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Comments 2101 to 2150:

2101. John Mason at 00:46 AM on 7 May 2023
      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.

2102. nigelj at 06:43 AM on 6 May 2023
      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.

2103. nigelj at 06:27 AM on 6 May 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      Charlie Brown @23

      Thanks. Makes sense.

2104. Bob Loblaw at 04:14 AM on 6 May 2023
      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.

2105. 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.

2106. Bob Loblaw at 23:59 PM on 5 May 2023
      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..

2107. Bob Loblaw at 23:06 PM on 5 May 2023
      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

2108. jgillis at 17:34 PM on 5 May 2023
      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.

       

2109. 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.

2110. nigelj at 08:53 AM on 3 May 2023
      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?

2111. 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.

2112. 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.”

2113. 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.

2114. John Mason at 09:35 AM on 1 May 2023
      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.

2115. Eclectic at 08:00 AM on 1 May 2023
      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.

2116. 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.

2117. Evan at 20:29 PM on 30 April 2023
      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.

2118. nigelj at 10:39 AM on 30 April 2023
      Why the food system is the next frontier in climate action
      

      Evan @3

      "I know a person who used to be vegetarian, but after having cancer his doctor recommended he start eating meat again."

      This statment  got my attention, having recently read about the cancer risks of high meat diets. Had a look on the internet and this came up:

      "Results from a large-scale analysis show that following a vegetarian or pescatarian (fish-eating) diet could significantly reduce the risk of developing cancer – but even limiting red and processed meat to five meals a week or less may also have a benefit...."

      "Compared with regular meat-eaters, the risk of developing any type of cancer was lower in low meat-eaters (2% less), fish-eaters (10% less), and vegetarians (14% less). This means that the absolute reduction in cancer diagnoses for vegetarians was 13 fewer per 1,000 people over ten years, in comparison to regular meat-eaters."

      www.ndph.ox.ac.uk/news/new-study-finds-lower-risks-of-cancer-for-vegetarians-pescatarians-and-low-meat-eaters#:~:text=Compared%20with%20regular%20meat%2Deaters,vegetarians%20(14%25%20less).

      The study is large, recent and significant.

      Now I'm not vegetarian or promoting vegetarianism per se. A low meat diet, especially a diet low in red meat, sounds sensible and makes for a decent reduction in emisssions. 

2119. One Planet Only Forever at 09:10 AM on 30 April 2023
      Why the food system is the next frontier in climate action
      

      Evan,

      Your question may be questionable.

      The climate change issue is primarily about human actions that are increasing ghgs in the carbon cycle (increasing the balanced state of ghgs in the atmosphere and causing other harms like increased CO2 absorption in oceans).

      That perspective helps identify and understand the differences between the variety of ghg impacts caused by human actions. Most important, it helps understand that some causes of CO2e from human food production and consumption are ‘not the concern’.

      Steady-state production of ghgs from food production and consumption is not the primary concern. That would be a sustainable carbon cycle. Food production and consumption that increases the level of ghgs, especially the use of fossil fuels, is the primary concern. An increasing population that eats less ‘higher impact food like meat or rice’ can actually result in a reduction of the steady-state level of ghgs. In addition to an increasing population having less consumption, the remaining consumption can be changed to be less harmful, like developing meat and rice production that does not cause as much ghg impact.

      Therefore, an answer to the question about the ‘per capita CO2e’ is that, due to the current developed problem of significant excess ghgs, especially CO2, already in the atmosphere, unnecessary CO2e impacts from human activity need to be ended and actions that will reduce the steady-state ghg levels in the atmosphere are required. (The peak level of ghg increase due to the historic, and continuing, lack of interest in seriously restricting harmful and unnecessary actions will undeniably be a harmfully excessive level).

      Also, the required changes of food production and consumption for the collective of human activity to be more sustainable will vary by region. Regions that currently have more people eating less than a ‘diet necessary for healthy living’ can be expected to have increasing impacts. But if such a region also has a significant amount of harmful unnecessary food consumption, due to a significant status gap in that region's society, then that region could, depending on how much harmful consumption is occurring in the region, reduce the total regional level of ghg impacts while the less fortunate in the region increase their impacts.

      PS. The titles of the two study reports linked in the last paragraph you are questioning are informative (the reports are even more informative): “A meta-analysis of projected global food demand and population at risk of hunger for the period 2010–2050” and “Future warming from global food consumption”. However, developed socioeconomic-political biases can bias what is investigated, how it is investigated, and how it is reported. That is likely a significant root cause of the populist political attacks on less biased science that establishes a requirement for significant changes of developed beliefs and actions, especially if it highlights the need for rapid changes of popular and profitable developments. It may also be why I did not see the obvious problem of harmful over-consumption being highlighted.

2120. John Mason at 01:03 AM on 29 April 2023
      EGU2023 - Highlights from the last week of April
      

      Graphs where online attendees have to turn their head on one side in order to read axis captions on their screens....

      Stefan's talk this afternoon, covering "what Exxon knew" was a must-watch. Baerbel will likely have plenty to say about it!.

2121. Bob Loblaw at 00:08 AM on 29 April 2023
      EGU2023 - Highlights from the last week of April
      

      "it's a pity that presentation skills are not taught at final year undergraduate level"

      It's a pity that they aren't taught at the graduate level, too. I saw far too many professors with nearly zero teaching skills during my academic career, and far too many scientists at conferences and meetings with nearly zero presentation skills.

      To your excellent list, add graphs with too many lines, graphs shown and removed before you can even read the axes to find out what is being displayed (and no explanation from the presenter), colours of lines or symbols that are almost indistinguishable.

      ...and modern software that makes animations, lack of contrast, etc. as "features", wher in reality theywork against clarity.

      For web sites, its as if the features epitomized at buduglydesign represent some sort of ideal, rather than something to avoid.

2122. Bob Loblaw at 23:53 PM on 28 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      nigelj @10:

      I'd be curious about the three versions of the 2nd law "violations" that you found. What were the key differences between them?

      I'd agree that the "energy can't flow from cold to hot" is probably the most common.

2123. Bob Loblaw at 23:51 PM on 28 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      I was still in public school when the significance of the term "law" was discussed in science class. The progression of confidence in scientific understanding  used to follow the path from hypothesis (untested) to theory (well-tested) to law (extremely well-tested over a long time).

      But even when I was in public school, it was explained that "law" was a traditional term and science recognized that all understanding is subject to revision as more evidence is gathered.

      We have "laws" of gravity, motion, etc that have been supplanted by the "theory" of relativity, etc. We still talk of "laws" of universal gases, thermodynamics, etc. As John says, use of this terminology is grandfathered in.

      In common use, even "theory" gets misused when a scientist would say "hypothesis". The put-down of "that's just a theory..." should have the caveat "but I'm not a scientist" attached to it.

2124. John Mason at 22:00 PM on 28 April 2023
      EGU2023 - Highlights from the last week of April
      

      My take on Friday so far: Baerbel has already covered sessions where we were both present above.

      I particularly enjoyed CL1.1.4: Deep-time climate change: insights from models and proxies. This session provided a wide-ranging series of palaeoclimate studies looking at various parts of and the whole Earth at key points in the past such as the Permo-Triassic transition, the K-T extinction and the early Cenozoic hyperthermals.

      Some topics were more familiar than others, for example looking at the selective nature of the K-T extinction interval in the oceans: the post-impact 'winter' actually had a positive effect on e.g. siliceous diatom productivity whereas the Deccan Traps large Igneous Province was mostly negative in that instance. Calcareous planktom however suffered greatly. The most though-provoking presentation, "Resilience and implications of an Antarctic monsoon during the Eocene", was something I had not looked at before. It appeasrs there were local ice-sheets even then, but unlike today the continent's periphery supported dense forest.

      It's refreshing to be with so many people to whom the key principles of climate forcings are no longer argued over but instead it's the increaingly minute details of past climates that are under investigation and being presented.

      One word on presentations: it's a pity that presentation skills are not taught at final year undergraduate level. I've seen talks varying from absolutely outstanding to hard-to-follow this week. The cause of the difficulty variably includes talking at breakneck speed about highly complex topics, large blocks of text in slides too long to read for their display-time and using too small a font size to even screengrab effectively. Some, by no means all people need to learn how to communicate findings more clearly (the EGU Guidelines are quite specific in this respect) and in addition, every author had a Supplementary Material folder in which to upload a more detailed file. Attention to such points would have made an aleady enjoyable event even more so!

2125. Evan at 21:38 PM on 28 April 2023
      Why the food system is the next frontier in climate action
      

      OPOF, thanks, as always, for your comments. However you slice it, ag-related emissions are a tough nut to crack. I eat primarily a plant-based diet, but during periods where I physically work hard, I have a difficult time keeping going without adding in a bit more dairy or some meat.

      I know a person who used to be vegetarian, but after having cancer his doctor recommended he start eating meat again.

      No doubt people in developed countries eat excessively and eat more meat and dairy than needed, but from my own experience I also know that the body has minimum requirements that change based on lifestyle (how hard I'm working) and current physical condition (my friend with cancer, or other conditions). No doubt in a world where we are properly feeding everyone, the GHG emissions will go up, just because properly nourishing everyone will require many to eat more and perhaps to eat more foods that are associated with higher GHG emissions.

      So I restate my last question. Do the authors have an estimate for baseline, per-capita GHG emissions (quantified in CO₂e) in a world where we do all the right things to reduce ag-related emissions and where all people are properly nourished, but not over-nourished?

2126. John Mason at 20:43 PM on 28 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      Eclectic #13 - 'principles' would be good but I like your point about an explainer - the only issue in this case is it would lengthen the rebuttal by another paragraph! Will give it some thought once EGU is over (today's the last day).

2127. Eclectic at 19:35 PM on 28 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      Quite so, John Mason ~  but my apologies for poorly conveying my thoughts.   I was not wishing to suggest terms like "Law" or other jargon of a technical or traditional type should be excised from the basic rebuttal . . . but rather that some sort of ultra-brief explanatory warning be used to put the earnest reader on guard against accepting "Laws" of physics (or anything else) as being more than a convenient summary (and nothing more real that that).

      The "Laws of Thermodynamics" can sound impressively authoritative ~ and I think this usage is sometimes purposely intended, to fool the layman into believing that the Denialist's objection to AGW has some validity.

      That said, I don't have a ready phrase or two which would serve.

2128. John Mason at 18:33 PM on 28 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      Ineed, Eclectic! It's like many terms in science, including a lot of mineral names, that are "grandfathered" i.e. they are not considered to systematic or ideal but because they have such frequent use they are regarded as acceptable with caveats.

2129. One Planet Only Forever at 14:14 PM on 28 April 2023
      Why the food system is the next frontier in climate action
      

      Evan,

      I agree that the last paragraph is stated poorly. The answers to your questions may be in the two studies linked to in that paragraph:

      • “50 to 110%” contains per capita and global total values evaluated to 2050. However, a quick scan finds the following within that report: “How do the +60% to +110% figures compare to our findings? We find that under SSP2 (which, like the FAO projections, is regarded as a business-as-usual scenario), total food consumption will increase by 51%, with a 95% confidence interval of +45% to +56%. This is substantially lower than the FAO2 and Tilman et al.1 projections of 60–110%.”
      • “research suggests” has the following in its Abstract: “We find that global food consumption alone could add nearly 1 °C to warming by 2100. Seventy five percent of this warming is driven by foods that are high sources of methane (ruminant meat, dairy and rice). However, over 55% of anticipated warming can be avoided from simultaneous improvements to production practices, the universal adoption of a healthy diet and consumer- and retail-level food waste reductions.”

      So it is not clear how the last paragraph comes to be stated the way it has been stated.

      However, my criticism of the report is that it fails to mention the following fairly obvious realities:

      • Immediate significant reduction of harm done can be achieved by reducing unnecessary consumption. Few people want to discuss that ‘herd of elephants in the room’ because that would reduce perceptions of economic prosperity that are based on all the unnecessary consumption, especially the conspicuous unnecessary consumption displays of higher status – like eating more meat.
      • The current developed socioeconomic results are loaded with harmful unsustainable activities. The system aspires to ‘meet the wishes of the winners of competition for status, power, popularity and profit’ and ignore, dismiss or make excuses for the harmful systemic inequities of the developed ‘starting point’.
      • The obvious best ‘ideal’ action to aspire to is all humans being governed, self-governing preferred, to limit their harmful actions to ‘essential (necessary) needs’ and limit the harmfulness of those essential needs. That means that anything beyond ‘essential needs’ has to ‘ideally’ be strictly limited, again preferably by self-governing, to harmless actions.

      An example of the report being written from the biased perspective of a '(potentially unwitting) promoter of the harmful unsustainable status quo' is the unquestioned inclusion of the following:

      "According to the World Economic Forum, investment in plant-based protein offers the highest heat-trapping pollution savings per dollar of invested capital of any sector but remains significantly under-invested. This burgeoning industry offers a major opportunity for smart policymaking and investing."

      That promotes 'unnecessary' industrial food production, potentially with many other harms 'but the focus is restricted to the climate impact'. Local family cooperatives producing 'natural meat in ways that sequester carbon' combined with diets corrected to consume less meat would be a better solution ... but that would reduce opportunities for investors and diminish their developed perceptions of wealth ... but 'investors pursuing their maximum benefit' are not necessarily beneficial, especially if they employ populist misleading messaging to hide or excuse harm done, especially if they promote positive perceptions that some people can be tempted to hope to obtain from more harm done.

2130. Eclectic at 13:19 PM on 28 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      Part of the communication problem is the word "Law"  ~  a word of great historical & cultural weight (especially among the religious).

      The sight of the word Law  has a mesmerizing effect on non-critical thinkers.   Law seems something forever unquestionable and beyond discussion;  something fixed and eternally true  ~  a divine decree received directly from the Hand of God.   Instead of being just a word meaning a convenient concept in the minds of physicists.   The word is mistaken for the reality.

      Perhaps there could be room for some brief form of words, to deflate the awesomeness  of a "Law" in the discussions about GreenHouse Effect.

2131. nigelj at 13:03 PM on 28 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      John Mason @7

      Thanks. I agree its useful to include general information on thermodynamics in the rebuttal. Make it a teaching session. But I just believe "at a glance" should be something reasonably short, so the full teaching session would be better in the "details" section. Seems obvious to me.

      Just to clarify. My version in ten lines is very much in my own words and structured, expressed  and ordered as I wished. I just used the realclimate resource as background information and a detailed point they made seemed very good. In other ways their account as a bit confusing.

      --------------------

      Bob Loblow @8. 

      I did a quick scan of the internet on the greenhouse effect violating the second law, because my own knowledge was sketchy. I found three versions. The one I mentioned was the most commonly expressed version I came across.

      I agree its a complicated area and does require a lengthy explanation but for me that is better in the "details"section. Or perhaps I'm being a bit OCD about how its organised!

2132. Bob Loblaw at 10:43 AM on 28 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      The tricky part about rebutting a "greenhouse effect violates the 2nd law of thermodynamics" myth is that there are so many possibilities and variations of such a myth. It's kind of like trying to get someone to say what they mean by "saturated" when they start spouting the "CO2 is saturated" myth.

      The specific version on the full rebuttal page is related to a specific statement from Gerhard Gerlich, and arguments made in a paper by Gerlich and Tscheuschner.

      When you hear someone exclaiming "2nd law of thermodynamics!", you really need to find out exactly what they think the 2nd law means before you can point out the errors (although the Gerlich and Tscheuschner flavour is pretty common).

      The 2nd law is a favourite "argument" amongst the Creation Science/Intelligent Design crowd, too - evolution "violates the 2nd law". (The argument is just as wrong there.) Back in the olden days of Usenet (before the Web and blog comments), I remember a Creation Science fan emailing me (Usenet exposed people's email addresses) with a 2nd law argument.

      After several rounds of email pointing out his errors in understanding the 2nd law, he came up with this strange argument of " the flow of information content" that he claimed had a similarity to the 2nd law of thermodynamics, so evolution violated his "2nd law of information content" and that mean it also violated the 2nd law of thermodynamics. Really bizarre stuff. (He never responded to my last email, where I said that calling it "the 2nd law of thermodynamics" was a lie, and why was he lying in the name of the Lord?)

      I've always suspected that the appeal of the "greenhouse effect violates the 2nd law" myth may partly be due to its familiarity as a false argument against evolution. If you believe that evolution is Bad Science, and find the 2nd law argument convincing, it's easy to accept it as an argument against the greenhouse effect when you're already convinced that climate science has it all wrong.

      As John Mason points out, there is no real shortcut to explaining what the 2nd law (and 1st and 3rd) actually means, which makes it more difficult to debunk any (or every) bogus 2nd law argument.

2133. Philippe Chantreau at 03:10 AM on 28 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      I'll take crack at the 3laws of thermodynamics, although I am only quoting:

      1- You have to play

      2- You can't win

      3- You can't break even

2134. Evan at 22:16 PM on 27 April 2023
      Why the food system is the next frontier in climate action
      

      The last paragraph indicates population is expected to grow by 50 to 110% over the coming decades, and yet we can abate 55% or more of anticipated warming. Does the 55% abatement mean 55% abatement of per-capita emissions or 55% of total emissions for a baseline year of something like 2022? IF this is 55% abatement of per-capita emissions, then it would seem that population will grow as fast or faster than we can reduce per-capita emissions, so that the net ag-related emissions will continue to grow. Or am I missing something?

      Do the authors have an estimate for baseline, per-capita GHG emissions (quantified in CO₂e) in a world where we do all the right things to reduce ag-related emissions?

2135. John Mason at 19:52 PM on 27 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      Not bad at all, although a key aim of these mostly short intros is to explain and fully introduce stuff - therefore the need to explain what thermodynamics is. Many folk "out there" do not know what the word means. Some rebuttals are therefore much easier to write in a very short fashion than others.

2136. nigelj at 19:13 PM on 27 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      My quick version of "at a glance" in about ten lines:

      "A climate myth claims that greenhouse gases cannot warm the earth because the flow of energy is from cold greenhouses gases to a warm surface, and this violates the second law of thermodynamics, which states that energy can only flow from hotter to colder objects (unless energy in some form is supplied to reverse the direction of heat flow).

      However the CO2 is not generating heat. It acts like a blanket to slow the transmission of heat energy from the surface and  in the atmosphere to colder space. The energy still transmits from hot to cold, just less heat at a  slower rate, so the second law is not violated. By analogy, if greenhouse gases violated the second law a blanket would not keep you warm."

      (Its based on memory of an explanation on a realclimate.org page. Its rough and needs refining, and I do not claim to have much scientific expertise, but I believe the essentials are there in about ten lines.)

2137. John Mason at 17:34 PM on 27 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      If any of you want to have a go at explaining why the greenhouse effect does not invalidate thermodynmaics #2 in ten lines, including (essential) an introduction to what rule #2 actually says, then feel free to have a crack at it!

2138. nigelj at 07:59 AM on 27 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      I tend to agree with Wilddouglascountry. The at a glance section was quite long. When I see "at a glance" I was hoping for a clear statement in ten lines. If a rebuttal cant be summarised clearly in ten lines, then the rebuttal probably isn't valid. Although clearly AGW and the greenhouse effect doesn't violate any laws of thermodynamics.

2139. Bob Loblaw at 00:39 AM on 27 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      Note: the link to the full rebuttal is also included in the green box at the top of this post...

2140. Bob Loblaw at 00:05 AM on 27 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      Wild (may I call you Wild?):

      This "At a Glance" version is intended to be brief. Although in this page, you only see the "At a Glance" part, the entire SkS rebuttal is available from the last link in the "Click for further details" section. This "At a Glance" has been added to the "Basic" tab in the full rebuttal (which also has an "Intermediate" tab).

      Short link from above:

      https://sks.to/thermo

      ...leads you to the long link of the actual page.

2141. wilddouglascounty at 23:52 PM on 26 April 2023
      At a glance - The greenhouse effect and the 2nd law of thermodynamics
      

      I took a gander at the 2010 TonyWildish original version of this and think that the revision you are offering here is a bit too dumbed down. Wildish and the related comments goes into the details of the dynamics of heat loss a bit more in-depth than your new version, while the new version focuses more on the paper that has been the source of disinformation on this topic, then says it is wrong without discussing enough the important physical details of heat loss/retention that make it wrong. I think the revision needs a bit more of those details; otherwise it's just a "they are wrong" argument without enough "why's" to really get to the heart of their mistakes.

      And by the way, please consider this to be my "form" that you asked feedback to be submitted by, since I didn't. I presume you look at the posted comments as well...

2142. One Planet Only Forever at 12:46 PM on 26 April 2023
      Drastic climate action is the best course for economic growth, new study finds
      

      I am pleased to see more economists are developing a more comprehensive and realistic accounting of the ‘current day costs of being less harmful’ and ‘the future costs of harm done by harmful current day activities’. Economic evaluations of the ‘perceived current benefits obtained from causing increasing future climate harm’ vs. ‘reducing the harm done’ needed to move away from the Nordhaus style of significantly discounting the ‘future harm done’ toward the more ethically sensible Stern style of evaluation which, by using a lower discount rate, is more concerned about harm done to future generations.

      “The Choice of Discount Rate for Climate Change Policy Evaluation” is a 2012 Discussion Paper that comprehensively presents the case for using lower discount rates. Longer term evaluations require lower discount rates, especially if there are harmful future consequences. Quotes from the paper and related points:

      In the Introduction “Using his own DICE model, Nordhaus indicated that the differences between the Stern-endorsed and Nordhaus-supported discount rate accounted for all of the difference between the more aggressive climate policy endorsed by Stern and the considerably more modest effort supported by Nordhaus.” The Stern-endorsed discount rate was 1.4%. The Nordhaus-supported discount rate was 4.3%.

      In 3a. The Social-Welfare -Equivalent Discount Rate “The choice of ‘social welfare discount rate’ is largely, if not entirely, based on ethical considerations: how much future well-being should count relative to current well-being in the social welfare function.” The Stern evaluation used a 0.1% social welfare discount rate. The Nordhaus evaluation used a 3% social welfare discount rate.

      Even the evaluation discussed in this article is from the perspective of a less ethical economic evaluation that is limited to the financial items that are easy to quantify and enter into the ‘economic models’. An example is the statement that “Achieving such rapid decarbonization would require climate policies commensurate with a global carbon price of about $250 per ton of carbon dioxide today but declining to below $40 per ton in 2100 as the prices for clean technology come down.” There is no ethical reason for high carbon prices to be reduced in the future. The ethical requirement is for the harmful impacts to be ended, not to have them continue to be in the competition for popularity and profit in an ‘economically fair way’. (Note: even the 2012 paper I linked to above is 'ethically neutral' even though it presents the case for using lower discount rates which is more aligned with ethical considerations).

      It is simply unethical for ‘Some people’ to benefit from causing harm that ‘others’ experience and have to try to deal with and repair. A continuously increasing price on carbon is one of the many mechanisms that need to be imposed to achieve the required correction of harmful developed activity, especially the correction of developed popularity and profitability of harmful over-consumption. And a Zero discount rate, and potentially a negative discount rate (increasing the evaluated cost of future harm being created), is probably more appropriate.

2143. Bob Loblaw at 11:25 AM on 26 April 2023
      2nd law of thermodynamics contradicts greenhouse theory
      

      Gootmud:

      Discussions of extreme events are probably better placed on this thread (after reading the original post):

      https://skepticalscience.com/extreme-weather-global-warming.htm

2144. Rob Honeycutt at 04:12 AM on 26 April 2023
      2nd law of thermodynamics contradicts greenhouse theory
      

      Gootmud @1522... There is an entire body of research related to precisely this topic known as attribution research. Your lack familiarity of the science shouldn't lead to the conclusion that "we can't explain causally." On the contrary, the overall causality of the shift in distribution is extremely well-known. The only place uncertainties appear are the chances that any given indivual weather event is driven by human causation. But even there, attribution research is demonstrating increasingly how much more likely these are to be primarily a result of the rise of CO2 concentrations in the atmosphere.

2145. John Mason at 03:45 AM on 26 April 2023
      2nd law of thermodynamics contradicts greenhouse theory
      

      Gootmud @ 1522,

      Hot weather tends to be associated with a high pressure system situated in a position to a) allow maximum insolation and b) to permit warm air advection. That's not "some random process". With global warming, in the synoptic situation I describe, it can be expected to be a bit hotter again. This should not be too difficult to visualise.

2146. Bob Loblaw at 01:38 AM on 26 April 2023
      2nd law of thermodynamics contradicts greenhouse theory
      

      Also note that this conversation is getting of the proper topic, which is the 2nd Law myth.

2147. Bob Loblaw at 01:36 AM on 26 April 2023
      2nd law of thermodynamics contradicts greenhouse theory
      

      Gootmud @ 1522:

      The diagram and explanation provide does not at all mean "some random process we can't explain causally". We can explain variation about the mean. It's called weather.

      If you think that every single normally-distributed measurement is a purely random process, you need to think again.

2148. Gootmud at 01:15 AM on 26 April 2023
      2nd law of thermodynamics contradicts greenhouse theory
      

      Rob @1520...that looks like "climate does weird things" presented as a graph. It suggests heat waves are the result of some random process that we can't explain causally.  We can only talk about the distribution, and we expect that as the mean shifts the tails will shift along with it. That contradicts the idea of attribution.

2149. Bob Loblaw at 01:10 AM on 26 April 2023
      2nd law of thermodynamics contradicts greenhouse theory
      

      Gootmud @1518:

      The 2C rise does not cause the 20C heat spike, it turns an 18C heat spike into a 20C heat spike. Rob's diagram @1520 shows this shift in the overall distribution.

      Rob's diagram also assumes that the spread around the mean remains constant. This may or may not be the case, and may vary locally. Another plausible scenario is that a location used to go +/-16C from it's mean, and now it goes +/-18C around its new mean that is +2C, so +20C (from the old mean) is the result of a 2C shift in the mean, and a +/-2C expansion around the mean. The +20C spike compares to a system that only saw +16C in the past.

2150. Rob Honeycutt at 00:52 AM on 26 April 2023
      2nd law of thermodynamics contradicts greenhouse theory
      

      And here is a simple graphic explaining it as well.

      

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