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Comments 29201 to 29250:

29201. bozzza at 11:12 AM on 22 May 2015
       Hotspot Found Again: Warming of the Tropical Troposphere Confirms Climate Model Prediction
       

       "This hotspot in the tropical troposphere is not specific to the increased greenhouse effect resulting from industrial carbon dioxide emissions. It would, for example, also be expected in a hypothetical scenario where warming was due to increased solar output."

        

       (the second bullet point)

29202. This Will Frighten You so You Will Delete It at 10:49 AM on 22 May 2015
       Hotspot Found Again: Warming of the Tropical Troposphere Confirms Climate Model Prediction
       

       Tom Curtis, the three graphs shown above clearly show that temperatures in both the Tropics and the Southern Hemisphere (SH) have risen by less than 0.4 degree since 1960, which is more than 50 years ago.

       I failed to notice that the NH graph has a different y-scale than the SH (an extremely poor and generally misleading graphing practice) so I misread it.  It shows that NH temperatures have risen by about 0.6 degrees in the past 55 years. 

       I don't know how to average two readings of 0.4 and one reading of 0.6 because I don't know how much territory the "Tropics" covers, but I know for sure the resulting average is far below the 0.765 degree you quoted.  Are you suggesting that the graphs in this article are full of errors?

       According to these graphs, Northern Hemisphere temperatures were clearly on a strong downward  path during the period 1960-1975.  This was, of course, a period of very rapid increase for CO2 emissions in the Northern Hemisphere. 

       The SH, which did not experience so much CO2 increase during this period, did not cool. 

       Thank you for drawing my attention back to the graph so I would have a second opportunity to notice this interesting cooling phenomenon.

       Moderator Response:

       [PS] Please see here for mid century cooling. Anyone wishing to respond to that point, then please do so on that thread. Reading the caption on the figure will tell you how much territory the tropic on the graph represents.

29203. barry1487 at 09:56 AM on 22 May 2015
       My Research with Steve
       

       I remember when your monicker first popped up by way of climate blogs linking to yours. Great to have seen intermittent snapshots from there to here. Congratulations on your first lead authorship, and good on ya for contributing to the sum of knowledge!

29204. Tom Curtis at 08:21 AM on 22 May 2015
       Climate is chaotic and cannot be predicted
       

       @113, I do not believe such gross misrepresentation of the claims in the IPCC should be allowed to stand.  Whether they were made due to deceit or stupidity, it does not matter.  More than enough has been discussed above that the author of the post should now understand the distinction between predicting precise values and predicting statistical spreads (means and standard deviations) and should no longer be confusing weather and climate.  Given that, he is clearly now only sloganeering.  He is also clearly not worth discussing issues with.

       Moderator Response:

       [PS] I agree on all counts. Comprehension of the comments policy at this site also appears to be problem.

29205. Tom Curtis at 08:10 AM on 22 May 2015
       Hotspot Found Again: Warming of the Tropical Troposphere Confirms Climate Model Prediction
       

       @2, the trend from mid 1965 on HadCRUT4 is 0.153 C/decade, for a total warming of 0.765 over the last 50 years, nearly double the increase that you claim.  That you took the lower figure for the tropics only, which we expect to be lower, is no surprise.

       Upvotes indicate a belief that the post is of particularly good quality, either because of the quality of the data presented and/or the quality of the argument.  Downvotes, conversely, indicate that the post is considered of particularly poor quality due to inaccurate or misleading data and/or specious argument.  I have downvoted your post for that reason.  I am sure the other downvote (at time of writing) is also for that reason.  Your attempt to coopt the thumbs up/down mechanism for specious rhetorical purposes is not appreciated. 

29206. Tom Curtis at 07:59 AM on 22 May 2015
       Breathing contributes to CO2 buildup
       

       Art Vandelay @51, there a couple of reasons to treat photosynthesis as the primary process (so that the CO2 is treated as initially coming from the atmosphere).  First, historically that is what happened.  Ie, before there were multicellular animals, there was photosynthesis, and indeed multicellular animals only became possible because of the existence of photosynthetic plants (or microbes) on which to feed.  Second, food consumption can be treated as a flow of energy from low entropy to high entropy.  As such the conversion from the lowest entropy energy supply generally available on Earth (sunlight) to the next lowest entropy source of energy generally available (sugars in plants) is the primary process.  So, thermodynamically photosynthesis (and hence extraction of CO2 from the atmosphere) is primary.

       However, these are not reasons directly related to the accounting of carbon flows.  For that purpose we can take several approaches.  The simplest approach, and the one in fact used by climate scientists, is to ignore churning.  That is, to only take account of change of carbon in biomass reservoirs.  If we account for carbon in that way, the human respiration is closely balanced by photosynthesis absorbing almost the same amount of Carbon.  As this is just churning, it is ignored, and the only thing that is accounted for is the slight increase in carbon storage in humans due to increasing population and obesity.

       Alternatively, you could consider human respiration as a relevant emission, but only if you consider all photosynthesis a relevant sequestration.  

       Looking at the IPCC graph I posted @42, we can either consider net land flux (=4.3 GtC per annum sequestered), or we can consider the two fluxes seperately, and say there are 118.7 GtC per annum emitted and 123 GtC per annum sequestered.  It makes no difference in the end.  What you cannot do is consider treat the total respiration as emissions, but consider only excess photosynthesis as sequestration, which is what the denier argument rebutted above tries to do.  That is similar to their similar dishonesty in suggesting anthropogenic emissions are very small because they are only 4.3% of total emissions because they are only 4.3% of total CO2 flux into the atmosphere while ignoring that the natural components of that flux are almost exactly balanced by natural fluxes from the atmosphere so that the net increase is entirely due to anthropogenic emissions.

       These figures are for the entire terrestial biosphere, but the same point applies to human respiration and the photsynthesis of the carbon content of human food.  Further, because that photosynthesis is a continuous process (as is the respiration), the two components almost exactly balance at any point of time, and certainly the time averaged processes do.  

29207. This Will Frighten You so You Will Delete It at 07:52 AM on 22 May 2015
       Climate is chaotic and cannot be predicted
       

       KR, you quote the IPCC as saying "The chaotic nature of weather makes it unpredictable beyond a few days." However, "when weather is averaged over space and time, the fact that the globe is warming emerges clearly..."

       This means the climatologists fully understand that predicting weather beyond a few days with a computer model is exactly as effective as predicting it with, say, chicken entrails.

       Knowing this, they go ahead and consult their entrails, examining them carefully to learn what the weather might be like in 50 years, if only entrails had predictive value. But since they know this is silly, they don’t stop there. They go on to examine the entrails of a million chickens.

       They average the results of the million chicken-entrails predictions together and, voila, pronounce the result “scientific.”

       It is amazing what nonsense people will allow themselves to believe.

       Moderator Response:

       [PS] You are simply ignoring the points made to you, and continuing with worn-out sloganeering, strawmen, and argumentative language. If you are not prepared to read the actual science with view to understanding, then you are in no position to comment on it. Commentators here have attempted to explain the difference between weather and climate what is predictable or not, but apparently to no avail.

       Please note that posting comments here at SkS is a privilege, not a right.  This privilege can and will be rescinded if the posting individual continues to treat adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

       Moderating this site is a tiresome chore, particularly when commentators repeatedly submit offensive or off-topic posts. We really appreciate people's cooperation in abiding by the Comments Policy, which is largely responsible for the quality of this site.
        
       Finally, please understand that moderation policies are not open for discussion.  If you find yourself incapable of abiding by these common set of rules that everyone else observes, then a change of venues is in the offing.

       Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter.

29208. This Will Frighten You so You Will Delete It at 07:43 AM on 22 May 2015
       Hotspot Found Again: Warming of the Tropical Troposphere Confirms Climate Model Prediction
       

       I'm more fascinated with the blue lines in the bottom three graphs than the red lines.  The blue lines show that the planet (at least the part of it where people actually live) has warmed by less than 0.4 degree in the past 50 years.

       Does that surprise anyone here?  Let's take a vote. Upvote this post if you are NOT surprised.  Downvote if you ARE surprised, because based on all the rhetoric you naturally expected to see a "hockey stick."

       And if you do not think people should be allowed to know this, then cast your vote by deleting this post.

       Moderator Response:

       [RH] Please note that posting comments here at SkS is a privilege, not a right.  This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

       Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter.

29209. Tristan at 06:21 AM on 22 May 2015
       2015 SkS Weekly News Roundup #21A
       

       Congrats to Dikran Marsupial, whose tash received a positive review at Salon.com. ;)

       Moderator Response:

       Edited to add link

29210. KR at 04:38 AM on 22 May 2015
       Climate is chaotic and cannot be predicted
       

       TWFYSYWDI - Let's add some context, shall we? IPCC AR4, FAQ 1.2, :

       "What is the relationship between climate and weather?

       [...] The chaotic nature of weather makes it unpredictable beyond a few days. Projecting changes in climate (i.e., long-term average weather) due to changes in atmospheric composition or other factors is a very different and much more manageable issue. [...] ...when weather is averaged over space and time, the fact that the globe is warming emerges clearly from the data."

       Which is exactly what climate models are used for, projecting averages. You are conflating weather with climate - and based on this, appear not to have actually read the opening post. 

       Moderator Response:

       [TD] When TWFYSYWDI persists in pushing the same "points" without incorporating any of the original posts or the responding comments, or the external resources that responders are pointing to, those comments by TWFYSYWDI's are being deleted.

29211. michael sweet at 03:27 AM on 22 May 2015
       Congress manufactures doubt and denial in climate change hearing
       

       President Obama made strong references to AGW in the graduation speach atthe Coast Guard Academy.  Los Angeles Times report.

       Hopefully the public will support action.

29212. dcpetterson at 00:00 AM on 22 May 2015
       Hotspot Found Again: Warming of the Tropical Troposphere Confirms Climate Model Prediction
       

       Very clear summary of a very technical paper. Thank you.

       And yes, it is not surprising to find the models once more got it right. The track record of the current models is pretty stunning. It is only shocking in a sad sort of way, in that it is a sobering reminder of the dire conditions we are causing.

29213. Concerned at 16:17 PM on 21 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Thank you all for your comments. I understand now that the number of undecided (or X) opinions is small, so X has minimal impact on the 97% conclusion. Thanks for the calculations, Tom Curtis.

       I read the paper more carefully while composing a response to an AGW denier troll, whose post was deleted (thanks, Moderator) while I was writing. Now I understand where the numbers come from and how the opinion categories were defined. I also note some confusion in the presentation, as I'll describe below.

       In the analysis of abstracts, by "(4a) No position" the authors meant what I was calling "irrelevant" and by "(4b) Uncertain" the authors meant what I was calling "considered but undecided", or X. I think the abstract part of the presentation would have been cleaner if category 4 had consisted of only 4b, so every one of the seven categories was an opinion of sorts on AGW. I think category 4a should have been renamed and set aside. Separation of 4 into 4a and 4b reflects the process used for a second phase refinement of the abstract analysis, but it makes the presentation harder to follow.

       In the case of the self assessment emails, the situation is further clouded by defining category 4 as: "Neutral: paper doesn't address or mention issue of what's causing global warming." This is evidently a rewording of category 4a, but the word "neutral," which could express an opinion, and the phrase "doesn't address or mention" are not the same thing. Thus, in the self-assessments, there is no explicit mention of category 4b, uncertain / considered but undecided / X, but I think there should have been.

       Anyway, all is good with me now. I agree with the 97% for the abstracts, possibly corrected to 96% for for the self assessments.

29214. Art Vandelay at 10:32 AM on 21 May 2015
       Breathing contributes to CO2 buildup
       

       Hi Tom, thanks for the explanation and clearing up the definition of biomass. 

       My background is in engineering, not geology, so I'm by no means an expert on atmospheric CO2 exchange.

       There's is however one part of your explanation that doesn't make sense to me: -   

       "So, we add the human carbon input, which comes from food and all of which comes initially from the atmosphere. You then have a cycle in which the ouput (human respiration) is very slightly less than the input (human consumption of CO2 indirectly drawn from the atmosphere). 

        

       I don't understand why CO2 initially comes from the atmosphere. I would have thought it correct to say that CO2 in the atmosphere initially comes from biomass (respiration) or an external input such as vulcanism, and that the atmosphere is the transport media in the system.  

       Rather than take the thread OT I'll consult with a geologist friend of mine in the next day of so to get a better understanding of why the atmosphere is regarded as the starting point in the cycle. 

29215. Tom Curtis at 08:59 AM on 21 May 2015
       Breathing contributes to CO2 buildup
       

       Art Vandelay @49, biomass is the total mass in animal and plant and microbial matter.  It does not include CO2 in the atmosphere or oceans, nor soil carbon in the form of humus.  This, it is not the total mass of carbon within the carbon cycle and can change over time.

       As to human respiration, you can look at it several ways.

       You can consider just humans and their respiration, in which case yes human respiration increases atmospheric CO2.  Such a view however is transparently incomplete for it does not account for where the human carbon comes from in the first place.  It in effect treats human biology as an ex nihilo creator of carbon.

       So, we add the human carbon input, which comes from food and all of which comes initially from the atmosphere.  You then have a cycle in which the ouput (human respiration) is very slightly less than the input (human consumption of CO2 indirectly drawn from the atmosphere).  It is very slightly less because the total mass of humans in increasing through population growth in the third world and obesity growth in the first.

       You can then look at how the food is produced, and look at effects on total biomass from human food production.  If you do, it is probable that the entire process of human food production reduces biomass, mostly by deforestation.  However, when you do that you are no longer looking at emissions from human respiration alone, but emissions from human respiration plus human food production.  More importantly, the emissions from human food production are already accounted for by estimates of emissions from LUC.  So, looking at that does not find a form of emissions that were not previously accounted for. 

29216. Tom Curtis at 08:37 AM on 21 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Concerned @25, I have now recalculated the values discussed in my preceding post using the papers rather than author values.  The results are:

       X= Multiplier Value End% Unc%
       Neutral 0.50% 3.82 96.90% 0.29%
       All 0.33% 7.17 96.62% 0.58%
       Adj 193.77% 13.90 96.20% 1.00%

       In each case, in calcuting the endorsement percentages, I rounded the value of X up.  As you can see, even the most generous projection still makes little difference, only reducing the endorsement percentage by 1%.  So, while Cook et al (2013) would have been improved had authors been given the option of an "uncertain" rating, it would have made no difference to the headline results.

29217. Leto at 08:03 AM on 21 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       CBDunkerson,

       My ealier post was about the fairness of your analogy, and explicitly did not go into the percentages of the consensus paper, which I will also not touch on this occasion.

       Concerned raises two issues:

       1) Relative to a debated scientific point, papers could potentially be divided into four categories: yes, no, undecided and irrelevant (Y, N, U, I). Concerned suggests that the headline percentage of consensus is best captured by Y/(Y+N+U), where U refers to papers that have actually attempted to consider the question, not merely mentioned a search term. This appears reasonable. He explicitly rejects I from the equation.

       2) He wonders if this affects the cited 97% consensus.

       
       My comments relate to the first issue. While it may be that Concerned has made mistakes in attributing papers to the categories Y, N, U and I, and that his percentages include papers from the I category, it is not fair to accuse him of misunderstanding the issue so badly that he needs to be told that the consensus ratio should not include I in the denominator. Your analogies suggested he was unaware of this, and in that sense were unfair and distracting.

29218. Tom Curtis at 07:53 AM on 21 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Concerned @25

       (Correction:  I have just noted that I used the numbers of respondents rather than the number of papers in calculating the values below.  I don't have time now, so will recalculate later if you have not already done so before hand.)

       A subsidiary survey found that among abstracts rated as neutral on AGW (category 4), only 0.5% expressed the position "... that human's role on recent global warming is uncertain/undefined" (category 4b).  On the simplest assumption, therefore, only 0.5% of the 759 category 4 papers from the author self ratings would similarly fall into an "uncertain category" had one existed, so X would be 2, yielding a 96.26% endorsement rate rahter than the 96.38% actually obtaind for the paper.

       Arguably that is too simplistic a way to project the results of the subsidiary survey onto the author ratings.  Presumably the reduced percentage of category 4 ratings in the author ratings would have come from truly neutral (category 4a) papers rather than from those with a discernable opinion in the abstract (category 4b).  That being the case, we should project the percentage of category 4b papers as a percentage of all papers.  Doing so lifts the value for X to 3.99.  

       Arguably the category 4b papers would also have expanded in relative number in the same way as the affirming and rejecting papers did.  On that basis, we should multiply our projected X by the ratio of papers taking a positon in the author rating divided by the ratio of papers taking a position in the abstract ratings, ie, by 1.96 yielding a value for X of 7.8 which we can round to 8.

       Using this value for X, the endorsement percentage for author ratings drops to 95.4% with an projected uncertain (category 4b) rate of 1.02%.

       So, even with this most generous estimate of X from the only available data, the endorsement rate scarcely falls.  Specifically, it does not drop outside the uncertainty interval of the original estimate.  And it does not drop to values which would support any contesting of the idea that there is a scientific consensus on AGW.

29219. MA Rodger at 05:58 AM on 21 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Concerned @25.

       You are incorrect to suggest that the self-assessment is assessing the opinion of the authors. The survey is asking for a self-assessment of their work, not the authors personal opinion of AGW.

       Also the suggestion that a histogram would be a more appropriate presentation of the results - I find this unconvincing. The reason a paper is rated, say,1 - Explicit endorsement with quantification rather than 2 - Explicit endorsement without quantification is more to do with the type of analysis being employed rather than the finding of that analysis. There is in all this the truth that there are very few pieces of research 1991-2011 attempting to prove what all climatologists know to be true. A tiny handful of researchers continue the struggle to undo this truth but without result. These denialist climatologists may say this is 'without result so far' or 'without an accepted result so far' but I have not seen a thing in a decade to suggest the truth is in any way in doubt.

       Your histogram can be gleened from the uploaded self-assessment data I linked to @21 (although the total is six short):-

       1 - 242
       2 - 557
       3 - 539
       4 - 759
       5 -   25
       6 -    5
       7 -    9

29220. Concerned at 04:30 AM on 21 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       CBDunkerson @24,

       Your first analogy about boys is not correct, as Leto said. Of course boys would be the denominator, as that is how the question was posed.

       What I was driving at is that the data should be presented as a histogram of those who have considered the question and have an opinion on the cause of global warming.  If some value the X out of the 35.5 % who adddressed and considered the issue were undecided on the cause, those X people have an opinion on the cause.  Then the histogram would have three values, yes AGW = 1342/(1342+39+X), undecided = X/(1342+39+X), and no AGW = 39/(1342+39+X).

       My basic question is, what is the value of X?  You are assuming that all 35.5% are irrelevant, so X is 0.  The words used to describe the 35.5% were "no position".  That is not the same as "irrelevant".   Some of those "no position" people could have considered the cause and be undecided.

       The problem here is the use of language.  "no position" is ambiguous.  I am asking how many of those "no position" people, X,  have considered the question, perhaps very carefully, and are undecided.  That value X affects the histogram.

       If there were 7 categories of opinion, then the results should be shown as a 7-column histogram, not yes or no.

29221. CBDunkerson at 03:10 AM on 21 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Leto, your statement that "Papers that do not consider the question at all are not at issue here" is simply incorrect. That is precisely the issue.

       The 35.5% figure Concerned cited actually came from the self-rating portion of the study. In that phase, abstracts for a total of 2142 papers were rated by their authors. Of those, 1342 (62.7%) endorsed the consensus, 39 (1.8%) rejected the consensus, and 761 (35.5%) did not address the issue.

       1342 / (1342 + 39) = 97% consensus

       Why not factor in the 761 abstracts, or some unspecified fraction of them, as 'undecideds'? Because this wasn't looking at opinions, but rather content... what the text of the abstract actually said. Either that text addressed the issue, or it did not... and for 35.5% of the papers their authors said that the issue wasn't covered.

       In short, 'the fact that another 761 papers were on other topics is irrelevant'.

29222. Art Vandelay at 02:19 AM on 21 May 2015
       Breathing contributes to CO2 buildup
       

       By def, Biomass (animal and plant) is considered to be the total mass within the carbon cycle at any given time so you can't change 'total' biomass, only its composition.  

       But again, the confusion here is due to my misunderstanding the original proposition - which specifically does not refer to human population growth perse. 

       Also, my proposition that population growth increases atmospheric CO2 assumes that it results in increased 'total respiration' and that is not necessarily the case - because human population growth is likely to be at the expense of other species. 

       Nonetheless, it would be interesting to know exactly what effect the rise of human population to 7 billion has had on the carbon cycle.

29223. KR at 01:14 AM on 21 May 2015
       Breathing contributes to CO2 buildup
       

       Carbon in biomass is also "in circulation", which is the primary point I think you're overlooking. And CO₂ in respiration comes from food consumption, with food still being part of the carbon cycle: carbon input = carbon output for any organism over both short terms and its entire lifecycle. 

       Side note: if total incorporated biomass has been raised by population growth (which requires an assumption that plant biomass isn't displaced) that sequestration of carbon in organisms can only decrease atmospheric CO2. 

29224. Art Vandelay at 01:03 AM on 21 May 2015
       Breathing contributes to CO2 buildup
       

       "changing the speed of carbon cycling between plant and animal, but not adding or subtracting from the sum carbon in circulation"

       See Tom's diagram. The land based inputs are respiration and fire, so the 'sum carbon in circulation' (as you put it) is always equal to the 'respiration and fire' that's fed into the system.

       However, that aside, I can see why we're in disagreement and it's because we're presenting two different arguments.

       Your proposition (argument) that human breathing (respiration) does not increase C circulation in the cycle refers to a static population, whereas I'm proposing that human population growth increases the input 'C' into cirulation in the system and therefore increases atmospheric CO2.

29225. KR at 23:51 PM on 20 May 2015
       Breathing contributes to CO2 buildup
       

       Note that CO2 in respiration and in carbon in plant and animal biomass is still in the biological carbon cycle. Increased respiration and CO2 output requires balancing increased food consumption and carbon input into the breathing organisms - changing the speed of carbon cycling between plant and animal, but not adding or subtracting from the sum carbon in circulation. 

29226. Art Vandelay at 22:56 PM on 20 May 2015
       Breathing contributes to CO2 buildup
       

       44@KR

       "Atmospheric concentrations can only have net changes over the long term if more carbon enters or leaves the biological carbon cycle"

       Yes, I agree, so it follows that baseline atmospheric CO2 will increase if either respiration increases or if photosynthesis decreases.  

       See Tom's attached IPCC flux diagram above which shows the exchange of CO2 in and out of the atmosphere.  It shows that total respiration has increased since pre-industrial times - which is interesting.  

       "Breathing does not, and can not, influence long term atmospheric CO2 concentrations. It's a complete red herring in the discussion of climate change."

       Well I do agree that it's a "red herring" in the dicussion of climate change because animal respiration is dwarfed by the burning of fossil fuels but I don't agree that human and other animal respiration cannot alter atmospheric concentations, and as Tom's diagram shows, respiration and fire are the only natural land based inputs into the cycle. 

       My argument isn't that animal respiration is in any way significant as a driver of global climate, but that doesn't mean that via modulation that it cannot or does not alter CO2 in the atmosphere over a given time scale.

29227. Leto at 22:39 PM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       CBDunkerson @22,

       I don't believe your analogy is at all fair to Concerned's question. I have agreed with you when you have made similar statements in the past, but those statements were made in response to a different question.

       Putting aside the details of the 97% consensus paper (I am not sufficently familiar with the details), it is true that the relevant denominator to consider, when calculating a consensus, is the number of papers considering a position, including those that eventually adopt a conclusion of "undecided" after such consideration - not the number of papers adopting a position. Papers that do not consider the question at all are not at issue here, which is why your gravity analogy is unfair. If there were a large number of undecided papers (I believe there were not), that would indeed affect the validity of the consensus.

       If 1000 authors explicitly wrote about the possibility of an El Nino in 2015 and 97 of them said one was on the way, 3 said we were definitely not having an El Nino in 2015, and 900 said it was too early to call it, there would not be a 97% consensus we were having an El Nino in 2015. The fact that another million papers were on other topics would be irrelevant.

29228. CBDunkerson at 22:01 PM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Concerned, suppose you have a class of 20 students; 10 boys and 10 girls... and you want to calculate the percentage of the boys who are white. The Cook paper methodology would have you count the white boys (say there are 7) and divide by the number of boys total... to get 70%. Your proposed methodology would instead have us find that only 35% (7/20) of the boys are white, 15% of the boys are non-white, and 50% of the boys are not boys.

       In short, you are asking why values not relevant to the calculation aren't included. That's a disturbing level of logical dissonance.

       Note that by such 'logic' the consensus level is essentially reduced to a factor of the size of the pool of papers reviewed. To take the extreme; the percentage of all papers on every subject imaginable which state a position on any given single issue is going to be near 0%. So your methodology of 'include non-relevant data' would indicate that there is approximately 0% consensus on everything. For example, approximately 0% of all papers ever written clearly state that gravity exists. Ergo there is 0% consensus that gravity exists.

       See 'where you went wrong'?

29229. MA Rodger at 21:14 PM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Tristan @20.

       The size of the two different 'pots' are relevant but they do apply to different data.

       Concerned @19.

       The self-assessment asked authors to rate their entire paper rather than just the abstract so it was different things being assessed as well as the assessors being different. The self-assessment survey asked for ranged from 1 = Explicit endorsement with quantification through 4 = No Expressed Position to 7 = Explicit rejection with quantification. There was thus no means of differentiating between 'irrelevant' and 'undecided'.

       The self-asessment results did a reasonable job of supporting the detailed findings of the Abstract assessment process, if anything strengthening the consensus finding. With the results so similar, it is likely relevant that the Abstract rating process only found a tiny proportion of 'undecided' Abstract, Tristran's "very few papers" (from Table 3 of Cook et al (2013) 0.3% of all abstracts were rated thus, ie "Uncertain on AGW"). It is thus likely that this tiny proportion would also have been found had the self-assessment allowed for such a catagorisation.

       However an author approached over this self-assessment process may well consider that if their paper fell into this 'undecided' category and they themselves were not convinced by the evidence of AGW that it should be rated more as a mild rejection of AGW rather than entirely neutral. And likely visa versa. Were there such an effect, again it does not support the idea of a large volume of 'undecided' literature being missed by the survey.

29230. Tristan at 20:36 PM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       If you change 'irrelevant' to 'unstated', that's exactly what the authors did.

       There was an 'uncertain' pot as well as a 'no position' pot.
        Very few papers were 'uncertain'

29231. Concerned at 18:46 PM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       I endorse AGW, but I am confused about the calculation of 97%.  The set of e-mail responses includes "no position on AGW (35.5%)".  As I see it, there are two possible viewpoints among the 35.5% having "no position":

       "irrelevant" — The cause of global warming is not part of the discussion. 

       "undecided" — The cause of global warming is considered, but the evidence does not support a yes or no vote for AGW.

       As I see it, the "undecided" papers should be counted as opinions, but "irrelevant" papers should be omitted.  If so, then there should be three fractions: yes, undecided, and no, which sum to 1.  Then the yes votes would be less than 97%.

       Kindly explain the logic and tell me where I am going wrong.

29232. Tristan at 14:30 PM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       1) A clear acknowledgement that 'science is a process, not a body of knowledge' so that the consensus of scientists is irrelevant to science and should be ignored; and

       
       Interesting. I just had this exact argument with Ms Nova. She refused to accept that Science was a noun as well as a verb (The noun was the original definition, even).

29233. Tom Curtis at 13:42 PM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       mancan @18, what deniers seem to what is:

       1)  A clear acknowledgement that 'science is a process, not a body of knowledge' so that the consensus of scientists is irrelevant to science and should be ignored; and

       2) A clear acknowledgement that only that which is 100% certain in science is an acceptable basis for policy.

       Leaving aside that science is both a process and a body of knowledge, the second requirement above presuposes that science is a complete body of knowledge, ie, one that cannot require further expansion or correction.  Their two desiderata, therefore, rely on contradictory and inaccurate conceptions of science.

29234. KR at 13:15 PM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       PhilippeChantreau - "Do we really have to bother with this nonsense?"

       While the N^th repetition of a denialist meme is rather tiresome to those who have been participating in forums such as SkS, I suspect that the occasional bit of nonsense is very instructive for undecided readers. Because they so clearly demonstrate the paucity of pseudo-skeptic positions.

29235. mancan18 at 12:58 PM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       BBHY comment coveers the basics of the role that carbon dioxide plays in the argument.

       Tom Curtis has dealt with the role of chaos theory in highlighting the differences between weather and climate.

       Climate is predictable. Tendencies in the weather that are central to all weather forecasting is also valid. It is based on weather records from each locality and comparing the situation of today with the average of all recorded situations at the same time in the past under the same conditions.

       Choosing whether a climate scientist chosen at random will support or reject the consensus on climate change is also predictable. The results from the Consensus Project are fairly indicative. Such predictions are based on the probabilities that are involved in making the prediction or determining the outcome.

       What deniers/obstructionists like TWFYSYWD seem to want is 100% certainty when in science there is none. That is why confidence intervals are used in making scientific assessments. There might be chaos in the phenomonen but that does not necessarily mean that it is entirely random or unpredictable. In a coin toss, the outcomes are entirely random and somewhat chaotic with H and T occuring around 50% of the time for each as more and more trials are conducted. However, that does not mean we will know exactly how many heads will come up, tails will come up, or whether the coin will come up on it's side, which is, although very remote, not entirely impossible. Coin on its side just doesn't occur with the same equally likely manner that the H/T outcomes do. There is no theoretical 100% certainty even with a coin toss.

       Outcomes related to climate change, while perhaps being based on a somewhat chaotic phenomonen,  will always be based on the tendencies determined by the underlying scientific principles of the phenomonen. So if you heat the planet by increasing the level of greenhouse gases, you will get more chaotic turbulence filtering through the weather systems which will ultimately impact on the climate. The idea that climate scientists can't precisely predict what is going to happen from their climate models is not a reason to negate the fundamentals of the argument. A statistical aggregation with related probabilities from all climate models is more likely to yield an accurate prediction and the IPCC does a faily good job of aggregating the research.

       Personally, I prefer the paleoclimate data to indicate what is likely to happen. From what I understand, there is only a 4 degree or so global temperature difference between an ice age with all those huge continental wide ice sheets and an inter-glacial, with the polar regions we see today. I don't think returning the planet to the CO2 levels of the past when there no icecaps and it was up to 4-6 degrees warmer, by burning all known recoverable reserves of fossil fuels, is such a bright idea. As for those who think that climate change is all natural and it just magically changes, well I would suggest that you don't have any real scientific understanding of what "natural" actually means. Climate scientists, while not necessaly having a complete understanding, do have a pretty good understanding of what is happening and why. Based on the probabilites, I think the Earth has a problem that needs to be addressed. 

29236. PhilippeChantreau at 11:49 AM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Do we really have to bother with this nonsense? I understand that mods give everyone the benefit of the doubt but, after a numberof years of this, I have learned to identify the signs showing that one has nothing of value to contribute.

       TWFYSYWDI can't be bothered to go the right thread after several commenters indicate they have responded there, and are kind enough to include links. He/she uses one of the most basic tools of dishonest rethoric (quote out of context). And on top of it all coats his latest comment with snark when it is obvious he/she lacks the most basic understanding of the issue at hand.

       It's not like any learning will happen here. No matter how the exchange proceeds, the individual will portray it elsewhere with the kind of faithfulness given to the IPCC quote. Can't we just dispense from the hassle?

29237. This Will Frighten You so You Will Delete It at 11:26 AM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Moderator - Thank you for your kind response and your helpful suggestions.  But now I am utterly confused.  Perhaps you can clear it right up.

       I quoted directly from an official IPCC report which unambigously states that "In climate research ... we are dealing with a ... chaotic system..."  I gave the source of this report so you and your readers may check for themselves:

       http://www.ipcc.ch/ipccreports/tar/wg1/505.htm

       You responded with an assertion for which you offered no supporting evidence, as far as I can detect.  You wrote "climate, by definition, is not chaotic."

       Now we must choose.  Either we must believe the IPCC, or we must believe your contradictory unsupported assertion.

       I don't wish to jump to the wrong conclusion.  Please help me with this difficult choice.

       Moderator Response:

       [PS] The points you made have been answered in the appropriate thread. See the pointers from posters above. As noted in comments policy, moderation complaints are always off topic. Please continue to discuss the main point but in the appropriate thread.

       However, given your chosen pseudonym, I must say that if your intentions are simply snark and trolling rather than engaging with science then please find another forum for your entertainment.

29238. chriskoz at 11:12 AM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       denisaf@11,

       Your point narrows the issue unnecessarily. The man made increase of CO2 is the result of not only "the operation of technological systems using fossil fuels" but broader human activities such as:

       - fossil fuels burning in a large sense, not only to operate technological systems, but e.g. burning coal/gas/petrol for heating,

       - land use changes,

       - cement production

       One broad definition that encompasses all such activiteis is: permanently (on human timescale) and irresponsively changing composition of the atmosphere by adding to it carbon that belongs to other reservoirs.

29239. denisaf at 10:32 AM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Assessment of the hypothesis that rapid, irrversible climate change is under way would be more credible if the point was made that it is the operation of technological systems using fossil fuels that is producing the damaging greenhouse gas emissions. Saying climate change is man made does not help rational consideration of the evidence. People made unwise decisions but it was the operation of the systems that has caused the CO2 atmospheric concentration level to increase rapidly.

29240. chriskoz at 10:04 AM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       For some reason, Tom's response on the apropriate thread cannot be "upvoted". I'd like to stress the valueable, insightful details of Tom's comment, especially its last paragraph (about the meaning of TWFYSYWDI web name), so I've upvoted Tom's link above here.

29241. KR at 06:53 AM on 20 May 2015
       Climate is chaotic and cannot be predicted
       

       "...a threshold keyed of long term averages rather than immediate weather states can also cross a threshold for hysteresis randomly" 

       Indeed. But that is true of any system with both hysteresis and noise, and is what I meant when talking about the probablistic blurring of hysteresis thresholds. 

29242. KR at 06:49 AM on 20 May 2015
       Climate is chaotic and cannot be predicted
       

       Technically speaking hysteresis doesn't induce the possibility of chaotic behavior - chaotic dynamics require sensitivity to starting conditions, which requires non-linearity. And even non-linear systems can be largely or wholly deterministic - for example many power amplifiers are non-linear yet deterministic over their entire operating ranges. 

       It's important to distinguish between hysteresis states and chaotic bifurcation attractors. Hysteresis states are separated by unmatched thresholds - the threshold from state A to state B is closer to B than the threshold from state B to state A. But bifurcated chaotic attractors (and the bifurcation itself breeding additional attractor regions) vary with the state of the system, and describe where a chaotic system may range while in that particular state. They are not the same thing at all. 

       Summary; hysteresis alone doesn't induce starting condition or state history dependent chaotic dynamics. But a non-linear system with hysteresis may in addition exhibit chaotic dynamics. 

29243. Tom Curtis at 06:43 AM on 20 May 2015
       Climate is chaotic and cannot be predicted
       

       KR @107, for the sake of discussion, assume that ENSO is in fact random.  If that is the case, it is possible that we could experience a long period of more frequent La Nina (or El Nino) states purely by chance.  Such an occurence would reduce the long term average of the GMST.  It follows that a threshold keyed of long term averages rather than immediate weather states can also cross a threshold for hysteresis randomly.  The difference is that the probability of crossing the threshold will be smaller when keyed of long term averages (and hence the return interval larger).   

29244. Tom Curtis at 06:33 AM on 20 May 2015
       Climate is chaotic and cannot be predicted
       

       KR @106, while I agree that hysteresis does not directly imply chaotic dynamics, hysteresis plus chaotic weather does open up that possibility.  As a simple case, we could imagine a system where the equilibrium level of the climate for a given forcing lies close to but above a threshold point, such that annual short term variability (forced plus internal) can kick it below the threshold with a return period fo 1/1000; and such that after crossing the threshold the same forcing results in an equilibrium level just below the threshold to return to the prior state, with short term variability again having a similar return period to kick it just above the threshold.  In such a system, with stable base forcing, the climate will kick between the two states at unpredictable intervals, but with a mean duration in each state of a thousand years.  It would be chaotic.

       In fact, some climate scientists at least believe the Earth is in a similar state (with larger perturbations required to cross the threshold and unequal return intervals), and that that accounts for the glacial/interglacial cycle.  (Science of Doom had a recent series of blog posts expounding, and linking to relevant papers, for just such a view.)

       Of more concern as it is more likely to impact us in the near future, a steady increase in forcing over time may cross unknown thresholds which may result in changes in climate unpredictable from the emperical data prior to the crossing of the threshold.  As I understand it, is is a common view of climate scientists that such thresholds do exist, but that the level of the thresholds is essentially unknown for most cases.  While not strictly chaotic, this does introduce a level of uncertainty in projections which is the fundamental point of denier arguments about the supposed chaotic nature of climate.  Of course, if it is in fact the case, it is bad news rather than good news for it significantly increases the probability of large impacts from AGW.

       Anyway, just to be clear about what I am claiming, hysteresis introduces the possibility of chaotic dynamics in climate.  That in turn means it is not true "by definition" that climate is not chaotic.  Further, there is evidence that hysteresis has introduced some level of chaotic dynamics to climate in the past, most notably with snow-ball earth episodes, and potentially other ice ages.  Consequently it is possible but not know to be the case that chaotic dynamics could be introduced at some threshold passed by warming in the next century or two from AGW.  Therefore, it is not true in all realized climate states that the climate is not chaotic.  I am not, however, claiming that we will experience chaotic dynamics in climate under current conditions or over the next few centuries.  I am inclined to think that we will not.  We just cannot rule out the possibility.

29245. KR at 06:09 AM on 20 May 2015
       Climate is chaotic and cannot be predicted
       

       Tom Curtis - Continuing: I suppose this comes down to the differences between immediate weather states (including aperiodic fluctuations such as ENSO) and long-term climate averages. If the averaging period of climate is long enough to encompass and average multiple chaotic weather variations then the bounds of variability are non-chaotic, no matter how non-linear. A boundary question of averages is very different from an initial state question of precise trajectories. 

       I suppose that D-O events and their uncertain timing may reflect some chaotic climate behavior, changing long term climate averages; but if they're truly cyclic phenomena they then aren't chaotic by definition. 

29246. KR at 06:00 AM on 20 May 2015
       Climate is chaotic and cannot be predicted
       

       Tom Curtis - Keep in mind that system hysteresis does not directly imply chaotic dynamics. Many physical systems show hysteresis that is quite predictable, with consistent thresholds, irrespective of previous state trajectory histories. 

       And while chaotic weather variations may kick global climate energy levels about a fairly small range, initiation of a transition is still based upon rather fixed if unknown thresholds. The chaotic weather simply adds a probablistic blur to those thresholds - long term average climate isn't going to show variegated wandering paths due to initial state dependence. 

29247. Tom Curtis at 04:36 AM on 20 May 2015
       Climate is chaotic and cannot be predicted
       

       The moderator (RH) responded to TWFYSOWDI elsewhere by saying, in part

       "First case in point, climate, by definition, is not chaotic."

       That is not quite true, and certainly not true by definition, in that cases of hysteresis open up the possibility of chaotic responses in climate.  Indeed, as hysteresis in climate typically involves a threshold effect, and as individual climate states are not predictable, in principle with some levels of forcing, the climate response must be chaotic in that the crossing of the threshold may only occur (with that level of forcing) with the occurence of a particularly improbable realizable state given that forcing.  Of course, with a steadilly changing forcing, the threshold will be crossed at some time, though the actual timing of crossing the threshold may vary considerably given a forcing history.

       Of course, deniers will not entertain this possibility.  Any broaching of the possibility is dismissed as "alarmist" and "hysterical".  Nor can they consistently allow for such possibilities in that for such responses to be chaotic, they must involve some combination of large climate sensitivity and/or significant lags in climate responses, both of which they deny (and both of which would be very bad news).  So, it may be the case that future climate response to anthropogenic forcing is unpredictable - that we may suddenly transition to an entirely different base climate at an unknown threshold of warming.  But that would be a far more alarming situation requiring a far more rapid mitigation response than that indicated by standard projections of future climate found in the IPCC.

       Moderator Response:

       [RH] I'm thinking in terms of a very broad definition, as in, deserts don't become rainforests in the short term. Climate is weather averaged over 30 years or more. It can change but it isn't chaotic in the sense that you don't know what the weather is likely to be in coming years.

29248. Tom Curtis at 04:10 AM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Like KR (and MARodger), I have also responded to TWFYSYWDI on the appropriate thread.

29249. Tom Curtis at 04:05 AM on 20 May 2015
       Climate is chaotic and cannot be predicted
       

       TWFYSOWDI elsewhere illustrates a desire to use one of the standard tools of pseudoscience, out of context quotation.  Typically understanding the full context requires not just quoting the full paragraph from which the quote derives, but sufficient background information to understand what is meant by it.  So in this case, TWFYSOWDI should have quoted the full paragraph, which reads:

       "In sum, a strategy must recognise what is possible. In climate research and modelling, we should recognise that we are dealing with a coupled non-linear chaotic system, and therefore that the long-term prediction of future climate states is not possible. The most we can expect to achieve is the prediction of the probability distribution of the system's future possible states by the generation of ensembles of model solutions. This reduces climate change to the discernment of significant differences in the statistics of such ensembles. The generation of such model ensembles will require the dedication of greatly increased computer resources and the application of new methods of model diagnosis. Addressing adequately the statistical nature of climate is computationally intensive, but such statistical information is essential."

       Had he done so, however, he would have undercut his message by showing that the authors of Chapter 14 of the IPCC TAR believed that there where some things that could be predicted about future climate, ie, the probability distribution (aka, the statistics) of future climate states.  He would also have shown that the authors believed a particular strategy was needed to make such predictions of the statistics, a strategy they in fact followed.

       However, full context requires understanding what the climate is, specifically:

       "'Climate' refers to the average weather in terms of the mean and its variability over a certain time-span and a certain area. Classical climatology provides a classification and description of the various climate regimes found on Earth. Climate varies from place to place, depending on latitude, distance to the sea, vegetation, presence or absence of mountains or other geographical factors. Climate varies also in time; from season to season, year to year, decade to decade or on much longer time-scales, such as the Ice Ages. Statistically significant variations of the mean state of the climate or of its variability, typically persisting for decades or longer, are referred to as 'climate change'. The Glossary gives definitions of these important and central notions of 'climate variability' and 'climate change'."

       So not only are the statistics of climate states in principle predictable, but climate itself is just the statistics of those states so while weather is not in principle predictable beyond a few days into the future, climate is.  At least according to the IPCC TAR.  Despite this, by unscrupulous (I would say dishonest) selectivity in quotation, TWFYSOWDI makes them appear to say the opposite.

       Note to the moderator:  Every now and then we get some insecure individual who is so lacking in confidence that their message can stand on it own that they feel they must give it a boost in their "nom de web".  I find such attempts at persuasion outside of reason annoying.  I particularly find them annoying when the consist of caclulated insults to their hosts.  May I suggest that such names be banned from SkS.  

29250. MA Rodger at 01:32 AM on 20 May 2015
       Climate is chaotic and cannot be predicted
       

       KR @102,

       Indeed, had This-Will-Frighten-You-So-You-Will-Delete-It read the remainder of the paragraph he quotes fron IPCC TAR 14.2.2.2 he would have learned that long-term averages and probability density functions are predictable, as the line following his quote reads "The most we can expect to achieve is the prediction of the probability distribution of the system's future possible states by the generation of ensembles of model solutions." And that is what is being delivered.

       And what fun, his nom-de-web was chosen especially for us.

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