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Comments 6151 to 6200:

6151. michael sweet at 16:18 PM on 13 February 2021
      2009-2010 winter saw record cold spells
      

      John Hartz,

      Reading your link and then searching a while online I see reports that the cold spell you report is the coldest in Europe in the last 10 years.  I found a report that one country set a cold record in a different cold spell in the middle of January.

      Going to the National Climate Data Center (USA national) they have a record temperatures page.  Settting the page on global records (they do not have a European only page) I see in the last week there were 837 cold records and only 273 daily high records.  In the harder to achieve monthly records there were only 12 low records in the past 7 days with only 2 high records.  There was only 1 all time cold record globally in the last 7 days and no hot records. 

      Trying to measure a longer time in the past year there were 50,000 daily cold records and 109,000 hot records, hardly an ending of global warming.  For monthly records there were 2100 cold records and 7,000 hot records.  For all time records there were 32 cold records and 487 all time hot records.

      In Europe last week it was cold compared to the past 10 years of hot weather.  It was normal weather for 100 years ago.  The denialists can only remember the past ten years so they think it is cold when it is really not.  In addition, they often say record snow means it is cold.  Record snow is not the same as record cold.  Science predicts that in a warming world there is more precipitation.  In cold areas that means more snow.

      By contrast, the Summer in Winter in the USA and Canada (in March 2012) produced thousands of daily records and hundreds of all time records.  In some locations the low temperature at night was higher than any previously recorded high temperatures!

      Of course, regular readers of SkS are already aware of this.  The NCDC records page is a good location to counter this denier myth.

6152. MA Rodger at 08:39 AM on 13 February 2021
      CO2 lags temperature
      

      brneilsen @629,
      I'm curious as to the origin of your 'greenhouse gas response' equation T=3.2563ln(C)-3.0323. And if there were any merit in such an equation, I'd be interested to learn how it 'yields' a "0.95 degC" boost to global ice age temperatures resulting from a 190ppm to 280ppm rise in CO2. My abacus (which I would be the first to admit is not always reliable) 'yields' +1.26ºC using this bizarre equation.

      The usual calculation of CO2 forcing is ΔF = 5.35 x ln(CO2_[1]/CO2_[0]) which gives a forcing of +2.07Wm^-2 and a thus 'direct' impact on global temperature of+0.56ºC which would cause climate feedbacks that would perhaps triple this value to +1.7ºC.
      The global average temperature rise out of an ice age is usually reckoned at +5ºC to +6ºC so this calculated CO2 forcing would perhaps be responsible for a third of this temperature rise. And this result fits with assessments which find the contributions to deglaciation warming to be roughly 50% surface albedo, 37% GHGs (of which CO2 is the major player) and 13% atmospheric albedo.

6153. MA Rodger at 08:29 AM on 13 February 2021
      Increasing CO2 has little to no effect
      

      devcarr @427,
      You ask about the altitude of the planet's IR emissions out into space, this ERL as you term it. The physical altitude is dependent on wavelength so there is no single altitude.

      The graph below shows contours of absolute temperature and when these emission altitudes are within the troposphere, the altitude can be inferred from these temperatures. The big 'bite' out of the emissions spectrum at 666 Wavenumber is due to CO2, the smaller one at 1050 Wavenumber is ozone. Note the small central spike within each of these 'bites'. These are caused by the emissions altitude of the central region of these wave bands being so high that they are up in the stratosphere where the temperature starts to rise again. Thus the spike yields a higher emissions temperature than the rest of the 'bite'.
      Being up in the stratosphere means that as the central spike expands with additional CO2, this specific region of the affected wave band will act to cool the planet while other parts of the 'bite' expand to warm the planet. The net effect remains a warming one.

      

      Significant change in CO2 concentration in the atmosphere will impact the shape of the 'bite' at 666 Wavenumber markedly, as well as kicking off other 'bites' (or perhaps 'nibbles') close to the ozone 'bite'. This is described in Zhong & Haig (2013) 'The greenhouse efect and carbon dioxide'.

6154. John Hartz at 06:00 AM on 13 February 2021
      2009-2010 winter saw record cold spells
      

      Here we go again!

      Climate deniers are using a spell of unusually cold weather in Europe to incorrectly argue that CO2 emissions are not warming the planet.

      How global warming can cause Europe's harsh winter weather by Jeannette Cwienk, Environment, Deutsche Welle (DW), Feb 11, 2021

6155. MA Rodger at 21:27 PM on 12 February 2021
      Increasing CO2 has little to no effect
      

      devcarr @427,
      I assume your surprise at the graphic @425Response showing the AGW temperature rise halting as soon as emissions stop because your questioning didn't expect the residual warming-yet-to-come to be pretty-much balanced by the reduction in climate forcing. Following the end of emissions, the GHGs are no longer being boosted by those emissions but instead falls as GHGs are naturally drawn out of the atmosphere.

      Perhaps your expected a response to your question @425 to be for the time for warming to end and equilibrium to be reached for a constant level of GHGs. This is of course a different question.

      The radiative imbalance is running at something like 1 Wm^-2 and if that were allowed to play out by keeping GHG levels constant, it would take a century or more before equilibrium is effectively achieved, with ECS=+3.0ºC suggesting an additional +0.8ºC. The time for this is uncertain as it is the longer-term processes that are poorly quantified when the ECS is assessed, and the value of ECS is famously poorly bounded.

      

      The left-hand graphic here is Fig 4a from Hansen et al (2011) 'Earth’s energy imbalance and implications'. It shows a large part of the warming-to-come appearing in the first decade and that followed by a further large part in the following century. The big uncertainty is in the longer-term warming and this is the major cause of ECS being so poorly defined. And that long-term warming is not entirely a thermodynamic thing. Major longer term warming due in albedo can be caused by a minor and quite insignificant temperature imbalance acting over a long period. So any such long-term warming will result from the warming-already-achieved (+1.0ºC) as well as warming-to-come (+0.8ºC). And so if climate forcing were maintained, this longer term could then become quite significant.

6156. michael sweet at 19:30 PM on 12 February 2021
      Increasing CO2 has little to no effect
      

      Devcarr:

      The emission altitude varies with the wavelength of IR light that you examine.  Some IR is emitted from the surface while other wavelengths are emitted from 15 kilometers up.  The average emission altitude is about 10,000 meters which is near the average height of the troposphere.  The top of the troposphere also varies in height.

      The temperature in the troposphere varies according to the lapse rate.  The lapse rate is about 6C per kilometer (this also varies).  Temperatures have increased about 1.2C.   !.2 devided by 6 is .2 km or about 200 meters.  That is a very rough estimate.  I was very surprised when I first learned that the increase in the emission altitude is so small.  (the change is slightly different for different wavelengths of IR light).

6157. brnielsen at 14:33 PM on 12 February 2021
      CO2 lags temperature
      

      typo corrections: Milankovitch; interesting

6158. brnielsen at 14:26 PM on 12 February 2021
      CO2 lags temperature
      

      This has been interetsing, and explains a lot about the confusion in the general public because of prior missives that CO2-Ice core data were proof of a causive link, when it was more likely a result. NASA covers this in the section on Milankovich theory, but fail to actually split the response from CO2, which is easy to do, since the greenhouse gas response is easily modelled with the equation T=3.2563ln(C)-3.0323, where T is the Earth's average temperature in degC and C is the CO2 concentration in ppm. From the ice cores, the change from 190 to 280ppm yields a contribution of 0.95 degC, so minor compared to the overall change of 7-8 degrees.

6159. devcarr at 09:59 AM on 12 February 2021
      Increasing CO2 has little to no effect
      

      Thanks. I see it is also called the Effective Radiating Level (ERL). But I can't find information on how much is has increased in altitude.

      I am surprised by the graph showing that temperature rise stops almost immediately when emissions stop. I would think temperature would rise until the Effective Radiating Temperature, at the ERL, caused enough outgoing radiation to balance the incoming radiation from the sun. Does that happen so quickly that it can be ignored?

      Is the ERL very close to the top of the troposphere, below it, or above it?

6160. Rob Honeycutt at 09:36 AM on 12 February 2021
      Increasing CO2 has little to no effect
      

      devcarr @424... I believe that's referred to as emission altitude or effective emission height.

6161. devcarr at 02:07 AM on 12 February 2021
      Increasing CO2 has little to no effect
      

      If we stopped emitting CO2, methane, and nitrous oxide tomorrow, how much would the average surface temperature rise before we reached equilibrium?

      Moderator Response:

      [DB]  Figure 3.9 (page 99) shows the persistence of elevated temperatures after emissions cease:

      "regardless of when emissions cease, GMST remains approximately constant for the subsequent millennium"

      
      
      

      That's based on:

      Gillett et al 2011 - Ongoing climate change following a complete cessation of carbon dioxide emissions

6162. devcarr at 01:46 AM on 12 February 2021
      Increasing CO2 has little to no effect
      

      What is the term for the layer near the top of the troposphere, where most infrared actually radiates away from the earth, because the air above has too few GHG to stop it? Is it just called the top of the troposphere? How much has that radiative layer gained in altitude since the start of the industrial revolution? As I understand it, that is the "extra blanket" that has forced warming of the earth.

6163. Bob Loblaw at 12:39 PM on 10 February 2021
      2021 SkS Weekly Climate Change & Global Warming Digest #6
      

      Xulonn:

      While I can appreciate your point that this use of "natural" has a long history, I think part of the idea of changing the term likely comes from the common "skeptical" argument that humans are not affecting climate because the changes are "natural" - i.e., calling it "natural" suddenly takes humans out of the equation.

      If you look at the Arguments list here at Skeptical Science (View all Arguments, in the sidebar near the bottom of the thermometer, or with this link: https://skepticalscience.com/argument.php), the word "natural shows up there a lot.

6164. Xulonn at 06:32 AM on 9 February 2021
      2021 SkS Weekly Climate Change & Global Warming Digest #6
      

      Certainly the motive for such a change in language is laudable, but the above proposal to rename "natural disasters" just doesn't resonate with me, an old guy with a degree in conservation of natural resources from a major university. 

      I prefer the use of pronouns than to try to artificially revise language using artificial "new-speak".

      The below general definition for "natural disaster" as used in the scientific community remains valid in my world.  One must also realize that "disaster" part of the phrase is related to the has nothing to do with the state of physical earth processes without humans, but only the fact that humans (or perhaps other species) are impacted makes it a "disaster":   

      Natural disasters are catastrophic events with atmospheric, geological, and hydrological origins (e.g., droughts, earthquakes, floods, hurricanes, tornados, wildfires, landslides) that can cause fatalities, property damage and social environmental disruption).

      Of course, some "natural disasters" have been caused by - or made worse for humans - for centuries, long before AGW/CC.  Consider dam failures, landslides, and wildfires caused by arson or accident, and they are still called natural disasters. 

6165. MA Rodger at 01:49 AM on 9 February 2021
      Increasing CO2 has little to no effect
      

      Here are the visualisations of 0.041% CO2 and the effect of molecules being so very small.

      VISUALISATION 1

      Although CO2 is only 0.041% of the atmosphere by volume, because air molecules are so very small, there is zero chance of a photon exiting from the surface into space without encountering a CO2 molecule; indeed many many CO2 molecules. This is simply because molecules are so small.

      Imagine if this were not so. Imagine if molecules were 12km in diameter and the atmosphere as a result a sheet of air just one molecule thick. Crazy but imagine.

      Only one part in 410 million of the world's surface would then have a giant CO2 molecule hanging over it. That is one part in 2,439. Thus from 99.959% of the planet, IR on a journey straight out to space would never encounter a CO2 molecule.

      But molecules aren't that big. For one thing, they are not arrayed shoulder-to-shoulder but have a bit of room to whizz about, and spin and vibrate. To scale*, a CO2 molecule relative to the volume of atmosphere it occupies would be roughly 1km in diameter we gave it 12km of room to sit in. And if we now allow for the empty space round our CO2 molecules, the chances of free passage straight out into space is 187-times more likely*. So we can say for a single-molecule-sheet atmosphere, the likelihood of free passage is 99.9997807%. and the chances of hitting CO2 is just 1-in-456,000.

      But molecules aren't 1km in diameter. So let's make them a bit smaller, say 1m in diameter. In a 12km-deep atmosphere, the chance of a free passage without hitting a CO2 molecule in one of the thousand layers of molecules sitting in their 12m square cubes above you is now 0.999997807^1000. So the chance of hitting CO2 is 1-in-3.

      The chance of a free passage is becoming less certain for an IR photon.

      But molecules aren't 1m big. And the smaller they get, the chances of a free passage shrink. With 1dm molecules, the chance of a free passage becomes less likely than not, 60-to-1 against. At 1cm, 645 quintillions-to-one against. The odds of free passage disappear as the size is reduced, at 1mm 1.25 x 10^187-to-1 against and quickly becoming so large that calculators cannot cope with such large numbers. And a CO2 molecule is actually 3 million times smaller than 1mm.

      I shoulkd add that while it is true that not all CO2 molecules will be in a state to absorb an appropriate IR photon, the odds are so great, that is not very significant.

      (*The usual number given for the size of a CO2 molecule is 0.33 nanometres diameter. From avogadro's number we can put the number of atmospheric molecules at 10^44 while our visualisation has an atmospheric volume of 510e12 x 12000 = 6e18 sq m. That would put each air molecule in a cube 4 nanometres wide. The box size is 12-times the diameter of a CO2 molecule. Within the projected box area of 16 sq nm, a CO2 molecule would project an area of 0.085 sq nm or one in 187 of the box projected area.)

      VISUALISATION 2
      There is today 3.2 trillion tons of CO2 in the atmosphere. The area of the earth is 510 million sq km or 510 trillion sq m so there is [3.2/510 =] 0.0063 tons CO2 above each square metre of the planet. The s.g. of dry ice is 1.7 so the volume of that 0.0063 tons CO2 in solid form with all the molecules stacked together is [0.0063/1.7 =] 0.0037 cu m. If you therefore spread this CO2 evenly over that square metre of planet Earth, you would get a sheet 3.7mm thick. And because there are [6e23 x 1 e6 / 44 =] 1.36e28 CO2 molecules per ton, the 3.7mm sheet will be 10.5 million molecules thick. (That puts the size of a CO2 molecule at 0.35nm.)

      Of course, in the real atmosphere, the CO2 is spread out up into the stratosphere but an escaping IR photon on a straight-up journey will still have to negotiate 10.5 million CO2 molecules for a clean escape. In the real world, a very large proportion will not impede an individual IR photon so the path length of an IR photon is greatly underestimated by this visualisation. But it does demonstrate that the 0.041% concentration does not in any way prevent CO2 acting as a very powerful GHG.

6166. MA Rodger at 01:38 AM on 9 February 2021
      Increasing CO2 has little to no effect
      

      Rob Honeycutt @421,

      I don't know of anybody attempting a model of Earthly climate without GHGs, with the exception of Lacis et al (2010) which modelled the cooling from present conditions up to the point when the ice-formation reached the ocean bed, that 50 years into the run. Their model still shows 10% of present atmospheric water vapour by that time.

      Regarding a role for water vapour, my own thoughts turn to our recent ice ages and how a cold planet moves water poleward to form very large polar ice caps. These would be larger still without GHGs. And without interglacials to melt them, the ice caps would presumably become in-the-main part of geology. Outside the tropics I'd assume there would be nowhere with noon-day temperatures capable of forming liquid water. And if it entered the atmosphere from there, any water (or indeed sublimed ice) would tend to be carried poleward.

      What the climate would be like with no GHGs, with atmospheric circulations no longer driven by high-altitude energy loss to space but solely by the larger surface temperature gradients? I think there are too many unknowns to speculate intelligently.

6167. Bob Loblaw at 00:08 AM on 9 February 2021
      Why does land warm up faster than the oceans?
      

      AerosGreen:

      Regarding ocean temperature gradients, I think you are missing the aspect that ocean circualtion at depth is also driven by salinity differnces (which cause density differnces)

      On an annual basis, land temperature cycles only influence the top 10m or so. The ocean mixed layer depth (mixed by surface winds - ie.. interacting more closely with the atmosphere) is more like 60-100m. So increased heat capacity plus much more volume.

      TIme constant for the mixed ocean layer is decades.

      For deeper oceans, we're talking hundreds of years for circulation patterns to run their course - so adjustment to surface changes is very slow.

6168. AerosGreen at 14:08 PM on 8 February 2021
      Why does land warm up faster than the oceans?
      

      Still confused about the answer above under "Warming Contrast". Specifically, "we would expect the contrast to disappear at equilibrium once the oceans have had sufficient time to warm up". Sounds like a statement made by a scientist that doesn't understand oceans.

      Change in temperature is a function of the amount of heat added (heat added over water is a bit less than the amount of heat added over land but we can ignore that for now) divided by the specific heat of the material (let's say that the ocean c is four times that of land) and mass of the material (the last one is a big clue).

      Land and oceans have opposite thermal profiles with depth and the mass of water is literally in a constant state of motion and mix.

      o Land has an internal heater so it warms with depth (about 3C per 100m). So the heat gained at the surface is primarily lost only to the atmosphere (at a rate propotional to the thermal gradiant).

      o Oceans cool with depth (nearly 1C per 100m for the first 1000m). And sea surface temperatures mix with other thermoclines via a variety of processes. So temperature is lost to both the atmosphere, which is on average always colder, and to deeper depths, which is also always colder. And once again, at rates that are propotional to their thermal gradients.

      If a model did show the contrast disappearing, wouldn't that be proof positive that the model is wrong?

      The statement going through the section on Heat Capacity was great. Add ocean turbulence (relatively rare on land) and I'm guessing those are the major factors.

      Think of it this way. Land is a sheet of aluminum foil laying next to your pond.

      How far off am I?  

6169. nigelj at 06:02 AM on 8 February 2021
      2021 SkS Weekly Climate Change & Global Warming News Roundup #6
      

      There is strong evidence climate change is an existential threat to various plant and animal species with up to 50% of species under threat, according to a David Attenborough documentary I was watching last night. Past mass extinction events are strongly associated with climate change. Its not clear to me why climate change would literally lead to extinction of the human race, even in tropical regions. Im not aware of any published science saying this. It is clear it could lead to sharply increased mortality with plenty of studies suggesting this. It is clear it could cause collapse of modern civilisation, but that is not extinction.

      The trouble is by just saying "existential threat" or "extinction level event" this is rather general and vague, and  young people might assume it means the human race. No wonder they get anxious. Children need to be told a more accurate and nuanced picture.

6170. Rob Honeycutt at 04:15 AM on 8 February 2021
      Increasing CO2 has little to no effect
      

      MA Rogers... Thanks for that further clarification. One thing that I always wonder is, what would the temperature structure of the planet be without GHG's? Setting aside the fact that we'd have a snowball earth, what would a pure nitrogen-oxygen atmosphere do? There would certainly be some conduction from the surface and convection off of that.  I have a hard time working out the results. I'm sure someone has modeled this. I've just never heard what the results were. Perhaps understanding this would help people to better understand why trace gases have such an important effect.

6171. MA Rodger at 00:46 AM on 8 February 2021
      Increasing CO2 has little to no effect
      

      Rob Honeycutt @418,
      I don't think it is entirely correct to say the 0.041% CO2 warms up the rest of the atmosphere. It is the result of the GH-effect that provides the warming and that encompasses far more than the IR absorbed by CO2. As well as absorbing IR, the CO2 also emits IR. And as only GHGs do this, the prospect of an atmosphere with GHGs absent takes a bit of mental grappling.

      But if there is CO2, within the 15 microns wave band.....
      I would describe the CO2 as providing two things. First a fog that prevents the 15 micron wave band of IR from travelling very far, this by absorbing the IR. Imagine a candle in a thick fog. A few metres away and there is no sign of it. The thicker the CO2 fog the shorter the distance.
      But there is the flip-side of this fog. The CO2 fog, as well as absorbing IR is also glowing, emitting IR. And because it is the fog itself that is glowing, the intensity of the glow is dependent on the temperature and not on the CO2 concentration. In the atmosphere, the lapse rate will thus give maximum glow close to the surface with the glow diminishing with altitude. The surface itself acts pretty-much as a mirror, reflecting back the 15 micron glow except being on average a little warmer than the surface air, it will glow a bit brighter.
      The diminishing brightness with altitude will also mean a net flow of upward energy and when the quantity of CO2 above gets so thin to allow the IR to shoot off into space, the downward flux starts to faulter and that causes an evolution of the net upward energy flux, creating the one out into space which is dependent on the temperature of the atmosphere at that altitude emitting into space.

      The effective size of a 0.041% CO2 concentration may also be worth a few words because, as Scaddenp @419 says, Avogadro's number is impressively large and that does make a bit of a nonsense of the “But it's only 0.041%!!” argument. I have (more correctly “had”) a couple of visualisations which hopefully shows how Avogadro's number makes a nonsense of such an argument and they might be worth setting out here for the thread.

6172. Rob Honeycutt at 08:17 AM on 7 February 2021
      Veganism is the best way to reduce carbon emissions
      

      Sorry, Klemet, but the link you provided doesn't address the question I asked, and specifically doesn't address any IPCC statement to the same effect. I found the FAO statement regarding 14.5%, though.

      One of my problems with all this is that the high end calculation for animal agriculture are assuming full supply chain. A large portion of those emissions are going to be surface/air transportation, buildings, and other industrial processes which are separated out in other GHG sector analyses, and are genuinely a different topic. 

      The other issue I have is that, you still have to replace the nutritional value of whatever is removed from that provided by animal agriculture. 

      In discussions of this topic I always have to point out that I've been a vegetarian for, now, 40 years. While I don't disagree that consuming less meat is more healthy and better for the environment, I do get annoyed when the science on this topic gets misused.

6173. Guilhem_S at 06:15 AM on 7 February 2021
      Veganism is the best way to reduce carbon emissions
      

      Thanks @Klemet I'm indeed not saying that global veganism is the single best way to achieve climate goal, or that everyone should go vegan before anything else. As previously stated I'm just saying that this whole article is in inadequacy with current scientific litterature on the subject, which might jeopardize the credibility of your website to anyone knowing a little on the subject
      
      I made a very complete commentary adressing specific points on your article and correcting them or rebutting them, I'm surprised not to have an answer for any of the specific things I've mentionned. I cannot waste more time chasing a goal post you're constantly moving. I've made a detailled comment about everything's that's wrong in your article and because you've made the pro-truth pledge I expected somehow to have a substantive debate about those point. If you don't want to pin point to  what we agree on and what you disagree with in my comment responding to the article, I don't know what's the point of submitting such a comment in the first place.
      
      I have provided you with many reference, a whole bibliography on the subject is here for you to dig on the subject in support of the point I'm only making because science says so.

6174. Klemet at 05:29 AM on 7 February 2021
      Veganism is the best way to reduce carbon emissions
      

      Lots of interesting stuff written here. I’ll try to join it :

      @Rob Honeycutt : If I remember correctly, the IPCC base their figures and tables in their Special Report on Climate Change and Land (Chapter 5 : Food Security) on the numbers derived from the FAO and over studies like the one of Poore and Nemecek (2018) in Science. Latest FAO numbers I’ve seen puts animal agriculture as responsible for 14.5% of GHGs emissions, so I’d say that Guilhem is in the right there. I might be wrong, though.

      @Eclectic : I agree with what you say, except that I don’t think that Guilhem wrote that making the vegan diet mainstream will be enough to save the world, or that’s it’s even the our best option. From what I read, Guilhem wrote that this article doesn’t sound on point with current science, and even kind of “strawman-ish” on some aspects, which I agree with. Plus, concerning the idea of achieving a worldwilde vegan of vegetarian diet, what evidence do we have that it is such a crazy idea ? Indeed, surveys seem to show that between 2014 and 2017, the number of vegans rose by 600% in the US, reaching almost 20 million people; and that’s not considering the fact that environmental considerations is only one argument for veganism, and often not the most compelling for people from what I’ve read.

      But I think that we might be missing the point here, which is that this article might need some revision. I completly agree with its premice (i.e. veganism is not the best option to reduce GHGs emissions at the individual levels), but some of the things written seem very odd or downright wrong, as Guilhem pointed out.

      • Concerning people’s willigness to change their diet (section 2), I don’t think that the fact that people are currently willing or unwilling to give up on animal products like meat and dairy does not refute the argument that this could be the #1 option to reduce individual carbon emissions (i.e. the subject of the article and PETA's quote). And while data exist on people unwilingness to go vegan, I deem it important to complete it with recent demographic data on veganism to get the complexity of the question, as it reveals veganism as one of the biggest trends in western societies.
      • Concerning increased waste in vegan diets (section 3), it is something that I have never seen so far in the main reviews that we have today, such as the one from Poore and Nemecek who does talk about waste. Does this argument hold if we take into account the quantities that are produced (e.g. if less meat and dairy is produced and bought than fruit and vegetables, isn’t it normal that less waste is associated with them) ? What of taking into account the fact that a great quantity of food resources (mainly cereals) are produced to feed livestock, which could associate their waste with meat and dairy ? What proof do we have that a switch to a vegan diet would increase the consumption of fruits and vegetables (as dairy and meat are often replaced by vegans with proteins sources such as soy products) ?
      • Concerning GHGs emissions due to transportation (section 3), everything I’ve read on this subject says that transportation is really not the main issue when talking about GHGs emissions. As summarized by the I4CE, or stated in Weber and Matthews (2008) (for the USA), Whyne and Nicholas (2017) (for comparison between plant-based diet and “local” diet), or Sandström et al. (2018) (for Europe), transportation is but a very small part (around 10% on average) of GHGs emissions for food products, and meat and dairy are always the foods associated with the biggest GHGs emissions. Knowing that, why focusing on tropical food exclusively, like is done in the paragraph (omitting the fact that it could be a very interesting option for people in the tropics themselves) ? And what of the impact of food for livestock that is grown in other countries, such as the soy often produced in brazil to feed cattle in europe or the USA ? Also, why focusing on food transported by plane when it seems to represent only a very small percentage of the food we produce, as Guilhem pointed out ?
      • Concerning the capacity to shift management practices of livestock to reduce GHGs emission, I don’t think that there currently is credible evidence of strategies of extensive management that can make animal produces much better for GHGs emissions. In fact, there are studies that seem to show that extensive management could be even worse, as hinted in Clark and Tilman (2017) or Hayek and Garret (2018). That said, how does one article (the one by Zomer from 2017 that is quoted) equals to enough evidence enough for what is proposed here, when current litterature suggest overwise ? Especially when recent research seem to temper the expectation of possible offtest of animal agriculture by soil sequestration, as with the article of Godde et al. (2020) that indicates that “any sequestration is time-limited, reversible, and at a global level outweighed by emissions from grazing systems”. The Food Climate Research Network also has a nice report on the issue, that synthetize most of what has be researched to date on the issue.
      • As Guilhem pointed out, the focus on the article of Kim et al. (2019) in section 4 seems a bit strange. The paragraph implies that a flexitarian diet is better than a vegetarian (not vegan) diet. But the article clearly states that a full vegan diet is the best in 97% of the countries studied; even better that the flexitarian diet that is mentionned. Why not mentionning this fact ? Why suddendly switching the focus on a vegetarian diet in a post talking about vegan diets, when the article that is quoted does talk about vegan diets ? And why not mentionning the majority of the recent litterature that do indicate a vegan diet as the best diet to reduce GHGs emissions, such as Poore and Nemceck (2018), the Lancet EAT study, or even the chapter 5 of the report of the IPCC “Climate change and land” ? It’s just so weird to me; but maybe I’m missing something. I don’t think that Dana (the author) is the type of person to do misinformation, so I’ll do my best to keep my mind open on that.

      So in the end, I'd suggest the following revisions :

      • To delete section 2 (“Are people willing to change their diets for the environment?”) , or to add it as an afterthought rather than a main argument; but I think that more data should be added to it to present the problem more globally.
      • To delete section 3 (“Problems with the vegan diet”), or to precise aspects concerning waste and add some more evidence-based environmental problems with the vegan diet.
      • To delete section 4 (“Vegan vs. Vegetarian vs. meat diets”), or to improve references to Kim et al. (2019) and add references to recent meta-analysis and reviews on the subject.
      • To make the article simpler and shorter, focusing on the ideas develloped by Wynes and Nicholas (2017), which I think are much more easy to understand and justify : veganism is not the best way to reduce our GHGs emissions simply because options like not having a child or ditching planes are more effective. However, while doing so, I think that credit should be given to vegan diets that it can have some other good effects on the environment than GHGs emission reduction (as stated in Poore and Nemececk 2018), as is done in section 5. The idea could be that instead of saying how "bad" a vegan diet can be as the article does right now (which I think is hard to argue with the current litterature), it would be easier to justify how good the other options are (having less children, not taking the plane, etc.). I think that this would keep the original intent, why not sounding like a hit-piece on the movie Cowspiracy (which I do not endorse).
6175. scaddenp at 08:30 AM on 5 February 2021
      Increasing CO2 has little to no effect
      

      4% seems like a small no. but easy to forget that Avogadro's number is very large - there are a lot of molecules. Beside the sheer no. of photos per meter square per second, the other intuition to help guide understanding is how far on average will a photon travel on average before encountering a molecule of CO2. I suspect people that think 4% is a small no. will imagine that it easy for a photon to escape whereas the mean path length is more like a few meters.

6176. Rob Honeycutt at 08:01 AM on 5 February 2021
      A Climate Bet Impossible to Lose
      

      Bob... I actually made that graph for Stephen Lewandowski for use on twitter. I guess Gavin picked it up from there.

6177. Bob Loblaw at 07:25 AM on 5 February 2021
      A Climate Bet Impossible to Lose
      

      RealClimate has a new post up about a number of climate bets of this sort. They have a graph very similar to Rob's first graph above, and link back to this post as one of the bets.

      http://www.realclimate.org/index.php/archives/2021/02/dont-climate-bet-against-the-house/

6178. Rob Honeycutt at 06:43 AM on 5 February 2021
      Increasing CO2 has little to no effect
      

      I was just thinking more about this question coming from devcarr. It seems like a very common logical track that people take. How can one CO2 molecule possibly heat up 2500 other atmospheric molecules? 

      The mechanism of collisional transfer is fairly complex (per Eli's piece) for a non-scientist. Maybe the more simple answer is in regards to the relative number of IR photons and molecular collisions constantly taking place. 

      For one radiatively active greenhouse gas molecule to heat up 2500 other radiatively transparent gas molecules is quite easy, when you think of it in terms of the many millions (billions?) of IR photons hitting those GHG's every... second? millisecond? I'm not sure what the right number is.

      People get stuck on the proportion of CO2 in atmosphere and forget the proportion of IR interacting with the CO2.

6179. Tom Dayton at 08:15 AM on 4 February 2021
      Increasing CO2 has little to no effect
      

      Thanks Bob! (Apologies. I forgot to check my link after posting.)

6180. Bob Loblaw at 07:54 AM on 4 February 2021
      Increasing CO2 has little to no effect
      

      Tom's link to "Eli Rabbet explained" seems to lead nowhere, but Eli has a full explanation on his blog:

      http://rabett.blogspot.com/2013/04/this-is-where-eli-came-in.html

      The short story is as MA Rodger explained.

6181. Tom Dayton at 05:03 AM on 4 February 2021
      Increasing CO2 has little to no effect
      

      devcarr: Pro scientist Eli Rabbett explained the details, and summarized "a quick estimate that only one out of 100,000 CO2 molecules excited into the (0,10,0) by collision or absorbing a photon, will emit." The vast majority either hang on to the energy or lose it by collision.

      Moderator Response:

      [TD] Fixed broken link.

6182. MA Rodger at 05:02 AM on 4 February 2021
      Increasing CO2 has little to no effect
      

      devcarr @411,

      The molecules of the atmosphere are in collision with each other at timescales measured in microseconds. The time for an excited CO2 molecule to use the excitement to emit an IR photon averages thousands of times longer. Thus the chances of an excited CO2 molecule being given time to emit an IR photon is very small. Effectively, this means pretty-much all the IR energy that bombards atmospheric gas and is absorbed by CO2 is transfered to the general atmospheric gas molecules as thermal energy.

      But the large number of molecular collisions suffered by CO2, as well as robbing them of almost all incidents of them in an excited state before they can emit IR, also imparts this same excited state into many many more CO2 molecules. And it is this enlarged population of excited CO2 molecules that provides the CO2 molecules for a few of them with the chance to emit an IR photon.

      This should make sense as it is the temperature of the gas, and thus the level of inter-molecular collisions, that determines the level of IR being emitted by the gas. And conversely, it is thus not the level of bombardment of IR photons that determines the level of IR being emitted from the gas.

6183. devcarr at 04:52 AM on 4 February 2021
      Increasing CO2 has little to no effect
      

      Thanks, Rob Honeycutt..

      Somehow the entire atmosphere is warming up, not just the GHG. A thermometer measures the nitrogen and oxygen just as much as the CO2 and water. You can't say the infrared radiation is warming the atmosphere if it only warms the GHG. I am asking how the heat transfers from the hot GHG to the cooler gases, which are 99.9% or more. I presume you are correct that some is transferred through collisions (conductance). I would like more details about how that happens, and how such a small fraction can heat up all the other gases so quickly.

6184. VictorVenema at 02:46 AM on 4 February 2021
      A Climate Bet Impossible to Lose
      

      If there is another round please let me know. I do would suggest to have a neutral party collect the money in advance. I do not expect these people to be less Trumpian in 10 years, if anything moral values in these groups are on a steep decline.

6185. Rob Honeycutt at 02:43 AM on 4 February 2021
      Increasing CO2 has little to no effect
      

      devcarr... Each IR photon leaving the surface is interacting with more than one molecule of CO2. Each photon is being absorbed and re-emitted many times. Some of the energy is transferred to other atmospheric molecules through collisions, but often it's being re-emitted only to collide with another GHG molecule. Some of that energy ends up back at the surface. Some eventually makes its way out to space.

6186. devcarr at 02:30 AM on 4 February 2021
      Increasing CO2 has little to no effect
      

      I need some clarification about how greenhouse gases warm the atmosphere. I understand how the GHG warm up by absorbing certain infrared wavelengths. How does the other 99.9% warm? According to the National Weather Service, only 5 units of the heat comes from convective currents, presumably originating with conductance at the surface. https://www.weather.gov/jetstream/energy. Another 24 units comes from condensation of water vapor. 104 units comes from longwave radiation absorbed by GHG. How does the heat transfer from the small volume of GHG to the large volume of other gases? Is it conductance at the molecular level? Wouldn't this have to occur very rapidly, given the very high ratio of the two volumes? How does this affect the ability of the GHG to re-radiate in the wavelengths originally absorbed?

6187. michael sweet at 01:30 AM on 4 February 2021
      Skeptical Science New Research for Week #3, 2021
      

      Thank you for all the work you put in to orgnaize these reference lists.  I am hoping that Gavin at RealClimate will comment on this paper.

6188. Doug Bostrom at 18:16 PM on 3 February 2021
      Skeptical Science New Research for Week #3, 2021
      

      Sorry, Michael, missed this until now. 

      Referring your question to better brains. :-)

6189. Nick Palmer at 22:22 PM on 2 February 2021
      A Climate Bet Impossible to Lose
      

      Good news! This means I can bulldoze my way into Gosselin (and his merry maniacs) Notrickszone armed with this wonderful phrase:  "If the loser of the bet refuses to pay, then he will be forever regarded as a useless deadbeat loudmouth scumbag with no honour."

6190. shoyemore at 19:49 PM on 2 February 2021
      A Climate Bet Impossible to Lose
      

      I often forget myself, but the first question a statistician is supposed to ask is "How was these data collected?".

      On the wildfires, Jewish Space Lasers, anyone?

      https://www.forbes.com/sites/brucelee/2021/01/30/did-rep-marjorie-taylor-greene-blame-a-space-laser-for-wildfires-heres-the-response/?sh=78c42e84e44a

6191. nigelj at 17:20 PM on 2 February 2021
      A Climate Bet Impossible to Lose
      

      bvangerven

      Its possible that many of the remaining climate denailist scientists have narcissistic  personality disorder. This affects about 1% of the general population. People with this disorder are psychologically incapable of admitting they are wrong, or find it extremely painful to do so, and so only do so rarely. Plenty of people have something close to this disorder. The point is there will always be a few denialists just as there is still a flat earth society.

6192. John Hartz at 15:13 PM on 2 February 2021
      We're heading into an ice age
      

      Recommended supplementary reading...

      Video interview of Ian Plimer at Sky News falsely claims that a new study announces an incoming ice age, partly based on an incorrect Daily Mail headline, Edited by Nikki Forrester, Article Review, Climate Feedback, Jan 20, 2021

6193. Bob Loblaw at 11:17 AM on 2 February 2021
      A Climate Bet Impossible to Lose
      

      Johnny's point about "raw data" raises an important issue. What is "raw" data? When does data processing start?

      For the satellite data, what is being measured is actually microwave emissions form the atmosphere, and it take a lot of modellig to derive "temperature" from that data. Rob's post has some good links in the "Selection of data sets" paragraphs that explain much more.

      Pretty much any environmental variable has some sort of processing that needs to be carried out. Even something as simple as the regular temperature measurements aren't that "raw":

      • In the "olden days" (and probably still at some community-based volunteer observing stations), a liquid-in-glass thermometer was used. The "raw" data is the length of liquid in a tube, and the model used to transform that into temperature involves the temperature-dependence of liquid volume.
      • Most current system measure temperture electronically, where the resistance of some material (either platinum or a semicondutor material) is measured. It is then transformed into temperature using models that relate the electrical properties of materials to temperature.

      Both of these still just give you the temperature of the thermometer, not the air, so the temperature measurement system has to try to make sure the thermometer is at air temperature, usually using a Steveson Screen or some other form of ventilated radiation screen.

      That gives you local air temperature, and then  you need to make sure that your local temperature is telling you the information you need at a regional scale. There is a good series of posts here on how temperature measurements taken for the purpose of weather observations are used to estimate global temperature changes:

      https://skepticalscience.com/OfAveragesAndAnomalies_pt_1A.html

      Everything in science has "models" involved at some point. Some are simple and extremely well-defined. Others are complex and involve considerably more uncertainty.

6194. Rob Honeycutt at 10:02 AM on 2 February 2021
      A Climate Bet Impossible to Lose
      

      Johnny... That's a very interesting point, and one that I will absolutely remember in the future.

6195. Johnny Vector at 08:49 AM on 2 February 2021
      A Climate Bet Impossible to Lose
      

      Speaking as a satellite systems engineer, please don't refer to that second graph as "raw data". That is already at least a "Level 1" product. Level 0 is raw data, right from the sensors. I build astrophysics instruments, so I don't know for sure that the graphed data is L1; I strongly suspect it's Level 2, which has had even more processing done to it.

      I mention this not for the sake of pedantry, but because it's worth pointing out always that any satellite numbers in Kelvins have already undergone a large amount of processing. The only numbers that come down in Kelvins are the internal temperatures of the satellite itself. (Okay, even those probably are downlinked in A/D counts, but the conversion to Kelvin is usually a simple linear calibration.)

      Anyway, I think it's worth avoiding the term "raw data" when referring to anything that's already been heavily processed based on a model, especially when there are two models whose outputs are outside each others' one-sigma error bars.

6196. bvangerven at 07:30 AM on 2 February 2021
      A Climate Bet Impossible to Lose
      

      Interesting ...

      
      I can 't figure out whether climate change deniers genuinely believe that the earth is not warming. But now I am starting to believe that some of them are sincere, even though they are wrong. I think it is called "emotional investment". As they have invested years, even decades of their life defending the denier position, admitting their mistake now would be admitting they have wasted years.

      
      Humans are a social species. Of course, believing falsehoods is not a clever survival strategy. But being loyal to the group you belong to – sometimes by agreeing with what everyone in your group claims to be true – IS a valuable survival strategy. You have a better chance of survival in a group than on your own. But that also means that such people cannot be persuaded by logical arguments or by facts.

6197. Bob Loblaw at 07:29 AM on 2 February 2021
      A Climate Bet Impossible to Lose
      

      Leprechauns? No way. It's pirates.

      https://pastafarians.org.au/pastafarianism/pirates-and-global-warming/

      ...but a nice piece on an interesting bet, Rob. As you said, it was a pretty sure bet. I think the "coolists" were out on a Snipe Hunt looking for support for their viewpoint.

      I think your cheating was the result of using physics instead of fizzicks to predict what would happen.

      It's the kind of bet I wish we would lose, but that will take a bit of time.

6198. Rob Honeycutt at 05:57 AM on 2 February 2021
      A Climate Bet Impossible to Lose
      

      Ah, luck of the Irish, I say. :-)

6199. Philippe Chantreau at 05:20 AM on 2 February 2021
      A Climate Bet Impossible to Lose
      

      You cheated. Ocean cycles were rebooted in the middle and then commandos of invisible leprechauns were lighting fires everywhere to heat up things. I'm pretty sure I saw it on FaceBook. It's all a hoax.

6200. Rob Honeycutt at 03:10 AM on 2 February 2021
      Veganism is the best way to reduce carbon emissions
      

      Guilhem... You're going to have to show me where the IPCC makes such a statement because I'm not finding it. 

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