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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.

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Greenhouse warming 100 times greater than waste heat

What the science says...

Select a level... Basic Intermediate

Greenhouse warming is adding 100 times more heat to the climate than waste heat.

Climate Myth...

It's waste heat

"Global warming is mostly due to heat production by human industry since the 1800s, from nuclear power and fossil fuels, better termed hydrocarbons, – coal, oil, natural gas. Greenhouse gases such as carbon dioxide (CO2 play a minor role even though they are widely claimed the cause." (Morton Skorodin)

At a glance

There are various kinds of climate science deniers out there, but one grouping can usefully be classified under the acronym ABCD - Anything But Carbon Dioxide. These people appear to accept the climate is heating up. Flailing around to try and identify something other than CO2 causing the heating, they will seize upon all sorts of candidate causes. This is one of them. There are many others.

All the energy we use dissipates into the environment post-use, be it a driftwood fire on the beach or the heart of a busy metropolis, on the go 24-7. So it should come as no surprise that 'waste' heat does have a role - a minor one - in heating the planet. Humans have always been fond of fire since they learned to ignite things and there's nothing better than sitting round a blaze of a night with a few friends. No need to feel guilty about that. It's harmless in the overall scheme of things.

Waste heat is of course a much studied subject. After all, more sophisticated heating systems, compared to that fire on the beach, are energy-intensive and that translates as expensive. Ways to minimise heat loss and thereby improve efficiency form an active research topic. In that sense, a number of studies have looked at the bigger picture: just how much waste heat is there?

Unsurprisingly, cities, where huge numbers of people work, rest and play, are megacentres of heat wastage. The term, 'Urban Heat Island', acknowledges this. But the planet is a big old place and cities occupy relatively small parts of it. To find the warming contribution of waste heat, you need to have two figures: the total energy lost and the surface area of the planet. Doing the maths you can then derive the amount, expressed in watts per square metre. You can then compare it to other heat sources.

All studies of waste heat have arrived at a similar conclusion. There's a lot of waste heat over cities but the total, global amount, expressed as watts per square metre of the planetary surface, is a tiny fraction of the heating caused by the greenhouse gases. So while it's highly desirable to find better efficiencies in energy use and conservation, thereby saving money, when it comes to temperature it's greenhouse gas emissions we have to hold firmly in our focus. ABCD indeed. Next.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

Heat is released to the atmosphere as a result of human activities, many of which involve combustion of fuels, directly or indirectly. Sources of this 'anthropogenic heat' include industrial plants, heating of buildings, air-conditioning, vehicle exhausts and many more. In cities, anthropogenic heat typically contributes 15–50 W/m2 to the local heat balance, and several hundred W/m2 can be reached in the centres of large cities in colder climates.

This heat doesn't just disappear - it dissipates into our environment. How much does waste heat contribute to global warming? There have been several studies over the years, widely-cited examples being Flanner (2009) (if you want to read the full paper, access details are posted here), Dong et al. (2017) and Varquez et al. (2021). All have come up with similar numbers despite differences in methodology: the core message is that while waste heat is an issue and is self-evidently undesirable, its contribution to global warming is a tiny fraction of that brought about by CO2.

Flanner concluded that the contribution of waste heat to the global climate was 0.028 W/m2. That was with respect to the mid 2000s. In contrast, the contribution from human-emitted greenhouse gases at the time was 2.9 W/m2 (fig. 1). So in the mid 2000s, waste heat amounted to about 1% of the total warming, with greenhouse gases making up much of the rest. The above numbers 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.

Relative radiative forcings due to waste heat and CO2.

Fig. 1: the relative radiative forcings due to waste heat and CO2 in the mid 2000s, from the numbers presented by Flanner (2009).

Since that time, both greenhouse gases and energy use have gone up (fig. 2), so it should come as no surprise to see increases in radiative forcing in both cases. Future projections have largely been focussed on recovery of the waste heat, such as that by Firth et al. (2019). An important conclusion of theirs is that, "full recovery of the theoretical potential is found to lead to a 10–12% reduction in the combined forcing of CO2 and waste heat over this period, mainly due to a reduction in CO2 emissions."

An important point to consider here is that the warming from thermal energy production occurs when a fossil fuel undergoes combustion. Whoomph! and that's that - the energy is produced in a single pulse then dissipates away. In contrast, warming from the emitted CO2 continues for the lifetime of CO2 in the atmosphere - potentially thousands of years (Zhang & Caldeira 2015). Zhang and Caldeira showed that "the energy released from the combustion of fossil fuels is now about 1.71% of the radiative forcing from CO2 that has accumulated in the atmosphere as a consequence of historical fossil fuel combustion." Again a small fraction of the CO2 radiative forcing, and emphasising the issue of the cumulative build-up of CO2 due to its relatively long atmospheric residence time.

Total energy use on Earth.

Fig. 2: total energy use on Earth, 1800-2023.

To conclude, greenhouse warming is currently adding some 60-100 times more heat to our climate than waste heat. That's not to say we should not be bothered about waste heat though, There are many sound reasons, including economic, for reducing heat wastage. It makes no sense at all to tolerate systems that for various reasons are grossly inefficient. But that needs to be considered as a separate entity from the huge problem of human CO2 emissions.

Last updated on 7 January 2024 by John Mason. View Archives

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Comments 101 to 125 out of 205:

  1. Thank you Tom for steering this in the right direction. The two "theories" are probably outliers even in the bizarre world of pseudoscience.
  2. Tom Curtis Fist up I'm not here to disrail anything as you know I've just created my first post here and had you guys jump all over it and If you were to take the time to see were I'm coming from you may get a clearer picture I do see and have a basic understanding of the green house effect and in NO way am I dissputing the theory I also lived through the 70's when our emissions were even more toxic to our health and the enviroment and if we kept going on like we were back then and didn't clean up our lead and sulfur emissions when there was only a third of the population then who knows were we would stand today. Anyway I was just about to watch a movie that has to go back But I do want to get back to you after it finishes with a heap more info I'll leave you with this. I'm more concerned about our com's and radar systems affecting the weather patterns then creating global warming I would like it if you would read this so we can create some common ground It's not the absorption but the exitement Do you remember when man had to re enter the atmosphere for the first time the fear was all about the angel of re entry to shallow and they would bounce off and to steep and they would burn up well thats what I'm getting at HOT spots created by forcing And the higher the frequencies the less is absorbed and can be reflected I'll get back to you And as you can see I'm not that well educated but I do pride myself on being smart enough to learn Cheers be back soon (-Snip-)

    [DB] Inflammatory snipped.  Please focus on the science.  And a suggestion:  Paragraph breaks and periods at the end of sentences would add to the readability of your comment.

  3. TomC: You are being very charitable in calling these 'theories.' No such formal structure exists in that world: Microwaves scatter THROUGH the atmosphere whereas solar radiation does not. As the microwaves penetrate to the surface, the water, ice, and atmosphere have microwave frequencies passing through them. This causes friction in the ice and water at the molecular level. This friction causes heat which is called Radio Frequency Heating. This is the basic principle behind the Microwave Oven. Speaks for itself. Perhaps we should put microwave towers in corn fields ... and grow popcorn already popped!
  4. muoncounter @103, what can I say? I'm a charitable person ;). I particularly liked the claim in one of the links that microwaves heated the ice and water, and IR did not, because IR was absorbed by the ice and water, while microwaves passed through them. (Your quote expresses a similarly bizzare sentiment.)
  5. jmorpus @102: 1) You claim that:
    " I do see and have a basic understanding of the green house effect and in NO way am I dissputing the theory"
    but in an earlier post on another thread (now deleted) your wrote:
    "You state in your last paragraph that CO2 is the primary driver for global warming Well I cant see it as the main driver it is only reacting to the radio waves that are ejected from the sun and man has been pumping man made noise into the atmosphere for more then a centuary When you guys start looking down the radiated electromagnetic path then I'LL start taking you seriously."
    Ergo, your claim to have not disputed the theory of the greenhouse effect is proven false; as also is your claim to understand it. 2) I make no apology if I have misunderstood your theory, because to the extent that I have it is because you have refused to elaborate it. Instead you have merely posted unexplained links and made cryptic comments without further elaboration. The former is in clear contravention of the comments policy which states:
    "No link or pic only. Links to useful resources are welcome (see HTML tips below). However, comments containing only a link will be deleted. At least provide a short summary of the content of the webpage to facilitate discussion (and show you understand the page you're linking to). Similarly, images are very welcome as they can be very useful in explaining the science. But comments with pictures in isolation without explanation will be deleted."
    (My emphasis) That has been explained to you several times, but still you persist, with your most recent post being the most recent example. What is more, failing to elaborate your theory is a doubly obnoxious behaviour. Obnoxious because it wastes the time of anybody who attempts an honest discussion with you. Obnoxious also because it constitutes a cowardly method of protecting your theory from criticism. Left to your devises you can always claim we have misunderstood your theory whenever the rebutal destroys what that theory appears to have been. Given my very low opinion of people who resort to such tactics (-snip-), unless your next response is a clear and direct statement of your theory, I would suggest moderators simply bar you from polite company, as you would clearly not belong in it. 3) Finally, having read your link, I can again report that it has no relevance to any theory that can be reasonably comported of the few vague hints you have deigned to let out. If you disagree, quote the relevant passages, and explain why they are relevant to your theory. 4) Given that past evidence indicates that you will not explain your theory, I will simply observe that the connection between the effects of cosmic rays and radio waves that you believe to be important in climatology is not so. Cosmic rays form precursors to cloud condensation nuclei because they ionize atoms with which they collide. In contrast, microwaves and radiowaves are not ionizing radiation. Therefore they can have no meteorological effect other than through transfer of energy, and as we know the energy they transfer is to slight to be of consequence.

    [DB] Inflammatory snipped.

  6. Tom C: "Given my very low opinion of people who resort to such tactics (-snip-), unless your next response is a clear and direct statement of your theory . . ." Unless, of course, jmorpuss decides to begin asking questions (on the appropriate threads) about AGW or criticisms of the "radio wave hot spot" proposition, and those questions are asked with the intention to learn and engage rather than to make accusations and protect his/her existing assumptions. If not, I agree: any engagement with jmorpuss is a waste of time.
  7. Tom @105 would you say that this thread is more about Blackbody radiation that follow the 2nd law of thermodynamics The way radiated heat is gobbled up and dispersed by a cooler atmosphere. What I'm trying to bring to the table doesn't fall into this thread, it's more about greybody radiation that is capable of on going heating as it passes through the air because most of the energy is not absorbed rather it vibrates the molecule and causes heat through friction. Also does the CO2 molecule have 3 sharp points (none linear)and has no real rest state unlike H2O which is linear and can spin like a top as well as tumbelling end on end. DSL @106 I'll try and engage but as you can see writing doesn't come easy to me and I'm a slow reader so try and be patient. Remember ladies and gents life is like a mirror you will always get back what you put out so be nice.
  8. jmorpuss @107: 1) You have the molecular configurations exactly backwards. CO2 is linear, with the oxygen atoms aligned 180 degrees from each other relative to the carbon atom. In contrast, in water the hydrogen atoms form a 120 degree angle relative to the oxygen atom. 2) Nearly absorption of energy from radiation by molecules is by alteration of the vibrational pattern or rotation of the molecule. In particular the absorption of microwaves by H2O is due to changes in the rotational state. A summary of this information can be found here. Information on the vibrational absorption patterns (IR absorption) can be found here. Also of interest are the following: General discussion CO2 H2O 3) Even if less energy was absorbed in microwaves, the consequence would be less heating. If that where not the case your theory would violate the conservation of energy. 4) You still fail to adress the very low energies involved in transmitted microwaves relative to incoming solar radiation, and outgoing IR radiation. To repeat, the total energy use of humans represents less than 100th of the additional warming due to CO2 as a result of the greenhouse effect. Total energy transmitted as microwaves is a very small fraction of that total human energy use. Therefore the total energy involved in your theory would be indistinguishable from noise (probably even indistinguishable as noise) relative to the enhanced greenhouse effect. 5) Finally, you have not as requested provided a clear statement of your theory, as per my point 2 in post 105. I therefore suggest to the moderators that we no longer entertain your nonsense.
  9. Tom @107 thanks for clearing up my mistake about linear thing.My theory is based around the greenhouse effect and how man has observed and replicated nature I mean of a night the only thing that ratiates into the atmosphere is blackbody radiation from the surface the moon and stars But man needs to communicate and detect 24/7 so the planet dosen't get time to rest. So the atmosphere is allready warmer then would be when the sun comes up Just one example is our mobile phone network with about 4 million towers and 4.5 billion subscribers. What sort of accumulative effect does this calculate to. The towers put out about a 100 watts and the phone about 2 watts and I haven't even looked at TV and radio, If you start to look at this you can see that there are many many things that add to this night time forcing process that would not be happening if you take man out of the equation. So the effect this has of a night is a thousands times more energy being released then the sun creates of a night.

    [DB] "My theory is based around the greenhouse effect and how man has observed and replicated nature"

    First of all, what you are doing is trying to formulate a hypothesis.  Things that are theories are robust, supported by observational evidence and are testable, having survived countless experimentations by scientists who have documented their work through thousands of research papers in reputable journals.

    One such theory is the radiative physics of greenhouse gases.  Another is AGW.  Centuries of research document and quantify their effects and they are well-supported.  Since you have not even properly quantified the effects of what you propose (like the next two comments already have), let alone support it with research of your own or citations to pre-existing research in the field, what you propose fails to rise to the level of hypothesis yet.

    Read the post at the top.  Learn.  Read the comments on this thread.  Learn more.  Work out the maths.  Read through the links in the OP and in the comments.  Learn more.  If you gain support for what you propose, write it up as a plausible hypothesis complete with maths and citations to other established work which you can then use to support your position.  Then bring the completed homework back here.

    Until then you waste everyone's time here.  And that is putting it nicely (Mr. Curtis has the paitence of a saint, and when he runs out of patience it is due to the intractability of the individual he is trying to help).

  10. jmorpuss you really need to put numbers in your theory, if not I may say that to have a pleasant swim this winter you can just drop a cup of tea in the swimming pool. 4 million 100 W towers plus 4.5 bilion 2 W subscribers sum up to 9.4 GW. That's a lot, sure, but the earth is huge; it's surface area is about 500 million Km2. Dividing the two you get about 2e-5 W/m2. Compare this number to, say, 4 W/m2 of CO2 forcing; it is 200 thousand times smaller. Do we really need to take it into account? The amount of waste heat is known, it's there but it's small.
  11. According to wikipedia, worldwide energy use was about 15 TW in 2008 which equates to 0.03 W/m2
  12. Flanner 2009 says:
    "Utilizing the second law of thermodynamics, it is assumed that all non-renewable primary energy consumption is dissipated thermally in Earth’s atmosphere. Country specific data of energy consumption from non-renewable sources (coal, petroleum, natural gas, and nuclear) were obtained from the U.S. Energy Information Administration (EIA) ( for year 2005."
    Presumably human energy consumption has increased since then. However, the US EIA 2011 World Energy Outlook put human primary energy consumption in 2008 at 13.56 Terrawatts including renewables, which is approx 0.027 W/m^2. NOAA places 2008 greenhouse forcings at 2.74 W/m^2. Clearly the numbers are not precisely known, but are known well enough to be certain that the enhanced greenhouse effect contributes approximately 100 times the effect of waste heat per annum to warming the Earth's surface.
  13. There's another tiny point relevant to cell phone signals: If atmospheric gasses absorbed those wavelengths, they wouldn't be much use for communication. And isn't that what these devices are designed to do? But in the internet era, every idea, no matter how devoid of substance, gets its own website. A close cousin are the folks who think that microwaves are the culprit. All that effort in support of an 'idea,' despite readily available science to the contrary. Now that's what I call waste heat! Hey, here's an idea which could use a website: Energy from the sun warms the earth's surface, which in turn radiates long wave IR back towards space. Something in the atmosphere absorbs that IR and ...
  14. Muoncounter @113, LOL. Your last idea is obviously too far fetched. It has none of the clean elegance of the Homeopathy for climate that is the microwave theory of global warming.
  15. I dunno. I'm still romantically involved with Hapgood's Crustal Displacement "Theory"; an affair that is unrequited due to the extreme paucity of evidence in favor of it and that damning thing called reality... Not that the paucity of evidence ever gets in the way of a good romance; the id-eology wants what the id-eology wants.
  16. Tom @112 Your link to 2011 world energy outlook states in the second line that it's about the energy market, so I prosume it only takes into account metered power or power that is taken from the grid. How I see it is all that gets taken into account is the poor old public sector and the military and goverments com's and detecting are not taken into account Things like these are of grid and use enormous amounts of power I could give you many more links to antena arrays that are of grid but I've been told not to link dump so I'ii hold back.
  17. muoncounter sorry mate but you critic to the microwave theory is wrong. Maybe you do not know that microwaves heat more because they are NOT absorbed. Read: "If you put ice in the sun rays, the ice will melt eventually at very slow rate. If you subject ice to a microwave frequency, it will melt at much more rapid rate. This is because the suns wave frequency absorb into water and ice, whereas, the microwave frequency will pass through the ice and water." The less power is absorbed, the more heating you get; a nice way to create energy. Or maybe heat is not energy ... I'm a bit confused here.
  18. jmorpuss are you saying that telecom and broadcast companies are off grid?
  19. 118 - Riccardo Maybe it's Shhh ;-] ;-]
  20. Riccardo @117, exactly, the less the energy absorbed the greater the warming. Hence the homeopathy theory of climate. We'll be in real trouble when jmorpuss realized that extreme low frequency radio waves are used to communicate with subs. They carry virtually no energy at all, and very little of what they carry is absorbed by water. Therefore by the homeopathic theory of climate change, they must cause massive warming. It turns out that its the ELFs that are doing it.
  21. Wikipedia has a good, somewhat relevant reference
  22. jmorpuss @116, "primary energy consumption" is defined as:
    "Primary energy consumption refers to the direct use at the source, or supply to users without transformation, of crude energy, that is, energy that has not been subjected to any conversion or transformation process."
    That is, it is the energy capacity of all oil, gas, coal, uranium and what have you that is extracted by any means, including all energy lost as waste heat, and including even the energy of fuels lost due to spillage. Ergo, it includes all energy used by military and governments, as well as that used in the private sector.
  23. Riccardo No their part of the public sector When I came across this It is about power beaming back in 1975 and it made me think what it is being used for today. And here's what is taking place now Do you see what I see
  24. 123 - jmorpuss What do you see? And, assuming it's something to do with your claims, how many kw do you estimate based on what input? Numbers are what counts; all else is just waffle. Well, OK, numbers and physics - but the rest is waffle.
  25. jmorpuss: What about all the energy radiated by high tension power lines? They are 'hot,' carrying many megawatts, 24/7. Why else would power lines be called 'hot'? To do a complete accounting of all this warming potential, you must add that to the count of cell phone towers and microwave ovens. The microwave heating fellow's credentials are stated on his about page: I was studying the Microsoft MCSE Exam 70-058 that I discovered, what I considered, a possible explanation for the Polar Ice caps melting. In the networking essentials book, they said that the connection on a wireless network was a microwave frequency. When I learned that, I was immediately struck with the notion that wireless frequencies could cause warming. I figured if the wireless connections were microwave connections, then with an enormous use of these connections there could be a significant environmental effect over a long period of time. I wish I had such clarity of insight. I'm doing my part by shutting off my wireless router and canceling my dish network subscription.

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