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Waste heat vs greenhouse warming

Posted on 27 July 2010 by John Cook

A vigorous discussion has erupted on the waste heat page. Problem is, there's not meant to be a waste heat page! As I encounter new skeptic arguments, I add them to the to-do list and gradually (very gradually) research the peer-reviewed literature then write an explanation of what the science says, usually in order of popularity. I hadn't got around to looking into the issue of waste heat. Nevertheless, one intrepid Skeptical Science user found the empty page waiting to be populated and began a discussion there (j'accuse Doug Bostrom). So let's look at waste heat...

Firstly, what is waste heat? When humans use energy, it gives off heat. Whenever we burn fossil fuels, heat is emitted. This heat doesn't just disappear - it dissipates into our environment. How much does waste heat contribute to global warming? This has been calculated in Flanner 2009 (if you want to read the full paper, access details are posted here). Flanner contributes that the contribution of waste heat to the global climate is 0.028 W/m2. In contrast, the contribution from human greenhouse gases is 2.9 W/m2 (IPCC AR4 Section 2.1). Waste heat is about 1% of greenhouse warming.

Radiative forcing from waste heat vs anthropogenic greenhouse gas radiative forcing

What do these numbers mean? They refer to radiative forcing, the change in energy flux at the top of the atmosphere. Or putting it in plain English, the amount of heat being added to our climate. Greenhouse warming is currently adding about 100 times more heat to our climate than waste heat.

UPDATE 27 July: there is some confusion about the term 'waste heat'. Here, what I'm talking about is all the heat generated by energy use. When humans generate energy, much of it is immediately dissipated as heat. The rest is converted to electricity or energy of some sort (eg - mechanical, chemical, etc). But even this energy eventually dissipates as heat into the environment. So yes, 'waste heat' is not an ideal term. Flanner uses the term "anthropogenic heat flux".

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Comments 251 to 300 out of 300:

  1. Hopefully someday, a paper will be passed around with my idea so you can come into the constructive "fold". Usually found on a roll, sometimes folded, sometimes crumpled, never "passed around."
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  2. RSVP, A value can only be integrated if it remains in the system. Your steadfast refusal to acknowledge that anthropogenic heat flux radiates out from the planet does not change the reality of the situation.
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  3. Bibliovermis "The energy does not remain present in the planetary climate. It radiates out from the planet into space" When the train leaves, and all the seats are taken, you cant get on the train. The hockey stick handle was flat. This implies equilibrium. Any excess energy is excess energy and WILL accumulate. End of story.
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  4. Energy comes in. Energy goes out. When the energy coming in equals the energy going out, equilibrium is reached. Equilibrium does not mean no outgoing radiation.
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  5. Energy FROM THE SUN comes in. Energy FROM THE SUN goes out. Add some "CARBONATED" energy from dead dinosaurs for 200 years and you get global warming my friend.
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  6. RSVP, Please try and understand what is being explained to you. Waste heat is released at a constant rate, it is included as part of the equilibrium input and output. When we are at equilibrium, then that means every unit of energy added by waste heat each year is being output into space. This is the definition of equilibrium, energy in equals energy out. There is no "excess" energy anywhere in the equation. If we increase the annual rate of waste heat release, then in the short term yes energy accumulates. The reason for this is it takes time for equilibrium to be restored. But restore it shall, and once it does energy once again stops accumulating. The reason waste heat doesn't add much to the equation is because the rate isn't growing; it's relatively constant so the earth has had plenty of time to reach equilibrium with respect to waste heat. The analogy to the train is off-base. Imagine instead a train that automatically grows or shrinks itself depending on how many get on or off. This is how thermal equilibrium works. Just keep these two critical concepts in your mind when you think about this: 1. In the long term, energy in MUST equal energy out (waste heat counts as energy in BTW). 2. The rate of thermal radiation is directly proportional to temperature. The faster you heat you add to an object, the faster it radiates that heat.
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  7. RSVP, We are not "adding energy" by burning fossil fuels, we are temporarily slowing the rate at which energy is released into space, causing a build up of heat.
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  8. RSVP, Please explain how anthropogenic heat flux is different than solar heat flux. Why will AHF build up rather than radiating away from the planet?
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  9. Bibliovermis #257 As an analogy, situate yourself at an orange grove that takes in oranges for packing and export from other groves in the vicinity. (This represents heat input and output from the Sun.) Every year, 100,000 oranges are brought in from surrounding groves, and 100,000 oranges are shipped to other locales. Not a single orange is left over. BUT! Since the grove began, 100 trees have begun to produce fruit. They are leaving 5000 oranges which either have to ship or rot. The market is saturated, so the oranges are not shipping, however, since the quality of what is coming in from other groves never was really perfect, some of what grows in the local grove does go out. However the 5000 surplus that cant sell remains in the grove. These are not necessarily oranges that grow in the grove, but at any rate 5000 oranges are now added to a rotting pile every year. This represents global warming.
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  10. You have yet to explain why anthropogenic heat flux does not radiate from the planet. Your analogies, the train & the orange grove, are flawed in that they assume a unchanging emission rate. This assumption is not valid when discussing a radiating body, e.g. the planet. Outer space is not saturated with energy.
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  11. #259 Of course anthropogenic heat flux radiates, along with, and indistinguishably from solar heat. However the baseline temperature is referenced from the situation where this heat source is non-existent. The addition of this heat source increases outgoing radiation while at the same time raises the average global temperature.
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  12. If anthropogenic heat flux radiates, how does it accumulate?
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  13. RSVP >The market is saturated, so the oranges are not shipping Listen carefully: this is physically IMPOSSIBLE in thermodynamics. There is no such thing as "saturation" when we are talking about how much energy a particle emits. The rate of output will always grow to exactly match the rate of input. Not some of the input, ALL of it. Your constantly accumulating surplus cannot and does not exist.
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  14. RSVP - And you completely ignored what I said here, that the sign of the TOA radiation imbalance completely disproves the waste heat theory. As to that 1% accumulating - well, it's been 1% for as long as the 99% greenhouse gas forcing, the CO2 side effects of that energy use, which is actually the major cause for warming. RSVP, you have continued to hold to this theory over >300 postings on multiple threads, despite numerous examples of why you are incorrect. I can only conclude that you have non-rational reasons for clinging to it. Given that, it's simply not worth the time to discuss it any further with you.
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  15. Still waiting on those 'typical' maps showing UHI effects stretching out far from their urban sources.
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  16. e #262 "The rate of output will always grow to exactly match the rate of input. Not some of the input, ALL of it. " If this were true, the ambient temperatures would never get over 0 Kelvin. I think you need to reword that sentence.
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  17. @RSVP: "If this were true, the ambient temperatures would never get over 0 Kelvin. I think you need to reword that sentence." No. *You* need to learn basic physics. Hint: heat transfer is not instantaneous (nor did e's post claim it was, hence the use of the term "grow"). Oh, and where are those UHI maps? Are you sure they exist?
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  18. KR #242 "radiation increases since we're now warmer than solar equilibrium... Greenhouse gases accumulate, decreasing the emissive spectra of the Earth." I have put these to clauses side by side to illustrate a "minor" inconsistency. You are obviously saying that more energy is escaping due to waste heat, while less energy is escaping due to GHGs. You mentioned I am not rational when in fact my entire approach is based on deductive reasoning. The Evans paper for instance is just the opposite in that it documents measurements made for the sole purpose of upholding a theory. I was going to say there are two schools of thought, empiricism and reason, however now that I THINK about it there is only ONE school of thought, and that is the school of reason.
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  19. archiesteel #266 "Oh, and where are those UHI maps? Are you sure they exist?" My words were, "as seen from a map" to depict the perspective as in "top view". You need to improve your basic reading skills.
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  20. RSVP >You are obviously saying that more energy is escaping due to waste heat, while less energy is escaping due to GHGs. Nope, that's not at all what KR was saying, you are just misunderstanding the definition of the terms. Decreasing the emissive spectra of the earth does not mean less energy escaping to space. What it means is the earth has to get hotter to equal the same output, which as I pointed out, it MUST do otherwise it violates the 2nd law of thermodynamics. In other words, the total radiation escaping to space is identical whether GHG's are present or not, the difference is the earth has to get a lot hotter to generate the same rate of emissions. This is the basic principle behind global warming.
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  21. RSVP>If this were true, the ambient temperatures would never get over 0 Kelvin. I think you need to reword that sentence. As KR pointed out, you are forgetting that there is a delay between when the input increases and when the output grows to eventually match the input. It is during this delay that temperatures increase. Once the output has had time to match the input, then we are at equilibrium and the temperature does not increase any further. Again, no accumulation beyond this point.
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  22. RSVP, what you wrote was; "So instead of the effect you describe, as seen from a map, there is typically a large smudge or plume that emerges around an urban center that tapers eastward... heat that is gradually dispersed but never lost" You have stated that this is the typical situation. The norm. Thus, surely you can show some evidence of it. Otherwise you'd have made a claim about something being 'typical' with no basis. I was able to find the 'anomalous' images below showing NO 'long downwind tail' without much effort. Surely finding images of the TYPICAL situation must be MUCH easier. Either that or the laws of physics still hold, urban heat (which is mostly due to albedo change rather than waste heat to begin with) rises due to convection, heated air then spreads out - forcing colder air downwards on all sides, and thus you get an extremely localized heat ISLAND. With that heat then dissipated higher up in the atmosphere it quickly escapes to space like all other heat rather than magically hanging around in the climate system for decades. But that's just physics and sanity talking. Please, show me a 'typical' map to the contrary.
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  23. CBDunkerson #271 Ironically, you have produced three two-dimensional figures, and then correctly describe the problem as involving three dimensions. Hard to diagram isnt it? and more difficult to imagine the heat spreading in all directions when the wind starts blowing, which was the context of my statement. And whether the shape is a tear drop or a mushroom cloud is neither here or there in terms of the discussion. If you think being wrong about this detail is sufficient to discount my theory or me, that is the ad hominem approach, which you are free to take, as I am not the moderator. You say, "urban heat (which is mostly due to albedo change rather than waste heat to begin with) rises due to convection, heated air then spreads out - forcing colder air downwards on all sides" Now some sanity (as you say)... Urban heat doesnt rise. Air that has been warmed by convection rises. Air that has been warmed by heating systems, car engines, and as you say asphalt, concrete, warmed by the Sun, etc. And yes, some of this heat escapes into infinity, but given the fact that there is a finite amount of heat emitters (IR radiators such as the asphalt and buildings themselves, CO2, H2O, steel highway girders, basically all grey bodies on Earth), some heat will accumulate. And YES, you get more radiation as temperature increases; but this is no different from what can be said about possible contributions coming from GHGs. There seems to be one more hitch. Imagine a lake whose level is seen to rise 3 inches in the course of 150 years due to a new spring breaking ground up stream. Perhaps after 5 years the original water in the lake has been completely replenished, and yet the level is steadily rising. After 150 years, the top three inches of the lake are not just from this new river.
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  24. e #268 You need to start seeing the Earth as an active rather than a passive element. Outward radiation does not have to be constant. e #270 Here you are blaming me for forgetting something that someone else omitted in their statement.
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  25. To CBDunkerson The lake analogy has to do with your remark about heat, "magically hanging around in the climate system for decades." If you cant make the connection here, there is no point in going on.
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  26. RSVP #272: "Hard to diagram isnt it?" Not at all. Heat goes up. Heat disperses. Heat leaves the atmosphere. I've seen dozens of diagrams of this... all those radiation balance diagrams on this site for instance. "If you think being wrong about this detail is sufficient to discount my theory or me, that is the ad hominem approach" Discounting your theory because the details of it are wrong is an ad hominem approach? Fascinating. "Now some sanity (as you say)... Urban heat doesnt rise." We have different definitions of sanity. Heat rises. Urban heat. Rural heat. Waste heat. Solar heat. Magma in the Earth's core which is hotter than the surrounding magma. You name it. Any portion of a fluid substance which becomes heated rises above the surrounding matter. This is a fundamental property of convection. Something which you go on about quite a bit, but apparently know nothing about. "Air that has been warmed by convection rises." That statement is an oxymoron. Convection causes air warmed by other sources (e.g. 'urban heat', 'sunlight', et cetera) to rise and COOL.
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  27. RSVP, You still have not explained how AHF radiates just like SHF and yet accumulates. Yes, you are using logic. However, you aren't using it to arrive at your conclusion. You start at a conclusion and deduce a path that will arrive there, disregarding any basic extant knowledge on the matter.
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  28. RSVP - I'm responding because you apparently, in this posting, did not understand what I said about two alternative theories for global warming. Sections (1) and (2) of that post indicate distinct alternatives for the major cause of warming - AHF or GHG's. (1) If AHF dominates, top of atmosphere radiative imbalance will become positive (more energy leaving than arriving from the sun, some fraction of the energy added at the surface), with that amount increasing as the Earth approaches equilibrium, ending up at solar input + AHF and a warmer Earth. (2) If GHG's dominate (and the 2 orders of magnitude difference in energy involved should point that direction), TOA imbalance will be quite negative due to the GHG spectral reduction, with that imbalance decreasing as the Earth warms and approaches equilibrium. At equilibrium, the TOA imbalance should be zero, with outgoing radiation again equaling solar input (albeit with a somewhat different emission spectra). What's the actual situation? Well, read Harries 2001 on Is the CO2 effect saturated; also Griggs 2004 and Chen 2007. The TOA imbalance is negative. This is scenario (2), and this means that GHG's dominate warming. I expect that AHF reduce the imbalance by, say, 1%, but I don't think that will even show in the noise. It's not waste heat, RSVP. You seem to have come to a conclusion you're happy with, and continue making poor analogies and quite frankly making up non-physical effects (not cherry picking - there isn't enough evidence for your view to pick) to support that. You've long since left the realm of scientific discussion.
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  29. RSVP >You are obviously saying that more energy is escaping due to waste heat, while less energy is escaping due to GHGs. e > Nope, that's not at all what KR was saying, you are just misunderstanding the definition of the terms. Decreasing the emissive spectra of the earth does not mean less energy escaping to space. Actually, decreasing the emission spectra of the Earth will decrease the amount of energy escaping to space at that temperature, until conditions change. Given the time constants for ocean warming and the like, it will take ~40-50 years for the temperatures to increase (with energy accumulating on Earth) to finally reach a new equilibrium, where integrated thermal emission once again equals integrated solar input. Of course, if GHG forcings continue to change, the climate will follow along, short term feedbacks (water vapor, clouds) first, longer term changes (ground cover, ice, ocean temps) lagging behind.
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  30. RSVP, The connection you are attempting to portray with your lake analogy is just as flawed as the train & orange grove analogies were. More water in means more out. Increasing the input will only cause a level rise if the output is restricted.
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  31. @RSVP: "My words were, "as seen from a map" to depict the perspective as in "top view". You need to improve your basic reading skills." My reading skills are fine. *You* need to provide evidence that supports your claims. KR said it best, and there's really no point in going any further on this matter: "I expect that AHF reduce the imbalance by, say, 1%, but I don't think that will even show in the noise. "
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  32. KR #277 "You've long since left the realm of scientific discussion." Since you seem to know so much, I would ask if you think it even be possible for anthropogenic waste heat to cause global warming? Not the amount that we are currently putting out, but some other larger amount. When this post got started, the reason AWH was being ignored was due to numbers, now it appears to be impossible according to what you are saying in 277. Which does it happen to be, or does the reason change with the zodiac?
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  33. @RSVP: "When this post got started, the reason AWH was being ignored was due to numbers, now it appears to be impossible according to what you are saying in 277." Actually, that's not what he said at all. He specified it does have an effect, but such a small one it would get drowned in the noise.
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  34. RSVP - As a thought experiment, consider a world where all of our power came from non-CO2 sources (Nuclear, perhaps?). Change in regards to radiative forcings (energy input) is formulated as: dT = λ*dF Where dT is the temperature change, λ the sensitivity, and dF the radiative forcing change. Given an anthropogenic heat flux of 0.028 W/m^2, and a climate sensitivity of 0.54 to 1.2°C/(W-m-2) for λ, you can calculate that: The expected equilibrium global warming contribution from AHF would be 0.01512°C to 0.0336°C. That amount is totally lost in climate noise. We've seen a change of 0.8°C in just the last 40 years, and we're far from equilibrium. AHF contributes, but it's only a tiny contribution. It's not the dominant cause by two orders of magnitude.
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  35. Small amusement (if the moderators let this by) - here's a nuclear powered car. No CO2 contribution at all, although I'm not fond of the idea of riding in front of a hot neutron source...
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    Moderator Response: That would be a perfect fit in the "Are we too stupid" topic. :-)
  36. Oh, golly, decisions! Do I want the reactor ahead of me, or behind? So often the only answer is, "it depends."
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  37. KR #283 As a thought experiment, imagine if you could simply answer the question and remain coherent, nor have to renounce your cherished beliefs and formula. Not easy is it?
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  38. @RSVP: he responded to your question, quite well too. The fact you don't like the answer is inconsequential.
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  39. Re: archiesteel (287) I believe that may have been RSVP's version of a concession speech...
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  40. To archiesteel... It is accurate to say a response is not an answer. KR The answer only required a YES or a NO, and a number please if YES. Let me put training wheels on the question and rephrase. Is there any amount of energy put out by man on a continual basis that could cause the Earth's temperature to rise, say 1 degree C?
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  41. Daniel Bailey #288 You just stepped in something. Check your shoe.
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  42. Is there any amount of energy put out by man on a continual basis that could cause the Earth's temperature to rise, say 1 degree C? The amusing thing about that question is that to a "skeptic" a proper answer would be impossible for all the same sorry reasons we're familiar with. A model would be necessary, feedbacks accounted for, parameterizations established, etc.
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  43. doug_bostrom #291 On the otherhand, for the so called "non-skeptic", if it isnt found on the internet, it cant be true... most amusing indeed.
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  44. @RSVP: I don't really think you're looking for an answer. You're just here to waste people's time. If I'm wrong, and you *are* looking for an answer, how about "100 times," since waste heat is 100x smaller than AGHG forcings. Two orders of magnitude. You know, what it says in the article above.
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  45. #292 One question leads to another, not that KR shouldnt provide a decent answer, but here's one more. Did scientific inquiry stop when AGW was formulated? Just a question.
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  46. Replying to yourself, RSVP? (You posted #292.) The answer to your question is no. It didn't even stop when contrarians began to ignore the facts to spew strange theories and engage in amusing but otherwise wasteful sophistry.
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  47. Oh, and KR did provide a decent answer. You should apologize to him for your rude behavior. Moderators, you should delete this entire exchange.
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  48. archiesteel #293 "how about "100 times," Looks like you forgot about the effects of GHG. 100 seems too high now. I do a lot of cooking, and turn the flame down when I put the lid on the pot. It doesnt take much to keep the pot going once the right temperature is reached.
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  49. @RSVP: you didn't mention that, in that hypothetical scenario, humans were still emitting GHGs. How am I supposed to know what's in your imaginary world? Maybe it's full of grazing unicorns whose flatulence actually remove methane from the air. Your cooking analogy is similarly flawed. But hey, you're clearly lonely, who am I to judge.
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  50. Oh, and where are those map-like top projections that show UHI effects "trailing off"? I mean, you must have some handy, considering you claimed they existed several posts ago, right? Right? You know, unless you made that up.
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