Absoutely Priceless Example of How Poor Alarmists’ Science Can Be

This is absolutely amazing.  I was checking out this article in the Ithaca Journal called "Climate Change 101: Positive Feedback Cycles" based on a pointer from Tom Nelson.

The Journal is right to focus on feedback.  As I have written on numerous occasions, the base effects of CO2 even in the IPCC projections is minimal.  Only by assuming unbelievably high positive feedback numbers does the IPCC and other climate modelers get catastrophic warming forecasts.  Such an assumption is hard to swallow – very few (like, zero) long-term stable natural processes (like climate) are dominated by high positive feedbacks (the IPCC forecasts assume 67-80% feedback factors, leading to forecasts 3x to 5x higher). 

So I guess I have to give kudos to an alarmist article that actually attempts to take on the feedback issue, the most critical, and shakiest, of the climate model assumptions. 

But all their credibility falls apart from the first paragraph.  They begin:

Our world is full of positive feedback cycles, and so is our society.
Popular children’s books like “If You Give a Mouse a Cookie” by Laura
Numeroff are excellent examples. In Numeroff’s tale, a mouse asks for a
cookie, leading it to ask for a glass of milk, and so on, till finally
it asks for another cookie.

Oh my God, they go to a children’s book to prove positive feedback?  If I had gone this route, I probably would have played the "sorcerer’s apprentice" card from Fantasia.  Anyway, they do soon get into real physics in the next paragraph.  Sort of.

Here’s an example everyone in Ithaca can relate to: the snowball. If
you make a small snowball and set it on the top of a hill, what
happens? 1) It begins rolling, and 2) it collects snow as it rolls.
When it collects snow, the snowball becomes heavier, which causes
gravity to pull on it with more force, making the snowball roll faster
down the hill. This causes more snow to collect on the snowball faster,
etc., etc. Get the picture? That is a positive feedback cycle.

OMG, my head is hurting.  Is there a single entry-level physics student who doesn’t know this is wrong?  The speed of a ball rolling downhill (wind resistance ignored) is absolutely unaffected by its weight.  A 10 pound ball would reach the bottom at the same moment as a 100 pound ball.  Do I really need to be lectured by someone who does not understand even the most basic of Newtonian physics.  (I would have to think about what increasing diameter would do to a ball rolling downhill and its speed — but the author’s argument is about weight, not size, so this is irrelevant."

Do you really need any more?  This guy has already disqualified himself from lecturing to us about physical processes.  But lets get a bit more:

And what happens to the snowball? Eventually the hill flattens and the
ball comes to a stop. But if the hill continued forever, the snowball
would reach some critical threshold. It would become too big to hold
itself together at the raging speed it was traveling down the hill and
it would fall apart. Before the snowball formed, it was at equilibrium
with its surroundings, and after it falls apart, it may again reach an
equilibrium, but the journey is fast-paced and unpredictable.

Two problems:  1) In nature, "hills" are never infinitely long.  And any hills that are infinitely long with minimal starting energy would find everything at the bottom of the hill long before we came into being 12 billion years or so into the history of the universe.  2)  Climate is a long-term quite stable process.  It oscillates some, but never runs away.  Temperatures in the past have already been many degrees higher and lower than they are today.  If a degree or so is all it takes to start the climate snowball running down the infinite hill, then the climate should have already run down this hill in the past, but it never has.  That is because long-term stable natural processes are generally dominated by negative, not positive, feedback. [ed: fixed this, had it backwards]

The author goes on to discuss a couple of well-known possible positive feedback factors – increases in water vapor and ice albedo.  But it completely fails to mention well-understood negative feedback factors, including cloud formation.  In fact, though most climate models assume positive feedback from the net of water processes (water vapor increase and cloud formation), in fact the IPCC admits we don’t even know the net sign of these factors.  And most recent published work on feedback factors have demonstrated that climate does not seem to be dominated by positive feedback factors.

It hardly goes without saying that an author who begins with a children’s book and a flawed physics example can’t take credit for being very scientific.  But perhaps his worst failing of all is discussing a process that has counter-veiling forces butfails to even mention half of these forces that don’t support his case.  It’s not science, it’s propaganda.

  • > That is because long-term stable natural processes are generally dominated by
    > positive, not negative, feedback.

    You mean the opposite.

  • Paul Buddery

    Do the children’s book or the snowball represent a feedback in the climate model sense?

    I’d have thought that seeing the mouse get a cookie causing a rat to want 10 cookies would be indicative of a positive feedback (or negative if they’re your cookies). Similarly, if the snowball caused an avalanche that would be a positive feedback. The mouse wanting more and more or the snowball keeping on rolling to me represent the continuation of a single process, analogous to the accumulation of CO2 in the atmosphere.

  • Nothing described above is a positive feedback process.

    A nice real-world example of positive feedback is the Chernobyl disaster. The reactor used carbon as a neutron moderator. The hotter the carbon gets, the better it moderates neutrons, leading to a larger chain reaction leading to hotter carbon etc. until the thing blows its top (if nothing intervenes, and nothing did in that disaster).

    And that’s exactly what happened. As Climate Skeptic points out, our climate hasn’t blown its top in hundreds of millions or billions of years.

  • View from the Solent

    Balls of different weights rolling down a slope …. .
    That faint whirring you can hear is the sound of Galileo’s bones spinning in the grave.

  • Tony Edwards

    Of course the other problem with all of this nonsense is that any feedback, positive or negative is already included in the measured (?) temperature results, so the small rise already noted has included all of these postulated feedbacks. Maybe Chillingar is right, by itself, maybe CO2 cools things!

  • Scientist

    Have you been confused by the word ‘Journal’ into thinking this a scientific publication? It’s a local news website.

    very few (like, zero) long-term stable natural processes (like climate) are dominated by high positive feedbacks – consider a lump of rock falling from a great height towards the Earth. As it gets closer, does the force of gravity on it increase or decrease? Does this make it fall faster or slower? Is this natural process dominated by positive or negative feedback?

    Climate is a long-term quite stable process – this preposterous statement has been made time and time again here, and it doesn’t get any less wrong. All the evidence shows that our climate is highly unstable, and has spent the last several hundred million years whip-sawing between two wildly different states.

  • Anon

    “As it gets closer, does the force of gravity on it increase or decrease? Does this make it fall faster or slower? Is this natural process dominated by positive or negative feedback?”

    Is this a trick question? The force is constant…there is no feedback.

  • Scientist

    No trick. The force of gravity is not constant – for two objects not moving at relativistic speeds it’s described by this equation:

    F = GMm/r²

    where G is the gravitational constant, M and m are the masses of the two objects, and r is their separation.

  • Alanstorm

    Scientist, you need to change your handle.

    A ball falling from a height? First, that’s not an example of feedback. If the ACCELERATION of the ball caused further acceleration, that would be a feedback situation – but that’s not the case. This is simply the effect of a constant force. Also, hills are never infinitely high, as already pointed out. The thing could not accelerate forever in any case.

    As for climate being stable, it is. “Stable” does not mean “stasis”. In this case, the climate varies around a median temperature by several degrees. Your use of the term “whip-saw” is an emotional one, not a descriptive term. THe planet’s climate does not show any long-term trend towards heating or cooling.

  • B.D.

    Scientist,

    You’re funny. You claim the force of gravity is not constant and then show an equation where G represents the gravitational CONSTANT.

  • Todd

    Guys,

    Please don’t be too hard on “Scientist”!! I enjoy his comments and don’t want him to scurry away from continuing to make them. In fact, after I read Dilbert and The Onion in the morning, I immediately come here to see what hilarious shenanigans he’s up to today! Wait… “Scientist”, you are a comedian right?

  • Scientist

    Oh dear, there was I thinking you people could understand gravity, at least, even if climate science remains hopelessly beyond you. But no, gravity is too much as well. There is a constant in the equation, but if you have even an extremely basic understanding of physics, you’ll notice that there are also variables. The important one for the example is r, the distance. As r gets smaller, F increases, and the acceleration due to gravity increases. That means that r gets smaller even faster. Quite simple, yes?

    THe planet’s climate does not show any long-term trend towards heating or cooling. – this statement has no basis in fact. If you look very hard at temperature reconstructions of the last five million years, I’m sure you can see a long term trend. And equally if you look at the temperature record of the last 100 years, you can also spot a trend.

  • Flatland

    The correct formula is F=ma with a being gravitational acceleration of 9.8 m/s^2. Increasing force (aka weight) due to increasing mass does not change the acceration.

    Therefore, the speed of the object cannot increase even though it is gaining mass.

    There are various other forces at work here that I can think of in this scenario, but they are all negative feedback.

  • Flatland

    If you want to keep talking about gravity, then you’ll have to talk about it at very large distances where the constant of 9.8 m/s^2 does not apply. This would be in Earth’s orbit. In this case, two objects of different mass will still have the same acceleration because the mass of objects cancels out. F=ma=GMm/r^2 or a=GM/r^2. Simply stated acceleration is related to the Mass of the opposing object (or Earth) and the distance between the two objects. (The acceleration is actually a combined accerlation of the two object (Earth and the snowball) moving toward each other, not just the snowball to the earth)

  • Hey, give PseudoScientist some credit, he got one thing right in all his months and months of posting here. The force of gravity is inverse-square proportional to the distance between the two objects. The gravitational constant does not represent the attraction in the system, it represents the baseline force created by one unit of mass (can’t remember what the units are offhand). The mutual attraction in the system is that baseline force mulitplied by the (number of units of) mass of the objects and divided by the square of the distances between them.

    Still, the change is very tiny, undetectable by any but the most sensitive instruments, at any distance entirely within our lower atmosphere, so it is a completely insignificant effect on a snowball rolling down a hill. Even the “weightlessness” experienced in orbital craft is not due to lower gravity, but due to the fact that an orbiting body is in perpetual free-fall, always accelerating at the same speed as gravity, and so their is no net force on the craft or the people in it.

    Of course, everything else he says is wrong, as usual. All of the above is completely irrelevant to any discussion of feedback.

  • “There are various other forces at work here that I can think of in this scenario, but they are all negative feedback.”

    The ability of the snowball to overcome rolling friction over snow should increase with it’s increased mass, within a certain range of mass, at least. That’s some positive feedback.

  • John Stanton

    The term “whip-saw” is better described in scientific terms as a reversion to the mean. Any system dominated by negative feedbacks does not exclude variability, but always exhibits a long term reversion to the mean. On the other hand, a system dominated by positive feedbacks becomes a run-away proposition, in one direction or another. Only a negative feedback mechanism could prevent this from happening, and force a reversion to the mean.

  • The term “whip-saw” is better described in scientific terms as a reversion to the mean.”

    Yes. The “whip” part of it is caused by the forces pulling it back, by the negative feedback countering the momentum away from the mean. Think about an actual whip, it moves somewhat smoothly outward until the person pulls it back suddenly. The actual climate record is more gradual – the whip does not suddenly “crack” – but it’s loosely analogous.

    Whipsawing is, in fact, a clue that there is probably net negative feedback in the system.

  • Dale

    When did mice learn to talk? I missed that one on CNN.

  • Hud

    Thanks, Kyle for acknowledging “Scientist” was correct, and that while a snowball rolling downhill is nothing like the AGW fantasy, it is nevertheless an example of positive feedback. Acceleration does increase as distances between centers of mass decrease. Accumulation of mass (a function of r^3) increases faster than surface area and frontal projection area (functions of r^2) leading to proportionally less rolling resistance and air drag.

    As I was scrolling down I was getting worried. Let’s not act like the “true believers” who must knee-jerk react to any science presented that refutes AGW, usually by ad hominem attacks. Sometimes even a blind hog finds an acorn. Just because “Scientist” says it, doesn’t make it untrue.

  • Scientist

    In a system oscillating between two states, there is no physically meaningful ‘mean’ that is being reverted to. And as always, the simple definition of feedback is being misunderstood. Positive feedback does not mean runaway warming or cooling in response to an initial perturbation. It just means that the initial perturbation is amplified.

    Hope everyone will keep on talking about gravity. More impressive howlers like ‘But G is a constant! Therefore gravity is constant!” will keep anyone with basic science knowledge amused.

    The actual climate record is more gradual – the whip does not suddenly “crack” – another wonderful slice of ignorance. Frequently throughout Earth’s history, the climate has changed quickly enough to trigger mass extinctions.

  • David

    Yes, I agree with Scientist, meteoroids are an example of a natural positive feedback situation – a slight perturbation in their orbit can cause them to feel increased gravitational force from the earth, which causes them to come closer, more force, and eventually a streak in the sky results.

    However, I just can’t believe that earth’s temperature could be a positive feedback loop – the T^4 dependence of radiation is such a strong term! Plus, unlike the meteoroid, I don’t see where the extra energy would come from to cause the accelerating change. Where’s the potential energy in the Earth to convert?

  • og

    “the climate has changed quickly enough to trigger mass extinctions”

    HAHAHA!! HAHAHAHAHA!!! I LOVE this. Not only has Scientist actually “Thought” those words, he allowed them to come out of his head, typed them on the computer, clicked “post” and actually had to read and type in the verification word. Several chances to stop from demonstrating the dementia, and he/she/it plowed right through and posted it anyway!!!

    And, um, Scientist, everyone on earth knows that gravity exists in direct proportion to the mass of an object. The failure is reading comprehension here: You assume (incorrectly, of course) that anyone here thinks that different objects of different mass exert the same force, which is of course, untrue. What everyone here has said, (and you have, for purposes of ad hominem, ignored) is that for an object of fixed mass the gravitational force is… what was that word? oh, yeah, “constant”.

    But of course admitting you are wrong could never happen, because you’re one of those “Scientists”

    Please feel free to call me some names now. It demonstrates to all of us just how intellectual you are. “utterly stupid” is one you seem to like a lot, and it amuses me.

  • Creation Scientist

    The planet’s climate does not show any long-term trend towards heating or cooling. – this statement has no basis in fact. If you look very hard at temperature reconstructions of the last five million years, I’m sure you can see a long term trend.

    Cute!

    I see your 5 million years and raise you 542 million year: a different graph from the same site showing a different trend.

    It seems the Earths temperature (on a site that our friend trusts) shows a wave oscillating between +-2 part per thousand change in δ18O (1=roughly a 1.5-2 °C change in tropical sea surface temperatures).

  • loki on the run

    Hmmm, I was under the impression that F = ma and F = (GMm)/r^2 were both correct and that the acceleration due to gravity of 9.8m/s was an approximation that is pretty damn good for reasonable distances from the surface of the earth (like up to maybe a mile) … I dunno, perhaps I am off, but

    if using those two equations I come up with a = GM/r^2 so the acceleration due to gravity should change with different distances from the surface/center of the earth, only I might not be able to measure it over small distances.

    I would also have thought that the increasing angular momentum of a snowball accumulating mass (and thus diameter) would tend to slow it down but maybe I am off base here (however, a skater can slow down his/her spin by spreading their arms).

  • Josh S

    In a system oscillating between two states, there is no physically meaningful ‘mean’ that is being reverted to.

    And in a chaotic dynamical system like climate, there is no single “state” to which the system tends. If more people understood this, we wouldn’t panic every time we saw the system change and fall all over ourselves trying to figure out how to keep it from changing, since the system is constantly changing.

    Frequently throughout Earth’s history, the climate has changed quickly enough to trigger mass extinctions.

    Yes, and those changes were caused by things like giant meteors crashing into the Earth and super-sized volcanic eruptions, not trace amounts of CO2 gradually increasing and triggering positivie feedback.

  • B.D.

    Hud,

    Scientist was “correct” in a technical sense, but in a real world sense, the difference between the speed of a 10 pound ball and a 100 pound ball rolling downhill is negligible, and so is the increased force in his rock-falling-to-earth scenario. He is very literal, much like say, a 4-year old, and he is only here to proclaim his righteousness. He does not contribute in any meaningful way to a debate that promotes better understanding on both sides of the AGW issue. The point of the author of this post is absolutely valid that the Ithaca Journal article is all about propaganda and not science.

    And on the topic of the long-term stability of the climate system – the point is that no positive or negative feedbacks have ever yet existed to such a degree that the system goes into a runaway state. Therefore it should come as no surprise that there are scientists who are skeptical of the alarmist view on AGW.

  • Earle Williams

    Scientist’s little foray into gravitational acceleration demonstrates a typical mono-focus on scoring argument points and disregards any actual discussion of the physical process. In his/her posited example where the F on the snowball is described by F=GMm/r2 he/she neglected to admit that the mass of the earth is not a point mass. Being the all-knowing scientist he/she surely knew that the mass of the hilltop exerts an opposite force on the snowball as well. I think he/she preached something recently about honesty, and that withholding information (by selectively quoting) is dishonest.

    Anyways, I would love to hear Scientist’s honest 🙂 appraisal of the science in that Ithaca Journal article. But something tells me that he/she is incapable of that degree of honesty.

  • Another guy named Dan

    After scribbling on a legal pad for about 20 minutes, I have concluded that a rolling snowball will either accelerate until it explodes, stop of its own accord, or under extrememly rare combinations of factors, reach an equilibrium velocity.

    In the figuring I did, the end result will vary with parameters such as the depth, density, compressability, and cohesiveness of the snow, the density of the air above the slope, the gradient of the slope, and the initial mass of the snow ball.

    It looks as though the system may go non-linear, as the rate of change of the radius will decrease as the weight of the snowball compresses the snow in the outer layers into ice.

    In short, in order to know the fate of the snowball, you need to know the initial conditions with a great deal of precision, which would require a set of extrememly accurate initial measurements. Why does this sound so familiar?

  • ErikTheRed

    Our world is full of positive feedback cycles, and so is our society. Popular children’s books like “If You Give a Mouse a Cookie” by Laura Numeroff are excellent examples. In Numeroff’s tale, a mouse asks for a cookie, leading it to ask for a glass of milk, and so on, till finally it asks for another cookie.

    Yes, but at what point does the mouse go into a diabetic coma? Is that a metaphor for sitting through one of Al Gore’s PowerPoint shows? The amount of mental activity one needs to have to go along with the hunt for ManBearPig? Maybe it’s a metaphor for climate scientists and funding for global warming research.

  • joshv

    F = ma, where a is acceleration. Therefore a = F/m. For a gravitational system, F = GMm/r^2, where M is the earth’s mass, and m is the accelerated mass, and r is the distance between the center of gravity of the two objects. So gravitational acceleration a = GM/r^2 (the little m’s cancel). r is effectively a constant at any given point on the Earth, the mass of the Earth is also not known to fluctuate much, and G, as others have pointed out is defined as a constant – so in most situations you and I would experience on the surface of the Earth, gravitational acceleration is indeed constant, and utterly independent of the mass of the object.

  • Scientist

    Hilariously, a few of you seem to have confused my rather simple demonstration of a natural process ‘dominated by positive feedback’ (to use the phrase the ‘climate skeptic’ loves so much) with some kind of statement about snowballs. I didn’t mention snowballs at all.

    og – it’s hard to tell what made you laugh like a twat, as you didn’t actually mention what sort of problem you might have with the statement that rapid climate change has caused mass extinctions in the past, or offer any kind of refutation to the statement. If you want to provide an adult argument, I’m sure I can show you why you’re wrong. You’ve also abysmally failed to understand gravity. Do you see that letter r in the equation?

    Josh S – those changes were caused by things like giant meteors crashing into the Earth and super-sized volcanic eruptions, not trace amounts of CO2 gradually increasing and triggering positivie feedback. – do a google search for ‘Paleocene-Eocene thermal maximum’.

    David – However, I just can’t believe that earth’s temperature could be a positive feedback loop – the T^4 dependence of radiation is such a strong term! Plus, unlike the meteoroid, I don’t see where the extra energy would come from to cause the accelerating change. Where’s the potential energy in the Earth to convert? – the gravity example is not analogous to the climate system. It’s just an example of a natural process ‘dominated by positive feedback’, a very simple and obvious example but one which the ‘climate skeptic’ bizarrely doesn’t believe in. In climate terms, the feedback factor would be greater than 1, leading to a runaway effect. In the climate system, the feedback factor is less than 1. ‘Potential energy’ is not a meaningful concept in climate science.

  • og

    Oooh! Twat! That’s new. Your mommmy must be so proud, she’s right there, ask her!

    As for my abysimal failure to understand gravity: yep. You’re right. I do not understand a thing. You’re EVER so much smarter than I am.

    Keep yapping, little doggie. The more time you waste here, the less you can interfere in the lives of actual people.

  • Sceptical of the arguments the Pro-AGW crowd make …

    I am not a ‘climate sceptic,’ after all, the climate is all around me.

    I am not a ‘CO2 sceptic,’ as I am convinced that it exists.

    The earth’s atmosphere has been around for a long time and there is reasonable evidence that CO2 levels have been higher than they are today and the planet did not roast …

    There is reasonable evidence that the atmosphere is dominated by negative feedback, and that more C02 will produce more plant growth and the sea will soak up more CO2 as well.

  • Scienlist

    Hilariously, a few of you seem to have confused my rather simple minded demonstration of a natural process ‘dominated by positive feedback’ (to use the phrase the ‘climate skeptic’ loves so much) with some kind of statement about reality. I didn’t mention reality at all. And I never will!

    og – it’s hard to tell what made you laugh like a twat, but I can tell you that “og” in Eskimo means silly twat. You’ve also abysmally failed to understand gravity. PS: it’s what makes apples fall from the tree.

    Josh S – those changes were caused by things like giant snow-ball sized meteors crashing into the Earth and super-sized volcanic eruptions of giant snowballs, not trace amounts of CO2 gradually increasing and triggering positivistic feedback. – do a google search for “og is a silly twat in Eskimo”.

    David – However, I just can’t believe that earth’s temperature could be a positive feedback loop – the T^4 dependence of radiation is such a strong term! Plus, unlike the meteoroid, I don’t see where the extra energy would come from to cause the accelerating change. Where’s the potential energy in the Earth to convert? – the gravity example is not analogous to the climate system. It’s just an example of a natural process ‘dominated by positivistic feedback’, a very simple and obvious example of snowballs, but one which the ‘climate skeptic’ bizarrely doesn’t believe in. In climate terms, the snowball feedback factor would be greater than 1, leading to a runaway snowball effect. This is why I am a scientist and you are an og.

  • og

    “og – it’s hard to tell what made you laugh like a twat, but I can tell you that “og” in Eskimo means silly twat.”

    Oooh, Eskimo is now a language. The Scientist says it, and therefore it must be so.

    I await the arrival of your credentials. Have your mom fax them right over.

    Yap yap, little doggie.

  • double-og

    Scienlist, I think you made a mistake. You say that gravity makes apples fall from the tree, but didn’t you really mean to say gravity makes snowballs roll downhill?

    And just what is “positivistic feedback?” I must admit, you rather have me double-og confused.

  • Hud

    B.D.

    I don’t disagree with anything you wrote. My point was we “skeptics” have the much better facts, science and arguments. We should have no fear of admitting when the true believers are correct, even when it IS only in a literal sense. Better to let them have their positive feedback snowball THEN show, as the original post and so many comments did, all the evidence that climate is NOT like a rolling snowball and an unlikely positive feedback system.

    We’ll never win the emotional argument. The WARMongers can make mistake after mistake, and the public will repeatedly forgive because they want to feel good about “saving the planet.” They want to believe! Our only hope is impeccable credibility and reason. Eventually that will persuade enough people that the true tipping point will be reached–AGW will be finished, and the Communists, radical environmentalists and media will have to start marketing a “new crisis” which will be nothing but a rehash, or should I say recycling of some old “crisis.”

  • IMHO — If Earth’s climate had positive feedbacks, the Earth’s climate would have ‘railed’ long ago as the extremes of hot and cold have been much greater than they are today. This would have happened long before man was around.

    Facts are facts, regardless who brings them up. The problem today is people trying to push hypothesis and computer models as proven fact. You can believe what you want, the real question is can you prove it. I think before governments make decisions that effect people’s lives, at a bare minimum, proof is required.

  • Luis Dias

    This gravity-million-dollar-contest is hilarious. Of course, scientist is one of the few here that got thescience right. But, it is an appalling example given by the “journal”, for if the purpose was to give an example that the people understood, then it should be a real-life example. And in our own experiences, Galileo was mostly right, forget about Newton or Einstein. Both of them only apply on experiences that we don’t deal with in our everyday lifes.

    Interestingly, we can even say that the journal was right, if we think of air and ground drag as an important part of the equation. The bigger and heavier, the smaller the drag, the higher the speed, but then the higher the speed, the higher the drag, oh darn it’s a fucking mess!!!

    I think we should conclude that it is a very bad example.

    Concerning the post itself, it is a obvious strawman. This is a hobby article, not a peer-reviewed paper. It’s entertainment in schadenfreuding the other people’s shenanigans about the same subject.

    Hardly a mature call.

  • Luis Dias

    PS: To conclude that that 5 million year graph trend of 4ºC / 5my is a “permanent” one, it would also indicate a 4000ºC trend in 5 billion years.

    Clearly, we haven’t warmed that much.

    Therefore, it is a cherry-picked graph.

  • Luis Dias

    PPS: There’s another graph here, try to dissect the trend of these 600+ my.

    Right here.

  • Stevo

    It’s an interesting question. To a first approximation, the time taken to roll down the slope is constant. The increase in gravity due to getting closer to the Earth’s centre is generally a smaller approximation than neglecting friction and air resistance. And it’s quite clear that it wasn’t what the author was getting at, so it’s a case of making feeble excuses to even bring it up.

    As the snowball accumulates mass, the force on it increases, but the acceleration stays the same. Uniform gravity puts F = mg so as the mass increases, so does the force. But F = ma as well, so mg = ma and g = a. The acceleration due to gravity is constant. (To the level of accuracy we’re considering things.)

    There is another effect to consider, and that is that the snowball is rolling. Energy is going into rotational motion too. This slows the acceleration down, but for rolling spheres or cylinders things cancel out again and the acceleration is constant. In general, the acceleration is g sin(theta)/(1+I/Mr^2) where theta is the hill’s slope, M the mass, r the radius of the ball/cylinder, and I the moment of inertia. Since the moments of inertia for sphere (2/5)Mr^2 and cylinder (1/2)Mr^2 are both proportional to Mr^2, the change in mass and radius cancels out, and the acceleration is constant.

    “This is a hobby article, not a peer-reviewed paper.”

    Good point. And since this blog is not a peer-reviewed paper either, will you grant it the same latitude and call for people to leave its technical shortcomings uncommented on? And comment similarly on the maturity of those who do so?

    It’s an educational presentation on global warming, the most important issue of our age according to some, and when sceptics cast doubt by means of such using scientifically dodgy material, that’s an outrage that ought to be banned by law they say. But when people speaking for it get basic science wrong, it suddenly isn’t. What does that tell you?

  • Joshv sort of has it right, although it seems counterintuitive.

    If you put two marbles (A and B) a meter apart, nothing much happens, right?
    If you put a marble (A) and a black hole(B) a meter apart, something DOES happen, right?

    The solution is that the TRUE acceleration between the two objects has TWO components. The acceleration A exerts on B was proved independent of B’s mass – but the acceleration B exerts on A is VERY dependent on B’s mass.

    In the rock vs. earth case, the rock is accelerated by the earth the same no matter how heavy it is – but it’s got to be one hell of a rock for you to notice how much the rock accelerates the earth!

  • Luis Dias

    Stevo, yeah, of course I grant that latitude, it’s just that the title misled me to thinking that it would humiliate some “alarmist scientist”. Instead, it humiliated an ignorant journalist, which alas, is nothing but rare. What it tells me is that I should no longer read newspapers for rigorous information, which I don’t, for years now.

    Jens, in common sense, you are “right”, but rigorously speaking you are not. Gravity theory implies that the earth exerts the exact same force on the rock as the rock on the earth. The problem is that F=ma, so for a given F, the small mass of the rock implies a much, much higher acceleration compared to the earth’s, which has an enormous mass. So acceleration does depend on the masses involved. The force that the black hole you mentioned on the rock is exactly the same force that the rock exerts on the black hole! It may seem counter intuitive, but that’s how it works. And science trumps feelings.

  • Stevo

    Luis,

    Fair enough. I can see how you might read it that way, although the apostrophe is in the wrong place for that interpretation.

  • “In a system oscillating between two states, there is no physically meaningful ‘mean’ that is being reverted to.”

    A pendulum is one simple example. The mean is the rest state of straight down. The weights or springs of the clock add energy, and the pendulum dampens the swings produced due to the negative feedback that pulls the pendulum to the center more strongly as it is perturbed further away from center.

    The climate oscillates (though not between two “states”) in a much more complicated manner, but essentially the same way. The sun, and the internal heat of the earth add energy, and the various negative feedbacks pull the climate back toward a mean, more strongly the further it gets perturbed, and then past that mean to an opposite extreme, from which it is again pulled back.

    The last, best hope for catastrophic AGW/CC is that there is a local maxima nearby on the solution space of possible climate states that we could push the climate over, analogous to pushing the pendulum so hard that it spins all the way around, or breaks off the clock completely. If that were the case, the climate could be pushed into either a different equilibrium around a different local minima, or into a regime of positive feedback.

    It’s possible, but very unlikely, as the climate has tested those boundaries numerous times in the past and always returned. Still, if that’s what you watermelons want to argue – and it’s the absolute last even remotely plausible argument you have left – you’ll have to start working on identifying where that nearby ridge is, what it would take to get over it, and what it will take to prevent it. You’re nowhere near even starting on that – you won’t even admit that we are in a long term stable regime dominated by negative feedback.

    “(Me:) “The actual climate record is more gradual – the whip does not suddenly “crack” ” (PS:)another wonderful slice of ignorance. Frequently throughout Earth’s history, the climate has changed quickly enough to trigger mass extinctions.”

    Way to go PseudoScientist. Pull a quote out of context and call it ignorant. My comment was with regards to an actual whip, and the suddenness with which it is pulled back by a countervailing force added all at once. The climate does not behave in that manner, though the interaction of various negative feedbacks can make it look like it does.

  • joshv

    Jens, I am not sort of right – I am right. In the case of the Earth and a tiny ball, both the tiny ball and the Earth are accelerated towards each other. The force on both the Earth and the ball are equivalent, and opposite in direction. For the Earth, F = Ma where M is the mass of the Earth. So acceleration a = F/M, or Gm/r^2 (big M’s cancel), where m is the mass of the ball, r is the distance between the center of masses, and G is the gravitational constant. Now G = 6.67300 × 10^-11 (0.00000000006673), r is 6.3 million meters, and m is a few kilos. So the Earth’s acceleration, Gm/r^2, is a really really really tiny number.

  • Sigh. The snowball and falling object examples are just pathetic. Yes, the falling object experiences increased forces as it approaches the earth (but NOT, if it is falling into a hole, after it passes the surface). But calling that positive feedback is really weak. It is really just slightly nonlinear.

    The climate system certainly has positive feedbacks, and it certainly has negative feedbacks. We are talking about an enormously complicated system and a wide range of time scales. Furthermore, there are a variety of forcing functions, from CO2 changes to Solar insolation changes to stratospheric particulates to biologically induced major ecological shifts (plant parasites, for example).

    CS’s point is that the climate is unlikely to be dominated by a positive feedback over a wide range of temperatures. Even if there is a >1 alpha at some point, the system is so nonlinear that this will change with temperature (and CO2, and water vapor, and sunlight, and cow flatulence, and…). Something is acting as an overall regulator because the temperature fluctuations have limits. I wouldn’t be surprised if the overall very long term trend is positive due to normal long term solar star aging. But the earth has tolerated a lot of very strong climate forcing, most of them without catastrophic effects on life. CO2, in comparison, is a weak forcing. Furthermore, if we characterize the nonlinearity of gravitational force on a falling ball as positive feedback, then the forcing function of CO2 clearly has negative feedback – the GW effect of CO2 (ignoring all other factors) is logarithmic with increases. Twice as much CO2 doesn’t give you twice as much warming – even in a lab.

  • John III

    Maybe next time they can ask the talking mouse with the cookie fetish to give the talk on positive feedback examples.