I Misunderstood the Greenhouse Effect. Here's How It Works.

I thought I understood how carbon dioxide emissions cause global warming turned out I got it completely wrong I was about to sweep my misunderstanding under the carpet but then I thought what if I'm not the only one what if we're all just pretending to kind of understand something we're spending trillions of dollars on maybe I should talk about it after all so how does the greenhouse effect really work how do we know that global warming is caused by humans and what predictions have climate models ever made that's what we'll talk about today here's what I learned in middle school about the greenhouse effect a literal Greenhouse works like this glass lets most sunlight through when the sunlight hits the ground of the greenhouse or a tomato or why are your socks in the greenhouse tennis then the sunlight gets absorbed and re-emitted at longer wavelengths in the infrared we can't see this infrared light but we can feel it it feels warm but glass acts like a mirror for light in the infrared here is an image of a man with a plastic back over his hands wearing glasses on the left you see a normal photo taken with visible light on the right you see an image taken with infrared light with the infrared light you can see through the plastic back but you can no longer see through the glasses so all that glass in a greenhouse traps the infrared radiation and that warms the air you actually don't need air and a greenhouse for that to work except that the air is the thing that you want to warm up and also Tomatoes don't grow in vacuum that's how an actual Greenhouse works now here's how I thought this works for our planet much like glass the atmosphere of Earth is transparent to most of the light that comes from the sun some of the light is absorbed in the upper atmosphere and some is reflected but most of the light is absorbed by the surface of Earth this heats up the surface which in return emits light in the infrared the infrared light however doesn't travel through the atmosphere that easily because some molecules in the air absorb it these are the so-called greenhouse gases of which carbon dioxide is one more carbon dioxide leads to more absorption of this infrared radiation which warms up the planet simple enough but what if I told you what if I told you that the infrared light which comes from the surface of the Earth is absorbed by greenhouse gases not wear a bear in the atmosphere but after 20 meters or so because that's what happens pretty much none of the infrared radiation goes through Earth's atmosphere already at the current carbon dioxide levels if the levels increase further then the distance that the light makes it from the surface decreases a bit more but so what it never made it out anyway it's all a hoax bring back coal okay here's the truth the greenhouse effect isn't quite that simple so let's try this again this time we add some high school physics and see if that makes any more sense sunlight contains many different frequencies but not in equal amounts frequency as a reminder is proportional to the energy of the light so higher frequency means higher energy and frequency is inversely proportional to the wavelength of light along a wavelength means lower energy if one plots the amount of light as a function of its frequency one gets what's called a spectrum the spectrum of the sun looks roughly like this it doesn't change all that much in the visible range which is why the sun looks pretty much white if you look at it which you shouldn't because keep in mind Isaac Newton did it and was still making fun of him today but this spectrum isn't specific to the Sun the spectrum of any object at a constant temperature has a shape like this the surface of the Sun has a temperature of about 5000 degrees Celsius but the higher the temperature the more the Spectrum shifts to higher frequencies and the more energy the body emits and the lower the temperature the lower the average frequency is the longer the wavelength and the less energy is emitted it's called Planck's law if you know the temperature then Planck's law tells you what light is emitted and how much energy is emitted in total if sunlight hits the socks on the greenhouse or the surface of Earth it's absorbed and re-emitted and as we just saw or the radiation Spectrum depends on the temperature but what's the temperature of Earth well Earth gets a certain amount of sunlight from the Sun and without a certain amount of energy the temperature of Earth increases until the total energy that's emitted is the same as what comes from the sun when energy in is the same as energy out this system is in balance and it doesn't change any further this means one can calculate the temperature of the surface of a planet from the amount of sunlight it receives if Earth didn't have an atmosphere its surface temperature would be minus 18 degrees Celsius good news if you're selling spiced pumpkin latte but most of us like it somewhat warmer luckily Earth does have an atmosphere and that keeps us warm this works as follows molecules resonate when light of certain frequencies hits them and then they begin to wiggle this converts the energy of light into motion of molecules so the molecules trap the light basically and convert it into heat but most air molecules don't wiggle for infrared light the atmosphere of Earth is more than 99 nitrogen oxygen and Argan and none of them are good infrared wigglers I mean we can breathe oxygen all right that's nice but it does nothing to keep us warm greenhouse gases on the other hand are great infrared wicklers the infrared light hits them they wiggle and those wiggling molecules then bump into other air molecules which distributes the energy in the air every once in a while one of those molecules also emits infrared radiation again which spreads it throughout the atmosphere the most relevant greenhouse gases on Earth are water vapor carbon dioxide and methane to understand how they warm the planet you need to know one more thing the Earth is round no seriously it's round and also seriously that's relevant because the Earth is a sphere it has a gravitational force that drops with an inverse Square law this gravitational force is the reason why the atmosphere doesn't just float off it's a good thing we have it but the gravitational force also decreases as you go up and the air pressure balances the gravitational force this means as you go up the air pressure decreases and the density and the temperature decrease with the pressure this is why you can't open the windows on an airplane it's really not healthy if you put a layer of air with greenhouse gas around a planet then this infrared radiation is absorbed by the air that heats up the air and that emits some radiation again and so on so the infrared radiation slowly spreads through the atmosphere from the surface up but if you go to higher and higher altitudes the air gets thinner even if the concentration of a greenhouse gas stays the same the total amount of greenhouse gas per volume still drops and eventually there are so little greenhouse gas that the infrared radiation can escape to outer space this means that most of the infrared radiation which leaves our planet doesn't come from the surface it comes from an altitude of several kilometers above the surface again the temperature of the radiation has to balance the energy that comes in from the Sun and since temperature decreased with altitude this means that the temperature further down on the surface of the planet must increase this is how the greenhouse effect really works greenhouse gases in the atmosphere prevent infrared radiation from the surface from going right into space instead the infrared radiation that goes into space comes from the upper atmosphere that radiation from the upper atmosphere has to balance the influx of energy from the Sun and since the temperature of the atmosphere decreases with altitude the surface of the planet has to reach a much higher temperature than without greenhouse gases hey I got it well actually this isn't how it works either no God no God please no or rather this is how the big planetary greenhouse effect works in general it's the reason why our planet has an average surface temperature of 16 degrees Celsius and not -18 but it's not the reason for the enhanced greenhouse effect which currently causes climate change because the temperature of the atmosphere only decreases up to an altitude of about 10 kilometers or so if you go further up it remains constant for a bit and then the temperature actually begins to increase again that's because the atmosphere up there absorbs some of the incoming sunlight this part of the atmosphere where the temperature increases is called the stratosphere I'll have more to say about this later so keep it in mind now remember that the greenhouse effect works because pushing the effective altitude of emission up reduces the temperature of the mission and that brings the system out of balance but what if I told you what if I told you that carbon dioxide at pre-industrial levels already pushes the effective altitude of emission up into the stratosphere if you further increase the carbon dioxide level after that the altitude of emission doesn't change any further because the temperature of the atmosphere doesn't change it seems that the warming effect is already saturated at the current level so I guess we're back to it's all a hoax okay to understand what's really going on we have to add one more subtlety it's that all those greenhouse gases don't absorb infrared light equally well at all wavelength they absorb light only in certain parts of the infrared Spectrum the best absorber is water vapor that's because the water molecule has a lot of resonances it's a really really good infrared wiggler if we look at Earth from above in the infrared and at the absorption from water vapor then the Spectrum changes roughly like this you can think about this as an increase of the effect of altitude of permission again but a slightly different altitude for different wavelengths for example a shorter wavelength the light comes on average from an altitude of about four kilometers at longer wavelengths it's more like five kilometers and each of those altitudes have their own effective temperature which you see on those two sides carbon dioxide now has a much stronger absorption but it's only in a specific part of the spectrum this is around a wavelength of about 15 micrometers the relevance of carbon dioxide for our climate comes from this emission band being pretty much near the peak of the infrared emission at pre-industrial levels carbon dioxide takes out a big chunk of radiation coming from the surface of Earth this lower part of the absorption line that's the emission curve that belongs to the temperature at the average altitude of emission about 220 Kelvin or minus 60 degrees Celsius but here's the thing if you increase the carbon dioxide level even more then this Stitch can't get deeper because the temperature at that altitude doesn't drop any further if you've ever had the pleasure of interacting with the climate change denier this is exhibit a look they'll say nothing we do will make any difference and it's in the correct that the bottom of the ditch basically won't change much but this isn't the relevant part the relevant part is that carbon dioxide doesn't just absorb light in this very narrow range it also absorbs it to both of those sides and in fact in some other parts of the Spectrum which I haven't drawn if the concentration of carbon dioxide increases further then the emission of more and more wavelengths in the Spectrum moves up to higher altitude so they move to lower temperatures which in this figure means that the ditch gets wider so increasing carbon dioxide levels filters out in increasingly bigger chunk of the wavelength window that we use to cool the planet another way to put it is that when carbon dioxide levels increase more and more of the infrared radiation is submitted from higher altitudes where the temperature is lower which makes the cooling increasingly less efficient and then the surface of the planet will warm until the energy balance is re-established this carbon dioxide ditch doesn't get wider by a lot it's just a tiny bit but this is the major reason for the enhanced greenhouse effect that we're seeing right now can such a small difference really have so big consequences well if you think about it global warming is a small effect in absolute terms the average temperature of Earth is something like 290 Kelvin we're talking about a change of a few degrees coffin that's a percent difference not a big change for the planet but a big change for us because we've made ourselves comfortable on this planet with a different climate the full story you won't be surprised to hear is vastly more complicated than this 20 minutes YouTube video suggests that's because besides carbon dioxide there's also methane and water vapor and the temperature in the upper atmosphere isn't actually constant in that region but that's roughly what's going on this tells us another thing remember I said that as you go up to higher altitudes in the atmosphere the temperature increases again in a region called the stratosphere this is because the stratosphere absorbs some of the incoming sunlight especially in the ultraviolet the concentration of greenhouse gases up there isn't high enough anymore to trap the incoming infrared light but the concentration of carbon dioxide is still increasing what does this do to the stratosphere well these additional greenhouse gas molecules will still emit infrared light when they wiggle this means that the stratosphere becomes better at getting rid of energy which means it cools this is called stratospheric Cooling and it's one of the key predictions that climate models have made it was predicted already in 1967 by monabe and weather Rod weather old died in 2011 mono Bay was one of the recipients of the 2021 Nobel Prize in physics this figure from the 1967 paper shows that when carbon dioxide levels increase the lower atmosphere should warm but the stratosphere should cool this was a super important prediction because of global warming was caused by an increase in solar radiation rather than by more greenhouse gases than they should both warm and the upper Stratosphere has in fact cooled here's a summary of the data from some satellites up there what happened in 1991 that was the eruption of Mount Pinatubo so if someone asks you what predictions climate models have ever made a good answer is stratospheric Cooling and if someone asks you how we know it's not a change in solar radiation a good answer is also stratospheric cooling I've tried to figure out why I misunderstood this for so long and I think what threw me off is all those errors for infrared light that go right through the atmosphere I think it'd be better to draw it like this the incoming radiation from the Sun goes through the atmosphere and hits the surface it's converted into infrared radiation and that heats the atmosphere From Below somewhere up here the infrared light escapes for good if the concentration of carbon dioxide goes up then the infrared light escapes from somewhat further up where the atmosphere is a little colder so now the total limited energy is smaller and the system is out of balance the Earth then has to heat from below until the emission comes into balance again and the effective altitude of emission can be slightly different for each part of the frequency spectrum I believe that those pictures originate from illustrations in climate physics books where the arrows don't depict the way that the radiation actually goes but just the total amount of energy that flows through those channels that's to say this illustration is all well and fine so long as you don't think this means that the infrared light actually goes through the atmosphere I learned all this from a great book by Raymond Pierre Robert which I would like to show you but it's got green on the cover can you turn off the chroma key for a moment here's the book and yeah this is how the sausages are made it's just a piece of green cloth pinned to the wall many thanks also to Adam Levy for helping with this video Adam has his own YouTube channel where he talks about climate stuff if you're interested in that go check it out was my explanation of any use let me know in the comments I hope you enjoyed this video which you got to watch for free because it was sponsored by not VPN so please hear me out why I tell you why we work with them not VPN is an app that you install on your phone or laptop it creates a secure connection to one of their servers and then you browse the web from there this keeps your data private even on a public wireless not VPN also comes with a threat protection that keeps you safe from malware trackers and malicious ads if you're still not sure what you need an app like this for let me mention that they have more than 5 000 servers all over the world and you can choose one this allows you to access websites in other countries by using a server located there so if a video or website is blocked where you are that's an easy way to solve the problem you can make use of our special offer if you use the link nordvpn.com Sabina or the coupon code zabina not VPN is super easy to use runs on pretty much all platforms and in stores in a minute you can combine it with the password keeper called notepass and a secure platform to store and share files called note Locker if you get them all together you'll get a better price and they all have a 30-day money-back guarantee once again that's not vpn.com Sabina or the coupon code Sabina links in the info below so go check this out thanks for watching see you next week

Channel: Sabine Hossenfelder

Views: 516,190

Keywords: greenhouse effect, global warming, climate change, what is greenhouse effect, how does the greenhouse effect work, climate change hoax, climate change carbon dioxide, carbon dioxide greenhouse gas, carbon dioxide saturation, greenhouse gas saturation, climate change denial, what is the greenhouse effect, climate physics, climate science, science of greenhouse effect, hossenfelder, science without the gobbledygook

Id: oqu5DjzOBF8

Length: 19min 51sec (1191 seconds)

Published: Sat Feb 04 2023

Reddit Comments

[u/Gnolam1]

Sorry babe, you still haven't figured it out. Take a garden trowel, a plastic plant container, and a book on gardening from your so-called greenhouse. They're all 80° temperature but will show up at three very different heats in Infrared Why? It's called emissivity. Same temps, different IR glow. Get it ? Same as our atmosphere, CO2 molecules are outnumbered 2500 to one. They are the same temperature as their surroundings. CO2 doesn't heat nothing, but is instead heated and cooled by the atmosphere. Yet it does reflect a different color than oxygen(blue), or any of the gases used in neon tubing. Different light emissions....it's why you don't just see one big red blob in the IR camera. It's why they can differentiate coins & keys from a gun in airports. Skeptics have to keep denying cuz alarmists can't understand "NO, you're wrong!"

[u/SftwEngr]

Sorry, the reason a greenhouse stays warms is due to a restriction in convective cooling, a very powerful method of cooling air that occurs on the planet at all times. You'll notice greenhouses have vents to control this restriction if things get too warm, and will release some of the hot air via convective cooling. If the greenhouse was getting too warm due to LWIR, you'd have to take the roof off to cool it down. Nice try though!

[u/FancyEveryDay]

This video is God tier, really does an amazing job of putting the pieces together in a way that is informative and concise.

Hard agree with her criticism of greenhouse effect illustrations, its shocking that they're so incorrect and still so widely used for teaching the GHE.

[u/JackEddyfier]

Skeptics should reply to Sabine H's OP on YouTube. She's actually a half-descent scientist with a bit of an open mind.

[u/FancyEveryDay]

u/Rddtis4butts

[u/doubledisme]

She now seems to understand the Physics well enough. But here're my thoughts regarding this presentation.

When she shows the CO2 absorption graphic with 2X CO2 overlaid, the widened bandwidth she showed looked a bit exaggerated. Although she said verbally it was tiny, the depiction implies it is to scale. When I average the bandwidth I get 180cm-1 at 400ppm and 195cm-1 at 800ppm; so about an 8% increase in the CO2 effect is indicated.

She also omits discussion of surface heat transfer via subsurface water via plants to leaves which is evaporated, moving latent heat to the clouds. She also ignores surface conduction to air and resulting convection. The narrow focus on radiative heat transfer from the surface exclusively can lead to exaggeration of the radiative resonance effect.

She doesn't mention the biological effects of CO2 changes. The additional plant density will increase relative humidity due to water evaporation from subsurface source. If CO2 were halved, we would see a substantial increase in decayed plant debris. Wind currents have been shown to carry this debris to glaciers and ice sheets darkening their surfaces. The biological effects may influence temperature more than the claimed radiative transfer effects.

Of course, she did disclaim that 20 mins can't cover it all.

However, she very specifically called out the CO2 effect at very low altitudes. I think this could have been a leftover cut-n-paste or leftover thought; regardless an error. It doesn't look like CO2 can be effective at altitudes shared with the much more massive water. Again, she quoted numbers from water radiative response but omitted latent heat of evaporation, and conduction then convection. When we combine all the ways water transfers heat from the surface, it's clear CO2 cannot play much a role at low altitudes.

She also globed in "other GHGs", like CH4. She knows fully well CH4 doesn't resonate within a substantial iridescence frequency. And, she knows full well that water makes CH4 contribution nil. And, she knows full well CH4 is oxidized so quickly in the atmosphere it cannot be a problem. Even knowing all this, she still did the name drop so as to stand her position and give the fearful something else they don't understand to worry about. Sabine, I love ya babe but come on. I get it, flying first class is good, no job is bad; I get it. Still, gotta say I'm a wee bit disappointed. One day you'll need to apologize to science.

One more thing. The high altitude CO2 average radiation center would only rise IFF cloud cover, aka relative humidity were constant. Come on again... you know it will not remain constant. It has already changed. Don't try to deny global greening due to recent decades CO2 increases. Don't try to deny the RH went up, and the surface temps below the leaves went down.

So what she said was all true, just dodgy on the details to mislead. The very limited physics discussed seems correct; with the details of disparities above. That does kinda suck, but she remains in first class.

[u/pr-mth-s]

OK I watched. FWIW.

My guess was wrong, she isn't strategizing. All that is going on is Hossenfelder has gotten to where msm atmospheric physicists have been for a long time and made a video about it. Why? TBF, the issue is important and she kind of is. Plus, her videos are assigned to students; it's even broken down in parts for teachers to assign.

To me she looks bonkers in the whole video. At https://youtu.be/oqu5DjzOBF8?t=742 she uses the phrase 'interacting with the climate change denier' is an example.

an ad hominem by me yes, but that's the turf she has chosen by that phrase. She crossed the line. And not only do I think CO2 is a (weak) GHG, I have heretofore praised her (mostly). Not that I matter.

the whole video is a subtle reprise of the alarmist's fake argument. It insinuates ‘Its a GHG so we have to have global totalitarianism run by us’. which is not logical.

Yes, there may be other reasons she has the face of a lunatic. I try to subtract all of them: maybe contacts, reading notes, works long hours, passionate in defending MSM science. Still to me she looks insane.

Not coincidentally I think passionately defending climate science especially in 2023 IS insane, considered how mental & evil that paradigm it has made globalists and with WWIII looming. Her looking insane & just now insanely defending the paradigm matches up. I conclude she is a lunatic, in this video in particular clinging to the past, where college professors can almost imagine they will run the globe. Not happening!

btw, when using the phrase ‘interacting with climate deniers’ she says 'they will say' something they noGHGers do not say AFAIK. [What is called a 'red herring' ]

tldr: one of Hossefelder's worst videos, targeted for Western HS students probably, not moving the tiller strategically; not anything new, just a 'look what i learned' video, which is rare for her.