Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.

Settings

Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup

Settings


All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Home Arguments Software Resources Comments The Consensus Project Translations About Donate

Twitter Facebook YouTube Pinterest

RSS Posts RSS Comments Email Subscribe


Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...



Username
Password
Keep me logged in
New? Register here
Forgot your password?

Latest Posts

Archives

CO2 is just a trace gas

Posted on 30 August 2011 by Sarah

ink in water

CO2 makes up 390 ppm (0.039%)* of the atmosphere, how can such a small amount be important? Saying that CO2 is "only a trace gas" is like saying that arsenic is "only" a trace water contaminant. Small amounts of very active substances can cause large effects. 

Some Examples of Important Small Amounts:

  • He wasn't driving drunk, he just had a trace of blood alcohol; 800 ppm (0.08%) is the limit in all 50 US states, and limits are lower in most other countries).
  • Ireland isn't important; it's only 660 ppm (0.066%) of the world population.
  • That ibuprofen pill can't do you any good; it's only 3 ppm of your body weight (200 mg in 60 kg person).
  • The Earth is insignificant, it's only 3 ppm of the mass of the solar system.
  • Your children can drink that water, it only contains a trace of arsenic (0.01 ppm is the WHO and US EPA limit).
  • Ozone is onlytrace gas: 0.1 ppm is the exposure limit established by the US National Institute for Occupational Safety and Health. The World Health Organization (WHO) recommends an ozone limit of 0.051 ppm.
  • A few parts per million of ink can turn a bucket of water blue. The color is caused by the absorption of the yellow/red colors from sunlight, leaving the blue. Twice as much ink causes a much stronger color, even though the total amount is still only a trace relative to water. 

"Traces" of CO2 

Although percentage is a convenient way to talk about the amount of gas in the atmosphere, it only tells how much is there relative to everything else; percentage doesn’t give an absolute amount.

For example, you have trouble breathing on top of Mount Everest even though the atmosphere still contains 21% oxygen just like at sea level. The percentage isn't important, you need a certain number of oxygen molecules with each breath, regardless of how much or little they are diluted by inert gases. At an altitude of 8000 m the whole atmosphere is diluted.

The total number of CO2 molecules above our heads in the atmosphere is more important than their percentage in the atmosphere. If the amount of inert nitrogen gas (N2) in the atmosphere were to be cut in half then the percentage of CO2 would jump (to about 600 ppm; 0.06%) without a change in the absolute amount of CO2 and no substantial change in the energy balance of the Earth. Adding a huge number of energy-absorbing CO2 molecules to the atmosphere doesn’t change its percent number very much, only because it's being added to a vast inert N2 background.

arsenic-mug

We know the amount of CO2 in the atmosphere has increased because we have measured it. We know the climate has warmed from current and historical data. The link between increasing greenhouse gases and increasing temperature is clear: just as ink makes water more colored, CO2 makes the atmosphere more absorbing. The extra CO2 in our atmosphere is trapping energy that would otherwise escape to space. The measured global warming matches closely with the amount of energy trapped from the greenhouse gases added to the atmosphere.

A doubling of the trace molecule CO2 from 280 ppm to 560 ppm is still a trace, but just like with arsenic, the difference between a small trace and a larger trace is fatal.


* To convert ppm to percentage divide by 10,000.

Photo credit: http://www.photographyblogger.net/15-cool-pictures-of-ink-in-water/

Note: This post is the Basic rebuttal to "CO2 is just a trace gas"

0 0

Bookmark and Share Printable Version  |  Link to this page

Comments

Prev  1  2  3  Next

Comments 51 to 100 out of 104:

  1. 50, Rob,
    48, Dikran,

    FYI, I had the same thought and did some quick googling for the Java app used to draw his animation. I didn't find exactly that one. There are some existing apps to base this on, but it wouldn't be a trivial thing to do from what I can see. One might even need to be written from scratch, although the mathematics behind it is laid out on several different web pages on the subject.

    It would use up a fair chunk of time to do, though. It is tempting to come up with a JavaScript version to embed in a web page, though, perhaps using GWT to implement it.
    0 0
  2. 48, Dikran,

    All you need to know is here. This was the best of the bunch I looked at.

    The source code is here.

    You could even just try to modify this to add an attractor to one side of the pendulum, reducing your work load considerably. You'd also want to change the graph to draw the actual position of the lower pendulum, rather than the angle or velocity options currently offered.
    0 0
  3. Dikran,

    Thank you for the response. It did teach me something and for that I appreciate it. I am looking to actually learn the issue, and not simply argue my bias. That being said, my understanding is that the Lagrangian math works great for 2 points, but becomes infinitely complex when you add 3 or more points to the equation. Maybe I am wrong here.

    Also, I am glad to see you mention that CO2 doesn't control the climate. The only point I see is in the politics of controlling output of man-made CO2 as the primary focus on policy, not the truth behind what is actually going on with the climate.

    Clearly,climate is a complex ball of wax and suppressing one part, without a full understanding of the unseen consequences, would have possibly worse outcomes. I also defer to Quine-Duhem theory with regards to the unknown variables present.

    Lastly, I think there is a radiative competent as to the upper limits of what CO2 can affect. For example my understanding is the TOA radiates at a constant 240W/m2 and energy radiated up from the earth’s surface is 396W/m2. There is a difference of 156/m2 . Does the introduction of more CO2 have an impact on this?
    0 0
    Moderator Response: See CO2 effect is saturated.
  4. Dan69: "Also, I am glad to see you mention that CO2 doesn't control the climate."

    That's not a good representation of the situation. Say rather that CO2 is an integral part of the current atmospheric dynamic. Removing it causes radical changes to global temp and the current biosphere. Here's the abstract from Lacis et al. 2010 ("Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature" in Science):

    Ample physical evidence shows that carbon dioxide (CO2) is the single most important climate-relevant greenhouse gas in Earth’s atmosphere. This is because CO2, like ozone, N2O, CH4, and chlorofluorocarbons, does not condense and precipitate from the atmosphere at current climate temperatures, whereas water vapor can and does. Noncondensing greenhouse gases, which account for 25% of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75% of the greenhouse effect. Without the radiative forcing supplied by CO2 and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state.
    (bold mine)
    0 0
  5. Dikran: Here's an applet for a double pendulum; here's an electrical analog.

    As you can see from the graphs, some chaotic systems are quite periodic and therefore predictable - and should model quite well, although you might need a bigger computer.
    0 0
  6. Dan69 @ 53... That same Richard Alley lecture does a good job of explaining what is called the "carbonate rock weathering thermostat." It's really very fascinating and well worth taking time to watch.
    0 0
  7. Dan69: To add to Dikran's excellent response, you need to remember that though CO2 is present in small quantities, for radiative forcing it's the initial small quantities that are the most important radiatively. See Chris Colose: Greenhouse Effect Revisited on the subject, where you can see that the 'bite' CO2 takes out of the longwave spectrum is already significant at just 2ppm, and large at 50ppm. It continues to grow, increasing its effect by the same amount each time CO2 doubles. The lines keep broadening as concentration increases, so the effect does not 'saturate'.

    I often wonder how the climate issue would have played out on a hypothetical Earth, sat a bit closer to the Sun, but with only about 50ppm CO2 in the pre-industrial atmosphere. On the hypothetical Earth, which would be much more (too much, most likely) sensitive to increases in CO2, our Industrial Revolution to present would have produced two whole doublings of CO2 concentration. The transient sensitivity would be something like 4C. I'm not sure there would be much argument as to cause on such an Earth, as the change would be frightening!

    I'd also highly recommend the Alley lecture - beautiful science communication.
    0 0
  8. Dan69 wrote: "That being said, my understanding is that the Lagrangian math works great for 2 points, but becomes infinitely complex when you add 3 or more points to the equation."

    I think you are referring to the N-body problem there, which is a different problem (as for the double pendulum there is a physical constraint on the distance between hinges. Also for the double pendulum, from what I have read the Lagrangian is used to set up the differential equations which are then solved numerically. If there was an analytic solution (i) it wouldn't be a chaotic system and (ii) the programmers would have used it. For General Circulation Models, the techniques used are essentially those developed for fluid dynamics, and work very well in a wide range of other applications, the apparent complexity of the problem is not as big an issue as you might think (GCMs don't work by predicting weather, but by simulating weather with statistically similar properties). So the N-body problem has very little to do with either double pendulums (pendula?) or climate modelling.

    "The only point I see is in the politics of controlling output of man-made CO2 as the primary focus on policy, not the truth behind what is actually going on with the climate."

    It is perfectly appropriate for policy to be focussed on controling carbon emissions. CO2 is not the only forcing, but it is an important forcing and the one that we have been using substantially since the start of the industrial revolution. We can't legislate about solar forcing, the Sun isn't subject to policy; carbon emitters are.

    The truth behind what is actually going on with the climate is well set out in the IPCC WG1 Scientific Basis. To a first approximation, the summary for policy makers is essentially "anthropogenic carbon emissions will cause global surface tempetratures to rise significantly over the next century; if you don't want that (and the resulting impacts) to happen, then we need to stabilise atmospheric CO2".

    "Clearly,climate is a complex ball of wax and suppressing one part, without a full understanding of the unseen consequences, would have possibly worse outcomes."

    Nobody is suppressing anything. As I pointed out earlier, "skeptics" (note the use of "") frequently claim climatologists are suppressing something, or they don't know about something, or that they know about something but pretend it doesn't exist. However that doesn't make it true and simply reading the IPCC WG1 report demonstrates that generally it isn't true. However that doesn't stop the gullible from swallowing it hook line and sinker.

    Secondly, it is impossible to have a full understanding of anything regarding the real world, we can only have imperfect or uncertain knowledge. We have know this since the work of David Hume. Following your logic we would never be able to draw conclusions about anything or plan our actions. However there is a thing called "statistical decision theory" which provides a provably optimal way of planning under uncertainty, which is what rational people do.

    "I also defer to Quine-Duhem theory with regards to the unknown variables present."

    I had to look that one up. Essentially it says that hypothesis testing is always subject to assumptions, something that all scientists know. However mostly those assumptions remain unsaid as they are part of the dominant scientific paradigm of the day. However it is not a reason to ignore the results of the hypothesis test. There is always residual doubt over the truth of any physical proposition, but it would be absurd to use that residual doubt as a reason not to act when the balance of the evidence suggests that action is required.

    Lastly, I think there is a radiative competent as to the upper limits of what CO2 can affect. "

    ISTR going over this recently. The radiative forcing from CO2 is logarithmic in the concentration, so no, there is no limit as the limit of log(x) as x tends to infinity goes to infinity.
    0 0
  9. Albatross, Rob, Sphaerica, muoncounter, many thanks for the suggestions and links. My basic idea was to implement the electromagnet idea with a knob the user could play with to change the current and a trace (with a running mean) to show the effect of the forcing. Learning about the maths would be half the fun for me as I've never studied mechanics (I'm O.K. with differential equations though which is a useful start). Hopefully I can persuade Mrs Marsupial to help with the programming (I only like numerical programming rather than user interface stuff).
    0 0
  10. Dikran,

    Thank you very much for taking the time to respond to my comments. Please let it be known that I am not a mathematician, nor physicist, simply pseudo-philosophical meanderings on my part.

    Since you bring up Hume, let me state what he is most famous for: The "Is-Ought" problem which states that many people make claims about what ought to be on the basis of observations about what is. However, Hume found that there seems to be a significant difference between descriptive statements (about what is) and prescriptive or normative statements (about what ought to be), and it is not obvious how we can get from making descriptive statements to prescriptive."

    When climate scientists debate what "is" they are using science; when they conclude what "ought" they have moved into the realm of politics.

    Although the IPCC may be a good clearing house for information, appeals to authority are in itself a fallacy.

    If this site engages in Popper's falsification theory then you must know the foundation for which your ought positions rests are speculative at best. I am not denying the nature of GHC, nor the properties of radiative forcing of CO2 etc., but what I am protesting is the ought prescriptions embedded in the science.

    Respectfully,
    0 0
  11. Dan @60,

    The IPCC assumes that economic prosperity and preservation of life are morally desirable, and provides its recommendations given this assumption and the results of scientific observation and logic. The only "ought" question is whether economic prosperity and preservation of human life are indeed morally desirable goals.

    I highly doubt you're seriously questioning this assumption, so your beef with the IPCC has nothing to do with the "is-ought" problem. Asking whether the IPCC's findings are correct given these moral assumptions is a different question entirely, and well within the domain of modern science.
    0 0
  12. Dan69 @60, Hume's greatest service to philosophy was that he awoke Kant from his "ideological slumbers", and Kant showed that if you accept a prescription of rationality, "ought statements" do indeed follow from "is statements".

    More importantly, Western Democracies, by their nature are committed to certain very explicit values ("ought statements"). In fact, in the US their nation is founded on a claim that "These truths are self evident ...". It is a common place of ethical theory that "ought statements" together with "is statements" can certainly imply other "ought statements", and the core values of Western Democracies together with the facts that science advises us of certainly prescribe that we take urgent action to mitigate climate change.

    That is in fact, the reason for climate change denial. Many people find themselves in the unfortunate position of wanting to do that which is precluded as immoral by a basic understanding of the ethical values of western democracies, and the basic facts of climate change. To resolve this dilemma, they choose to deny the science.
    0 0
  13. Dan, you've slid from questioning the scientific basis in #44 to questioning the philosophical basis in #60 (a tad O/T for this thread).

    Remember that the science pertaining to what we 'ought' to do tells us a lot about temperature, precipitation, likely soil moisture, weather extremes, acidity levels of the ocean, sea levels etc, all physical quantities. These are all valid scientific questions that have a direct bearing on food production and other necessities of human habitation of parts of this planet. (unless you think food production is not a necessity?)

    The science is bound into the SRES scenarios, so we look at what is likely to happen if certain economic and social conditios prevail in the future (e.g. BAU). The results are perfectly scientific, given the future emissions and actions of people, and most crucially the decisions that people must make in regard to their future cannot be made without that scientific basis. And you'll see if you've followed the links I and others have given you, the trace gas CO2 is very important in determining what that future will look like.
    0 0
  14. Dikran Marsupial @48

    For your double pendulum analogy to be truly accurate, the electromagnetic field must be powered from the dynamic non-linear chaotic motion of the pendulum itself. Moreover, the drive which powers pendulum can only account for 62% of it's peak drive energy, the other 38% must somehow be derived from the conductor (pendulum) passing through the magnetic field (CO2)...powered by the pendulum...which gets 38% of it's drive energy from the electromagnetic field feedback...etc. Now I suppose 38% represents the entirety of atmospheric forcing not just CO2, so adjust accordingly. Good luck!
    0 0
  15. LJRyan @64, if you wish to make a point refuted, if not a thousand times, then over 500 hundred times in just one thread, then you could at least have the decency to make that point where it is on topic.

    As it stands your analogy is inexact. Indeed, the double pendulum is too simple to be a useful analogy of the various parts of the climate system. It does, however, usefully prove that claims made about chaos and predictability by skeptics are false.
    0 0
    Response:

    [DB] Spot-on recognition, Tom.  Ryan L.J. = L.J. Ryan, who wasted many a participant's time earlier.

  16. And, Dan69, remember that science itself as an activity is essentially political. What does science look like in a totally privatized world--pure free market? Different? Do the same scientists who practice today under government funding work as scientists under the conditions of the pure free market? I don't want to start an economic argument here; my point is that currently science is the social construction of knowledge, and it is therefore necessarily political. When Rick Perry says he wants to re-staff the EPA with a different kind of people, he knows that doing so will have a direct effect on the production of knowledge. Politicians alter the social construction of knowledge, restricting it in some areas and expanding it in others, according to their needs.

    As skywatcher implies, the "ought" actually comes before the science. It comes in the form of the social structure that frames and re-frames the practice of science. Climate science exists because it has been determined that it ought to exist in order to serve human progress. Some politicians and, quite frankly, political tools (Morano) want to end climate science--indeed, imprison climate scientists. In other words, there "ought" to be no climate science.
    0 0
  17. I hope not be be castigated as some "denier" as I deny nothing. I acknowledge climate change. A science friend of mine told me there is a difference between Greenhouse gas theory and AGW. Understanding the science behind GHG theory (settled physics) doesn't mean acceptance of AGW (package dealing).

    The AGW (Anthropogenic Global Warming) message is appealing. It promotes the fear of catastrophe with the hope of salvation. It is promoted as the 'right thing to do'. The dark side, is that if AGW is wrong, the path to salvation is the most unnecessary and self destructive thing we can possibly do to our economy.

    The science tells us the truth about climate and there are many sources of high quality data. This broad spectrum of data must be examined in detail and reconciled with the physics. All anomalies must be adequately explained and all influences correlated among the different data sets. Jumping to conclusions without thoroughly understanding the data will inevitably lead to an incorrect result whose errors affect all subsequent analysis.

    You should understand confirmation holism with regards to predictive values of models. Convergence is NOT a scientific conclusion. At least it seems to me.

    This might be my last post as it does not contain much science or physics, and for that I am sorry, as I feel inadequate to address the actual math and fear I am wasting everyone's time.
    0 0
    Response:

    [DB] You promote a false dichotomy:  you claim to acknowledge the physics of GHG but deny that rising GHG levels are a problem (even though the physics of GHG say they are).  That is internal inconsistency at its skeptic finest.

  18. Correct me if I am wrong, but doesn't the GHG theory basically result in a slowing of cooling? If that is the case, is it possible to have increasing GHG levels yet have decreasing temperatures at some point?

    If GHG theory can be shown to be part of both circumstances, then I would not be promoting a dichotomy.
    0 0
    Moderator Response: [Dikran Marsupial] It seems to me that you are carrying a substantial amount of misinformation regarding climate science and the best way for you to make progress would be to go back to the start and understand the basics, and ask questions about the more advanced issues later. I would recommend Spencer Weart's excellent book, there is an on-line version here.

    To answer your question directly: (i) CO2 is not the only forcing, so even if CO2 is rising temperatures can still fall in the long term if there is a negative change in other forcings (e.g. solar) that more than compensates for the increase in CO2. An example of this is the levelling off of temperatures in the mid 20th century that is thought to be due to an increase in sulphate aerosols. (ii) The climate has internal variability, due to things like ENSO (which redistributes heat between the Pacific ocean and the atmosphere). ENSO acts on a timescale of about a decade, and has an effect that is much larger than the change in CO2 radiative forcing. However ENSO is cyclic and averages out to nothing in the long term, but CO2 forcing doesn't, so in the short term the effects of ENSO can mask the effects of CO2 giving a short term (a decade or two) cooling even though there is a long term warming trend due to CO2. The "skeptic" canard that is based on this is debunked here.
  19. Dan69#67: "AGW message is appealing"

    If you feel the message is appealing, why do you follow immediately with 'fear of catastrophe'? That is the hard core rhetoric of the group with which you say you do not want to be associated.

    "The dark side ..."

    Appealing ... dark side; again, you're not sending a clear message. And again, this 'most self-destructive to our economy' is straight from the pages of those d-word folks. Are there no jobs in renewable energy? No new investment in technologies? No benefit from increased efficiency? No freedom from foreign energy suppliers? None of those items are in any way self-destructive. If you truly don't want to wear the cloak of denial, I suggest you re-evaluate your rhetorical choices.

    "Convergence is NOT a scientific conclusion."

    Sure beats divergence; a scientific conclusion supported by only some of the evidence isn't all that firm. One supported by the convergence and weight of the evidence is.
    0 0
  20. Dan68#67: "I feel inadequate to address the actual math and fear I am wasting everyone's time. "

    Many of us have difficulty with the actual math. That is no inadequacy; nor is a bona fide effort to learn a waste of time. What tends to waste time is the repetition of debunked fallacies pulled straight from the disinformation sources. Those who are wasting everyone's time are those who refuse to admit that there are things to be learned.
    0 0
  21. #67 & #68: Dan, you're way off the mark here. Your 'science friend' was wrong, as 'greenhouse gas theory' is utterly and intimately tied to AGW. The 'A' just means that we are making an extra contribution to the greenhouse effect, through our CO2 emissions. The reason that this causes warming, and the magnitude of the forcing, is explained by the physics of greenhouse gases. Nothing emotive or philosophical there, just physics.

    Reading through the literature, or perusing the IPCC summary reports will show you that what actually happened is what you describe for much of your 3rd paragraph of post #67. The only ones jumping to conclusions without consulting the full body of evidence are climate skeptics, the most recent example being Roy Spencer, who will happily ignore both observations and palaeoclimate evidence for high climate sensitivity while claiming to overturn the established science.

    In a physical sense, you can argue that GHGs slow the Earth's cooling rate - without GHGs we'd be about 33C colder. By the same logic, adding GHGs further slows the Earth's 'cooling' rate, warming the planet. But unless you change another forcing by a sufficient magnitude, you won't be actually cooling the Earth while adding GHGs. At present, you'd need a cooling off of the Sun not seen in human history (much larger than Maunder Minimum), or a series of very large volcanic eruptions in order to drive a long-term cooling.
    0 0
  22. "The AGW (Anthropogenic Global Warming) message is appealing. " You must be the only person in whole world who thinks this unpleasant reality is appealing.

    "the path to salvation is the most unnecessary and self destructive thing we can possibly do to our economy."

    And this is fear-mongering. Substantiate that. There might be bad ways of dealing with problem, but there are many other ways.
    0 0
  23. Dan69,

    I find appeals to economic catastrophe to be the most laughable reaction to global warming.

    First, global warming aside, ignoring impending oil shortages coupled with geometrically increasing world development and energy demands are a recipe for sure economic disaster for a country like the U.S. who has enjoyed a century of cheap energy.

    Second, the actual expense of converting to renewables and more efficient energy use, the same expense that will be needed to prepare for the coming energy crunch, is not anywhere near catastrophic, and will create new jobs and efforts that will help to boost the economy at this point in time.

    Lastly, every year of ignoring the problem makes it more expensive, and the ultimate expense of ignoring the problem until it is beyond critical could in fact mean economic catastrophe, along with untold and unnecessary human suffering.

    When I hear people say "economic catastrophe" I am listening to selfish, short sighted people that don't want to make the slightest, tiniest sacrifice to prepare for the future, much like people who graduate from high school and can't be bothered going to college because they can make money and buy a car with a job at the gas station right now.
    0 0
  24. Holy Toledo, Dan69: "The AGW (Anthropogenic Global Warming) message is appealing. It promotes the fear of catastrophe with the hope of salvation. It is promoted as the 'right thing to do'. The dark side, is that if AGW is wrong, the path to salvation is the most unnecessary and self destructive thing we can possibly do to our economy."

    "It" does not "promote" anything. The theory is a physical theory, not a rhetorical strategy. Its presentation to the non-scientific public definitely involves a rhetorical strategy based on fear. You know why? Because it's a deadly situation. If a scientist working on disease found evidence of a virus that could wipe out 10% of the global population, would you expect the scientist to keep her mouth shut and continue to work on whatever she was interested in or was paid to study? Or would you expect her to change the program and begin working on verifying the find and the potential consequences? Would you say that she was "promoting fear" by mentioning the find?

    I'm wondering, Dan, what evidence would convince you of the seriousness of the problem. Do you rely on someone else for your opinion regarding the seriousness? Or do you understand the situation well enough to provide an argument against the seriousness?

    And as for "appealing" I can think of little appealing in AGW. It means destruction and disruption on a global scale; only the wealthy are largely protected, and only the wealthy and the opportunists can turn the chaos into profit. Unlike many here, I am highly skeptical of fast development of market solutions in the current mode, particularly when the current mode is in a crisis phase that is only marginally related to the climate crisis. People tend not to make the best long-term decisions when their short-term survival is in question. Of course, I'll still bike to work and work on local solutions, but the history of capitalism is too full of catastrophic failures of vision to give me much hope for the near future.
    0 0
  25. Ryan L.J.

    Analogies and models are not intended to be truly accurate, they are necessarily simplifications intended to help convey an idea. GEP Box wrote "All models are wrong, but some are useful". Pedantry regarding the inaccuracies of analogies, or attempts to extend the analogy in ways that do not reflect reality, are a common way in which "skeptics" try to evade discussion of what the analogy is intended to convey and derail a discussion that is heading in a direction they don't like. It is a cheap rhetorical device, I;ve seen it all before, and I am not impressed this time either.

    The important idea conveyed by the analogy is that forcings affect long term statistical behaviour of a chaotic system, and that this change in statistical properties is predictable, even if the trajectory of the system itself is not.

    BTW, I got home from work yesterday to find that Mrs Marsupial had written a Java program animating a double pendulum and had worked out the maths for the version with the electromagnet. :o)
    0 0
  26. Moderator,

    Thank you for answering my question when you state:

    "To answer your question directly: (i) CO2 is not the only forcing, so even if CO2 is rising temperatures can still fall in the long term if there is a negative change in other forcings (e.g. solar) that more than compensates for the increase in CO2."

    You seem to be agreeing with my premise; wherein CO2 levels could be increasing, yet the temperature could be falling.

    To be very clear here, it is my understanding that CO2 slows cooling. That means the resulting temperature would be due to an underlying factor outside the effects of CO2 itself. If the temperature were to be retreating (and not through aerosols, but something more fundamental), CO2 would still be slowing the rate of cooling. There is no change to the physics regarding CO2, so I am in harmony with the science.

    Deductive Approach:
    Hypothesis – Theory – Observation – Confirmation.

    Inductive Approach:
    Observation – Pattern – Hypothesis – Theory.

    Inductivist methodology supposes that one can somehow move from a series of singular existential statements to a universal statement.

    Based on Popper's falsification theory, what part of your hypothesis, i.e. that man introduced CO2 will destroy the environment, can be falsified?

    If I were to hypothesize that CO2 is increasing in the environment, and more CO2 creates better living conditions, how would you falsify this premise?

    I detect the slippery slope fallacy coming.

    (an interesting side question; if we were heading toward an ice age would this community advocate increasing CO2 levels to reverse this trend?) Answering this question will create interesting conflicts of thought.

    Based on the current 2 ppmv added to the environment, it will take 175+ years to double the CO2 content and potentially realize all the catastrophic results implied.

    I deny nothing but conclusions. Using ad hominem labels, such as "denier", will not change the narrative.
    0 0
    Response:

    [DB] "my premise; wherein CO2 levels could be increasing, yet the temperature could be falling"

    All other forcings and feedbacks staying uniform, increasing levels of CO2 will raise temperatures.  Period.  It's physics.

    "There is no change to the physics regarding CO2, so I am in harmony with the science."

    The physics are unchanged, you are just not in harmony with them.

    "I deny nothing but conclusions. Using ad hominem labels, such as "denier", will not change the narrative."

    The "narrative" is unchanged: centuries of physics and research shows adding GHG will warm the climate.  We are adding GHG at a rate 10x that of the PETM and the climate is warming accordingly.

  27. Dan69#76:

    Let's start here: You state a. "it is my understanding that CO2 slows cooling." and b. "That means the resulting temperature would be due to an underlying factor"

    There is no logical connection between your premise a and conclusion b.

    To state the CO2 'slows cooling' is a bit like saying that placing a lampshade over a lamp 'slows darkening' once the light is turned off. That metaphor holds a glimmer of truth, but reveals little about actual mechanisms. Mountains of measurement show the physics of CO2 and radiation; there is no need to use anything but the appropriate language.

    If you appeal to 'underlying mechanisms,' you must specify what they are and how they work. Then and only then can you hypothesize, deduce and falsify. To state that an undefined 'something more fundamental' might be operating and simultaneously claim 'harmony with science' is a position of absurdity.

    Your arithmetic is sketchy: Even at a constant 2ppm per year, getting from 390ppm now to 560ppm (doubled pre-industrial level of 280ppm) doesn't take 175 years.
    0 0
  28. 76, Dan69,

    First, your entire post should be deleted because you are dragging this thread off topic and using it as a podium for your personal rants rather than to discuss the subject at hand.

    Second, your understanding of CO2 is weak and inaccurate. You should be using your time on this site to read and understand, rather than to pontificate about what you don't in any way grasp.

    Third, all of your nonsense about falsification is a foolish distraction. You can't argue the facts, so you instead want to discuss how many angels can dance on the head of a pin.

    Fourth, CO2 levels are currently at 390. Doubling the preindustrial level of 285 to 570 will only require another 180 ppm. At 2 ppm per year, this will happen in 90 years, so your math is wrong.

    That aside, it's also a foolish distraction. First, the effects don't all wait until that happens. It's not like turning off a ticking bomb seconds before it detonates. In fact, the worst of the warming comes earlier, rather than later, due to the logarithmic nature of the beast.

    Second, the presumption that the increase will only be 2 ppm per year goes along with the presumption that the rest of the world will not pick up pace in economic and social development. That's not a very safe assumption.

    Lastly, Dan, you do deny everything. You are so lost in what you want to believe that you have no clue whatsoever about what the problems are or we should do, and you contribute nothing to the dialogue except noise. You're like the kid sitting in the corner with his hands over his ears chanting "nah nah nah I'm not listening nah nah nah."

    Study first. Think second. Participate in the discussion after you've accomplished those two things.
    0 0
    Response:

    [DB] "Study first.  Think second.  Participate in the discussion after you've accomplished those two things."

    On a personal note, that is the orbit trajectory I followed.  Despite have degrees in the field, it had been well more than a decade since I had done anything professionally related to it.  So when I came back to it, I spent nearly 2 years studying & reading the literature before I posted my first blog comment.

    Not saying this is the ideal path for anyone; for me, even with the educational background in the field, I felt I needed that 1,000 hours or so of reading & studying to get my comprehension levels back up to snuff.  The field had progressed rapidly and had made huge strides in that interim.

    And I was getting old.  :)

  29. Dan69 @76, it's about time you stopped playing fast and loose with philosophical concepts of which you obviously have no understanding. You yourself introduced to this discussion the Duhem-Quine hypothesis, ie, the thesis that theories cannot be tested in isolation, but only in conjunction with a number of assumptions about initial conditions and the validity of other underlying theories. The immediate conequence of the Quine-Duhem hypothesis is that naive falsificationism is invalid as a scientific methodology. Indeed, Popper recognized this, but his solution, that the determination that a particular theory has been falsified must always be in part a matter of convention leaves something to be desired.

    But despite your introduction to Duhem-Quine to the discussion, you now insist on just the sort of naive falsificationist tests that it precludes. Either you are deliberately playing a deceptive rhetorical game, or you have introduced concepts you do not properly understand because you have a vague feeling that they support your position when, in fact they do not. That is a rather common tactic among deniers with a certain level of sophistication - to introduce Popper into a discussion as a means of reversing the burden of proof.

    Likewise it was you who introduced Hume and the "Is-Ought" gap into the discussion. If principled, that would require you to be very careful of the distinction between fact and value. But no, now you wish to introduce as a supposedly scientific hypothesis that is falsifiable the claim that, "If I were to hypothesize that CO2 is increasing in the environment, and more CO2 creates better living conditions, how would you falsify this premise?" "Better", is of course, a value laden term, so that your hypothesis, by the principles you supposedly espouse cannot be a scientific hypothesis; and a singular statement (by Duhem-Quine) cannot be falsified in any event.

    And just for good measure, you throw in an irrelevant reference to "slippery slope" fallacies.

    A person who understands concepts uses them to illuminate discussion. In contrast, you are using the concepts of philosophy inconsistently and with the apparent intention to make the discussion obscure. You sully treasures which you do not comprehend.
    0 0
  30. Dan69wrote: "If I were to hypothesize that CO2 is increasing in the environment, and more CO2 creates better living conditions, how would you falsify this premise?"

    Like most "skeptics" who pontificate about Popper, you have just demonstrated that you fundamentally don't understand the idea of falsificationism as the above is obviously directly falsifiable. We could conduct an experiment where pehaps we doubled atmospheric CO2 using fossil fueld emissions, if this failed to produce better living conditions (note a follower of Popper wouldn't have left the prediction as vague) then the hypothesis would be fasified.

    I see this sort of philosophy of science garbage used frequently as a means to refuse to accept well founded scientific theories, and I am sure that the originators of those philospohies of science would be just as appauled by it as I am. For instance David Hume showed that it is not possible to have certain knowledge regarding the real world by any empirical means. Does that mean that scientists should not perform experiments or draw conclusions from the outcome? Of course not. Hume himself said "A wise man proportions his belief to the evidence.", in other words, even though certain knowledge is not possible, you can still guide your actions by weighing the strength of the evidence (this is merely common sense and pretty much what scientists actually do).

    No wonder I am reaching the point of "whenever I hear the word 'epistomology' I remove the safety from my Browning" [metaphorically speaking of course]; it is rare these days to engage in a proper discusion of philosophy of science or epistomology these days that doesn't end up in frankly BS use to ignore inconvenient truths that are quite obviously on sound foundations to anyone capable of using their common sense in intepreting the bounds on certainty.

    Perhaps it is just that work with uncertainty (in a statistical sense) that I find it so hard to understand this issue. We can't have certain knowlede; but we have a perfectly good framework for optimal decision making under uncertain knowledge (which is available)

    "The true logic of this world is the calculus of probabilities."
    — James Clerk Maxwell

    Any more discussion of philosophy of science ought to be off-topic.
    0 0
    Moderator Response:

    [DB] "Any more discussion of philosophy of science ought to be off-topic."

    Agreed.  So let it be written, so let it be done.

  31. Dan69

    I wrote: "To answer your question directly: (i) CO2 is not the only forcing, so even if CO2 is rising temperatures can still fall in the long term if there is a negative change in other forcings (e.g. solar) that more than compensates for the increase in CO2."

    you wrote: "You seem to be agreeing with my premise; wherein CO2 levels could be increasing, yet the temperature could be falling."

    This is a clear case of confirmation bias. I was not agreeing with you at all. All things being otherwise equal, a rise in CO2 will produce a rise in global surface temperatures over a time scale long enough for internal variability not to mask the change. That is basic physics, which has been very well understood for at least sixty years, and is not contested by skeptic scientists such as Pat Michaels or Roy Spencer or Roger Pielke Sr... (in fact is there any skeptic climatologist that is willing to make such a claim anymore?).

    You are way out on a limb on this one, and don't have the backing of the all but the most extreme scientists on either side of the discussion. It is clear you don't understand the basic physics, I suggest you go and read the sources I suggested and come back wehn you can at least coherently explain the widely accepted theory of the greenhouse effect. If you can do that, and put the philosophy of science to one side, then and only then will you have reclaimed the status of being worth talking to that you have thrown away by your behaviour so far on this thread. It is your choice.
    0 0
  32. Mark Chu-Carroll over at Good Math/Bad Math often critiques mathematical crankery as espoused by those who set themselves against one or more broadly-accepted phenomena in science; one of his most pointed critiques is that the worst kind of math is no math at all.

    If I may, I feel the same criticism can be levelled at Dan69 here: when trying to rebut a well-supported conclusion in physical science (e.g. CO2 warms the atmosphere when added by anthropogenic fossil fuel combustion), the worst kind of science is no science at all - an appeal to philosophy of science is of little value in and of itself.
    0 0
  33. An open thread where things like Dan69's current understanding of GHE can be worked through would be nice. Newbies could use it as a foyer (then to be directed to the appropriate thread). I would like to read Dan's current understanding of AGW all at once (summary form, preferably semi-narrative) instead of this piece by piece kind of deal (unless it only exists in pieces).
    0 0
  34. 83, DSL,

    Another call for the Climastrology thread!
    0 0
  35. Dan @ 67... "The dark side, is that if AGW is wrong, the path to salvation is the most unnecessary and self destructive thing we can possibly do to our economy."

    You're setting up a false dichotomy. There is nothing to suggest that switching to CO2-free energy sources would do harm to the economy. In fact, quite the opposite is true. The greater likelihood is that the US can be a world leader in new energy and create a great deal of economic activity within our borders that would strengthen our economy.

    The fact is that, even if AGW were wrong (though it's not), fossil fuel sources can not possibly keep up with increasing global demand for energy. It's a limited resource that is becoming more and more expensive to acquire, process and deliver. Renewable sources of energy are on the opposite track. They are nearly limitless and falling in cost every year. Current estimates are that Solar PV will reach grid parity with coal in about 5 years.

    The fear people seem to have is that somehow a tax on carbon is going to cause damage to the economy. Nothing could be further from the truth. In actuality a carbon tax is just shifting the point at which we pay for the effects of atmospheric carbon. Estimates are that there is already $20/ton of cost to society for the production of carbon. A tax merely shifts the place where we pay that cost. Ultimately there is little or no economic loss. So, even without AGW there is no damage. The added benefit is that because of the climate effects from increased CO2 in the atmosphere there are tremendous benefits to dealing with the problem now over BAU.

    Look at a current US weather map today. The entire east coast is covered with exceptionally heavy rains. Those are real dollars of economic damage. And this is resulting from just a 0.8C rise in global temps resulting in 4% more moisture in the air. What happens when we have a 2.0C increase in temp and maybe a 10% increase in moisture? Any economic activity directed toward alleviating that scenario is money well spent.

    Sorry, I know this has gone off topic. If we want to continue this track there is a better thread here.
    0 0
  36. Climate is a complex subject.

    GHG theory states “greenhouses gases” – water vapor, CO2 and methane (plus some others) - absorb longwave radiation and re-emit radiation both up out of the atmosphere and back down to the earth’s surface. And without this absorption of longwave radiation the earth would be 35°C cooler at its surface. (do I have this correct).

    If so how would you explain dynamical collisional equilibrium:

    CO2 emits infrared radiation not only of the same intensity but also of a very similar frequency as the one it absorbs. (this next part is not me, it is from my professor friend who indicates that the term "heating" with regards to vibrational activity of molecule collisions are wrong. Again, these are not my remarks, but seem persuasive.

    "What Happens when a Greenhouse Gas Absorbs Energy?
    Once a gas molecule has absorbed radiation from the earth it has a lot more energy. But in the lower 100km of the atmosphere, the absorbed energy is transferred to kinetic energy by collisions between the absorbing molecules and others in the layer. Effectively, it heats up this layer of the atmosphere.

    This is only half the story and because of seeing only the half story , the conclusion is wrong.

    What you say is the following :
    A* + B -> A + B_
    In words – the vibrationnaly excited molecule A* interacts with a molecule B , its excited state decays to A and the molecule B increases its kinetic energy to B_ . This is right.

    But what you forget is that by time symmetry we have also :
    A + B_ -> A* + B
    The molecule A interacts with a molecule B_ , its vibrationnal state excites to A* and the molecule B_ decreases its kinetic energy to B. This is btw the process that makes a CO2 laser work .

    In LTE what is the basic hypothesis in all these posts we can even say more , namely that the rate of both processes is exactly equal and we have an equilibrium that can be written :
    A* + B A + B_
    Please note the difference to the initial A* + B -> A + B_ !

    The conclusion that follows is that the number of A* (vibrationnaly excited molecules) is constant .
    Also another way to say the same thing is that the distribution of the kinetic energy of the B molecules is constant too.

    Still another independent way to find again the same result because they actually all use same concept of energy equipartition , is to note that the distribution of vibrationnal energy levels is constant for a given temperature (Maxwell Boltzmann law).

    So it appears that whatever some IR absorbing molecule A* (CO2 , H20 , CH4 etc) does , there is at least one thing it doesn’t and it is to “heat the atmosphere”."

    Again, not my work, but it was explained to me, although I do not have the skills to verify.
    0 0
  37. Dana69

    An important element of radiative heating/cooling is that emissivity equals absorptivity when the object (in this case the atmosphere) is at thermal equilibrium.

    If the atmosphere is hot enough it will emit more energy than it is absorbing, and it will cool. If it's cool, and receiving more energy than it's emitting, it will warm up. this is governed by the Stefan–Boltzmann law.

    If the atmospheric temperature is not at the point where its emissions match incoming IR, it will change temperature.
    0 0
  38. KR,

    Thanks for your remarks. Just curious, isn't convection a stronger force than radiative force in the troposphere?

    My understanding is that the Stefan-Boltzmann law applies in the stratosphere where convection and conduction are weakest.

    Respectfully,
    0 0
  39. Dana69 - The Stephan-Boltzmann law applies everywhere, at all times. Objects always have an absorptivity, and an emissivity, and those spectra match at thermal equilibrium.

    Convection (thermals) accounts for ~17 W/m^2 of energy rising from the Earth. Evaporation is around 80 W/m^2, while IR averages 396 W/m^2 coming off the surface, meaning that thermal radiation is >20x convection. Please see Trenberth 2009, Fig. 1, for details.

    Note that without convection, we would be much warmer - convection helps move warm air up to where it can radiate to space. But the majority of that energy is carried by thermal radiation.

    And please, read that Trenberth article carefully - convection is very noticeable, but not dominant in terms of energy transfer when you actually run the numbers. There have been any number of posters on any number of blogs who make a common sense error in that regard, and it always seems to take quite some time to correct such misapprehensions.
    0 0
  40. KR @89, a slight nitpick. 40 W/m^2 of the surface radiation escapes to space, so the energy absorbed by the atmosphere from the surface by radiation is 356 W/m^2.

    More importantly, Trenberth and Fasullo quantify energy transports from the surface to the atmosphere. They do not quantify energy transports within the atmosphere, and within the atmosphere, or more specifically the troposphere, convection dominates over radiation as a means of energy transport. As I understand it, the reason for this is that it would take weeks (?! certainly days) for the atmosphere to reach a purely radiative equilibrium while it only takes hours to establish a convective equilibrium. Consequently the troposphere has a lapse rate determined by convection rather than radiation.

    Dana89 is right if he thinks this face weakens the greenhouse effect. If the troposphere's temperature profile was determined by radiation rather than convection, the Mean Average Global Temperature would be closer to 90 degrees C than to 15! It is only because convection reduces the greenhouse effect that the surface of the Earth is inhabitable!

    But reducing the greenhouse effect is not eliminating the greenhouse effect. Since the 1960's, the effect of convection on the greenhouse effect has been fully taken into account by atmospheric scientists, and their predictions, including the prediction of increased surface temperatures as a result of increased CO2 concentrations incorporate that fact, and are based on it. The only way to find solace in the dominance of convection is to studiously pay attention to that one fact, and ignore all the others that you find inconvenient.
    0 0
  41. 86, Dana69,
    So it appears that whatever some IR absorbing molecule A* (CO2 , H20 , CH4 etc) does , there is at least one thing it doesn’t and it is to “heat the atmosphere”."
    This is wrong for three reasons.

    First, your explanation assumes an unchanging system at equilibrium. But what we are talking about is adding more A to that system, which will change the balance of the equations (after raising the temperature).

    Second, the equations you've been given all work for a closed system in equilibrium, which leads us to the last point, which is...

    Third, there are more equations to consider (I've numbered them to be able to sort them out).

    These are what you've considered so far:
    (1) A* + B -> A + B_
    (2) A + B_ -> A* + B

    The conclusion that follows is that the number of A* (vibrationnaly excited molecules) is constant."
    This conclusion is wrong unless the system is in equilibrium (which it can't ever be, because the sun sets and rises, adding more or less * to the system, so it is constantly changing).

    The big problem with this is that set of equations is incomplete. The system is not closed (it has differing amounts of IR entering and leaving) and is not in equilibrium until it has warmed (if you increase the amount of A (CO2) in the system).

    You have two more equations:
    (3) * + A -> A*
    (4) A* -> A + *
    Here, to be consistent with the previous notation, I am using * to represent the introduction of infrared radiation to the system, to excite a CO2 molecule (A).

    What is important to recognize is that these equations are not in a simple 1 to 1 equilibrium, and so the balance is more complex.

    First, equation 4 happens a lot less than equation 1 lower in the atmosphere, it balances more and more as you get higher up and the air is less dense, so collisions (Eq. 1 and 2) are less likely to happen, until you reach a point where equation 4 happens more than equation 1.

    So ultimately the balance in these equations depends on how often 1 and 2 occur, which is determined by the temperature and density of the atmosphere (since temperature affects average velocity of the molecules) and also the amount of A* in the atmosphere, which is altered since equation 3 elevates the amount of A*.

    The frequency of equation 3 depends on the amount of infrared coming into the system, which is dependent not only on the temperature of the surface but also the temperature and composition of the nearby layers of atmosphere. Equation 3 also depends on the amount of A/CO2 in the system. More A means more chances to intercept IR, and so more chances to become A*, and so more chances for equation 1 to occur (passing that energy on to B and heating the system).

    Equation 4 depends almost entirely on the amount of A* (excited CO2) in the system, which depends on the rates of equations 1, 2 and 3. Lower in the atmosphere, it doesn't get to come into play as much, because equation 1 robs the atmosphere of A* so quickly (100 such collisions [Eq. 1] occur on average before it is able to emit [Eq. 4]).

    Higher up the reverse is true, so that equations 2 and 4 happen more often, and in that case CO2 actually acts to cool the stratosphere.

    So I'm afraid, yes, CO2 does heat the atmosphere, but the interaction is far, far more complex than the simple two equation scenario that your chemist friend has presented, and the answer to how much requires understanding all of the factors, including how often collisions occurs (eq. 1 and 2), how much IR is entering the system (eq 3), and how long a CO2 molecule "waits" before emitting IR (equation 4) relative to the rates of equations 1 and 2.

    But most importantly, the question is not "does A heat the atmosphere?" but rather "does increasing A heat the atmosphere beyond what it was before the increase?"
    0 0
  42. Just to add clarity, by using English, to the equations above:

    1) A* + B -> A + B_ : excited GHG molecule A increases the velocity of non GHG molecule B (raising the temperature)

    2) A + B_ -> A* + B : GHG molecule A collides with non GHG molecule B, becoming excited and robbing molecule B of velocity (lowering the temperature)

    3) * + A -> A* : Infrared radiation strikes GHG molecule A, exciting it

    4) A* -> A + * : Excited GHG molecule A emits infrared radiation, becoming de-excited
    0 0
  43. Tom Curtis - 40 W/m^2 escapes directly through the atmospheric window. However, ~160 W/m^2 leaves the ground through various means (IR, evaporation, thermals, minus 333 W/m^2 back-radiation). And ~80% of that energy leaves the surface via IR.

    But yes, convection is a major contributor to that heated atmosphere being able to radiate to space. A good thing, too - an average temperature 10 degrees C under boiling would be, um, uncomfortable...
    0 0
  44. here is another comparison of trace gases.

    Hydrogen Sulfide - H2S. it occurs naturally typically in swamps and sewers as well as emmitted from volcanoes.

    0.00047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic odor of hydrogen sulfide,[14] normally described as resembling "a rotten egg".
    Less than 10 ppm has an exposure limit of 8 hours per day.
    10–20 ppm is the borderline concentration for eye irritation.
    50–100 ppm leads to eye damage.
    At 100–150 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger.[15][16]
    320–530 ppm leads to pulmonary edema with the possibility of death.
    530–1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing.
    800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure (LC50).
    Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.

    http://en.wikipedia.org/wiki/Hydrogen_sulfide
    0 0
  45. The average depth of the troposphere is 17km.

    400ppm of a 17 km path is 400/1,000,000 x 17km = 0.0068km

    So 6.8 meters (~22 feet) of the shortest possible optical path for an IR photon leaving the earth is occupied by CO2.
    0 0
  46. Paulie200, see http://funnel.sfsu.edu/satlab/docs/wthr_sat.1.html for just one example that seems to contradict your pathlength calculation.
    0 0
  47. 95, Pualie200,

    The equation you gave is ppm / km. This means that the units of measure of your answer is in ppm / km, not km. This basically represents molecules-of-CO2 per molecules-of-atmosphere per kilometer of depth, which is a fairly meaningless number.

    I'm not sure what you were driving at, however, by your post. Can you explain what you are trying to do?
    0 0
  48. Sphaerica @ 97:

    OK, that is a bit confusing What I was trying to do, in keeping with the spirit of the original post, was to come up with some simple example of why "trace" does not mean insignificant. A 6.8 meter "layer" of CO2 sounds a little more significant than 0.039% for those who don't easily grasp numbers.

    But I can't say 'layer', because the science sticklers here might make me do the calculations to bring it all to a uniform pressure and then calculate the optical depth of the layer, not to mention explaining the quantum mechanics of absorption and all the other physics ;) So I chose path length.

    390 pmm CO2/1,000,000 ppm Atmosphere, is a ratio. The 'ppm' cancels. (I rounded to 400ppm because we'll be there soon enough.)

    Consider a cylindrical volume of any diameter straight up through the troposphere. By the Ideal Gas Law all gases occupy about the same volume at a given temp and pressure. For any given diameter, the volume of the cylinder times the percent concentration of a gas component, gives the volume of that gas.

    The cylinder is uniform, and CO2 is well mixed, so the ratio of CO2, times the length of the cylinder, ALSO gives the effective length that a photon must transit of that particular component were it all in one place (Albeit at different pressures and temperatures along the path.)

    What I was trying to say is that yes 0.039% of something doesn't seem like much. But if that something is large, like a layer of atmosphere 17 km thick, it's actually a lot more than it first appears. (I'm not a PhD, but I do get to use IR instruments on occasion, it doesn't take a whole lot of CO2 to make the instrument useless for measurements in and near the CO2 absorption band because of how effective an absorber it is.)
    0 0
  49. Eric @ 96,

    I really don't comprehend why you want to send me on a fishing expedition for what you want to say, but I did read the little brief on IR satellite images. Interesting, but perhaps you got the wrong link? Or maybe I'm missing something?

    I'm open minded, just let me know how my admittedly simple exercise in first approximations is wrong, then point me to the correcting information.
    0 0
  50. Paulie200, I posted the link merely to point out that IR reaches the sky. Your post didn't give the proportion of photons absorbed in the minimal path that you calculated (I assume it's close to zero) or the proportion absorbed over 17 km. I don't know if it is small or large, but the IR satellite (typically inverted color) implies it is on the large side if the earth shows up as black. Sorry that I implied your calculation was wrong, but I was wondering about the significance of the shortest path calculation.
    0 0

Prev  1  2  3  Next

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.



The Consensus Project Website

TEXTBOOK

THE ESCALATOR

(free to republish)

THE DEBUNKING HANDBOOK

BOOK NOW AVAILABLE

The Scientific Guide to
Global Warming Skepticism

Smartphone Apps

iPhone
Android
Nokia

© Copyright 2014 John Cook
Home | Links | Translations | About Us | Contact Us