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Comments 29801 to 29850:

29801. 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.

29802. 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.

29803. 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.

29804. 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. 

29805. 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. 

29806. 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).   

29807. 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.

29808. 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. 

29809. 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. 

29810. 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.

29811. 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.

29812. 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.  

29813. 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.

29814. Cooper13 at 01:21 AM on 20 May 2015
       My Research with Steve
       

       These are the stories you don’t read about in scientific papers, which out of necessity detail the methodology as if the authors knew exactly where they were going and got there using the shortest possible path. Science doesn’t often work like that. Science is about messing around and exploring and getting a bit lost and eventually figuring it out and feeling like a superhero when you do. And then writing it up as if it was easy.

       LOL - I think a LOT of scientists in just about any field of publication can relate to this!! Congrats on the first 'first author' article!

29815. dcpetterson at 00:25 AM on 20 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Part of denialism is based on the argument that if we don't know everything, it means we know nothing. I think ThisWillFrighten is making that same basic argument — if any part of the climate system (which includes daily weather) is chaotic, that means it all is, and models are useless.

       This is also, I think, the basis for disputing the "consensus" argument. For example, if any questions can be raised about methodology, it means the study was imperfect, and therefore cannot be trusted (or "can be dismissed", which is the same thing).

       Another example: Are you =certain= the "true number" for consensus isn't 96%? or 94%? or even 90%? If it isn't =precisely= 97%, that proves the study is flawed, and we shouldn't draw any conclusions from it.

       This "reasoning" is insidious — even if all doubt could be removed that there is, in fact, a 97% consensus on this matter, that means 3% are unsure — if anyone is unconvinced, there must be legitimate question about the matter, and we shouldn't move forward.

       I don't know how to combat this problem. It's funnny, because the same people who make these arguments are willing to, for instance, play poker, or bet on football games, or even cross the street when there could be cars around. The "if we don't know everything, we can't know anything" ploy is really a rationalization, not an argument that is sincerely held. It is an excuse for ignoring what is really a convincing reality.

29816. chrisd3 at 23:52 PM on 19 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       @Frightened: You don't understand what that quote means. It means that we can't predict the exact state at any particular time. It doesn't mean that we can't project long-term averages or trends with reasonable confidence.

29817. KR at 23:47 PM on 19 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       TWFYSYWDI - I've responded on the appropriate thread. 

29818. KR at 23:46 PM on 19 May 2015
       Climate is chaotic and cannot be predicted
       

       TWFYSYWDI - Weather is certainly chaotic, a non-linear phenomena strongly dependent on initial conditions and difficult to predict more than a week out. Climate, on the other hand, is a boundary condition problem where long term averages are driven by energy balance, and is not chaotic. Exact future weather can't be predicted. But those averages can. 

       Apples and oranges, as they say. 

29819. KR at 23:41 PM on 19 May 2015
       Breathing contributes to CO2 buildup
       

       Art Vandelay - In terms of the balance of biomass shifting from plants to humans with population growth, carbon has simply moved from one set of organisms to another - and not added to atmospheric concentrations. Again, breathing is carbon neutral, as what is exhaled simply cycles between food and CO₂ and back again. 

       Atmospheric concentrations can only have net changes over the long term if more carbon enters or leaves the biological carbon cycle - from volcanic activity (no net long-term change), from weathering (slow drawdown, not relevant over century time-scales), fossil fuel burning (the relevant cause of change over the Industrial Age), etc. Breathing does not, and can not, influence long term atmospheric CO₂ concentrations. It's a complete red herring in the discussion of climate change. 

29820. This Will Frighten You so You Will Delete It at 23:35 PM on 19 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Scad, regarding your assertion that "climate...does not appear to be" chaotic, you are not in agreement with the scientific consensus.  This is what the IPCC has written:

       "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."

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

       Moderator Response:

       [RH] Welcome to Skeptical Science!  There is an immense amount of reference material discussed here and it can be a bit difficult at first to find an answer to your questions.  That's why we recommend that Newcomers, Start Here and then learn The Big Picture. 

       I also recommend watching this video on why CO₂ is the biggest climate control knob in Earth's history.

       Further general questions can usually be be answered by first using the Search function in the upper left of every Skeptical Science page to see if there is already a post on it (odds are, there is).  If you still have questions, use the Search function located in the upper left of every page here at Skeptical Science and post your question on the most pertinent thread.

       Remember to frame your questions in compliance with the Comments Policy and lastly, to use the Preview function below the comment box to ensure that any html tags you're using work properly.

       Your previous post was delete for being baseless gish-gallop. If you're going to post here you're going to have to be able to support your positions, and when you can't, you'll need to have the capacity to concede the point. 

       First case in point, climate, by definition, is not chaotic. If you believe this to be an incorrect assertion you need to support that with research that shows otherwise. Merely repeating the assertion without support will lead to having your posts deleted.

       (edit) Note that SkS has several articles on the issue of chaotic systems. Start here.

29821. jgnfld at 21:05 PM on 19 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       It would be trivial to point out there is no overwhelming "evolution consensus" in the biological literature by counting up the number of published articles that explicitly endorse evolution in the text. Yet the argument is made that each climate paper must make an explicit claim or not be relevant to any consensus.

       Odd reasoning.

29822. BBHY at 20:07 PM on 19 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       Carbon Dioxide absorbs infrared heat energy. You can do 1000 experiments and get the same result 1000 times: that CO2 absorbs infrared heat energy.

       I don't care if it's Freeman Dyson, Judith Currty, or just some guy in congrss or on TV, none of these people have come up with any way to refute this very basic fact.

       Adding more CO2 to the atmosphere will cause the atmosphere to absorb more infrared heat energy. Adding sugar to water makes water sweeter. Adding black ink to white paint makes it darker. At the most fundamental level this is not so very difficult for people to understand. 

       It's far past time to stop with all this crazy denial of the basic, obvious physical reality.

29823. Art Vandelay at 16:22 PM on 19 May 2015
       Breathing contributes to CO2 buildup
       

       @KR "Now, if a population increases, there is a corresponding sequestration of carbon in biomass - and in that fashion the 7 billion people on the Earth represent a carbon sink, not a carbon source. Breathing, however, is simply not a net cause of rising CO2."

       I agree with the latter - that a static human population cannot on its own cause CO2 to rise.

       However, on the former point, 7 billion humans came into existence in a very short time frame in geo terms, and as we know, every carbon atom in every human is plant borne, which means that there must be less plants to sink the 'respired' CO2 with 7 billion people than there was before the 7 billion people existed. IOW, the carbon that was sequestered in plants is now sequestered in humans, and unlike plants human are combustion engines needing carbon and oxygen to produce energy and expelling CO2 as waste in the process.

       Consider the position if only plants existed. Their growth would be ultimately limited by insufficient CO2 in the atmosphere from photosynthesis.

       And now consider paradoxical the position if human population rises to the point where all vegetation is consumed as food. 

29824. One Planet Only Forever at 14:31 PM on 19 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       scaddenp,

       Using the comments made on sites like WUWT as a basis for what is commonly believed is like looking at the insects near an outdoor light bulb at night to determine the ratio or relative proportions of different insects that are active at night in a region, or looking at the birds at a garbage dump to determine the ratio or relative proportions of birds in a region.

29825. scaddenp at 13:39 PM on 19 May 2015
       Why the 97 per cent consensus on climate change still gets challenged
       

       A quick glance at commentators at say WUWT would contradict your first point. A UN/liberal plot to rule the world with falsified data when clearly climate is normal seems pretty common belief.

       "for the same reason that a butterfly flapping its wings in China can have an influence on subsequent hurricane formation in the Atlantic."

       Not remotely. Weather is chaotic but climate (weather averages over a 30 period) does not appear to be. Consider that you can get a wet cold day in summer but summer average temp is always going to be warmer than winter average temp because there is more irradiation of the surface during your hemispheric summer. Adding more non-condensing greenhouse gases to the atmosphere has same effect, but globally.

       Plenty deny it. The point of consensus is that consensus may or may not be right, but it is the only rational guide to setting policy. The consensus is that we need to reduce emissions and it appears that majority are very unwilling to do so or hate proposal that would be effective in achieving that;

       As to climate models not predicting slower warming, well what what part of  "climate models have no skill at decadal level prediction" is hard to follow? You can for instance see more of this discussed here. However, if you want to discuss this further please do so on this topic. Take very careful note of the comments policy on this site, especially the on topic/appropriate thread.

29826. Tristan at 12:00 PM on 19 May 2015
       Climate sensitivity is low
       

       Interesting, I would not have intuited that result at all!

       
       bobl's difficulties in finding the sensisitivity to GHGs would be further compounded by the fact that you shouldn't be looking at the net antho effect anyway - as that ignores the negative anthro forcings.

       
       It seems that you can't determine the ECS (or it's more relevant brother, TCR) from the recent temp record without first accepting the validity of quite a number of papers, something that bobl would never admit to doing in the first place. He's kinda stuck.

29827. Tom Curtis at 10:20 AM on 19 May 2015
       Climate sensitivity is low
       

       Tristan @362, out of interest I just downloaded the forcing data from the IPCC AR5.  From that I was able to determine the relative contributions of natural and anthropogenic components between certain dates and 2009 using five year running means:

       1850 104.52%
       1880 102.34%
       1900 94.58%
       1950 109.72%

       Note that the ratio of difference in forcing is not the same as contribution to difference in temperature.  That is because there is some internal variability in temperature, because volcanic temperature responses are not commensurate with instaneous volcanic forcings due to thermal inertia, and because earlier forcings will have more fully worked through the system than will have later forcings.  With these caveats, however, the relative contribution to change in forcing is a good first approximation to the relative contribution to change in temperature.  

       Allowing for the caveats, I believe the 1880 and 1900 figures significantly overstate the anthropogenic contribution.  In particular, the anthropogenic contribution to change in forcing falls to 57% in 1885 and to 76% in 1904.  Given the extent and intensity of volcanism that cause those falls, it would be foolish to assume a simple five year mean of the forcings captures the temperature impacts of that volcanism.  Further, there is good reason to believe there was a significant contribution from internal variability to the temperature increase from 1910-1940 which will be diluted but also relevant to the temperature increase to 2010.

       Of course, Bobl is not entitled to these caveats.  In his calculation he ignores internal variablity (which of necessity cuts both ways), and by assuming TCR = ECS, he also ignores thermal inertia.  Given that, it would be inconsistent of him to not use the relative contribution to forcing increase as the relative contribution to temperatue gain.

29828. Tom Curtis at 06:19 AM on 19 May 2015
       Breathing contributes to CO2 buildup
       

       Phil @40, below is the most recent IPCC estimate of the various fluxes in the carbon cycle (with changes to the process since the preindustrial shown in red):

       

       If you look closely you will see that "Gross photosynthesis"  minus "Total respiration and fire" results in a positive flux of 2.6 +/-1.2 Petagrammes Carbon per year out of the atmosphere.  That is an increase over the preindustrial value by more than the 90% uncertainty.  Ergo it is simply false that "Of course land use change (specifically de-forestation) has been a significant carbon source, offsetting any increase in other forms of biomass."  (As an aside, "respiration" in these terms includes natural decay.)

       FYI, these values are known fairly well because they can track the decline in O2 in the atmosphere, which excedes the corresponding increase in CO2 from fossil sources, even after allowing for ocean uptake (CO2) and outgassing (O2).   

29829. TheCheshireCat at 06:07 AM on 19 May 2015
       Inoculating against science denial
       

       Bland Denial is merely one component of the strategy first published by Peter Clyne in "How not to pay your debts - a handbook for scoundrels". Clyne proposed that successful evasion (of scientific truth, or obigations, or indeed debts) required these 4 steps: Deny, Delay, Confuse, Part-Pay (in an endlessly recurring sequence with slight amendments for each recycle). For example:

       1. Deny: (climate change is a myth)
       2. Delay: (More research is needed, wrong to act precipitously)
       3. Confuse: (Climate change is multifactorial, therefore wrong to focus on one single cause)
       4. Part-Pay: (okay climate change is here, but its not man-made)

       Spice this up with some crooked language and logic, as Cook suggests, and there you have it. Add to this industry sponsorship of scientists and regulators to add some much-needed bias, and, well, here we are.

       I'm reminded of the Upton Sinclair quote: 'It is difficult to get a man to understand something, when his salary depends on his not understanding it.'

       Alice.

29830. Tom Curtis at 06:05 AM on 19 May 2015
       Breathing contributes to CO2 buildup
       

       Art Vandelay @38, any carbon in animal matter has first existed as carbon in plant matter.  Any carbon in plant matter was in turn first extracted from the atmosphere by photosynthesis.  The food chain may be extended in that, for instance plants (planckton) may be consumed by carnivorous planckton, which may in turn be consumed by planckton eating fish, that may be consumed by low level carnivous fish, that may be consumed by a top predator like Tuna, that may in turn by consumed by humans - but that does not alter the fact that every molecule of carbon in humans was first extracted from the atmosphere by photosynthesis (ignoring plastic based prosthetics).  Therefore your argument fails because it reverses the logical order of the process, assuming in effect that the CO2 in humans comes into existance by a creative act and needs to be then, later extracted by photosynthesis.

       Given this, there are only two ways that human respiration can increase atmospheric CO2.  The first is if the whole cycle ceases, so that CO2 respired is not then taken up by plant matter.  The second is if the whole cycle changes its time constants so that the carbon in the cycle spends relatively less time in biomatter and relatively more time in the atmosphere.  For both of these, because they involve the whole cycle and not just human consumption it is not particularly appropriate to look at it in terms of respiration.

       Of the two methods mentioned above, it is known that the first is not occuring.  The second, however, is occuring, but is already accounted for in carbon budgets under the label of Land Use Change (LUC).  Land Use Change, however, includes a large number of inputs in addition to changes in the relative rate of respiration.  It includes, specifically, deforestation for the timber industry; and deforestation for land clearing (in which the timber is simply waste, and does not enter the human carbon cycle).  These components dominate the LUC budget, so it is not possible to extract from the LUC figures any meaningful estimate of the change in relative times of carbon in the atmosphere from those figures (SFAIK).  

       One thing that is known, however is that net biosphere productivity is a sink for CO2.  That is, once you add up all of the effects of deforestation, changes in agricultural practises, growth of urban areas, draining of swamps etc, and subtract from that the effects of increased plant growth due to increased humidity, the fact that human timber is better protected from decay than natural equivalents, (and hence precipitation) and any carbon dioxide fertilization effect, the total biosphere is absorbing more CO2 from the atmosphere than it is emitting.

29831. Phil at 04:35 AM on 19 May 2015
       Breathing contributes to CO2 buildup
       

       KR @39
       

       Now, if a population increases, there is a corresponding sequestration of carbon in biomass - and in that fashion the 7 billion people on the Earth represent a carbon sink, not a carbon source.

       But this may be offset by a decrease in other animal populations. Admittedly the rise in human population may have also produced a concomitant rise in domestic animals, however the population of wild animals has crashed over the past century. The population of non-photosynthesising organisms is dependent on the population of photosynthesising ones, and that in turn is dependent on the land mass available to them, along with the "ingredients" for photosynthesis. Of course land use change (specifically de-forestation) has been a significant carbon source, offsetting any increase in other forms of biomass.

29832. KR at 02:25 AM on 19 May 2015
       Breathing contributes to CO2 buildup
       

       Art Vandelay - "...the fact that we're net emitters (of CO₂) rather than net absorbers of it, unlike plants"

       Um, No. Aside from our fossil fuel emissions any stable population of organisms is carbon neutral, as the carbon in them comes from the environment and upon death returns to the environment. While carbon-containing food comes from the environment and is itself cycled back as (among other things such as fertilizer) CO₂. 

       Now, if a population increases, there is a corresponding sequestration of carbon in biomass - and in that fashion the 7 billion people on the Earth represent a carbon sink, not a carbon source. Breathing, however, is simply not a net cause of rising CO₂. 

       But then we go and burn fossil fuels that have been sequestered for hundreds of millions of years, and we go straight from carbon neutral to immense net emitters... sigh.

29833. bozzza at 01:43 AM on 19 May 2015
       Monthly global carbon dioxide tops 400ppm for first time
       

       I've always wanted to know if this would work...

29834. Art Vandelay at 01:09 AM on 19 May 2015
       Breathing contributes to CO2 buildup
       

       RJS

       I liked your water baloon analogy.

       The debate in some of the climate threads in cyberspace over whether the respiration of 7 million human inhabitants adds significantly to AGW is obviously alive and well, particularly among skeptics. 

       On the face of it the total emissions from animal respiration are considerable but of course we know that the carbon cycle is also a closed system.

       Having given this some thought though I'm of the view that respiration from 7B people must increase atmospheric CO2 if for no other reason than the fact that we're net emitters rather than net absorbers of it, unlike plants. 

       To maintain an equilibrium it's obviously necessary for respired CO2 to be offset by photosynthesis in plants, which requires us to grow synthesising plants at the same rate that we're consuming them.  We all agree on that I'm sure.  

       However, the net effect is to amplify the carbon cycle in much the same way that higher tropospheric temperature amplies the water cycle.

       In the same way that the atmospheric transportation of water increases with temp so too does the transportation of CO2 into the atmosphere from increased animal respiration, resulting in an increase in the static level of atmospheric CO2 that's proportional to the population.   

       Since the laws of physics can't be broken the only way that this is possible is by converting O2 into CO2 and by transporting sequestered carbon (from trees and plants) into the atmosphere. Although humans grow crops to maintain the equilibrium they've needed to remove existing trees and plants to accomplish it, so effectively the amount of carbon that's stored in plants must have decreased as population has increased.  

       To what measnureable extent humans contribute to an altered ratio of OC and CO2 in the atmosphere is impossible to measure but I'm sure that it's dwarfed by CO2 borne from fossil fuels, but nonethless I don't think we can or should claim that human respiration from 7 billion people does not increase atmospheric CO2 to some degree.

29835. CBDunkerson at 22:38 PM on 18 May 2015
       Monthly global carbon dioxide tops 400ppm for first time
       

       chriskoz, aviation accounts for ~2% of emissions. Adding in the few categories of large ground vehicles which require an energy density that only fossil fuels can currently deliver might raise it to 3%. Thus, while I agree that we will likely continue to see some fossil fuel use for decades to come, I stand by my prediction that the peak of fossil fuel usage is less than a decade away.

       Indeed, China may have already turned the corner. India and the rest of the 'developing world' countries which had been driving increases the past couple of decades aren't far behind.

       Obviously, it will take time to replace the existing fossil fuel infrastructure with renewables, but we are very near (possibly even past) the turning point. Total CO2 emissions basically held steady last year despite global GDP growth. Trends so far this year suggest that CO2 emissions may well drop.

       We talk about environmental tipping points, but such things also exist in politics and economics. We are very close to the point where renewables finish supplanting fossil fuels as the darlings of the global economic and political castes. Soon they will be growing not just because they are better, but also because they will be propelled by the same forces which have thus far been deployed to hold them back.

29836. MA Rodger at 22:18 PM on 18 May 2015
       Models are unreliable
       

       Klapper @923.

       You conclude "So both the TOA spread from model to empirical and the SAT warming rate spread agree the models look to be running too hot." but your inclusion of "TOA spread" in this statement is entirely unsupported.

       Imagine a world and a model-of-that-world with the model running hot. We impose forcings of equal size onto both. The model SAT rises faster because it runs 'hot'. But all things being otherwise equal, that would reduce the TOA imbalance as a higher SAT leaches more energy back into space. Thus my comment questioning whether high TOA could not be seen as a symptom of a 'cool' model.

       But in climatology, things are never 'otherwise equal'. A 'hot' model with increased SAT presumably results in higher 'forcing levels' due to higher positive feedback. Now if the world & the 'hot' model had an SAT that were equal, their conforming increase in SAT would have equalised different proportions of the initial forcing as the level of feedback is different. In the model because of the larger feedbacks, this equalisation will be less - there will be more of the forcing remaining - more TOA imbalance. So we can propose that the TOA imbalance would differ because proportinately less forcing would be equalised in the model. The difference would be most dramaitc in a 'well-equalised' situation, where most of the forcing has been equalised. But let us assume the forcing is roughly half equalised in the world with the 'hot' model showing 33% more TOA imbalance, 33% less forcing equalised, but the same SAT. This implies ECS in the model is 50% too high.

       But if in the model both TOA imbalance were higher and SAT were higher (this last the Klapper definition of a 'hot model' and exemplified by the CMIP5 projections 2006-2014) , ECS would have to be now greatly different to balance the books. @923, a value is suggested for the model ΔSAT = 150% of world values yielding a model:world ECS of 2.25:1. But this does not actually relate to the post-2006 period. To compensate for both TOA imbalance and the differences in SAT we are therefore talking, what, ECS proportionately 3:1, 4:1, more.
       Given the CMIP5 models perform well prior to 2006, is it then at all likely that ECS in the models is so wrong? So how can we simply attribute the post-2006 performance to them being 'hot models'?

29837. Tristan at 13:42 PM on 18 May 2015
       Climate sensitivity is low
       

       @DB, thanks for checking, those arguments definitely sound like ones he'd make, though I dont know if that's him.

       @michaelsweet, thanks, can't blame a layperson for using hadcrut in this instance, and I'm waiting for his response on the as-yet-unrealised warming.

       @MARodger, the best moment I've had recently was when someone told me that you couldn't use EVs for continuous random variables, and when I pointed him to a description of how you could he claimed "Queen's Gambit" and that he just was proving that I could spot a cherry pick. Which, I dunno, means he can accuse me of dishonesty in the future if I fail to agree with him that something is a cherry pick? Guess he got me.

       @TomC, thanks, I actually posted that very graph before coming here, to which Bobl responded: my math is pretty much indisputable. I expect if he did [post it at Sks] I’d not get one refutation, they’ll either pick an irrelevancy like Tristan did, or for example want to pick a higher figure for the warming from 1850.

       Every few months I go back, thinking, "maybe there'll be some people who respond in a reasonable manner", but the content is 40% rhetorical games, 30% slurs, 20% crazy,  and only 10% the sort of argument I'm looking for. And then you I moderated for...who knows. I was told narcissism. I guess for not showing enough deference.

29838. KR at 13:09 PM on 18 May 2015
       The climate 'hiatus' doesn’t take the heat off global warming
       

       Owenvsgenius - See IPCC AR5 on detection and attribution for a summary of the literature on what percentage of recent warming is attributable to anthropogenic factors. The mean estimate is that ~110% of the warming over the last half-century is due to us. 

       I believe the other references you've been given on ocean sampling are a good start, and will defer additional comments in that regard until you've done some reading.

29839. bozzza at 11:42 AM on 18 May 2015
       Ice loss in west Antarctica is speeding up
       

       owenvsgenius, have you ever heard of dimensional analysis?

29840. scaddenp at 11:27 AM on 18 May 2015
       Ice loss in west Antarctica is speeding up
       

       Antarctica as a whole is losing ice (eg see here) at rate in order of 150Gt per year.

       There is some expansion of sea ice around the continent (which at first glance is paradoxical as the sea warms) with complex causes. Note that an increase in sea ice in winter (when there is no sun) in no way offsets loss of arctic ice in summer (which causes a loss of albedo).

29841. scaddenp at 11:16 AM on 18 May 2015
       The climate 'hiatus' doesn’t take the heat off global warming
       

       I think the information on you want (level of uncertainty in ocean indicators) can be found Schuckmann and La Traon

29842. Tom Curtis at 11:04 AM on 18 May 2015
       New study finds a hot spot in the atmosphere
       

       chriskoz @11, in my comment @3, the first two images are the images used in the RealClimate post to show that both CO2 and solar forcing result in a tropospheric hotspot.  The third image is, as you show the effect of halving CO2 (after 100 years).  The fourth image, for comparison, is the effect of maintaining 1/3rd Pinatubo forcing for 100 years.

       I would certainly be interested in, and gratefull for, Chris' rerunning of the GISS model for the equivalent experiment.

       I cannot comment on Ben Santer's input as I have not seen it.  Could you provide a link.  Further, if he is commenting on the topic somewhere, and you can respond, could you ask his opinion of my point 4 immediately above.  Specifically, what is the algorithm for "MSU Space"?  Does converting to it have the effect I postulate?  Also does he have any graphs of absolute temperature values with altitude in MSU space as the test of the effect of using MSU space?

29843. bozzza at 10:56 AM on 18 May 2015
       2015 SkS Weekly News Roundup #20B
       

       Precisely correct, Bjorn Lomborg is blind to intergenerational inequality. His political message is a global one: that carbon emissions be allowed to warm the earth by three degrees. (What was his choice of measurement btw as I  cannot recall?)

29844. Tom Curtis at 10:55 AM on 18 May 2015
       New study finds a hot spot in the atmosphere
       

       Tom Dayton @9 & 10, Michael Mann writes:

       "Just compare the GHG signal in Santer et al '13 (which shows a hot spot) and the volcanic (which doesn't, and shows a change of sign at 500 mb, which is very close to the 595 mb PEAK of the TMT weighting function--if there were a mid-tropospheric hotspot, it should be seen in TMT)."

       My emphasis.

       Below is a figure showing the trend warming rates from 1979-2012 in the troposphere by altitude for all CMIP5 RCP8.5 models:

       

       The source of the diagram is John Christy, which is dubious in some respects, but I presume he has not misrepresented the model outputs.  That being the case, the CMIP5 models show a clear upper tropospheric hotspot with a multimodel mean peak warming at 250 mb.  Despite this the trends from 1979-current are:

       GISS 0.158 C/decade

       RSS TLT 0.121 C/decade

       RSS TMT 0.077 C/decade

       RSS TTS 0.011 C/decade (from 1987)

       RSS TLS -0.269 C/decade.

       Clearly the trends decline as the mean altitude of measurement rises, with the TMT trend being less than either the TLT or surface trends, and greater than any trends above it.  It follows that if Mann's claim highlighted above is true, then there is no tropospheric hotspot contrary to the model predictions.  In other words, if Mann's highlighted claim is true, the models have been falsified on a fundamental issue that is vital to estimates of climate sensitivity and future warming.  Michael Mann may want to claim in response that his claim is only applicable to volcanic warming, and not warming in general.  If so that is just the rankest special pleading.  If not he either has to accept my claim @8, point (3), above, or radically revise his reliance on models, and his view as to the dangers of AGW.

       Further, the GISS Model E vIII 1880-2000 all forcing response by altitude is shown below:

       

       As you can see, the peak warming is around 350 mb (337.5 mb).  That is in fact lower than the CMIP5 multimodel mean, and also lower than the CMIP5 versions of the GISS Model E (six versions, shown with dotted lines of various shades in the first figure above).  That discrepancy may be simply due to the different forcing periods, but if anything the evidence is that the altitude of peak warming has shifted upwards from CMIP3 to CMIP5, not downwards as would be required for the GISS model E images I have been using to be in need of significant correction.  

       As an aside, there is certainly no reason to prefer the data from cone CMIP3 era model, ie the Parallel Climate Model (PCM) as shown in the IPCC reports and used by Mann over another model of the same vintage (GISS Model E vIII).  As a further aside, the peak cooling for the one third Pinatubo forcing shown @3 is also at 337.5 mb).  This point should be irrelevant in that I originally rebutted Mann's claim that,  "if global warming really *were* due to a (natural) decrease in volcanic activity over time ... then we would expect to see an increase in global surface temperatures WITHOUT any mid-tropospheric "hot spot"".  Mann now appears to be trying to make the issue about the exact altitude of peak warming, which shifts the goal posts.  He also misrepresents the altitude of the peak warming (or cooling) in the GISS model, claiming (@10) it is about 140 mb higher in the atmosphere than actually shown by the model.

       3) Fairly abviously, the PCM models shown @10 do not use a period with significant volcanic forcing, with the consequent that any coldspot is too small to register for the volcanic forcing given scale.  The same also applies with sign reversed for the solar forcing.  That is telling in that solar forcing is definitely one of the forcings which does show a hotspot, but shows no hotspot in the PCM figure.  As Mann accepts that solar forcing generates a hotspot, he must attribute the lack of a visible hotspot in the solar forcing panel to the small quantity of warming relative to the temperature scale used.  He cannot therefore consistently argue that that is not also the case with respect to the volcanic forcing.

       4)  Finally, with respect to figure 2 from Santer et al (2013) (see your post @6 above), Santer et al write:

       "Zonal-mean atmospheric temperature trends in CMIP-5 models (A and D–G) and observations (H and I). Trends were calculated after first regridding model and observational TLS, TMT, and TLT anomaly data to a Graphic latitude/longitude grid, and then computing zonal averages. Results are plotted in “MSU space,” at the approximate peaks of the TLS, TMT, and TLT global-mean MSU weighting functions (74, 595, and 740 hPa, respectively)."

       My emphasis.

       It is not explained what "MSU Space" is, although it is almost certainly not a linear function of temperature with altitude.  More likely, at each altitude, the value shown is the weighted average of the TMT, TLS and TLT trends, with the weighting determined by the relative weight of each channel at that altitude as shown in my post @8, although different algorithms with similar effect could also be used.  As such, it loses vertical structure.  That is because it first reduces the vertical structure to just three values, and then tries to recompose it from those three values.  It is, in effect, a complex smoothing of the data.  As such it will not more show the tropospheric hotspot than will the TMT channel (for reasons given above).  What it will show is what will be found by attempts to reconstruct the vertical temperature signal from the MSU or AMSU channel outputs.  That, of course, is very useful for comparison with satellite data, but renders the graphs positively misleading about the detailed vertical temperature structure of the atmosphere.

29845. Daniel Bailey at 10:47 AM on 18 May 2015
       The climate 'hiatus' doesn’t take the heat off global warming
       

       @ Owenvsgenius

       Here's a couple to give you a head start on your research:

       1. ESRL NOAA
       2. Abraham et al 2013
          

       Google Scholar wants to be your friend.  Call him.

29846. bozzza at 10:46 AM on 18 May 2015
       The climate 'hiatus' doesn’t take the heat off global warming
       

       Owenvsgenius, you can't measure everything: this is called 'the uncertainty principle'. Thus all measurements have to be verified by other means making repetition of results central to scientific method!!

29847. chriskoz at 10:09 AM on 18 May 2015
       New study finds a hot spot in the atmosphere
       

       Tom Curtis @3,

       Looks like Mike Mann did not even change the details of his hypothesis based on your input. And as it turns out MM hypothesis is backed by Ben Santer, your inquiry to the authority of Gavin Schmidt on the subject is unlikely to change anything. Meanwhile Chris Colose offered to run GISS model you claim about volcanic hot spot is based on, to run it and check the apparent discrepancy: we are all eager to see the results, thanks Chris!

       Meanwhile, pardon my punt, I don't see the extraordinary evidence you need to provide in support of your extraordinary claim taking on the top scientists. If particular, your third image is just a hot spot cooling due to a loss of 50% of CO2, as seen in the NASA link you cite. Where is the "1/3 rd Pinatubo level volcanic forcing" picture where you claim "the patterns in the tropics are very similar"? Maybe you've seen but missed that picture. Please provide it for the benefit of us better understanding your point.

29848. Owenvsgenius at 10:02 AM on 18 May 2015
       The climate 'hiatus' doesn’t take the heat off global warming
       

       Can anybody tell me the spacial resolution and coverage of ocean temperature surveys? This question impacts the subject matter directly, as models use survey data

       Moderator Response:

       [JH] Perhaps you should do your own research on this matter. 

29849. Tom Curtis at 09:43 AM on 18 May 2015
       Climate sensitivity is low
       

       Bobl writes, "Now the IPCC says that 50% of warming is probably coming from humans and 50 % is natural variation ...".

       What the IPCC actually wrote was that:

       "More than half of the observed increase in global mean surface temperature (GMST) from 1951 to 2010 is very likely due to the observed anthropogenic increase in greenhouse gas (GHG) concentrations."

       where "very likely" means "90-100%" likelihood.  In other words, what the IPCC claimed was that there is a less than 10% chance that only 50% or less of 1951-2010 warming was due to anthropogenic forcings.  That is sufficiently different, indeed contradictory of what Bobl claimed the IPCC wrote that prima facie, he is a bald faced liar.

       Indeed, it is worse than that.  The IPCC also provided a figure with the mean and uncertainties of attribution.  This allows you to generate the Probability Density Function (PDF) of the AR5 attribution, as was done by Real Climate:

       

       From this, in turn, it can be determined that the actual likelihood of less than 50% anthropogenic causes of warming since 1951 is 0.06%.  It follows that at best Bobl is calculating the lower bound of the 99.9% probability range of the "climate sensitivity".  To perform the calculation correctly (ignoring other errors), he should have used an attribution of 107.7% (the mean value of the PDF).  Correcting for this factor alone would more than double his "climate sensitivity" estimate.

       It should be noted, of course, that the IPCC attribution statement only covers the period 1951-2010.  It cannot be arbitrarilly extended to cover periods back to 1900, 1880 or 1850.  Natural forcings were negative from 1850 to about 1910, strongly positive from then to 1940, and remained positive to about 1950, as they more than recouped the losses to 1910, and have been effectively neutral or slightly negative since then.  The result is that 70% is a better estimate than 108% for the anthropogenic contribution since 1900 (or 1880), but 100% is probably more accurate for the anthropogenic contribution since 1850.  These figures, of course, are highly uncertain and not particularly precise.  Sufficiently so that I consider estimating climate sensitivity from temperature differences between two dates with the first date prior to 1950 to be essentially a waste of time.  If you are going to make those estimates, you should greatly increase the data used  to counter the uncertainties.  You do this by fitting a Transient Climate Response (TCR) function to annual data as Kevin Cowtan has done.  The result is a TCR around 2 C per doubling of CO2, with an Equilibrium Climate Sensitivity necessarilly greater than that.

29850. Owenvsgenius at 09:09 AM on 18 May 2015
       The climate 'hiatus' doesn’t take the heat off global warming
       

       KR, I would like to point out that we do not posses the coverage needed to properly survey the ocean and its depth to come up with anything concrete. Our surveys currently rely on a lot of speculation

       Moderator Response:

       [TD] You need to back up your contentions with data.

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