[Berzerker]

You stated two specific differences between the two planets, you have now twice failed to tell me why these differences are relevant to a discussion of Terran cclimate change...

I told you the differences and why they are relevant, I'll repeat myself

Venus is upside down, not spinning, with no magnetic field for protection. It is a dead planet... What more do you need explained? That the Earth spins and has a magnetic field and is not a dead planet?

 

[BasketCase]

I think I just found the real motivation behind the environmental lobby.

A Smoking Gun

Australia has begun pumping carbon dioxide underground to reduce greenhouse gas emissions, using a technology that locks dangerous gases deep in the Earth.

Officials opened a plant in southern Victoria state on Wednesday that they said would capture and compress 110,231 tons of carbon dioxide from industry emissions and then inject it 6,500 feet underground into a depleted natural gas reservoir.

The research and demonstration project has been developed with federal and state government support.

Australia is one of only a handful of places that uses the technology, known as geosequestration, and environmentalists immediately criticized the project as a token gesture that distracts from the bigger goal of getting industry to slash emissions.

The minority Greens political party said the project would achieve little and should be abandoned in favor of plans that would achieve much bigger emission cuts.

The project "is government-funded PR for the coal sector and would be a perfect place to start for a government looking to find budget cuts," Green Party Sen. Christine Milne said.

Officials said scientists at the site would monitor the reservoir to measure gas leaks and other factors, with the ultimate aim of demonstrating that geosequestration is a safe, viable way to combat global warming on a large scale.

"The project has a very important role in demonstrating the technical and environmental feasibility of geosequestration to Australia and the world and preparing the way for its widespread application," Peter Cook, the project's chief executive, said in a statement.

The technology is similar to that used at about 144 sites in the United States, where carbon dioxide is injected underground to help recover oil reserves.

Since 1996, 1.1 million tons of carbon dioxide a year have been injected under the Sleiper oil field in the North Sea and about the same amount under Algeria's In Salah gas fields in the past two years.

If global warming is such a dire threat--and especially in light of the fact that the U.S. keeps refusing to toe the environmentalist line--then a sequestration program should be a good thing.

But is that really what environmentalists want?

Or do they already have their guns trained on automobiles and factories? Are they trying to stop global warming, or is global warming just a high-yield missile aimed at getting people to do what they want?

This is not a new thing. I've seen anti-nuclear activists do this as well. Back in the 80's, when I spent every day of my life wondering if World War III was about to start, and when the idea of SDI was brand-new, the anti-nuclear wingnuts campaigned AGAINST the SDI program. Yes, anti-nuclear activists campaigning against a system to shoot down nuclear warheads before they hit anything. Why? Because their goal was not to prevent cities from going kaboom. Their STATED goal was to get rid of nuclear weapons, and they were willing to place the entire human race at risk in order to do it. SDI got in the way of their agenda. The threat of total destruction was their weapon--a weapon of fear, aimed at us in an attempt to get us to disarm. Strategic defense was saving the human race in the wrong way, and with anti-nuclear activists, it was not about what was done, but how.


What is it you global warming alarmists actually want?

Don't answer that. I know what you're going to say in here. And when you say it, some of you will be lying.

If global warming is actually a problem, we should be worrying about reducing greenhouse gas levels in the planet's atmosphere. We should not be worrying about how--except, of course, that I'm pretty sure we all agree that exterminating two-thirds of the human race to cut our emissions is not an acceptable solution.

 

[Erik Mesoy]

Stop the presses. Erik Mesoy and I actually agree on something.

Time for CAKE.

Yay!

Okay, we seriously got our wires crossed here.

I agree completely with the above, Erik--that is the whole point I was trying to make. The first time you add X cubic kilometers of CO2 is when you get the most warming. If you add X again, you'll get less. Add X a third time, and you get less than the second time. Right?

On average, yes. This is what Venus tells us. It's not necessarily the case in a specific environment due to feedback effects that may flop it from one stable region to a higher stable region as a result.

You've got it perfect. Here's where you went wrong, and actually it's a minor detail: the non-linear progression must include the CO2 that was already there to begin with. Before humans came along and messed up the system, the planet's atmosphere had something like 200 parts per million of CO2 in it. Add another 200 parts per million, and you'll get less warming than that first 200 ppm was producing.

As we humans dump more and more greenhouse gases into the system, we are contributing to the problem at a slower and slower rate.

Ahhh. I think we've been talking past one another when we say "non-linear".

Let's say the next 200 ppm has two-thirds of the effect of the former 200 ppm. That'll get us... oh, another 20 degrees of warming over the 30 that's making the planet habitable. (Note: The number two-thirds is pulled out of my ass just now and does not have any sources backing it, but it fits nicely with what you said about Venus: if each 200 ppm has two-thirds the effect of the previous, adding 200 ppm a large number of times will approach a three times as high temperature. Also, other caveats about stable states and feedback effects apply.)
Image spoiler:

Spoiler :

Houston, we may have a problem.

Bad example--we can't see the entire galaxy. We can see the entire Earth, and our skills at geology and archaeology give us a pretty complete picture of how the planet's environment has changed over the eons.

Last I checked, we can see the entire galaxy if we're bothered to look at a lot of boring stars with our telescopes, but not the entirety of Earth's history. Wikipedia: "There probably were mass extinctions in the Archean and Proterozoic Eons, but before the Phanerozoic there were no animals with hard body parts to leave a significant fossil record." (article: [wiki]Extinction event[/wiki])

We can estimate past CO2 concentrations from ice cores; we can see sudden changes in the planet's climate (and this has happened many times) from changes in sediment composition and layering, as well as sudden changes in the fossil records. When 90% of all the planet's species die off, it's clearly visible in the fossils we dig up.

I don't mean to sound Creationist on you here, but we can't actually see all of these. Our knowledge of the fossil record is quite incomplete. Attention gets paid to those areas that we know a lot about and those species that we find more fossils of, but there are lots of areas where we go "this species was last seen in this period, and probably went extinct by the end of the next period, because it definitely was extinct by this third period, when s--- happened" or the like.

There have been many periods in Earth's history where CO2 concentrations were much higher than today--during which positive-feedback runaways did not occur.

Which periods? Can it be because it had already occurred and then hit a new threshhold were negative-feedback kicked in? (e.g. if the ice caps start melting, turning light snow into dark water, and this goes on until the ice caps are gone, the runaway will stop.)

Now, there are a large number of potholes to watch out for here. Our view of the Earth's climate history is definitely not perfect. Maybe a climate hiccup occurred and we simply haven't found evidence of it yet. Maybe the complexity of the system prevented hiccups that were supposed to happen.

Those caveats do not mean the entire idea should be discarded as false. If you're not sure, you can't say "false". YOu have to say what BasketCase says:

And BasketCase says "undecided".

I am not sure if human beings are causing global warming.

Outside of mathematics, we are never sure, so this is an unreasonable demand. What we do have is a certainty that we are pumping CO2 into the atmosphere, a set of approximations to how much CO2 various parts of earth put out and in, the knowledge that rising CO2 is associated with increased temperature of an uncertain magnitude, and several global warming-related extinction events in the past. As the Royal Society puts it:
http://journals.royalsociety.org/content/3x081w5n5358qj01
"The past relationship between global temperature and levels of biological diversity is of increasing concern due to anthropogenic climate warming. However, no consistent link between these variables has yet been demonstrated. We analysed the fossil record for the last 520Myr against estimates of low latitude sea surface temperature for the same period. We found that global biodiversity (the richness of families and genera) is related to temperature and has been relatively low during warm ‘greenhouse’ phases, while during the same phases extinction and origination rates of taxonomic lineages have been relatively high. These findings are consistent for terrestrial and marine environments and are robust to a number of alternative assumptions and potential biases. Our results provide the first clear evidence that global climate may explain substantial variation in the fossil record in a simple and consistent manner. Our findings may have implications for extinction and biodiversity change under future climate warming."

But these events have only occurred five times in BILLIONS of years. Plus, the Earth has had many periods where CO2 levels were much higher than they are now--without these Extinction Level Events occurring. The planet has gone along just fine for tens of millions of years at a time, with surface temperatures five to ten degrees warmer than now (Celsius) with life getting along just fine--in fact, better than fine. Plentiful. I'm talking green plants in Siberia.

Five climate runaways over billions of years of history. Those are called what?

Betting odds.

This sounds strange. The interpretation that rings more likely in my ears is that whenever the CO2 level rises drastically, we get an extinction event, and then after it's risen, we get a new state where the planet is five to ten degrees warmer and life flourishes again. "Betting odds" isn't exactly what I'd call it if we are precipitating a grand CO2 level increase, because then the question isn't whether or not we're in an unlucky party of history, but whether or not this is one of the increases that triggers such an event.

Also, I'd like to see a source for the five climate runaways, because I think you may have them confused with the five mass extinction events in history where we lost over 50% of species. There have been a bunch more extinction events where we lost something like 30% of the species.
Image:

Spoiler :

http://commons.wikimedia.org/wiki/Imagehanerozoic_Biodiversity.svg

Because of the large number of cellular-organism-level species, and the fact that extinctions fall disproportionately on larger species, complex species, and species at the top of food chains, even a 10% extinction event will be very nasty. On top of that, extinction of X% of species usually means about half as large a survivor rate* for organisms.

*No, this is not the same as twice the death rate. 60% of species dead and 120% of organisms dead would be silly. 60% of species lost means 40% left, and 20% of organisms left, or 80% death rate.

 

[BasketCase]

Houston, we may have a problem.

On the assumption that you weren't being tongue-in-cheek here, the above is already my opinion on the issue. I'll just take this and let the rest go. No, I still don't agree with a lot of it.