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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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Comments 851 to 900:

  1. EPA’s car pollution rules would save Americans trillions of dollars

    My two cents worth on tire wear.

    "A Tesla Model 3 Performance with AWD weighs 4,065 pounds — 379 pounds more than a BMW 330i XDrive (A typical similar size and quality of ICE car to the best of my recollection).

    www.cnet.com/roadshow/news/americas-new-weight-problem-electric-cars/

    This weight difference is not going to cause much additional tire wear , so its not significant for vehicle running costs. These sorts of objections to EV's seem trivial to me.

  2. michael sweet at 06:16 AM on 13 May 2023
    EPA’s car pollution rules would save Americans trillions of dollars

    Reading Eric's link about Brake and tire dust I noticed that they always said "brake and tire".  That suggests to me that brake dust is more important.  The article suggests that this research is just beginning because ICE pollution used to be so much bigger that people did not bother looking at brakes and tires.

    I Goggled a little and found that a lot of EV's use one pedal driving.  I have found that with one pedal driving I rarely use the brakes.  I have not measured but I would estimate much less than 5% of the time.  It appears that all electric cars use regenerative brakes.  The brake wear from electric cars will be much lower than current ICE cars.  I saw a youtube video (what could be more accurate ;) where after 90,000 miles (about 145,000 Km) the brake pads were about 15% worn.  Google says brake pads should be replaced every 20,000 miles, although some pads last longer.

    The mechanic estimated that the tires had been driven 65,000 miles and had 5,000 miles left on them.  The car was a Tesla model.   70,000 miles is not much different than an ICE car tire wear.  I note that when you buy tires some have much longer warranty milage claims than other tires.  Presumably tires with a longer lifetime release less dust per mile.  The size of the dust particles is probably also different but I have no idea what the differences are.

    My conclusion is that elecric cars release much less brake dust and probably a little more tire dust than ICE cars.   Since these are currently not even measured because ICE cars release so much particle pollution, switching to electric cars will dramatically reduce small particle pollution.

  3. Eric (skeptic) at 13:05 PM on 12 May 2023
    EPA’s car pollution rules would save Americans trillions of dollars

    Michael thanks for the generative braking reminder.  I forgot about that. 

  4. EPA’s car pollution rules would save Americans trillions of dollars

    Michael @4 , in my role of Devil's Advocate, I can confidently and citationlessly point to the heavier mass of EV's . . . combined with their often temptingly brisk acceleration . . . that leads to faster tread wear.  And presumably the rubbery engineers prioritize grip & low rolling resistance & quietness for the EV market, and tread life is much lower on the list.  The attention to particle PM2.5 pollution has been as an exhaust concern, rather than a rubber concern (even among youthful environmental scientists).  But perhaps this could change in the future.

    It is all very well for you Teslarazzi  to use regenerative braking.  But for those of us with more Scottish blood (read:  pessimistic & dour & penny-pinching) tend to use the disk brakes far more.  The line of thought is that ~ with today's primitive lithium batteries, we wish to avoid the frequent reversals of current flow which shorten battery life.  New battery technology (with ultra-high cycling life and low capital cost) may come eventually . . . but for now, us penny-pinchers would like to eke out the battery long enough to get the rest of the car up to its economic life (rust & plastics degradation) in 15 years or more.  Aye, and a chance at 20.

  5. EPA’s car pollution rules would save Americans trillions of dollars

    Please note that there has been previous discussion of EVs on this thread, and that the distinction between "emissions" from tailpipes vs tires, etc. was brought up in this comment and the ones that follow. Distinguishing between gas emissions (such as CO2) and particulate emissions (such as soot, etc - the things that show up as find particles measured by PM2.5) is very important. In the reference listed on the above thread, tire wear is largely related to vehicle weight, not the source of power.

  6. michael sweet at 10:21 AM on 12 May 2023
    EPA’s car pollution rules would save Americans trillions of dollars

    Eric,

    My Tesla Model 3 uses the motor for almost all of the braking.  I will be very surprised if the vehcle ever requires new brake pads.  I have read that many other (most? All?) electric cars primarily use the motor for braking since they generate electricity to increase driving range.  Can you provide a reference that says electric cars will wear out brake pads faster than ICE cars?  Even hybrids use regenerated braking to increase range.

    What do other model electric car users who read SkS find about brake use?  All Teslas primarily use regenerative braking with the engine and not brake pads.

    I have heard a little about tire wear.  My niece, who is a environmental  scientist working on land management, had never heard of this type of pollution, which suggests to me that it is not very important.  Can you provide a link that describes the importance of electric cars versus ICE and tire wear?  I expect that tire manufactures will reformulate tires to reduce wear if it is a problem, how much that would help is another question.

    I notice that fossil fuel proponents raise a lot of red herrings about electric cars, like brake pad and tire wear.  Are these really issues or are they fossil propaganda?

  7. Skeptical Science News: The Rebuttal Update Project

    The blog post was updated on May 11 with the links ot the latest rebuttals getting the "at a glance treatment":

    The 97% consensus on global warming

    Global cooling - Is global warming still happening?

  8. It's cooling

    Please note: the basic version of this rebuttal has been updated on <date> and now includes an "at a glance“ section at the top. To learn more about these updates and how you can help with evaluating their effectiveness, please check out the accompanying blog post @ https://sks.to/at-a-glance

    Thanks - the Skeptical Science Team.

  9. There is no consensus

    Please note: the basic version of this rebuttal has been updated on May 11, 2023 and now includes an "at a glance“ section at the top. To learn more about these updates and how you can help with evaluating their effectiveness, please check out the accompanying blog post @
    https://sks.to/at-a-glance

    Thanks - the Skeptical Science Team.

  10. EPA’s car pollution rules would save Americans trillions of dollars

    Eric, thank you for the links.

    I suspect that the PM2.5 from rubber is not easily reducible.  However, PM2.5 from brake pads could well be an area of improvement, if research effort is put into it.

    Bobhisey, it would be interesting to see more details about the 5c/mile and 12c/mile figures ~ surely there would be vast differences from country to country.  Taxes vary a lot, and a cynic would point out that funding nominally earmarked for road maintenance . . . somehow gets bled off into "general revenue".  Local regional taxation can also go into road repairs, often combined with federal grants.  It's very often a mish-mash.

    At worst, it sounds (to me) like the overall costings situation is likely close to being a wash.  And there is still much scope for future battery improvements in cost & performance (and possibly a smaller EV battery combined with a fuel-cell range extender).  But you are right ~ death & taxes will never be out of the picture.

  11. Eric (skeptic) at 23:13 PM on 11 May 2023
    EPA’s car pollution rules would save Americans trillions of dollars

    758 page EPA "proposed rules" link above is broken.  I tried looking the same document up and found other sites with the same link like this eelp.law.harvard.edu/wp-content/uploads/EELP-EPA-Clean-Cars-Rule-Summary-April-2023.pdf. They describe some more of the quantitative benefits in that document.

    I have a question however.  Have the vehicle emissions been segmented into tailpipe and non-tailpipe?  In this source they say "Thus, non-exhaust sources, including brake and tire wear PM, have become larger contributors to traffic-related emissions as well as to ambient PM2.5 (particles less than 2.5 um) concentrations."  www.me.ucr.edu/news/2020/10/05/brake-and-tire-wear-particles-emerging-source-air-pollution

    Another question is hormesis.  There's a J-curve to many things like particulates.  There's a slight detriment to having none, then a benefit at low amounts, then more detrimental at increasing amounts and very detrimental at high amounts.  Figuring out where people are on the curve will change the costs and benefits for various groups.  City dwellers will always have more pollution but will also (and have also) benefitted the most from EVs.  I can't tell if they did that segmentation or not.

    Final question is how soon to transition for various groups considering the grid mix.  In some places it will make sense to wait considering the battery will be worn out with charge cycles before the grid has been transitioned away from mostly fossil.  The segementation by group could probably be applied by county based on vehicle-mile density and grid fuel mix.

  12. EPA’s car pollution rules would save Americans trillions of dollars

    Just one comment of man possible.  The 12c/mile includes Federal and state taxes to maintain roads.  The 5c/mile for electrics does not.  They just sort of forgot about that.  

  13. CO2 is not the only driver of climate

    piotr @78,

    Going back to your up-thread enquiry, the responses were not entirely nailing you initial question.

    piotr @70
    I think you confuse the dips in the 11-year solar cycle with the Maunder Minimum. And I would add that associating the Maunder Minimum with a frozen River Thames rather defies the evidence. Frozen Thames events were very rare and only happened in winters when a long cold period of weather engulfed the region. And they stopped happening when they demolished the old London Bridge and embanked the river through London. Without such work, we would have witnessed a frozen Thames in 1963.

    piotr @72
    You asked what Martin Mlynczak was talking about when he talked of something that "will not cause noticeable cooling at the surface."
    The source of that quote is here and I don't think it directly quotes Mlynczak although Mlyncsak was being quoted directly upthread @69 when he says "There is no relationship between the natural cycle of cooling and warming in the thermosphere and the weather/climate at Earth’s surface," the source here dating to 2018.

    And what Martin Mlyncsak was talking about is the newly established Thermosphere Climate Index which back in 2018 was dropping due to the ending of sunspot cycle 24 and with the arrival of sunspot cycle 25 has since risen from 'cold' and approaching 'warm'. This is the "natural cycle" Mlyncsak referred to when he says it has no imact on surface temperatures and given this Thermosphere is a hundred+ kilometres up in the atmosphere, this should not be any great surprise. A graphic of the Thermosphere Climate Index.

  14. CO2 is not the only driver of climate

    Hm my post has not been placed but in short: thanks a lot to your effort to explain as precise as possible. very pleased to not getting dumb comments.

  15. CO2 is not the only driver of climate

    Let me just say thanks a lot at first for your effort to explain. Give me some time to respond. Its very pleasend not to get downed with dumb comments and instead get lot of effort.

  16. Charlie_Brown at 01:46 AM on 10 May 2023
    At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Thank you, Philippe.

    I want to make two edits to emphasize a key point about the external energy of the sun and to clarify G&T's assumption about being radiatively balanced.  Try this.

    Insert after “… requires adding external energy, electricity, to make it work. The sun is the external source of energy to increase or to maintain the Earth’s temperature given the external energy loss to cold outer space. There is no violation of the 2nd law.

    Replace: “… incorrect description of global warming. They assume that the radiant energy input from the sun is equal to the radiant heat loss to space and the system is “radiatively balanced”. That would be true for the greenhouse effect before the industrial revolution but increasing greenhouse gases (GHG) upsets the balance and causes global warming..”

    With: “... incorrect description of global warming as well as the Earth as a cyclic device in perpetuum. They ignore the energy flows from external hot reservoir of the sun and to the cold reservoir of space by stating that the heat transfer between the Earth’s surface and the stratosphere is “radiatively balanced.”"

  17. Philippe Chantreau at 01:01 AM on 10 May 2023
    At a glance - The greenhouse effect and the 2nd law of thermodynamics

    It is getting better. That latest one is pretty good, especially the analysis of G&T's trick, which is nothing more than a sophisticated straw man.

  18. CO2 is not the only driver of climate

    Piotr @73 ,

    another puzzle is your comment about "thousand parameters" [unquote] which you mention in your third paragraph.   I would very much care to learn what these parameters  are.   (Personally, I would struggle to nominate more than a dozen relevant parameters.)

    Are you repeating the words of some non-scientist . . . or are you being very loose with your language ?   It is desirable to be accurate & precise - not loose & hyperbolical - when discussing climate.  Otherwise, you are wasting your time and are confusing yourself.

  19. CO2 is not the only driver of climate

    Another source of temperature reconstructions is the IPCC sixth assessment report. The following figure is from the Summary For Policy Makers. Full scale image is available at this link. The grey shading represents the uncertainty. Nothing even comes close to piotr's claim of a "decrease up to 1.5°C".

    Temperature reconstructions

  20. CO2 is not the only driver of climate

    piotr @ 73:

    I am not sure what your "not directly" statement refers to. I presume that the Martin Mlynczak quote is the one in comment 69. To put it simply, the thermosphere and the earth's surface respond to solar radiation in very different ways. You can read about the thermosphere on Wikipedia. Note that the thermosphere is at very high altitudes (>80km), and its temperature structure is the result of the absorption of UV radiation. It also has very low density, so even though average kinetic energy is high ("temperature") it does not hold a lot of heat. It is not strongly linked to the surface, which is heated by the absorption of solar radiation over the full spectrum.

    This paper by Lean, Beer, and Bradley (1995) shows in figure 2 that variations in total solar irradiance are much less than for the UV range (in %).

    Lean 1995 fig 2

    To use the 4W/m2 drop in that figure, you need to first reduce it by a factor of 4 (area of a sphere vs. area of a circle), and then adjust for global albedo (0.3), giving an overall forcing of only about 0.7 W/m2. Sustained over only a period of about 50 years, this is not going to have a major cooling effect on its own.

    You say that "it noticeabl[y]e cooled large parts of the no[r]thern hemisphere", which I presume is a claim with respect to surface temperature responding to these solar variations. You then throw in volcanic effects. You seem to grossly overestimate those solar effects, though - with no references to any supporting information. If you look at this SkS post, the first figure shows that reconstructed global temperatures for that period are much smaller than your claimed "decrease up to 1.5°C".

    Temperature reconstructions

     

    In your second paragraph, you start talking about "The past 10.000 years where up and downs in global mean temperature like +/- 2°C for dozen decades, even for nearly 2000 years - as we can reconstruct with little data-points." This starts to wander into the last glacial period, where Milankovitch cycles start to play a role. You are mixing together a lot of different forcing mechanisms, as if they are all equivalent in some fashion.

    You then start into urban heat island effects, and finish off with a couple of paragraphs that represent an argument from incredulity. If you actually want to learn something about temperature reconstructions from proxies, Wikipedia has a decent article on this, too. The Wikipedia page also has a graph that shows even less variation in temperature than the one above:

    Temperature reconstructions

     

    The numbers you are throwing around in your "just imagine" scenarios seem to be ones that you have a lot of confidence in. The problem is that they also appear to disagree with broad swaths of the scientific literature. You appear to be claiming that science is unsure of what happened in the past - but you are. It seems highly unlikely that you are correct.

    If you want to have any credibility here, you are going to have to provide references to the numbers you post. This is not a site where you will be permitted to post a lot of unsubstantiated opinion. As you are a new user here, I strongly suggest that you read the Comments Policy.

  21. Climate communications: Laura Helmuth and Susan Hassol talk about language

    I accept the terms climate change and global warming were always both used in the scientific literature. However this discussion page is about popular use of terms.  In New Zealand the media used the word global warming for some years after the climate problem became known, and  then the term climate change became the dominant  term used. My understanding is its the same in other countries.

  22. CO2 is not the only driver of climate

    Piotr @73 ,

    Wind & ocean currents move heat energy around the planet - and so there is a considerable "averaging" effect on global temperatures.  Even today, you do not need thousands of observation stations in order to assess changes in global temperature.  Analysis shows that less than 100 stations are needed (if well-distributed, of course) to give a closely accurate picture of conditions.

    A so-called Grand Solar Minimum is not actually very grand ~ studies such as Feulner & Rahmstorf, 2010  and Anet et al., 2013  indicate that a GSM produces a global cooling of around 0.3 degreesC.  (Other studies indicate slightly smaller changes.)    And this is because our Sun is a very stable star, with a very stable output of radiation.   Very little variation.

    Even the Little Ice Age was not spectacularly cold  ~  a global cooling around 0.5 degreesC   . . . which had been helped along by a number of cold winters from volcanic eruptions.

    There have been periods of decades of marked cooling in the neighborhood of Greenland earlier in the Holocene, as a result in temporary changes in ocean currents.   But these had little effect on average global temperature (the planet is big, and there is a vast amount of tropical ocean).   The one exception is the millennium of strong cooling (the "Younger Dryas" ) about 12,000 years ago  ~ and this was a one-off event produced by the single event of melt/discharge of the Laurentide Ice Sheet situated in Canada.

    Piotr, you seem to have a wrong idea about earlier warm periods (of the Holocene) such as the so-called Minoan / Roman / Medieval Warm Period  ~ these were only very slight changes, around 0.3 degreesC or smaller.  These were only tiny "blips" on the general slow cooling from the Holocene Maximum temperature (slow cooling owing to the Milankovitch Cycle).

    Possibly you have been misled by reports based on Arctic region temperature estimates (the Arctic shows bigger swings than the average global temperature).

  23. Charlie_Brown at 03:30 AM on 9 May 2023
    At a glance - The greenhouse effect and the 2nd law of thermodynamics

    My next attempt.  I hope this is getting better.  I changed the first part quite a bit to emphasize that the key problem with G&T, often overlooked, is their assumption that the input solar and output IR radiation are balanced (see Fig 32).  I think these are worthwhile revisions.  The structure seems fact-myth-fallacy-fact because I wanted to begin by separating the 1st & 2nd laws, but bring back the 1st law facts to seal the deal.  Please feel free to edit and use the input as you deem suitable.

     

    The 1st law of thermodynamics is conservation of energy. The 2nd law describes limitations on how energy can be used in forms of heat and work. It is difficult to express without introducing the concept of entropy - a state of disorder that is hard to understand. Instead, the 2nd law can be expressed practically in the form of statements and corollaries. One translation of the Clausius statement is: “It is impossible to operate a cyclic device in such a manner that the sole effect external to the device is the transfer of heat from one heat reservoir to another at a higher temperature” (Wark, Thermodynamics, 4th ed., 1983). A key phrase is “sole effect external to the device.” A cyclic device can be a heat engine and the classic example is a refrigerator that requires adding external energy, electricity, to make it work. Gerlich & Tscheuschner’s paper describes modern global warming theory as a perpetual heat engine that transfers heat from the cold stratosphere and the warm surface. That would violate the 2nd law, but that is an incorrect description of global warming. They assume that the radiant energy input from the sun is equal to the radiant heat loss to space and the system is “radiatively balanced”. That would be true for the greenhouse effect before the industrial revolution but increasing greenhouse gases (GHG) upsets the balance and causes global warming.
    Some take the myth even further to claim that thermal radiation cannot transfer energy from a cold body to a warmer one. Gerlich & Tscheuschner steer the discussion into distraction by emphasizing the technical distinction between heat and energy. Consider two walls facing each other. All objects above absolute zero radiate energy. The warm wall radiates more energy toward the cold wall, but the cold wall still radiates some energy toward the warm wall. The debate amounts to whether it is energy or heat that moves towards the warm wall.

    Conservation of energy for any defined system is:
    Input = Output + Accumulation
    The global system can be defined as from the Earth’s surface to the top of the atmosphere. The input to the global system is the sun. The surface temperature is regulated by balancing heat input from the sun with heat loss from the top of the atmosphere toward space. When balanced, accumulation is zero. There are three output energy pathways: 1) Infrared (IR) radiation from the surface at wavelengths that are transmitted directly to outer space (the transparent range). 2) IR radiation from GHG in the colder atmosphere at wavelengths that are emitted by GHG, and 3) solar energy reflected by clouds and the surface. As the concentration of CO2 increases, energy output to space (path 2) is reduced. This upsets the global energy balance. Energy accumulates and the surface temperature rises. As the surface temperature rises, energy output from the surface through the transparent range (path 1) increases until the balance is restored. This is how global warming works.

  24. CO2 is not the only driver of climate

    @Bob Loblaw

    Not directly. I was just wondering on Nasa's Martin Mlynczak statement to Grand solar minimum "and will not cause noticeable cooling at the surface". Yeah, not globally, except the overall temperatures may decrease a bit in statistics too. But it noticeable cooled large parts of the nothern hemisphere, like big vulcanic eruptions can cause for few years and did in even the last 150 years too -> global mean temperatures decrease up to 1.5°C, besides some areals warmed then too.

    So what is Martin Mlynczak talking about? The past 10.000 years where up and downs in global mean temperature like +/- 2°C for dozen decades, even for nearly 2000 years - as we can reconstruct with little data-points.

    Overall my main questions is the concerning how plausible is the reconstruction of earthly temperatures over thousands of years just with indirect data besides modern technology with thousend parameters, stations around the globe and on every time (even in grown urban places, which totally heat up just being sealed ground and overcrowded for decades). modern observation for like 30 years am totally cool with, but the rest is a large extrapolation of indirect measurement and got "worse" at we strife further away in time.

    Just imagen if we would have high technology measurements like today in for example 6000 BC to 5500 BC, then we would see global warming for at least 0,5 - 0,8 °C over aproxx 1-200years similar like today and we knew that for some areas or changing habitats like sahara desert, but not excessive like modern data amount. btw. its also stated there were same co2 ppm levels as pre-industrial times.

    i think its "fascinating" to have data from million years ago, when no modern human lived and we think to "know" how life was back then, globally, just by knowing some single fragments and feeding supercomputers with, which try hart to simulate complex features like climate or even local weather to be back then. Im a big fan of astronomy since my child days and read about the fist extrasolar-findings back in the days. but thats much more extreme, as we can never proof for real, even if its pretty possible to conclude a habital place somewhere on a planet just by reconstruction of the atmosphere, despite being back in time maybe million years ago. its hilarious to say "we found a possible earthlike planet!".

  25. Climate communications: Laura Helmuth and Susan Hassol talk about language

    You can read more about the "they changed the name..." myth on this SkS page.

  26. Climate communications: Laura Helmuth and Susan Hassol talk about language

    I don't think it is accurate to state that "global warming became climate change" without noting that the two terms were used interchangeably over many years - for example the landmark Plass paper in 1955 was titled, "The Carbon Dioxide Theory of Climatic Change".

  27. Climate communications: Laura Helmuth and Susan Hassol talk about language

    Excellent video.

    I have an old  book titled "Asimovs Guide to Science" 1987 edition Penguin Books, 880 pages that cover every branch of science and in surprising detail for one volume. The man is a genius. Its all beautifully written in a public friendly style. The writting does have a lot of jargon but its explained and he just has this smooth easy to grasp style of writing, all beautifully well structured and organised and easy to follow.

    There are no equations in the main text but some apendicies at the back include some maths of the key issues. Once you put equations in the body of the text you pretty much alienate most of the general public and Asimov understood this. The more equations and maths the worse it gets. I recall a book publisher discussing the issue of equations and the dismal affect this has on sales of a book. Sadly to say, because an equation explains something that requires a lot of words to explain.

    However I have some reservations about the suggestions in the video on terminology:

    Global warming became climate change and the denialists used that to accuse scientists of changing the story for nefarious purposes. The denialists were wrong on every level but mud sticks. Now we hand them more ammunition by calling it "climate disruption: I really dislike changes in terminology unless its really necessary.

    Postive feedback is the scientific term. Yes it makes it sound like a good thing but is using different terminology like self reinforcing cycle  the right response to the problem? Why not just define postive feedback  in brackets as "a self reinforcing cycle that amplifies the warming process" (or whatever process is being discussed ). Generally I think definitions in brackets is best. It only needs to be done once in an article. If every science writer comes up with their own terms as substitutes for jargon, it will just confuse the public even more.

    Heat trapping pollution is not a great term. There was controversy about whether carbon dioxide is a pollutant as such, started of course by the denialists. There is a good argument that carbon dioxide is a pollutant but why hand the denialists ammunition? The public generally understand pollution to be something added to the atmosphere that directly affects health or degrades the environment and this is the typical dictionary definition. CO2 acts more indirectly.Heat trapping gases would be better terminology (the video did suggest that as another option).

    Perhaps these are nit picks. Clearly the writer is correct that the scientific jargon often creates the wrong impression with the public. But the simple answer is just define it in brackets in plain language where possible, or as a footnote, as opposed to dreaming up completely new terms and using those.

  28. CO2 is not the only driver of climate

    piotr @ 70:

    You ask what might have caused the Maunder Minimum. First, you should think about exactly what the Maunder Minimum was: a period of low sunspot numbers. Wikipedia has a good article, and they include this figure:

    Wikipedia Maunder Minimum

     

    Technically, "what caused the Maunder Minimum?" is a question of astrophysics, not climatology. But what you are probably wanting to ask is "what caused the xxxxx?, where xxxxx is something that you feel is correlated with the Maunder Minimum. Reduced solar irradiance? Lower temperatures? The Little Ice Age?

    So, this means that you are looking at something where the Maunder Minimum is an indirect/proxy indicator of some potential climate factor. You do realize that we do not have direct evidence that the Maunder Minimum caused a specific decrease in solar irradiance? You do realize that many of the observations indicating cooler temperatures - such as ice on the Thames -are local, and not global? The Little Ice Age appears to be related to a number of factors. You can read about it a bit more in this post.

    Understanding of past climates is based on things like vegetation, sediments, etc. A lot of those have automatic time-averaging (trees don't grow in a year) and spatial averaging (sediments and pollen  get carried in to lakes from large watersheds). The analysis of past climates includes a wide variety of proxy indicators. You can read more about it on this post.

    In short, you need to be more specific in explaining what you do understand, and what questions you have.

     

  29. CO2 is not the only driver of climate

    Piotr @70 ,

    Think about it this way  ~  causes and effects.

    In this universe, if you see an effect, there must be a cause (and with enough study, you can find that cause - which may be a single cause, or a combination of causes).

    Past studies (by experts) have shown broad changes in climate - not measured in tenths of a degree as per modern thermometers, but in broad assessments of indirect indications of climate average temperatures / sea level changes / vegetation changes / and so on.  From this, it is evident that the climate changes when there is a causative change (a change in solar output, or in atmospheric CO2 levels, or in reflective "albedo" from global ice coverage, or in stratospheric aerosol particles from major volcanic eruptions).

    All these jig-saw pieces fit together nicely, to give the scientists (and us) a good understanding of how climate "works".

    Beware of non-scientists who say that "stuff just happens"  [excuse the American expression].   They seem to wish to believe that the past century or two of very rapid global warming is somehow not caused by the obvious causes.  And that it came for no identifiable reason.  They seem to wish to believe that the modern warming "just happened for no cause"  (sometimes expressed in the meaningless phrase "it is just a rebound from the Little Ice Age").

    (The Little Ice Age had its own causes - frequent major volcanism plus episodes of reduction in solar output.)

    Or they say that the modern rapid warming must instead be caused by "long-term changes/oscillations in ocean currents" ~ which actually does not make scientific sense (if they bothered to think it through).

    Piotr, there are definitely some people who do not wish to think.

  30. CO2 is not the only driver of climate

    Greetings. @Daniel Bailey

    ""Observations have shown that solar flare activity on the surface of the Sun is in the quiet phase of its continuing 11-year cycle. This causes cooling of the thermosphere—a layer of the atmosphere that starts 65 miles above the surface—and will not cause noticeable cooling at the surface""

    - so how could happen the Maunder Minimum, when the baltic sea and the thames were frozen then?

    Btw. Im still curious on early indirect data measures. We use satelites and probably thousand of observation-stations everywhere, even in already urban densed areals where its hotter due to soil sealing/buildings etc. than decades ago.

    but how precise can data be when hundreds or even thousand of years ago, where we usually collect data from drilling cores from ice, dendro analysis etc.?  the modeled graphs showing co2 concentration or temperatures from early periods of the neogene era for example could never be scaled that detailed like modern oberservations, so how do we could know other than extrapolate or try to forecast on this "rough" data? just saying the data of the past century heavily fluctuates with different natural events as we have a lot of different parameters and thousend of different stations to check. but few hundred years ago there are some marks here and there for months or years, not thousends a day - you know what i mean?

    so anyway do we have a chance to differentiate natural occuring warming of the past few decades from self-induced co2 with this methology?

    I just think we cannot use modern nanotechnolgy to understand stone-age tools were used, or maybe better metaphor: collecting a bunch of single bones from an ancient creature is no evidence to know how it moved or hunted, even we know a lot of biomechanics today and may let us classify the biological type/race etc.

    hope its understandable, as im no native speaker obviously :)

  31. At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Also note that when each rebuttal page is updated with these, it will retain the fact-myth-fallacy structure we've used all along.

  32. At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Going in way over most people's heads, Charlie. Introduce, introduce!

  33. Charlie_Brown at 08:09 AM on 7 May 2023
    At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Here is my next attempt for the At-A-Glance section.  It is 356 words.  I will start by copying the "Myth" from the top of the main page.  That saves trying to paraphrase it in the discussion.  

    "The atmospheric greenhouse effect, an idea that many authors trace back to the traditional works of Fourier 1824, Tyndall 1861, and Arrhenius 1896, and which is still supported in global climatology, essentially describes a fictitious mechanism, in which a planetary atmosphere acts as a heat pump driven by an environment that is radiatively interacting with but radiatively equilibrated to the atmospheric system. According to the second law of thermodynamics such a planetary machine can never exist." (Gerhard Gerlich)

    The Clausius statement of the 2nd law of thermodynamics is: “It is impossible to operate a cyclic device in such a manner that the sole effect external to the device is the transfer of heat from one heat reservoir to another at a higher temperature” (Wark, Thermodynamics, 4th ed., 1983). The myth claims that back radiation or downward infrared (IR) radiation emitted by greenhouse gases (GHG) is the mechanism that increases the temperature of the Earth’s surface. Since that would not be possible according to the 2nd law, the myth concludes that global warming is false. However, the myth overlooks the fact that the sun is the external energy source that drives global warming and outer space is the external cold reservoir. The sole external effect is transferring heat from the hot sun to cold outer space. If heat loss to space is reduced, the planet will get warmer. Some take the myth even further to claim that thermal radiation cannot transfer energy from a cold body to a warmer one. Consider two walls facing each other and that all objects above absolute zero radiate energy. The warm wall radiates more energy toward the cold wall, but the cold wall will still radiate some energy toward the warm wall.

    The 1st law of thermodynamics is conservation of energy – input = output + accumulation. The global system can be defined as from the Earth’s surface to the top of the atmosphere. The input to the global system is the sun. The surface temperature is regulated by balancing heat input from the sun with heat loss from the top of the atmosphere toward space. There are three output energy pathways: 1) infrared (IR) radiation at wavelengths that are transmitted from the surface directly to outer space (the transparent range). 2) IR radiation at wavelengths that are emitted by GHG in the cold atmosphere, and 3) solar energy reflected by clouds and the surface. As the concentration of GHG increases, energy output to space (path 2) is reduced. This upsets the global energy balance. Energy accumulates and the surface temperature rises. As the surface temperature rises, energy output from the surface through the transparent range (path 1) increases until the balance is restored. This is how global warming works.

  34. At a glance - The greenhouse effect and the 2nd law of thermodynamics

    NigelJ #28 - yes it is a complex challenge achieving balance in this business. The deniers have the advantage that they can make stuff up. We cannot!

    Also, some myths are very straightforward to rebut - e.g. "it hasn't warmed since 1998". This particular one we are discussing here is something of a pig by contrast!

    Realclimate has improved by strides since its inception. I was working on "Further details" about the Urban Heat Island effect - a debate largely triggered by a paper by Ross McKitrick and Pat Michaels in 2004. Realcimate's response was robust but only undererstandable to someone with serious statistical training. I nevertheless linked to it but with a note to that effect.

    Fortunately, most of the myths on the database can be laid to rest in the At-a-glance pieces in less than 500 words, that being the ideal word limit for that class of rebuttals. Like I said, the one we are commenting on is a bit of an outlier in this respect because so much needs introducing to the layperson. But I firmly believe we need to be near-absolutely inclusive in this business - near because I accept that there are people out there who have reading difficulties, but nevertheless reaching the biggest possible audience is the aim here.

  35. At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Just my two cents worth on communications style. I believe this website is well written overall and would be reasonably intelligible to the general public. It avoids complex jargon and when it uses jargon there are definitions. It has beginner and advanced sections in the myths. This is a great feature.

    In comparison realclimate.org is too technical.

    It's a very hard balance to strike. The thing is its only possible to simplify science to a certain extent before it starts to become meaningless. And science is hard and some people will never understand.

    Of course its always possible to refine and improve things. I'm just saying that theres probably not a whole lot more that can be done to communicate the science better. The real problem is people who don't want to understand or receive the message, or who don't see climate change as an urgent threat. Just writing the science differently won't solve those particular problems.

    I thought Charlie Browns original comment on radiation physics and the second law @17 was rather good, and sounded technically correct and would be reasonably intelligible to a lay person. People do undertand numbers and probably have some understanding of the terms used enough to get the right message. I liked its brevity so you wouldnt want it to get too much longer.

    I think with a little bit of refining the comment would be 100%. 

    The only real criticism I would have Is your final statement was "Nothing about this radiant energy flow violates the 2nd law of thermodynamics" It might have helped to briefly explain why and define the law. It left me sort of hanging, for want of a better word. I understood why but others may not have put two and two together.

  36. At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Charlie Brown @23

    Thanks. Makes sense.

  37. At a glance - The greenhouse effect and the 2nd law of thermodynamics

    There is a huuuge number of comments on the main post, so that's one tough slog you've made for yourself, Charlie!

    My apologies to anyone that followed the link to Eli's Green Plate Effect post, read the comments, and had their head explode. I re-read them this morning, and boy do you need a head vice for the weapons-grade idiocy from a few of the determined commenters. Same goes for the comments Charlie is reading on the main article here at SkS. Take your head vice, don't drink coffee while reading...

    I've referred to the Manabe and Wetherald paper a number of times over the years. There is a reason it's a classic. I sometimes find these older papers do a better job of covering some of the basics - stuff that won't be included in later papers because it's all old and well-established.

    The same can be said for the IPCC reports - start with number 1, if your climatology background is limited. It could be used as the basic text for an undergraduate climatology course. The newer reports leave so much of that "old ground" out, because they assume that the reader has taken (and passed) the prerequisites.

  38. Charlie_Brown at 02:56 AM on 6 May 2023
    At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Excellent comment, Bob.  Far too many words are spent on misunderstanding technical distinctions.  Concepts need to be conveyed succinctly at understandable levels.  That requires knowing just what is being misunderstood.  Input from a non-technical person is helpful.  To understand the point of view of denialists, I have been working my way through the comments on the main aarticle for this thread.  I now understand Philippe's comment @8 above, (@1112 in the main thread.  I just saw your reference to Manabe & Wetherald @1134 which you provided to me a little while ago.  I am thinking of having another go at drafting something as input for at-a-glance. I am hopeful that I can distill and limit the 2nd law myth into something managable.  It's a tall order, but maybe my 2-cents would help.

  39. At a glance - The greenhouse effect and the 2nd law of thermodynamics

    I think you guys are illustrating the difficulty of specialized terminology versus common usage. In day-to-day conversation, "heat" and 'energy" are almost interchangeable, but the difference is important at a technical level.

    For conduction, you are still looking at bulk properties what talking about heat flow from warm to cold. Temperature only has meaning as the average kinetic energy level of a large number of molecules. Individual molecules will be transferring energy from one to another via collision, and individual collisions can transfer energy in any physical direction. It will always be from the higher energy molecule to the lower energy molecule, but that is not dictated by the bulk properties of "hot" versus "cold". It's only when you get to the average of a large number of collisions that you can say "heat/energy goes from warm to cold"

    So, even "conduction" is a net transfer result. For radiation, if you have two plates facing each other with a vacuum between, the net radiative transfer will be from the hot plate to the cold plate - but there will be photons travelling in both directions. The photons emitted from the cold plate have no knowledge of the existence of the hot plate and its emitted energy. What individual photons do is not limited to matching the net result of many photons - just as individual molecular collisions are not limited to matching the net result of conduction.

    The "heated by..." phrasing is also ambiguous in common usage. People can imaging being "heated by" an electric blanket that is warmer than they are. A regular blanket that is cooler than the person? "Heated by" make a little less sense, but "kept warm by" is perfectly reasonable. The use of "heated by" instead of "kept warm by" isn't enough to say that a regular blanket violates the laws of thermodynamics, though.

    Likewise for IR radiation and the greenhouse effect. The surface is "heated by" back-radiation? Maybe a bit sloppy in terminology? How about "kept warmer by.."? But to make sense, you really have to get into the overall energy balance and some mathematical descriptions. The main article for this thread includes a link to an excellent post by Eli Rabbet on The Green Plate Effect. It has a loooong comments thread, but in it you can see some of the die-hard denialists at work. The extreme cases are people that claim that downward-directed IR from the atmosphere to the surface simply does not exist - usually with some "2nd Law" faulty logic involved.

    As I mentioned earlier, countering a "2nd law" argument depends hugely on exactly what flavour of "2nd law" the person is claiming. The only common element is that the person making the claim has misunderstood something - what they call "2nd law" is not actually the real 2nd law..

  40. CO2 is just a trace gas

    jgillis:

    The photos of the different blue dye concentrations in your twitter feed are illuminating. Or should I say, absorbing. Or, oh, heck - radiation terminology can be so complex....

    I also used dye to illustrate how concentration affects absorption in this "from the email bag" posting a year and a half ago. In addition to showing the effect of small concentrations, it illustrates how it is really the absolute amount of dye that is important - not the concentration.

    https://skepticalscience.com/from-email-bag-beer-lambert.html

  41. CO2 is just a trace gas

    I had this idea to pack some extra punch into the "ink" analogy.
    If you use ink to color a candle, you may in fact experimentally verify that a dark colored one melts in the sun, while a lighter one stands firm.

    This may be a fun experiment to educate children, but also to sway doubters that rely solely on "common sense" to form opinions.

    Described in this twitter thread.

     

  42. Charlie_Brown at 01:19 AM on 4 May 2023
    At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Nigelj, Thanks for the question.

    You are almost correct, although I would rephrase "... the (weak) radiant heat source heats the warmer surface".  "Heats" implies raising the temperature of the warmer surface, which would be a violation of the second law.  Since the warmer surface radiates more energy away than it receives from the weak source, the temperature will drop unless there is another source of energy keeping it warm.  Rephrase it to "... the radiant heat source directs (or sends or radiates) energy to the warmer surface."

    Yes, touching surfaces changes the mode of heat transfer from radiant to conduction.  The net heat flow between the two surfaces is from warm to cold in either case, but with conduction there is no flow toward the warmer surface.

  43. At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Charlie Brown

    Your comment @21  "This statement does not say that it is impossible to transfer heat from a cold body to a hot body (Look and Sauer, Thermodynamics, 1982). As stated above in the “At A Glance” description, it is “the net sum of the energy flows will be from hot to cold”."

    Makes sense. This is my understanding as follows as a lay person. Its probably naive. If you shine a weak radiant heat source at a warmer surface than the source then surely the radiant heat source heats the warmer surface? I mean the radiant heat isnt going to bounce off the warmer molecules.  But over time the warm surface will loose its  total energy to a colder surface somewhere so the second law isn't violated. 

    If however you had a warm and colder sufaces physically touching each other so you have conduction, then heat flow would be from warmer to colder.

    Am I right or wrong?

  44. Charlie_Brown at 08:04 AM on 3 May 2023
    At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Clearly countering a highly technical argument using non-technical explanations poses a difficult problem. I don’t think that I am capable of meeting the objective of simplifying this to the level necessary for the non-technical reader. As stated above, the Gerlich & Tscheuschner paper contains many technical errors and distractions. Primarily, they misrepresent the technical basis of the greenhouse effect and then criticize the erroneous description. In particular, they criticize the use of thermal conductivity when thermal conduction has nothing to do with the greenhouse effect. They also spend a lot of time criticizing the radiative explanation. This becomes a problem for non-technical people because they have trouble figuring out which scientist to believe. Interestingly, G&T argue that there are many examples of consensus scientists being wrong, but make no mention that individual contrarians, such are themselves, might be the ones who are wrong.

    The first law of thermodynamics, conservation of energy, is relatively easy to understand. The second law is much more difficult. In its shortest oversimplified form, it says that entropy increases, which doesn’t mean much to most people. It has the Kelvin-Planck and Clausius statements and several corollaries, which are helpful concepts. The Clausius statement is: “No process is possible whose sole result is the removal of heat from a reservoir at one temperature and the absorption of an equal quantity of heat by a reservoir at a higher temperature.” This statement does not say that it is impossible to transfer heat from a cold body to a hot body (Look and Sauer, Thermodynamics, 1982). As stated above in the “At A Glance” description, it is “the net sum of the energy flows will be from hot to cold”.

    G&T oversimplifies the Clausius statement to:
    “– Heat cannot move itself from a cooler body into a warmer one.
    – A heat transfer from a cooler body into a warmer one cannot happen without compensation.”

    G&T continue their argument by addressing and discounting potential criticisms of their paper. They quote climatologist Stefan Rahmstorf, who has it right, then proceed to reject Rahmstorf with some undefined nonsense about the distinction between heat and energy.

    G&T quotes Rahmstorf: “Some ‘sceptics’ state that the greenhouse effect cannot work since (according tothe second law of thermodynamics) no radiative energy can be transferred from a colder body (the atmosphere) to a warmer one (the surface). However, the second law is not violated by the greenhouse effect, of course, since, during the radiative exchange, in both directions the net energy flows from the warmth to the cold.”

    Then G&T counters: “Rahmstorf’s reference to the second law of thermodynamics is plainly wrong. The second law is a statement about heat, not about energy. Furthermore, the author introduces an obscure notion of “net energy flow”. The relevant quantity is the “net heat flow”, which, of course, is the sum of the upward and the downward heat flow within a fixed system, here the atmospheric system. It is inadmissible to apply the second law for the upward and downward heat separately redefining the thermodynamic system on the fly.”

    Unfortunately it is G&T who are plainly wrong, even after very clear and accurate explanations are provided for them.  How can it be resolved  when two scientists are called "plainly wrong" when both should be knowledgeable on the technical issues? 

    Maybe an example would help.  Consider two walls of different temperature facing each other, perhaps as a large radiant heating panel in a room. The net flow of radiant heat will be from the hot wall to the cold wall. All objects above absolute zero radiate energy (heat), so the cold wall must be radiating heat in the direction of the hot wall. Raise the temperature of the cold wall to warm, so now the flow of energy from the warm wall is increased and the net flow of heat is reduced. One can go to the extreme of making the temperatures equal and the net heat flow will be zero, but both walls will be radiating.

  45. One Planet Only Forever at 03:08 AM on 2 May 2023
    Why the food system is the next frontier in climate action

    Evan @6,

    I briefly reviewed the 2014 Research Article you pointed/linked to (note it is almost 10 years old). I would update my previous comments to add that human actions causing increased N2O in the nitrogen cycle are to be considered the same way I refer to impacts on the carbon cycle. And I would add that there are other good reasons for more aggressive reduction of nitrogen cycle impacts than climate change (refer to Planetary Boundaries).

    I will also clarify that reducing methane emissions from rice is still an opportunity for reducing the peak level of ghg impacts even if that methane could be considered to be ‘part of the natural carbon cycle (an action that does not increase the amount of carbon in the carbon cycle the way that burning fossil fuels or leaks of methane from fossil fuel operations or permafrost melting do).

    More specifically, the report’s evaluated floor level of non-CO2 emissions from food production and consumption (Global total 7 GtCO2e/year by 2050 with more if population continues to grow beyond 2050 and also influenced by 'potential changes of attitudes towards being less harmful') appears to be based on the perceived willingness of the UK population, at the time the report was prepared, to learn and be less harmful consumers. And the evaluated UK willingness is extended globally with all people expected to want develop to live in ways comparable to the less harmful ways that the UK population was evaluated to be willing to live.

    The following is a quote from the “Options and barriers to mitigating food system non-CO2 emissions - Agriculture” section of the Research Article:

    “For both N2O and CH4, socioeconomic and environmental circumstances dictate the extent to which changed agricultural technologies and practices can deliver cuts in emissions at a systems level. Stakeholders suggested that important factors influencing uptake of mitigation options affecting the UK revolve around cost, dominant practices, the aging farming community and attitudes of ‘young farmers’, existing infrastructure, cultural norms, changing climate as well as a feedback linked to levels and patterns of consumption.”

    A quote from the “Options and barriers to mitigating food system non-CO2 emissions - Consumption” section of the Research Article:

    “Within the UK consumption-based scenarios, the most significant dietary change considered was a 70% per capita cut in meat consumption, with the deficit replaced with rises in other food types. However, even with changes to per capita meat consumption, absolute emissions levels are driven by population growth (consistent across the scenarios) as well as growth in per capita consumption levels. Population growth per se strongly constrains N2O mitigation, as crops for consumption and for feed for livestock continue to require manure or mineral fertilizer. Barriers to changing patterns of consumption are confirmed through consumer focus group analysis: moderate changes in meat consumption (20% per capita) were considered in line with financial pressures to reduce expenditure given the context of the 2009–2012 recession, whereas a 70% reduction was perceived too substantial a change for many [Citation33].”

    That indicates that the evaluation was (likely unwittingly) biased by accepting questionable opinions like ‘the higher cost of being less harmful is a valid reason to be more harmful’ and ‘the developed popularity of eating more meat is a valid reason to not reduce meat consumption’. Note that I tried to present both of those points in a way that highlights that populist political misleading messaging significantly caused those attitudes to develop to be so influential that they compromise the evaluation and the way it is reported.

    Quote from “Discussion - Implications for cumulative GHG emissions”

    “Finding ways of reliably reducing non-CO2 emissions will become increasingly pressing as global demand for food rises. A wide range of feasible CH4 mitigation options were put forward by stakeholders, taken from the literature and quantitatively assessed during the scenario process, providing evidence for greater scope for achieving substantial CH4 mitigation than for N2O. This, coupled with the much longer lifetime of N2O compared with CH4 as well as the influence of carbon cycle feedbacks in raising the GWP of CH4 from 21 to 34, highlights the critical importance of fully exploiting CH4 mitigation potential whilst increasing the research effort towards developing agricultural systems that can minimize N2O production.”

    That indicates that if the developed research bias is corrected there could be more reduction of N2O resulting in a lower ‘floor level’.

    Quote from “Discussion - Implications for managing and mitigating CO2”

    “The focus here on non-CO2 reinforces other studies that identify the existence of an emissions floor, further emphasizing an urgent need to mitigate CO2 emissions where it is most feasible and quickest to do so. The higher the non-CO2 floor, the more rapidly CO2 emission cuts are needed within the constraints of a chosen climate target. Conversely, relying on a low or non-existent emissions floor suggests a larger CO2 budget is available, again relaxing the rates of mitigation for a chosen climate change target, delivering a more palatable but less realistic assessment of the climate change challenge.”

    This emphasizes that the learning from the report is that more rapid efforts to reduce fossil fuel use are required.

    Quotes from the “Conclusion” of the research article:

    “A continuation of absolute growth in global N2O emissions, despite assuming optimistic mitigation has, because of cumulative emissions, direct implications for how urgently and deeply to cut both CO2 and CH4 for an assumed climate target.”

    This reinforces the need for more research to reduce N2O and the need to more aggressively cut CO2 and CH4 unless new research develops viable ways to rapidly reduce N2O.

    “As energy systems become decarbonized, global non-CO2 emissions largely associated with food consumption and production will increase in the share of annually produced GHGs. Emphasizing the importance of making cuts in food-related emissions highlights an urgent need for policymakers in Annex B nations to consider not only technological and supply-side interventions, but tackle the thorny issue of levels and types of consumption. Unlike large-scale infrastructure developments, measures tackling consumption and demand have the potential to cut emissions of CO2 and non-CO2 alike in the short term and could improve the diminishing chances of remaining within the carbon budget commensurate with the 2ーC threshold.”

    That highlights the need for policymakers to “tackle the thorny issue of levels and types of consumption” because the reports conclusion is that current over-developed populations are not as willing to be less harmful as they should be.

    A quote from the “Future perspectives” part of the research article:

    “If the challenges posed by climate change are to be overcome, at least in part, a meeting of minds to define problems can offer new, much needed insights. This is already emerging in some quarters, with an increase in interest from research funders around the food–water–energy nexus as well as a rise in the number of researchers keen to engage in genuinely interdisciplinary activity. Of course disciplinary research may, out of necessity, continue to dominate, but the emerging expertise in interdisciplinary research needs support and encouragement given the extent of the systemic and complex challenges facing society.

    "The climate change challenge becomes ever more urgent each year, with time limiting the options available for mitigating emissions to be largely those that can deliver change in the short term. Perhaps with agronomists, biologists, engineers, political and social scientists working increasingly in single units, systemic ‘solutions’ to the climate challenge can be found. Specialists in demand and consumption require the same prominence in the portfolio of research endeavour as technologists, physical scientists and engineers. Only then will resilient options be derived and ultimately implemented in a timescale befitting of the scale of change facing society.”

  46. Charlie_Brown at 14:27 PM on 1 May 2023
    At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Eclectic@18:

    Good catch.  The conversion was my mistake.  It should be 15,000 meters (50,000 feet) for the cold layer of the atmosphere between the troposphere and the stratosphere.

  47. At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Charlie #17:

    There you portray the dilemma in an illustrative way. Now go back through it and, critically, add an asterisk after every single word/acronym that, to your knowledge, the typical "consumer" has not meaningfully encountered before.

    The vast majority of folk are slightly to non-curious about global warming until one of its effects comes a-banging on their door. We have to reach them - they ARE the majority here. Deniers and activists are in contrast a small percentage at two ends of a spectrum- although I figure activists are far more populous these days but at the same time some deniers still have a disproportionare noise-allowance. But it's the everything-in-between we have to reach and explain what's happening.

  48. At a glance - The greenhouse effect and the 2nd law of thermodynamics

    Thanks, Charlie_Brown.

    But permit me a grumble or two.   What is this 15,000 meters (25,000 feet) business of equivalence?   One, or two, typos/errors ?

    And 15-micron band broadening . . . is over-technical and of minimal relevance to the basic topic.

  49. Charlie_Brown at 00:16 AM on 1 May 2023
    At a glance - The greenhouse effect and the 2nd law of thermodynamics

    I would like to have a go at this.

    All molecules above absolute zero vibrate and radiate energy. With each bend and stretch, the molecular internal energy state changes, which emits radiant energy. The amount and wavelength of the emitted energy depends on the temperature and the molecular structure. The sun emits energy at about 5,800 degrees Kelvin (6,000 C, 11,000 F) and a small fraction is intercepted by the Earth. Due to the high temperature, very little solar energy is emitted at wavelengths above about 5 microns. The Earth’ surface emits radiant energy at infrared wavelengths above 5 microns based the average surface temperature of about 288 Kelvin (15 C, 59 F). Part of that infrared energy between about 14 and 16 microns (the 15-micron band) is absorbed and re-emitted by CO2 in the atmosphere until it reaches an altitude of about 15,000 meters (25,000 feet) where it is emitted at a temperature of about 217 Kelvin (-56 C, -69 F) toward space, which is at absolute zero. As CO2 increases, the edges of the 15-micron band strengthen and energy loss to space is reduced. Nothing about this radiant energy flow violates the 2nd law of thermodynamics.

  50. Why the food system is the next frontier in climate action

    OPOF#4, I am not any kind of expert on GHG emissions in the food cycle, but from what I've seen and read, there are baseline emissions that are difficult to eliminate, such as methane emissions due to rice cultivation. I've heard and read of 1 ton CO2e/person/year as a reasonable baseline estimate (read the Conclusions here where they refer to an emissions floor).

    nigelj#5, I don't disagree with your statements about the benefits of a vegetarian diet. My friend is a particular case in that he had cancer, and for his specific situation his doctor recommended he give up his vegetarian diet because his body needed animal protein to fight the effects of the cancer he had. So his was a special case, but it still highlights that there is not always a one-size fits all answer.

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