Forcing is a Broken Word

This is a minor posting, just a bit of a pet peeve. It’s the use of the word “forcing” in “Climate Science” to mean “causes to happen”. I have several issues with this usage.

First, though, a minor housekeeping note: The last couple of days I’ve had “Yo Yo DSL” and as of now I’ve just shut it off. (Starbucks is your friend ;-)

This only impacts my access, it does nothing to WordPress. However: If you only see me popping in from time to time and if postings seem a bit more “sporadic” for a couple of days, you will know it’s because I’m trying to regain the service I’ve paid to get… Oh, the joys of AT&T Tech Support…

For the terminally curious: Yes, AT&T is my provider. They own the wires here and no matter from whom you buy the service, it’s AT&T that provides the wires. I have my own modem/router and nothing in the config has changed. I’ve seen this before with AT&T. It just starts dropping speed, then starts going up and down and up and down and up and down…. Then, usually about a day later, it’s ‘all better’. This time, not so much.

I’m leaving my side down for 24 hours in the hope that someone else gets the sick port and when I bring it back up I’ll get a new port and a new IP. We’ll see. I’ve had that work before, and it’s quicker than calling AT&T and getting to someone cluefull most of the time…


For most of my life there was a perfectly good word used to me “Pushes things that way and helps to make it happen.” That word was “driving” or “drives”. As in “The Sun is the driver of ocean heating that drives hurricane formation. There is no need for the neologism of “forcing”.

So why do we have it? It’s a propaganda tool. “Driving” is not as strong a word as “forcing”. The very reasons that make “driving” the correct choice are the reasons it fails as a political and propaganda tool.

Driving weather events, much like driving cattle, has a certain element of chance to it. Things may, or may not, go directly where you tell them to go. “Force” on the other hand, implies There Is No Choice And No Doubt. Police “force a door open”. The IRS forces you to pay taxes. An unstoppable force runs into things, and they are flattened. Drive a herd of cattle and you have some mavericks. Drive a new product launch, and you may yet have a flop. Have the sun drive a hurricane and, well, some of them just end up tropical storms.

The correct and proper term for CO2 is “driver”. In fact, if someone said “CO2 drives warming”, I’d likely agree with them. It well might. There is nothing about a ‘driver’ that says “how much”, nothing that says “dominant”, and nothing that even says “will win the race with all the other drivers”. But FORCING, well, that’s not to be doubted. A “forced” door IS open. An attack in force, did attack. And a rape is forced sex, not just a dinner and bar bill followed by a polite “Oh, look how late it is…” So, if something is ‘forcing’ it is not subject to skepticism or doubt.


Force has a perfectly good meaning. A change of speed, direction, or shape comes out of application of a force. Force = mass x acceleration. The change of momentum over time. There is no temperature, no IR emissions spectrum, no warming or cooling implied in change of momentum.

To use “forcing” for infrared absorption spectra, or for change of temperature is to be very sloppy with your physics. It is, in a word, incompetent. A person who does so needs to start over again, with Newton, and work their way back up through freshman physics. No, I do not consider that point “negotiable”. The term ‘forcing’ is only used in the context of describing the expected behaviour of physical systems. That is physics. That means using the jargon of physics. And that jargon defines force as “F=ma”. There is no doubt. “Forcing” must mean “ma-ing”, not “well, I think the ocean may change how warm it is in the top 10 cm on a good day in the Gulf while cooling in the Arctic” nor “the troposphere will get a hot spot while the stratosphere cools” nor any other clap trap.

Forcing is Sloppy

Is a climate forcing in Watts? Watts / hour? Watts / meter? Watts / meter^2? Watts / meter^2 / hour? Joules? Degrees per second? Degrees / m^2 / second? Or perhaps it is in Calories or Calories / second or who knows what. Maybe it’s “Ice Tons / year melting” or “wind miles / hour” or “tons of rain / acre”?

It is a physically meaningless term whose units are at best guesswork, always vague, and completely untrustworthy. There is no S.I. unit of “forcing” nor any English or American Standards Institute unit of “forcing”. If it can be anything, then it is nothing.

You can’t ‘keep a tidy mind’ and have the equations work out right when one of the key steps is a dimensionless property with no physical definition.

So why not give it one?

Well, perhaps because there are already perfectly fine terms for all the real physical properties. If someone means Watts/hour, then they ought to say that as we all agree on what it means.

As it stands, the use of “forcing” is just shorthand for: I’m too lazy to work out what really happens in the physics, or I think you are too lazy to follow me, so, just assume “Magic Happens” and I’m right.

That, to me, is very unacceptable.

It is at best sloppy, at worst lying with propaganda. In between lies sheer incompetence. I do not want to be anywhere on that spectrum.

In Conclusion

There are some more minor issues I could raise, and I may well do so in comments as time permits. These, though, are the major points. But if those are not enough for you, consider this last point:

Whenever I hear the word “forcing” I assume the person likely has poor grasp of physics, has mediocre language skills, and is subject to belief in propaganda. I also expect they will have an ‘un-tidy mind’ and and are sloppy with their logic. If they really just mean “causes to happen” then they ought to say so, and doing otherwise means they are not clear in their thinking and like using flowery excessive bafflegab.

I’ve seen the same sentiment expressed by other folks. Often those with the most physics background and the best reasoning skills.

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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17 Responses to Forcing is a Broken Word

  1. Adrian Vance says:

    Jim Hansen started using “forcing” when he could no longer ignore the fact that water vapor is responsible for, far and away, most atmospheric heating. He admits to 70% and my analysis shows it to be 99.8% because I include E = (h X c)/w where E is energy, h is Plancks Constant, c is the speed of light and w is wavelength. Hansen claims that CO2 molecules control water vapor and tell it when it can evaporate. This would require tiny pilots on all molecules involved, Divine or Satanic intervention. While he is at is I would like him to answer the classic question, “How many angels can dance on the head of a pin?”

    Free conservative thought, science and humor at The Two Minute Conservative for radio/tv hosts, opinion page editors and conversationalists. Also on Kindle.

  2. Titan28 says:

    You’re absolutely right. Forcing as a neologism in this case has always vexed me because the meaning is never immediately clear. I find I have to mentally pause, almost to say to myself, “Yes, forcing, that’s what it means here, to cause, influence.” Yes, it’s gobbledygook. But what would you expect from the masters of language? They’ve taken over the schools, they understand the importance of language to manipulate and conceal. So did Stalin. Thank God Orwell took the time to pick up the pen; otherwise we’d all be bouncing around in the dark of gullibility.

    Keep up the good work here.

  3. Hal says:

    Dr. Gavin Schmidt uses the “f” word (forcing) a lot.

    Propaganda value.

  4. Laurence M. Sheehan, PE says:

    I certainly agree that the use of the word “forcing” is inappropriate, and in the case of CO2, there is none of significance.

    Putting it into perspective, the amount of CO2 in the atmosphere relative to other gases is about the same as 10 gallons of water in a 25,000 gallon swimming pool.

    There is no possible way that CO2 can have any significant role in atmospheric temperatures. There is just not enough of it, whatever its “heat trapping” powers. About like trying to trap water with a barbed wire fence.

    Molecules of gases in the atmosphere are not “black bodies” either.

    If speculations can’t be expressed in mathematical formulae, subject to falsification, they remain speculations, certainly not theories, nor even hypotheses.

    What these “climate scientists” are doing is pretending that they can foretell the future, using their own version of the equivalent of Tarot cards.

  5. Pascvaks says:

    (SarcOn) Quibble, quibble, quibble, this is all ‘settled’, ‘proven’, ‘undisputed’ ‘science’. What’s the big deal anyway? Besides isn’t English a ‘living language’? Don’t most who speak English as a second language deserve a little simple help with the vocabulary, I mean what do we really need all those millions of different silly words for anyway? ‘Science’ should be simplified for the common people, should it not? Simple people are the salt of the earth, are they not? You don’t like people do you? Admit it! Admit it! Admit it! Don’t feel as though I’m forcing you or anything. Want an M&M? I like M&M’s, don’t you? Cold day today isn’t it? It’ll be a lot warmer soon. Pretty soon there won’t be any snow. Let’s not quibble! OK? I like you, you’re funny. Want another M&M?(SarcOff)

    We need to be careful what we say. Someone may be listening. And we may not get any M&M’s.

    I heard it again this morning, “this is a nation of laws and not men”. I hate that saying. Who do they think wrote and approved the damn laws? This is a nation of people, men and women and kids, laws are made to limit not rule. Guess I won’t get any M&M’s today.

  6. PhilJourdan says:

    Good post! I see your point. “Driving” is like a contributor since the driver needs the car. “Forcing” is the whole ball of wax – it is not the neighborhood association breaking down your door, just the police.

    It seems that they tried “sexing” up the AGW scare long before Der Spiegel decided to out them on it.

  7. Jason Calley says:

    Pascvaks said on January 6, 2011 at 3:59 am:
    “I heard it again this morning, “this is a nation of laws and not men”. I hate that saying. Who do they think wrote and approved the damn laws? ”

    This is true about nature as well as about men. Just as E.M. says about the misuse of the word “forcings”, I feel the same way about the use of the word “law” with reference to nature. There are no “Natural Laws”. There are most certainly patterns in nature, but the “laws” are simply human summaries of which patterns we have noticed. Appealing to a “natural law” as a proof or disproof of a postulated or observed event is nothing more than a sophisticated way of saying “My teacher says that never happens!” In truth, Madam Nature does what she will, law or no law, and we poor monkeys formulate “laws” as shortcuts to modeling what we have seen. Note, please, what I am NOT saying. I am not saying that the basic concept of immutible patterns in nature do not exist, but only that human formulation of those patterns is a hueristic tool, not a limiting factor. As the old saying goes, “When you hear hoof beats, think horses.” If I have to bet, then, yes, I will bet on horses, and not on zebras. On the other hand, if someone says, “I just returned from Africa, and heard hoofbeats from these strange striped creatures,” I would be foolish to respond, “They must have been horses. Only horses make that noise!”

    By the way, speaking of the old tried and true Newtonian formulation of F=Ma, that is not what he wrote. Newton wrote that F=sum of delta Mv over time. That is NOT equivalent to F=Ma, but rather to F=Ma + delta M * v. In other words, Newton’s formulation retains the possibility of changes in mass associated with velocity.

    He was a VERY bright guy…

  8. Larry Geiger says:

    Thank you, thank you, thank you. I see that word all the time and I’ve never spent the time or energy to figure out what they mean by it. I’m not bright enough to figure out that it was just propoganda. I guess that I always assumed that it had some special meaning deep in the bowels of some “reviewed” papers.

  9. Jeff Alberts says:

    I’d say switch to cable, if you can. Much better than DSL.

  10. Paul Hanlon says:

    Heh heh,

    Everytime I see the word forcing, I get this little mental image of a CO2 molecule with an AK47 saying ‘Gimme all your heat!’

  11. Frank Ch. Eigler says:

    The word ‘forcing’ may have been innocently imported into this topic via mathematics, where ‘forcing functions’ are the various inputs to a differential equation that models some system.

  12. tckev says:

    Thank-you Frank Ch. Eigler for explaining that.

    And I foolishly thought forcing was from the same usage as employed with a Thanksgiving or Christmas turkey… Stuffing!
    That is to say you fill voids with something aromatic that enhances and contrast with the main meat of the meal.

  13. oMan says:

    Dear E.M.: totally agree. “Forcing” is wrong for all the reasons you state, and more. We can speculate as to the motives of the “scientists” who have adopted it, but the acid test is, does it improve or worsen the Signal/Noise in what they say? And to that, the answer is obvious.

    How many billions (dollars and person-hours) have been consumed with undoing the poor thinking and writing in this area, I can only guess.

    PS, sorry to be a grammar cop, but “who’s” should be “whose” in the possessive form…

  14. Verity Jones says:


    I did a blog post related to this a while ago – inspired by you and Anna v.

    I think you’ve got a better rant than me though.

    But I did find this:

    Image from the Visual Thesaurus, Copyright ©1998-2010 Thinkmap, Inc. All rights reserved.

  15. Verity Jones says:

    OK that link didn’t work, never mind

  16. E.M.Smith says:

    Frank Ch. Eigler

    The word ‘forcing’ may have been innocently imported into this topic via mathematics, where ‘forcing functions’ are the various inputs to a differential equation that models some system.

    Thanks for that insight / suggestion. (FWIW, I’ve found two other folks who “suggested” the same thing but with rudeness and insult with their postings in the SPAM filter… one presumes WordPress has an erudite filter ;-) at any rate, if I get time I may ‘clean them up’ and put them back here).

    The problem I see with that explanation is that it still leaves much to be desired in the usage. The proper math jargon is “Forcing Function”, not just “Forcing”. “Forcing” has it’s own meaning in mathematics, so if someone is using “forcing” to mean “forcing function” they are at best being very sloppy and at worst, well, we go into ‘at worst’…

    In the mathematical discipline of set theory, forcing is a technique invented by Paul Cohen for proving consistency and independence results. It was first used, in 1962, to prove the independence of the continuum hypothesis and the axiom of choice from Zermelo–Fraenkel set theory. Forcing was considerably reworked and simplified in the 1960s, and has proven to be an extremely powerful technique both within set theory and in other areas of mathematical logic such as recursion theory.

    Descriptive set theory uses both the notion of forcing from recursion theory as well as set theoretic forcing. Forcing has also been used in model theory but it is common in model theory to define genericity directly without mention of forcing.

    So if folks mean “forcing function” and say “forcing” it’s still a broken word in that context and they are mangling the meaning.

    FWIW, the usage in recursion theory doesn’t help the case:

    Forcing in recursion theory is a modification of Paul Cohen’s original set theoretic technique of forcing to deal with the effective concerns in recursion theory. Conceptually the two techniques are quite similar, in both one attempts to build generic objects (intuitively objects that are somehow ‘typical’) by meeting dense sets. Also both techniques are elegantly described as a relation (customarily denoted ) between ‘conditions’ and sentences. However, where set theoretic forcing is usually interested in creating objects that meet every dense set of conditions in the ground model, recursion theoretic forcing only aims to meet dense sets that are arithmetically or hyperarithmetically definable. Therefore some of the more difficult machinery used in set theoretic forcing can be eliminated or substantially simplified when defining forcing in recursion theory. But while the machinery may be somewhat different recursion theoretic and set theoretic forcing are properly regarded as an application of the same technique to different classes of formulas.

    So even there we’ve “got issues” with the use of “forcing” unadorned…. it’s got to ‘prior claims’ on the meaning in mathematics alone.

    Now, if someone really meant “forcing function” and didn’t say so, they have a slightly different set of problems. First off, to the non-mathematical listener, all the above listed issues in the posting apply. Second, to the mathematical listener, they are mangline the jargon and confounding set theory into things.

    But assume (and we all know what assume means…) for the moment they were sloppy and left off the key word “function”…


    I’ve bolded some bits:

    7.1 Linear, Time-Invariant Differential Equations

    The differential equation in (39) is called a forced, linear, time-invariant differential equation. For now, associate the fact that the faign i=1 are constants with the term time-invariant, and the fact that the left-hand side (which contains all y terms) is a linear combination of y and its derivatives with the term linear.

    The right-hand side function, v, is called the forcing function. For a specific problem, it will be a given, known function of time.

    Note the requirements. It is a GIVEN and it is KNOWN and it is a function only of TIME.

    For CO2, it is NOT a “given”, it is an assumption or a question at best. It is not “known”, it is the question. And it is not a function of time alone.

    There exists a fairly long list of things that drive (or may drive) CO2 production. From outgassing of uncosolidated snow at the poles, to decay of biologicals, to human fuel burning, to the volcanic activity of the planet. A large and complex set of things that depend on far more than time. (In particular, warming feedback will change ice melt rates and increasing CO2 causes more plant growth so more absorption, oh, and what drives the quasi cyclical nature of volcanoes is anyones guess).

    Heck, we’re not even sure which way the CO2 causality runs. Does CO2 warm the planet, or does warming the planet release CO2 from the oceans? In prior times we’ve had ice ages with high CO2 levels and we’ve had CO2 both rise and fall without fosile fuel useage.

    So, to call CO2 a “Forcing Function” (even if the ‘function’ was left out but implied in a sloppy manner of speech) is to commit a whole new raft of intellectual sins, so it’s still a broken usage. It implies knowing what is not known.

    (or worse, it states dependency only on time for things that are known to be multi-factor dependent).

    So, I can easily see your point that it might well have wandered into the speech of the Model Makers and from them to others in “climate science”, but if that’s the case, it’s still a very broken word to use in the way it is used.

  17. Adrian Vance says:

    The data show very clearly that CO2 changes follow temperature changes when they are plotted together. This was noted in the Fourth IPCC report, but no one dare make note of it or admit that it dashes the anthropogenic global warming concept.

    I have one such graph on my Two Minute Conservative blog at It was done only a few days ago so you can page down to it or input “It is so simple” to the search routine in the upper left corner.

    Money and power are driving this just as they have corrupted an entire generation of science education. Our new scientists are ignorant compared to the old ones and no wonder: At Stanford every physics lecture begins with a five to 15 minute presentation by a “Green” indoctrinator. Yes, we do live in a “brave new world.” Stop it, I want to get off.

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