Hi, could I bounce a question off you? If the emissions to space are always below the ideal black body curve (due to absorption in the IR), then how does that missing outgoing energy actually leave the earth? It must exit by some means other than the IR spectrum or we would all boil pretty quickly. I know this may seem like a dumb question, but I really am interested. Thanks, A.

​@@andrewbrass5476 I'm happy to try to clarify this issue. Your wording suggests that you could be confusing some different questions, so I'll answer two distinct questions. Q1. If an object (or planet) emits less thermal radiation than an ideal black-body, then how can it emit all the heat it needs to emit? A1. When we say that something emits less thermal radiation than an ideal black-body, it is implicit that we mean "at the same temperature." All the object needs to do to emit more thermal radiation is to get warmer. Suppose you place two objects out in the Sun. They absorb the same amount of sunlight, but one has a high-emissivity coating and one has a low-emissivity coating. When they are at the same temperature, the object with low-emissivity will (by the definition of emissivity) emit less thermal radiation. However, what will happen in practice is that the low-emissivity object will accumulate energy and get hotter. After they are allowed to come into steady-state, the high-emissivity object will be cooler than the low-emissivity object and both objects will be emitting enough thermal radiation to balance the amount of heat they are receiving from the Sun. This is really how the "greenhouse effect" works; basically, an atmosphere with greenhouse gases acts as a "low-emissivity coating" for a planet which causes the planet's temperature to need to be higher, in order for the outgoing energy to balance the incoming energy. Q2. If the outgoing thermal radiation emissions to space are always less than the thermal radiation emissions from the surface (which happen to be depicted with blackbody curves), then how does the excess outgoing energy from the surface ever escape to space? A2. It's a misconception that there is "excess outgoing energy" at the surface which NEEDS to escape to space for the temperature to be stable. What is required for equilibrium is: (a) [Energy in] = [Energy out] for Earth as a whole, as measured at the top-of-atmosphere (TOA). (b) [Energy in] = [Energy out] at the surface. The first of these, energy balance at TOA, is what is both most important and simplest to understand. Measured at TOA, we see that the net sunlight entering the system is 240 W/m² while net thermal radiation leaving is 239 W/m^2. Thus, the system is slightly out of balance, with a bit more than 1 W/m² arriving but not leaving, which accounts for Earth's temperature increasing at present. What happens at the surface is complicated and confusing to most people. Focusing on what happens there is called the "surface budget fallacy" since it so frequently leads people to false conclusions. However, there is a balance that occurs at the surface, if one is willing to rigorously attend to the details. 160 W/m² of sunlight is absorbed by the surface (other sunlight having been absorbed in the atmosphere). Of this 160 W/m², 1 W/m² goes into heating the oceans and melting ice and is retained, 103 W/m² is sent to the atmosphere via evaporation, convection, and conduction, about 40 W/m² is sent to space by thermal radiation passing through the "atmospheric window" (a range of wavelengths transparent to thermal radiation), and about 16 W/m² is sent to the atmosphere via radiative heat transfer between the surface and the atmosphere. It's all perfectly in balance, since 160=1+103+40+16. There is no "excess heat" that needs to be gotten rid of by some as-yet-unnamed mechanism. You might be confused, though, since it's also said that the surface radiates 398 W/m² of thermal radiation. Above, I only accounted for 56 W/m² of radiant heat leaving the surface. What accounts for the difference, the 398-56=342 W/m² of thermal radiation that I haven't accounted for? This is where it becomes essential to understand that there is a difference between "thermal radiation" and "radiative heat transfer." When we measure "thermal radiation" we are talking about radiation flowing in one direction. When we talk about "radiative heat transfer" we are talking about the NET energy transfer after radiation in all directions is taken into account. There are canceling flows of 342 W/m² of thermal radiation upward and 342 W/m² of thermal radiation downward at the surface. Like any two pieces of matter at similar temperatures, the surface and the lower atmosphere are constantly exchanging thermal radiation -- but that exchange of thermal radiation doesn't necessarily have any NET effect, and if there is no net effect, it doesn't constitute heat transfer, and doesn't affect temperatures. So, yes, there is 398 W/m² of thermal radiation that leaves the surface. But, most of that is cancelled out by a downward radiation flow, so the net upward radiative heat flow is only 56 W/m². Bottom line: there is no "extra energy" at the surface which "needs to leave" in order to prevent the surface from getting too warm. All that has been properly accounted for. # # # This might still be confusing, so let me explain a bit further. Imagine that initially the air had no greenhouse gases. All radiation emitted by the surface would reach space. The planet would have a temperature of about -18℃ and everything would be in balance. Now imagine that greenhouse gases are suddenly added. The greenhouse gases would reduce the radiation emitted to space relative to what leaves the surface. The radiation emitted to space would be reduced, things would be out of balance at TOA, and so energy would accumulate and the system would warm up. Eventually things would be warm enough that energy emitted to space would equal energy received from the Sun, and things would again be in balance. But now the surface would be hotter and would be emitted more thermal radiation than it was initially. This "increased emissions" is not "excess"; it's what needs to be emitted to ensure that enough emissions will make it to space to create balance. There's a lot to keep track of to follow this whole story. Scientists carefully track all those details. I hope these explanations make at least a little bit of sense? Do you have more questions?

@@zzubra Hi, thanks for the reply. I appreciate you taking time to write this. I think my confusion arose because I had assumed that the black-body curve plotted was was that of the earth without an atmosphere, and all all frequencies the outgoing energy for a given wavelength was always below the curve. In such a case, if we start with the no atmopshere curve, add some greenhouse gasses that block some outgoing wavelengths, the question arises how does that energy actually leave? Since it must ultimately go somewhere on the plot of intensity vs wavenumber. What I had not realised was the change in the curve temperature. When the atmosphere is added the earth warms up, and so the curve moves up a little. So then it is a whole new curve and the energy all presumably balances out overall. Best regards, Adrian.

Thanks for clarifying that the Greenhouse gases prevent the absorbed heat on the Earth's surface from leaving (if I understood correctly) which makes more sense as I was wondering why wouldn't the increased gases cause an overall cooling effect. If we have a certain temperature heating a fixed amount of gas, then increasing the amount of that gas, we would see an averaging of the temperature rise with more gas molecules heating to a certain lower temperature instead of the initial fixed amount of gas to a higher temperature. However, if the Earth's surface is the one heating wouldn't that heat be absorbed by whatever's on the surface. I would guess that the majority of the Earth's landmass is inhabited by people, animals, sand, trees, plants...etc. Then why wouldn't that heat get picked up by our daily living. If the sun heats the streets in a city, for example, where people are constantly walking, wouldn't their shoes get warmer? Just wondering.

@@mohamedsharif8325 Yes, the surfaces we walk on are slightly warmer than they were many years ago, but only by a few degrees. So, it’s hardly surprising if you don’t notice the difference.

Uh, in case you haven't yet submitted your essay, it isn't anthropologic, but anthropogenic. Anthropogenic, made by humans. Anthropological, related to humans, from Anthropology, science that studies humankind, going from the early evolution (related to Paleontology, fossils) to the current cultures (related to Sociology, societies and their issues.) Good luck.

Haha! Whoops! I think my phone autocorrected my comment or something? Or maybe my fingers went faster than my brain while typing!😂 I do know the difference thankfully. And fortunately my computer did NOT autocorrect anthropogenic to anthropologic on my essay. Thanks for trying to help! I’m relieved I know the difference so i only looked silly in a KZfaq comment and not my assignment! They would’ve been pretty embarassing!😜

Same👍

😊😊😊😅

As a physicist, I’m telling you you’ve misunderstood what is claimed, so that your “debunking” is based on false premises. One key problem is that you’ve fallen into the “surface budget fallacy” in which you think that the greenhouse effect is primarily about what happens at the surface; that orientation consistently leads to misunderstandings. Heat is NOT “trapped in the atmosphere which then warms the surface.” Rather, the flow of heat out of the surface+atmosphere system as a whole is reduced, thereby causing the temperature of both surface and atmosphere to rise in response to heating from the Sun. What is important is the rate of heat flow into the top of the atmosphere (TOA) and out of the top of the atmosphere. The greenhouse effect is a reduction in the rate of radiation emission to space, for a given surface temperature. The emission of radiation to space is the ONLY mechanism Earth has available to cool itself. Conduction, evaporation, and convection move heat from the surface into the atmosphere, but can’t and don’t move heat into SPACE. That occurs only via radiation. Evaporation, convection and conduction are the most important mechanisms for heat transfer from the surface into the air - but that doesn’t cool the EARTH AS A WHOLE. That’s what matters. Cooling of the surface is a “red herring” which can’t ultimately tell one about how the temperature of the planet as a whole is determined.

@@zzubra "As a physicist" Q: Did you show us published empirical experiments validating the IPCC assumptions on which their greenhouse effect model is based? A: NO. You provide no experimental validation for the assumptions you make, or support. You do NOT behave as a real scientist. You behave like another armchair theorist - making it up - like all the other fake scientists out there. If you want to contradict / refute me / change my mind - so ahead - publish experimental validation for the IPCC greehouse gas model assumptions. I'm not stopping you doing basic science. It will be a very cheap experiment to do. I already know that NONE of you people will ever do that because you are not real scientists. I already know that you will never attempt to validate these IPCC assumptions - because people like you care more for you groupthink, career, ideology and politics - than you do for actual science. Also - because I think most of you already know the IPCC assumptions are based on arm-chair bullshit and are "not even false". Not even false because they are not even scientific claims.

@mark4asp additionally note that CO2 with heat is kind of like a wire with electricity - it does not store it just helps it move along faster - CO2 is highly absorptive and emissive so when CO2 concentrations rise in mid upper atmosphere it shines into space faster . And all things above absolute zero radiate IR ... not just green house gases.

@@zzubra >Conduction, evaporation, and convection move heat from the surface into the atmosphere, but can’t and don’t move heat into SPACE Do we live in the upper atmosphere where's it's -18 and less? The "heat" we're concerned with is kinetic, yes? Hot air. The heat transfer by conduction, evaporation and convection is the primary source of heating the air. Once heat rises, we're cooled. Once it rains, we're cooled there too. So, hot air parcels are carried up to where they can't conduct or convect heat away anymore and where IR takes its place and gets to space. IR is only a function of temperature anyway, not a source. IR itself plays no significant role in warming the atmosphere. Playing with energy budgets in w/m2 is just a way to circumvent inconvenient facts about thermodynamic heat transfers. You can't reduce the rate of cooling by slowing down light by a femto second. Especially light that is a function of temperature in the first place.

@@thomasmartin406 CO2 is very different than a wire with electricity. In the atmosphere, CO2 acts more like an insulator than like a conductor. It reduces heat flow through the atmosphere. This reduction of heat flow isn't something that is true of CO2 under all conditions, but only under conditions where there is a temperature gradient. Greenhouse gases like CO2 absorb thermal radiation at low altitudes, where it is warm and everything is emitting lots of radiation. The same gases emit thermal radiation at high altitudes. But, temperatures there are cold, so far less radiation is emitted. So, instead of lots of radiation escaping to space from the surface, a smaller amount of radiation escapes to space from greenhouse gases emitting at a high altitude. The net effect is a 40% reduction in how much thermal radiation is able to escape to space, for a given surface temperature. It's that reduction in the escape of energy to space which constitutes an insulation-like effect, leading to the surface being warmer. The idea that everything above absolute zero radiates energy is a "lies-to-children" oversimplification. On a conceptual level, it is in principle true. But, in practice, not so much. It matters exactly how much different substances radiate. In practice, nitrogen and oxygen radiate tiny amounts of IR thermal energy, but on a per-molecule basis they radiate around a million times less than do gases like CO2 and water vapor. So, even though nitrogen and oxygen have thousands of times more molecules, their net effect is negligibly small compared to the effect of greenhouse gases. And argon (1% of air) emits so little thermal IR that, as far as I can tell, how much thermal radiation argon emits has never been measured.

You have been consuming too much anti-science propaganda. What you wrote is a misleading mix of half-truths. Water vapor is responsible for about 50% of the greenhouse effect, with clouds being responsible for 25%, and CO2 being responsible for 19% (Schmidt et al 2010). The amount of water vapor present in the atmosphere is a function of temperature. As a result, water vapor doesn’t drive temperature changes; instead, it amplifies temperature changes due to other causes. If there were no CO2, Earth would be a frozen ice ball with no water vapor in its atmosphere. The bit about how much CO2 humans contribute is another half-truth. Before humans, CO2 addition to and removal from the atmosphere were in equilibrium, with no net change in recent millennia. Human emissions have disrupted that balance, causing emissions to exceed removal, resulting in increased CO2 levels. Thus, though human emissions are smaller than natural additions, they are responsible for 100% of the INCREASE in atmospheric CO2 levels.

It's a bit more complicated than that. When fossil fuel is burned it creates equal amounts of CO2 and water vapour. However, there is around 2% of water vapour already in the air as opposed to 0.042% of CO2, so adding more water vapour makes very little difference. These amounts are added in addition to any natural processes which, unlike the burning of fossil fuels, include absorption.

" is very small" == utterly meaningless

@@grindupBaker Consider the atmosphere is -18 avg and the surface is +15 avg so heat transfer from the surface is quite large.

You should look up how different in temperature in the upper atmosphere can be to the lower atmosphere and reflect on how many molecules of gas it contains.

Isn’t it amazing how people who with a child’s understanding of thermodynamics are certain that people with an expert understanding are wrong about it? As a physicist, I’m telling you that the greenhouse effect does NOT violate thermodynamics. It’s only childish misunderstandings of the the greenhouse effect which appear to violate thermodynamics. The real greenhouse effect is perfectly consistent with physics and the laws of thermodynamics. Are you familiar with “emergency blankets” or “space blankets”, which are sheets of plastic with a reflective coating, used as a lightweight way of keeping people warm in winter? And are you aware that modern building insulation includes a reflective “radiant barrier” that helps reduce heat flow through the wall? The greenhouse effect works in an analogous way.

@zzubra these things only stop or reduce heat loss, they however do not increase the temperature.

@@katiposcotty Temperature is determined by the conditions under which the rate of energy leaving and the rate of energy arriving are in balance. Thus, the rate of heat loss has just as much impact on temperature as does the rate of heat gain. (I once saw a demo in which somebody baked a potato using a battery and a resistive heater by surrounding the potato and heater with an enormous amount of insulation. That allowed the temperature to rise to a temperature suitable for cooking, despite the small input of energy.)

@@zzubra If you were a real physicist - then you would know that a blanket slows down convective heat loss as does a roof in a green house and that CO2 is highly emissive as well as absorptive and if CO2 increases in upper troposphere then it cools faster as more CO2 shines Infrared faster into space. But a real scientist would want to see a repeatable experiment that demonstrates the core premise of mann made global warming that doubling CO2 raises the air temp 2.7F to 8.1F.

That's what I had surmised myself rather than reading, but not the quantity detail. When I commented complaining about these junk videos on Realclimate July 2021 they censored my comment. Can you provide a reference for your "1 CO2 molecule in 100,000 becomes de-excited through" ? Thanks if you can. Did I ask you this a few years ago ?

The idea that “re-emission” has anything to do with the greenhouse effect is a common misconception, which the video unfortunately reinforces. In reality, greenhouse gases absorb longwave radiation, and also emit thermal radiation - but as an independent process unrelated to how much is absorbed. Emissions occur purely as a function of air temperature. Collisions excite just as many CO2 molecules as are de-excited (actually, a bit more are excited), and that’s what leads to emissions. None of this debunks the greenhouse effect. It’s just that the explanations offered by popularizers (like he author of this video) are a bit sloppy in explaining how things actually work. No scientific theories rely on “re-emission”.

​ @zzubra Yes that's what I'd inferred by pondering it in 2017 mostly because I took "a couple of photons per second" as the typical emission rate somebody gave me and calculated from that H2O gas photons emitted ~20 million times as many per unit time as surface photons emitted in the same unit time (~6 million times as many photons for CO2) and that seemed to me a bit overwhelming for photons going into surface being due to photons leaving surface. It would require a photon to be absorbed & re-emitted ~20 million times before getting back into the surface if they all originated at the surface. I question your "unrelated to how much is absorbed" because a specific molecule cannot be simultaneously absorbing & manufacturing by collision so I would expect an inverse correlation (warmer gas parcels allowing more LWR to pass through them than colder ones) but I do understand that the relative amount of this putative inverse correlation of mine depends on the portion of the molecules that are in their de-excited state and thus available to be excited by collision or LWR absorption (just another thing I've not had time to study yet).

@@grindupBaker I once calculated that for CO2 molecules to process the amount of thermal radiation they are said to process in the atmosphere (estimated at roughly 3.6 W absorbed and 3.6 emitted in each cubic meter of air near the surface), then each CO2 molecule would need to absorb a photon OR emit a photon (but not both) once every 10 seconds or so. That’s basically “all the time in the world” for processes that happen on a molecular scale. The amount of “work” that each CO2 molecule needs to do is remarkably undemanding, by those calculations. (I’m not sure what you were basing your calculations on. If you provided the details, perhaps I could offer a more useful comment.) In the lower atmosphere, each CO2 molecule experiences several billion collisions each second. All it takes is a few collisions to completely destroy any correlation between what the CO2 molecule was doing before and what its current state is. So, there is no chance of absorption and emission interfering with one another unless they both occur in the sub-nanosecond period between two collisions. Thus, the rate of emission and absorption required of CO2 molecules would have to be billions of times larger than it is before I would expect to see any competition or interference between the emission and absorption processes. Atmospheric conditions are nowhere near a regime in which that would be a relevant consideration.

Wrong, wrong and deadly wrong. A) The doubling will raise the altitude where IR can escape to the outer space. Therefor it will make Earth warmer, since the black body radiation at higher altitudes (and lower temperature) is weaker. B) Adding CO2 will not benefit most crops since the plants are evolved to certain levels. What about water preservation? The climate change will seriously alter precipitation patterns rendering a lot of (if not most) farming lands too dry or wet. These claims are frequently touted by the fossil fuel lobby, which is saddening to say the very least. So stop lying and get your facts correct, buddy. Ignorance is NOT bliss.

@irinaratushinskaja7900 my facts come from Dr William Happers presentation. The first working group of the ipcc also have the same figure .7 percent. Judging by your flag I can only assume your an subversion activist .

You are correct except of course that it only applies to the troposphere because the stratosphere works backwards, but basically you made the correct point. Pity that English isn't your 1st language but not your fault, I speak-read-write no other languages at all.

the albedo varies from 0.28 to 0.36 ( shiny stuff that reflects the sunlight away from being absorbed) causing a huge variation - the claims of CO2 forcing are a trivial part of that even if true and ignored is negative stabilizing feed back that warmer means more clouds which lowers albedo causing cooling.

You are indeed wrong because the GHE for the IR-active gases has been calculated by competing teams of physicists, who are bods with about 99 times the brain ability of "@StrayanGamer" and about 999 times the knowledge of the physics as "@StrayanGamer".

@@grindupBaker the measurements are for increasing CO2 while Temp rises are precise; however, the premise is CO2 is causing it alone while a solar system of other variables anything from interstellar dust to corrupt scientist is ignored. In real science there would be an experiment that demonstrates the core premise of Mann made global warming. The premise that doubling CO2 from say present 410ppm to future 840ppm raises a parcel of airs temp between 2.7F and 8.1F . We have seen radiatively active properties of CO2 and others - they absorb and emit InfraRed quite quickly - but like a wire that transmits electricity quite well, the wire does not store electricity.. Well the CO2 does not store the heat.

@StrayanGamer- we should all be very thankful for the cooling effects of CO2 and the atmosphere in general since daytime would be a scorching 225F with out the atmosphere.

​ @thomasmartin406 You typed drivel because solar SWR has been accurately measured for decades (ACRIM, SORC, TIM and others) and just cycles up & down on its ~11 year cycle which only makes Earth temperature go up & down by ~0.04 degrees, it's negligible. The incoming & outgoing radiation are all accurately measured and hence your comment (in this venue with no audience whatsoever) is drivel. Your "absorb and emit InfraRed quite quickly .... CO2 does not store the heat" is the usual mix of babbling & irrelevance that simply shows you've never studied the physics and are utterly clueless about it. Rather you lazily Parrot whatever inane memes you came across from the other liars & clowns. That ain't studying science. That's worthless.

No. Water vapor contributes only 50% of the greenhouse effect; CO2 contributes 19% (Schmidt 2010). You're listening to anti-science propaganda. / The amount of water vapor in the air is a function of temperature. As a result, water vapor doesn't cause temperature changes; it amplifies the effect of temperature changes due to other causes. Without CO2, Earth would be a frozen ice ball with no water vapor in its atmosphere.

Water vapour is condensable. The amount of water vapour in the atmosphere is determined by air temperatures therefore it amplifies the warming due to CO2 and methane but can't drive warming per se. There is also typically less water vapour at higher/colder latitudes whereas CO2 can spread around the planet more evenly.

Because there is a fucking agenda to make believe that CO2 is, and "HUMAN" emitted CO2 are the problem. To much $$$$ to be made

It’s true that water vapour is the gas which contributes most strongly to the greenhouse effect. However, people frequently misunderstand the implications of that. Water vapour levels are basically set by temperature. As a result, water vapour acts like an amplifier to warming caused by other sources.

Yup. Co2 Is a very poor greenhouse gas .

@@itsmorphed6416 That’s not a fair statement. Within its absorption band, CO2 absorbs thermal radiation hundreds of times more strongly than does water vapor, even taking the lower concentration of CO2 into account. (I’ve plotted the absorption curves.)

@zzubra Dr will Happer says its a poor greenhouse gas . In fact he says doubling it would take 100 years and only add .7 degrees which is small .

😎

All vulcanos *together* emit about 1% of humans.

@@enderwiggin1113 that's extremely hard to believe. From the things I've looked up humans occupy anywhere from 10% to 20% of the land on earth. I would assume these are cities/towns. Not including roads. And I've also read that 90% of people live in the northern hemisphere. Being that there's roughly 7.5 billion people in the world and 90% of that population live in the northern hemisphere just shows how big Earth is. Now of course these numbers aren't at all accurate, but I would say it's a solid visual of the general population. Now I could do more research but I would assume of that 90%, most of that population is in Asia. And certian countries like India. That's a relatively small amount of land compared to the entirety of Earth. The fact that a single volcano eruption can be seen and felt in other countries just shows the shear amount of power a volcano has. And the amount of pollutants it shoots out. Not including all the volcanos in the ocean going off everyday. I would assume that volcanos put out way more than 1%.

@@ZantZ "humans occupy anywhere from 10% to 20% of the land on earth [...]" Why on Earth should this be relevant?!?

@@ZantZ "The fact that a single volcano eruption can be seen and felt in other countries just shows the shear amount of power a volcano has" And why exactly should power equal 'much CO2'??? Look up Mt St Helens - one of the biggest eruptions in the 20th century. Nevertheless, it emitted less than 50 million tons CO2. Humans emit 40 *billion* tons every year.

@@ZantZ Youi know: that is somethign which is very, very, very easy to research for yourself. E.g. 'What do volcanoes have to do with climate change?' (NASA)

It that your way of saying that you are a Climate Denier?

@@mikemccormick6128 the science that drives climate is complex, I merely look to people more knowledgeable than me to explain what is actually meant by CO2 traps heat.What is trapped, what do they mean by heat, what is the means by which it is trapped in a gaseous atmosphere in which molecules and atoms move freely. How is the energy the Sun puts into the atmosphere lost to Space. If you are one such knowledgeable person, help me understand.

@@wrath276 I'm not a knowledgable person, but when 97% or something like that of scientists say that the sun sends heat to the Earth, and that the CO2 in the atmosphere blocks the escape of that heat back into space, I tend to believe them because they are the ones that are studying it. Most of the skeptics are the ones who don't have degrees in that field of study. Plus there is actual real evidence that the Earth is getting warmer just from the fact that I'm almost 60 years old. I can see the planet getting warmer as the decades go by. Also, it doesn't make sense to me that a lighter object falls to Earth at the same rate of speed as a much heavier object, but that's what happens whether it makes sense or not. Sometimes the experts get stuff wrong, but they have been studying climate change for many decades now, and the evidence just keeps getting stronger and stronger.

The phrase "trap heat" is easily misunderstood. It simply means "reduces the rate of heat loss to space." So, given Earth's current surface temperature, the surface emits longwave radiation at a rate of 398 W/m^2. If there were no greenhouse gases (or clouds) then all that radiation would pass through the atmosphere and escape to space. That would be Earth's rate of cooling. However, because Earth does have greenhouse gases (and clouds), the amount of longwave radiation emitted to space is 40% less, only 239 W/m^2. The rate of planetary cooling is reduced by 40%. That is what is meant by heat being "trapped." The heat isn't literally stuck; it's just that its flow rate is reduced. That's the main thing to understand. Perhaps that renders some of your questions moot? / "Back radiation" is a confusing side issue which I wish people didn't unhelpfully use to try to explain the greenhouse effect. It's actually a normal aspect of all radiation heat transfer. (The cool walls of your room are currently radiating your warm body with "back radiation".) Back-radiation doesn't actually warm the surface; instead, it simply reduces the rate of radiative heat loss away from the surface. That allows the heat of the Sun to accumulate at the surface, which is what actually causes the surface temperature to increase. However, focusing on what happens at the surface mostly confuses people. Concentrating on that is called the "surface budget fallacy"; it's a reliable way of coming to false conclusions about planetary warming. It's far simpler and more reliable to concentrate on the energy balance that occurs at top-of-atmosphere, i.e., the interface between Earth as as a whole and space. Greenhouse gases reduce radiation loss to space; simplistically, it's much like the way smoke in a room reduces the passage of visible light through that room. (The details are a bit more complicated than that.)

@@zzubra That was a great explanation and very simple to understand. You are a lot smarter than I am so the emission rate went a little over my head, but nothing to complain about.

The narrator apparently chose to focus on stable greenhouse gases rather than what I call "responsive" greenhouse gases. Water vapor is "responsive" in the sense that water vapor levels are a function of temperature. As a result, water vapor responds to other sources of temperature change, amplifying warming due to other sources, rather than being a cause of temperature changes. If there was no CO2, the Earth would be a frozen snowball, with no water vapor in its atmosphere.

So you have provided a post in the main thread that provides an excellent explanation that is so often not discussed. However your final comments on heat transfer and radiation, suggest that the heat is from another source not CO2. Yet you are telling me that with out CO2 as a greenhouse gas we would have an ice ball earth? With out CO2 the surface of the land and seas will still warm from the solar radiation from the Sun. In turn this adds to the Water Vapour (pendent on cloud coverage and other effects) in the atmosphere, which then performs as you have described stopping the earth from freezing once the earth has rotated to face the opposite direction. Hence why I question why the video tutorial would choose to ignore it.

@@johnhewitson001 You write "your final comments on heat transfer and radiation, suggest that the heat is from another source not CO2". Yes, ALL the heat that drives Earth's climate is from the Sun. What people often don't understand is that temperature is determined by the balance between [energy arriving] and [energy leaving]. If an excess of energy is arriving, energy accumulates and temperature rises -- which tends to cause energy to leave more quickly. On the other hand if there is an excess of energy leaving, energy drains away and temperature falls, which tends to cause energy to leave more slowly. The end result is that temperature naturally adjusts towards whatever temperature causes the rates of energy arriving and leaving to be equal (on average, with the average being over 1 or more years). This means that a planet can be warmed either by (a) increasing the rate at which energy arrives or (b) decreasing the rate at which energy leaves. Both mechanisms are equally effective at altering temperature. CO2 causes warming by decreasing the rate at which energy leaves the planet. As the planet warms, this increases the water vapor in the air, which further decreases the rate of energy loss, producing more warming (but not so much that there is a run-away chain reaction of warming). If there was no CO2 in the atmosphere, this would allow the rate of energy loss to increase. Enough heat loss would occur to create a new "ice age" with massive glaciers. (The last ice age involved an average global temperature only about 6℃ colder than our current global temperature, if I recall correctly. But, in prior ice ages, there was still some CO2 present.) The colder temperatures would reduce water vapor in the air, which would lead to more cooling. Also, the ice sheets would reflect a lot of sunlight, which would make things even colder. That would eventually cause the oceans to freeze over. Ice is a very good reflector, and a lot of the sunlight illuminating Earth would be reflected back to space, preventing it from having a warming effect. The atmosphere would be very dry, with very little water vapor or clouds to slow energy loss to space. There would be an "ice ball" Earth. You wrote "With out CO2 the surface of the land and seas will still warm from the solar radiation from the Sun. In turn this adds to the Water Vapour (pendent on cloud coverage and other effects) in the atmosphere, which then performs as you have described stopping the earth from freezing once the earth has rotated to face the opposite direction." You might think so, but that's not what the math suggests would happen. You need to factor in how much less water vapor there is when temperatures are colder, and how much ice forms, reflecting sunlight back to space. Overall, water (via water vapor, clouds, and ice) has an amplifying effect on any temperature changes that CO2 produces. It's the combined effects which lead to an "ice ball" Earth in the absence of CO2. The way the effects of water interact with those of CO2 is a bit complicated (though it’s very clear that the net effect is to amplify warming when CO2 increases or cooling when CO2 decreases). I imagine that's why most popularizers trying to offer a simple explanation of the greenhouse effect often avoid trying to go into all these details. Those details don't alter the fact that CO2 levels have an important impact on Earth's temperature.

@@johnhewitson001 >JH: " your final comments on heat transfer and radiation, suggest that the heat is from another source not CO2." Yes, the heat that warms the Earth all comes from the Sun. Greenhouse gases just make it harder for the Sun's energy to leave, forcing temperatures to rise before the planet can shed as much heat as it receives. >JH: "Yet you are telling me that with out CO2 as a greenhouse gas we would have an ice ball earth?" Yes. >JH: "With out CO2 the surface of the land and seas will still warm from the solar radiation from the Sun." Yes, but the solar energy would quickly leak back to space. Think of a house in winter heated by a wood-burning stove (so there is no thermostat). Suppose someone leaves the windows open. The house will get much colder, even though it is being heated at the same rate. A similar effect would happen if you removed all the CO2 from the atmosphere. >JH: "In turn this adds to the Water Vapour (pendent on cloud coverage and other effects) in the atmosphere" How much water vapor goes into the atmosphere doesn't depend on how much sunlight arrives, but on the temperature of the ocean surface. If the temperature drops somewhat due to CO2 being removed, then that will reduce the amount of water vapor in the atmosphere, which will result in further reductions in the greenhouse effect, and further cooling. The net effect is that any temperature change produced by a change in CO2 levels is typically more than doubled because the resulting cascade of changes in atmospheric water vapor levels. In general, water vapor levels respond to temperature. Water vapor doesn't tend to be a root cause of temperature changes; it amplifies the impact of other factors that change temperature.

You're clearly reading far too much anti-science propaganda, in which people with a child's understanding of science conclude that "all the experts are wrong." I'm a physicist with no axe to grind other than correct application of science. The sort of arguments you are alluding to consistently turn out to be misguided nonsense, when closely investigated. At best they are based on misunderstandings, and at worst they seem to be malicious misrepresentations. As a trivial point, contrary to what you're suggesting, the Sun emits 99% shortwave radiation. Less than 1% of solar emissions are longwave. People are sometime confused about that because the Sun emits a lot of shortwave infrared radiation (wavelength less than 4 microns) while Earth emits 99% longwave infrared radiation (wavelength greater than 4 microns).

Yes but because c02 us a very poor greenhouse gas , even doubling from where it is now would only have .7 degrees different. And that's assuming other variations stay the same. That would take along time also and probably would be of benefit

@itsmorphed6416 The IPCC Sixth Assessment Report (AR6) stated that there is "high confidence" that ECS is within the range of 2.5 °C to 4 °C, with a best estimate of 3 °C, their range for ECS has changed hardly at all since the first reports. With that 50% increase in CO2 that's occurred there's been a 1C rise in temperature, and as heat is still moving into the oceans there's still plenty of warming that's going to happen, (about another 1C) even if atmospheric CO2 were held constant at current levels.

@andrewworth7574 that's funny , Dr will happer says the ipcc has the same information which is 0.7 degrees for doubling co2. Isn't it the first working group that has the decent science? Based on the planck curve and the schwarzchild curves . Apparently the models don't stand up against current observations also . The other weak 1600 scientists signed a declaration that there is no climate emergency.

seems that the ideal gas law explains it and Green houses can be left alone with their roofs in tact.

@thomasmartin406 the point I made have nothing to do with the ideal gas laws and it's certain you've got no argument to the contrary.

Yes, you're writing "absolute nonsense." If you shine visible light on a black object which absorbs that light, what do you think happens to that energy?? It can't just disappear, since energy is conserved. It becomes thermal energy. And, yes, that affects temperature. Any wavelength of radiation can transfer heat. Once energy is absorbed, it no longer has a wavelength. It's simply energy. / The rest of your comment descends into deeper and deeper levels of nonsense.

yyuryyubicuryy4me

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Always fascinating how one can always find on youtube comments some random people who have figured out that all the academic community is wrong. From every field of science, climatology, paleontology, epidemiology, even how the Earth isn't round neither orbits the Sun. If only humanity would accept as truth what all of those random guys say, as opposed to what actual researchers have gathered and debated over the last centuries and beyond.

"The kinetic heat transfer processes of the contiguous atmos molecules render that scenario impossible" Whatever.

" the GHGs require "extra" energy " No. Apparently, you've not even watched the video.

That's so smart of you

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Because it's irrelevant? That's like asking why people ignore the heat that bounces off your oven roasted chicken. The ONLY thing we care about is the internal and surface temperature of chicken, as it needs a specific temperature to cook properly. It doesn't matter how much heat bounces off back into the oven!

It's not mentioned because it doesn't happen. There is essentially NO "incoming longwave radiation." Radiation from the Sun is over 99% shortwave. (People get confused because "infrared" can be shortwave or longwave. The Sun emits shortwave infrared, which Earth emits longwave infrared. The former has a wavelength shorter than 4 microns, while the latter has a longer wavelength.)

I've found ~99% of the few "explanation" videos I've watched are incorrect exactly like that. Makes it much easier for the "Surface warming itself, LOL !" moronic meme to fly. Dunno if all the video blokes are getting some Koch chump change for that.

@@grindupBaker yeah, there are so many videos of people just rehashing the same stuff around and around. Very few understand what is going on in reality, but they don't know and don't care either. They are just publishing because they want to get a profile built. The problem is that anybody coming to youtube gets the same message again and again from different places, so they naturally assume that so many people can't be wrong. Not a lot of folks really have the scientific background to understand these things for themselves. This isn't suprising really. Despite what a lot of people say here, Physics is not usually basic or simple. Also science is never settled either. But these messages don't make good youtube content, so the ignorance just swirls around in circles. I really don't know how we might cure this. Scientific disinformation is becoming a real problem for the general public and they don't even know. I'm not a conspiracy theorist, in case you were wondering, just an observer with a scientific background. All the best, A.

The idea that "re-emission" happens is a common mistake that popularizers make -- but no scientist would ever make that mistake. Emission happens, but it's not "re-emission." It's simply emission because collisions excite CO2 molecules just as often as they de-excite them. So, the popular explanations might be a bit "off", but that's a problem with the explanations for the uninformed -- it's not a problem with the actual science of the greenhouse effect.

@@zzubra . thanks for the reply. I think when you say "collisions excite CO2 molecules just as often as they de-excite them" that is thermally stimulated emmission you are talking about? If I am following the plot then this does happen, but not significantly in the lower atmosphere. In the upper atmosphere then this is the primary mechanism that the earth dumps IR into space, beacuse the air is very sparse and the CO2 can radiate before it undergoes a collision. In the lower atmosphere the collisions are too frequent so the energy is lost by collision almost always. Thanks, A.

@@andrewbrass5476 Yes, essentially all the emission talked about in the context of climate could be termed “thermally excited emission.” However, if you think that this emission isn’t significant in the lower atmosphere, then you are badly misunderstanding something. What collisions do is create a thermal energy distribution, i.e., a Boltzmann distribution, in which the fraction of molecules excited to an energy E is proportional to exp[-E/(k⋅T)] where k is Boltzmann’s constant and T is the air temperature. This energy distribution leads matter to emit thermal radiation in accordance with (the real-matter version of) the Stefan-Boltzmann law, M = 𝜖 σ T⁴, or, if the medium isn't optically thick, in accordance with the closely-related Schwarzschild equation for the propagation of thermal radiation in a partially-transparent medium. There is no such thing as “too many collisions” when it comes to thermally-excited emission. If the de-excitation rate is higher, then the excitation rate will be higher as well. These rates generally do not matter to the rate of thermal emission. What matters is the fraction of molecules that are in an excited state at any given time. Once there is even a modest collision rate (such as is found anywhere below about 30km in altitude), the fraction of excited molecules stabilizes. Further changes in the collision rate do not alter the excitation fraction. So, the the Schwarzschild equation (which describes how the thermal emission of a real gas is related to the emissions of a black-body at the same temperature) applies throughout the troposphere. There is no lack of thermal emissions in the lower atmosphere. It’s just that in the lower atmosphere, the air is thick enough that any emissions get absorbed again long before they can reach space. In the upper atmosphere, the air gets thin enough that the emissions can reach space without being absorbed first. There is one more subtle effect that collisions are responsible for: collision-induced spectral line broadening. The more collisions there are, the broader the range of frequencies that molecules can absorb and emit. This line-broadening effect means that greenhouse gases are more effective, on a per-molecule basis, at higher pressures than at lower pressures. This is part of why thermal radiation gets absorbed in the lower atmosphere but can escape to space at higher altitudes. It’s also a major factor in why the greenhouse effect is small on Mars and large on Venus.