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On Consensus

Posted on 2 August 2010 by Daniel Bailey

Guest post by Daniel Bailey

As individuals, we learn through hard experience in our lives how to make choices.  Over time we learn to make optimal choices, that is, choices based on as much evidence as possible that will then lead to the best possible result.  That is essentially the scientific method in action.  In science, when evaluating all the available evidence, the theory that best explains what the data shows is usually the best choice.

A small number of people meeting to make a choice usually do so by discussing the various points that matter most to each, usually leading to a quick resolution and decision.

When a large number of people come together to make a decision about something, however, chaos can ensue.  There exists not equal abilities to both communicate and to share the time available to communicate, resulting in an impasse.  To resolve this, people typically appoint a knowledgeable person they trust to make an optimal decision on their behalf.  These appointed people form a committee, a smaller number of informed individuals empowered to make decisions for the good of the whole.

In committees, choices are made by the input of the group of people comprising the committee.  This group-made set of choices is said to be the consensus of the group.  The group consensus is then relayed back to the rest of the people, either by the individual members of the committee or by an appointed representative of the committee.  The people then have a choice:  to accept the consensus developed by the person they entrusted to make it, or not.

This arrangement has worked quite well for most bodies of people in the world throughout history.

But when it comes to communicating the consensus of climate science, it does not.  Consensus delivered to the public from scientific organizations worldwide on climate change is met with derision, vitriol and dismissal.  

Let us consider an example of that.  

Submitted for your approval:  The Teacher and the Student.



Teacher:  It has become apparent that a disconnect exists between the understood level of agreement, or the Scientific Consensus, on climate change within the scientific community and that of the rest of humanity. 

Student:  (thinks, vaguely remembers reading “Scientific Consensus” last night between many beers, smiles at memories of beers, nods) OK.

Teacher:  The current level of Scientific Consensus on climate change was expressed most recently by the National Academy of Science in their publication Advancing the Science of Climate Change.  In it they specify: 

A strong, credible body of scientific evidence shows that climate change is occurring, is caused largely by human activities, and poses significant risks for a broad range of human and natural systems….
Some scientific conclusions or theories have been so thoroughly examined and tested, and supported by so many independent observations and results, that their likelihood of subsequently being found to be wrong is vanishingly small.

Such conclusions and theories are then regarded as settled facts.

This is the case for the conclusions that the Earth system is warming and that much of this warming is very likely due to human activities.

Student:  Huh?

Teacher:  (translates to student-speak) Rock-solid.

Student:  Oh.  So what does “very likely” mean, then?

Teacher:  “Very likely” means a greater than 90% likelihood of probability.  I.e., pretty certain.

Student:  Lemme see if I got this right:  the Earth is warming = rock solid.  That we are the ones causing it is pretty certain.

Teacher:  Yes.

Student:  So what’s all the fuss about, then?

Teacher:  People don’t want to believe, for various reasons, so they desperately look around for anything they can to perhaps put off having to face reality.

Student:  So people are in denial?

Teacher:  That’s a strong word.  We usually use the word “Skeptic” and reserve “Denial” for those beyond rehabilitation.  Usually they’re the ones without a strong background in Critical Thinking or the Scientific Method.  An additional problem for them is that, in order to find something concrete to overturn the human-causation of global warming, they would have to come up with a physics-based theory that explains why the greenhouse gas effect of CO2 only works part of the time and not others.   A deeper problem exists for those Skeptics who have enough knowledge of the science to be dangerous, but not enough awareness of self to realize the limits of their knowledge.

Student:  Explain further this semi-mythical “greenhouse gas effect of CO2”, oh Fount of Knowledge.

Teacher:  Snark won’t score you extra credit, boy.  Based on the radiative physics of greenhouse gases, here’s what we know:

1.  Increasing the level of a greenhouse gas in a planet’s atmosphere, all else being equal, will raise that planet’s surface temperature.

2.  CO2 is a greenhouse gas.

3.  CO2 is rising.

4.  Therefore (given 1-3 above) the Earth should be warming.

5.  From multiple converging lines of evidence, we know the Earth is warming.

6.  The warming is moving in close correlation with the carbon dioxide.

7.  The new CO2 (as shown by its isotopic signature) is mainly from burning fossil fuels.

8.  Therefore the global warming currently occurring is anthropogenic (caused by mankind).

Student:  That’s a lotta links.  So, in order to disprove human-caused global warming, deniars skeptics would have to find a viable physics-based alternative to one of the points in that chain you just outlined?

Teacher:  Correct.  And to date, none have been able to do so.  Plenty have espoused alternative theories on blogs, but none have been able to survive scrutiny in a peer-reviewed publication.  At this point, the chances of viable alternatives arising are remote.

Student:  So why hasn’t the general public caught on?

Teacher:  Excellent question, my young apprentice!  It’s due to some skeptics and media types using a slightly different view of consensus, popularized by Funtowicz and Ravetz in 1990: 

1. No opinion with no peer acceptance;
2. An embryonic field attracting low acceptance by peers;
3. Competing schools of thought, with medium peer acceptance;
4. A dominant school of thought accepted by all but rebels;
5. An established (many validation tests, causal mechanisms understood) theory accepted by all but cranks.

The skeptics and media types paint a picture of climate science as being in the 2 or 3 range on that scale.  However, take into consideration the NAS report Advancing the Science of Climate Change discussed previously, and these other statements from leading academic bodies and governments around the world:

Consensus Statements at Logical Science

Consensus Statement at the Union of Concerned Scientists

The Signed Consensus Statement on Climate Change by 18 Associations

Signed Consensus Statement on Climate Change by 11 International Science Academies

By these measures, on the Funtowicz and Ravetz scale, the consensus on climate science would come in between 4.5 and 5, with the only remaining discussion revolving around why it shouldn’t be a full 5, given the overwhelming mass of converging evidence extent today.

Student:  Your Immenseness is truly in rare form today!

Teacher:  (smiling to himself, envisioning the poor grade forthcoming) Like the public, you have no idea.

This, then is where science stands:  consensus on climate change exists and has been delivered.  And been met with apathy, denial, anger, fear, ridicule and accusations of corruption.

So where do we go from here?

What is our path forward?

Let your opinions be known, as the committee on this issue now includes all mankind. 

For all are affected and at risk.

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Comments 1 to 46:

  1. The turn from cooling to warming during the last ice age and the turn from warming to cooling before that are the major events which should be used to back check the models. Certainly these weren't caused by carbon dioxide as the temperature turned up first.
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    Response: The switch from ice age to interglacial (and vica versa) are not initiated by carbon dioxide but by changes in the Earth's orbit. For example, around 20,000 years ago, the Earth's orbital configuration was such that there was more sunlight hitting the South Pole at spring time. This caused warming in the Southern Ocean which led to outgassing of carbon dioxide which both amplified the warming and spread it to the north. This is why CO2 lags southern temperatures. But importantly, northern temperature also lags southern temperature - and northern temperature matches CO2 closely. Here are more details on the CO2 lag...

    So the CO2 record is entirely consistent with the warming effect expected from CO2. Of course, you don't have to go back into the Earth's deep past to work out whether CO2 causes warming - satellites directly observe CO2 trapping more heat over the last few decades.
  2. For some reason I'm thinking of the Tour de France. You've got your peleton (NAS summary, IPCC), your leaders and attackers (domain-specific researchers just reaching the bottom of the Greenland ice sheet, etc. and competing to get ahead of everybody else) as well as those who've been dropped but are still being encouraged by coaches to pedal a little harder and try to catch up.
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  3. Ice ages, C02 etc. are tractable and in any case are not analogous with the present situation. See CO2 lags temperature - what does it mean?, On temperature and CO2 in the past, The significance of the C02 lag for some more information
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  4. Doug, you're too quick! I was just about to post that response to handmjones @ #1. This reflects on both the previous post and this one - with many skeptics out there, it's about communication. They have read or heard a little bit of stuff, and comments like "CO2 lags temperature" seem to neatly explain the denialist position. Sadly, very few of them then go searching for more information to see what the science actually says on that (which highlights the problem in the recent post about so-called 'balanced' media coverage). handmjones is actually way ahead of the curve here - he/she is reading a website that reports and discusses the actual science behind the statements. Well done on making it this far, and enjoy the learning experience - as much as is possible while finding out about the approaching train-wreck that is global warming...
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  5. A good science teacher needs to impress on students the differing levels of certainty available from various fields of science. Physics relies directly on mathematical modeling; can perform controlled experiments with testable predictions over thousands or millions of trials; can make predictions of locations of planets hundreds and thousands of years in advance with highly accurate precision. Medical science performs thousands and millions of tests and trials and measures whether outcomes match predictions. Life spans are small enough and there are millions of human subjects such that predictions are relatively easily tested without great risk of life by staging trials with a small number of subjects before exposing the entire human population to risk. Climate science is in a relative infancy when compared to physics or medical science. The ability to do controlled tests is non-existent as Earth Climate is not a closed system. The Earth is a massive thermal dynamics experiment with most of the heat for climate stored in deep oceans. Twenty years ago deep water was not part of any climate modeling. I think climate scientists are on the right track. But we still don't know the inter-workings of much of the sub-surface. Students should understand: Physics is a 5 Medical Science is a 4.8. One expects 99.999999% accuracy from physics. One expects 60-99% accuracy from medical science. Doctors still have difficulty predicting which treatments will work on which patients and doctors may need to try different prescriptions to determine which will work for them. Climate Science has yet to make a testable prediction with any sort of mathematical accuracy. By accuracy, I mean a series of predictions that reflect at least a 90% accuracy on a global basis. Until then, Climate Science hovers around a 3 or a 4. The teacher really needs to focus the student on the fact that "Science" requires a stated hypothesis, a future prediction and testable and tested results. Climate science is no where near the certainty of the harder sciences. Advocating that Climate science is actually a 5? That is clearly dogma, not science!
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  6. And why is medical science a 4.8? I'm inclined to the view that climate science is very much on the same footing as medicine. Ever heard the mantra, "Every prescription is an experiment?" Anatomy, biology, chemistry all tell us that vaccines and drugs have certain effects. At a population level this is absolutely true. At the individual level, the combination of other drugs, physical weaknesses and strengths, immune predispositions and all the rest of it mean that the effect may be exactly as desired, more or less efficacious, totally ineffective or downright dangerous. Just like climate science predicts the global effects, but no-one can be sure of local weather effects. I'd put climate science at the 4.5 to 5 range.
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  7. Re: nhthinker at #5 and adelady at #6 above: There is a very extreme similarity between medicine and climate science: in both, extremely negative events can occur. Experiments with far-reaching effects carrying risks of terminal consequences can occur. A catastrophic failure in a single patient is an experiment that can be run once. Similarly, a catastrophic result due to changes in radiative imbalance causing climatic disequilibrium also carries fatal consequence (and can be done once). A result that we may unfortunately have to post-mortem. In terms of clinical understandings versus real-world application, medicine is a safe comp for climate science. Great understandings and uncertainties exist in both. The Yooper
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  8. Excellent piece. Well done, thanks!
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  9. The list of 'links' (1-8) from radiative physics proving AGW is very good. Unfortunately, the list of points describing/defining the "skeptic's definition of scientific consensus" (1-5) is very bad. No one can tell what you think the skeptics really mean by 'consensus' from such a description, which in turn means your attempt to refute it fails miserably. This is particularly tragic since the skeptic's sense is wrong, and should be easy to refute -- if only they would make up their minds what it is. But here is where the real problem is: the skeptics have figured out that they can persuade many without EVER clearly stating what they think 'consensus' is. They have figured out that all they have to do is cast doubt on the sense scientists really use. But this is easy to do, since their audience really does not (as you point out) understand either critical thinking of the scientific method. Nor do they really trust scientists. This devious method of rhetoric is described in the reference I gave before on the topic, Specifically, in Book II part 1, he says: "But since rhetoric exists to affect the giving of decisions... and put his hearers, who are to decide, into the right frame of mind". For those who argue against any action to mitigate AGW, it is very easy to put their hearers into that "right frame of mind"; in this case, that frame is dismissal of the scientific consensus, because they don't trust scientists. All they have to do is appeal to that distrust.
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  10. Among members of the public the truly dismissive of mainstream climate science are in a pretty small minority. Numbers fluctuate over time; it's interesting to see the effects of distractions over winter apparently fading. That graphic was taken from this study which does a superior job at slicing and dicing public attitudes and beliefs w/regard to climate change, compared to newspaper polls and the like. The 2008 version of the same study has some fascinating tables describing where beliefs are clustered w/regard to ideology and other factors unrelated to science itself. There's a ton of activity among social scientists in this arena these days. The whole thing is morphing into a social science problem, for that matter. Can a horse be led to water and made to drink? A fascinating question.
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  11. I agree with Matt I think on consensus. I am quite sure that deniers haven't thought through the steps to consensus and come to a rational decision that climate science is in the range of "2. An embryonic field attracting low acceptance by peers; 3. Competing schools of thought, with medium peer acceptance;" I am quite sure they don't think in such terms at all - it would mean, after all, that if they could be persuaded that the science was at the 5 level they would all come around and immediately ask what we should be doing to reduce greenhouse gases, now. My reading is that they think consensus=conspiracy. That climate scientists have got together and agreed upon a position which they are grimly defending, lying about, faking results to support. The idea that reality is precisely the reverse of this, that consensus simply means that all results and analyses point in the same direction, completely escapes them. Aided, in this failure of comprehension of course, by the denier blogs and the likes of Monckton, who push and push the consensus=conspiracy translation. I don't know how we get around this, because the more we say "there is a consensus" the more they hear "there is a conspiracy which has more and more members".
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  12. If the Theory of Evolution is anything to go by - still not accepted by a large percentage of people in America - how do you persuade people who just don't want to/can't accept science facts that go against their beliefs ?
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  13. As we move from discussion on science into discussion on the responsability that follows to make a change on others behaviour its worth reading about cognitive dissonance. Its counterintuitive that how much someone will defend an argument is not proportional to what they have to gain or lose. Wiki it. From a policy maker point of view, psycology aside, all desicions are made with a very short term econimic consequence in mind, I say short term of course from geological point of view. Is the duration of term of office and ergo microscopic period of accountability the detremining facor for not very sensible desicions on climate from governments?
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  14. JMurphy #12, the difference between AGW and evolution is that AGW will directly impact the people who currently deny its existence. It will be 'in their face' more and more as time goes by. 'Young Earth creationists' actually argue that the standard value for the speed of light is off by several orders of magnitude because it yields ages in the billions of years for distant objects... while everyone knows that God created the universe about 6000 years ago. This is, of course, pure madness disproved by satellite communications (which measurably travel at the expected standard speed), atomic energy, and a hundred other aspects of modern technology... but the creationists don't understand any of those things. They can't 'see' the speed of light directly and grasp it in any meaningful sense. AGW is different. People can see when the birds that visit their yard change over the course of a couple decades. When trees and other plants that used to grow near them no longer do as well. When the water from mountain runoff gets lower and lower every year. Et cetera. Sure, they can deny that these things are happening or that people are causing it... but as time goes by more and more of these changes will pile up and it will get that much more difficult for people to deny reality. What I worry about is the '1984 syndrome' where the denialist story changes radically over-night and all the deluded just accept that it has always been that way (e.g. 'we have always been at war with Oceana'). First deniers said that it wasn't getting warmer. Now it IS getting warmer, but it is a natural cycle that will reverse soon or just a minor trend which will never get very serious. When that proves false it'll probably switch to, 'God is punishing us for spurning his gift of oil by not using it all' or something equally mad... and some will believe it. However, right now that lunatic fringe IS the fringe. Most people accept evolution. Most know the world is not 6000 years old. And within the next decade anyone remotely sane will accept AGW as reality... because the changes are speeding up and getting serious. So the primary worries I see are the lunatic fringe getting stronger (as they have been) and/or it taking too long for people to wake up.
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  15. nhthinker wrote: "One expects 99.999999% accuracy from physics." This is not correct, for instance, Einstein apparently once said "As far as the laws of mathematics refer to reality, they are not certain, and as far as they are certain, they do not refer to reality.", and I think we can agree that he knew his physics. GEP Box (an expert on time-series prediction) said "Essentially, all models are wrong, but some are useful", in other words, we shouldn't expect any [mathematical] model to provide completely accurate predictions of the real world. For a concrete example, consider a double pendulum, like this one (shamelessly blagged from Wikipedia): Now the behaviour of a double pendulum can be modelled exactly by a few mathematical equations, but can physics predict the behaviour of a double pendulum with 99.999999% accuracy? No, because it is an example of a chaotic system; in fact, given a sufficiently long prediction horizon, physics can't predict the position of the pendulum with any skill at all. The double pendulum is rather apposite example, as the weather is also a chaotic system, which is why weather forecasts rapily loose any skill beyond a few days prediction horizon. However, climate is not the same thing as weather; climate describes the long term statistical behaviour of the weather (most often in terms of means or long term trends). Just because the weather is chaotic, does not imply that climate is also chaotic (and hence unpredictable). Again, the double pendulum can be used to demonstrate this is true as well. Consider a double pendulum, where the weight is made of iron, but this time imagine an electo-magnet placed to the right hand side of the pendulum. Physics still can't predict the exact path of the double pendulum, however it is able to predict that as the power to the electro-magnet increases, the position of the pendulum will be increasingly biased to the right. In this example, the position of the pendulum corresponds to global mean temperature (the further to the right, the higher the temperature) and the power to the electro-magnet corresponds to climate forcings (e.g. CO2 radiative forcing). Likewise, we can't predict the course of the weather with any real skill, as like the movement of the pendulum it is chaotic, but we can predict the effiects of a change in the forcing, in terms of trends and long-term averages. Particularly that if we increase the forcings, global temperatures can be expected to rise. Of course the physics of a global circulation model (GCM) is rather more complex, but the basic idea is the same - model the long term statistical behavior, not the exact course of the weather. As it happens, physics/statistics can actually do rather better than that, by using an ensemble of models, all starting from slightly different initial conditions, but with the same forcings. In physics this is known as a Monte Carlo experiment. In the case of the double pendulum, we would set of a number of simulations, with different initial positions and velocities of the two weights and let them run with exactly the same signal sent to the electro-magnet in each case. This would provide a distribution of values for the predicted position of the double-pendulum at the end of the simulation, describing which configurations are the most plausible and those which are not plausible. In this case, it would be expected to be skewed to the right, the more power applied to the electro-magnet, the more skewed the distribution. We can then form a credible interval, describing the smallest region that is expected to contain the actual position of the pendulum with 95% confidence. Likewise, climatologists routinely do the same thing by running many simulations of the future climate, and then take the mean (in order to average out the chaotic effects of the weather). They also form mult-model ensembles to average out the effects of uncertainty in our knowledge of the detailed physics of the climate. So how is that relevant to nthinkers post? Simple, it is pretty meaningless to talk of a climate prediction being accurate to an arbitrary level (such as 90%). The accuracy of the prediction can only be discussed relative to the stated error bars on that prediction. First we need to see if the observations are consistent with the models (i.e. do the observations lie within the spread of the model ensemble). They generally are (possibly because the error bars are often rather broad, recognising that there is inherent uncertainty involved in climate prediction). In science, theories (models) can't be proven right, they can only be demosntrated to be false (at least that is what Popperians would say). So if the observations lie within the error bars, then the model is as accurate as it can reasonably be expected to be. Anyway, this explains why climatology can be in the 4.5-5 bracket, even though the predictions made can easily be made to look wrong by confusing short-term weather phenomena (which the modellers don't claim to be able to predict) for long-term climate (which they do). HTH
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  16. I dont think maniacs are the problem although newspeak references are very apt. Look at the green pages of any paper and they talk about the fur trade one day and global warming the next as if they are related in magnitude. People with an ecological conscience need to clearly demonstrate climate change is of unparalled critical importance with biodiversity and animal rights issues way way down the task list. Really climate change needs to shed its green feel trappings. We may loose a few supporters but theres a lot more to gain. Less hippies and more economists would be ideal.
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  17. Theory of Evolution and smoking I am amazed at how many young people I see smoking when there is so much medical evidence of its harmful effects . I like the 1984 syndrome too , Ive been to WUWT a few time an seen the doublethink that goes on there . Humans are very stange indeed
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  18. HTH, Not a very good defense. Most of Climate science relies on imprecise historic record on temperature by use of proxies. Modern measurements by satellites (both of the Earth and of the Sun) are immensely more accurate and precise in a scientific sense. The next 50 years will raise climate science closer to the precision of medical science- but it will still less, because of the lack of ability to control experiments and because the time periods required to analyze impacts. Science for measuring the heat content and flow in deep water is truly in its infancy. You claim climate science is about making accurate LONG term predictions. These predictions need some accuracy to them in order to be useful as science. What is your iconic climate model prediction that has proven accurate by the test of time? When was that prediction made? Is that climate model still in use? What we get told is that the dangers are too great to wait for the results to come in. We are told that the Earth's mechanisms can not cope and it is in "disequilibrium". Disequalibrium is a completely unscientific term. The Earth is never in equilibrium but instead, always reacting to changes that are occurring both inside the atmosphere and outside the atmosphere. Earth's equilibrium, if it had one, would be a deep ice age with a ability to sustain a very small fraction of the current level of human life and other life. Note that there were starts of a few interglacial period that were much warmer than the current temperature levels. There is no real objective evidence that warmer is not better. How do you think we should plan to stop China and the rest of the developing countries from using coal and burning wood? War?
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  19. andrewcodd "Is the duration of term of office and ergo microscopic period of accountability the detremining facor for not very sensible desicions on climate from governments? " Perhaps the more important factor is less the time horizons and cognitive dissonance of governments. It is the time horizons, cognitive dissonance and inability to look beyond the narrow 'what can I do in my life' perspective of individuals. Ultimately, governments are peripheral. They may enact the policies needed. But they don't determine the need for the action. We do. Until the populace give government the permission to act, government will not act. What does action mean? First break the dominant paradigms, then ask that question again. Otherwise action is limited by the paradigm and will be minor, token & ineffectual. To break paradigms, government needs our permission, nay, our directive, to do so. Until then they only act within the existing paradigms. So how do we mobilise the populace to say that we have to think outside the square, to ask what may be retained, and what must be sacrificed in order to avoid sacrificing everything. Like a ship in peril on the sea, the overarching question is; When should we take to the lifeboats? When should we start sacrificing parts of our lives and societies in order to avoid sacrificing our souls and everything. The captains of the world will never issue the Abandon Ship order if we do not give them our permission. And we are at the Abandon Ship stage Now. We can't save everything. We have to start deciding now what we sacrifice so that we can save some things. And as always, the Leaders Follow.
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  20. Re: nhthinker Equilibrium is a relative term. In the context that for the past 6000-8000 years, the seasons and rains have a sense of stability to them, allowing for the rise of civilization and ordered societies. From that perspective, the globe has been in equilibrium climatically. Now science and our ability to measure change is sending danger signals. The world is transitioning into a new geologic epoch; a change we as humans have measurably and demonstrably aided. Indeed, evidence suggests that the climatic stability of this present interglacial has been in part ordered by the activities of man (cf. William Ruddiman's book Plows, Plagues, and Petroleum: How Humans Took Control of Climate here). In that same vein, debating the minutiae beyond a certain reasonable point becomes fruitless. Because no comparatives exist (to my knowledge) in the paleo record to the rate that we have injected a bolus of carbon into the world's carbon cycle. Tipping points, some of which we are aware and some not, clearly exist. The thing that scares me most is that I cannot bound the risk that the coming changes to the world's climate might put our species' existence at stake (systemic interactions due to drought, famine, pestilence, war, etc.). The fact that it is even a non-zero chance should be of concern to all. What to do about it is the point of this post. Not devolving into the weeds. We have raised ourselves up to our hands and knees from the weeds and see the trees for the first time now, and sense warning signs to the species. And we continue to operate with the presumption that we still have time to avoid the fate to which we are consigning ourselves. That presumption may be hubris. That also scares me. The Yooper
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  21. nnthinker said "Not a very good defense". Science is not about rhetoric, it is about logical argument. Casual dismissal of posts intended to be helpful is not an indication of genuine scientific scepticism. Physics can't predict the exact behaviour of a double pendulum because it is chaotic; being able to measure the initial conditions more accurately extends the useful prediction horizon a little, but it doesn't change the fact that a double pendulum is inherently unpredictable. Likewise the weather is inherently unpredictable, and more accurate measurements don't substantially change that, just pushes the useful prediction horizon back a little (for a more advanced treatment, see here). Model predictions are not dependent on temperature records, paleoclimate, thermometer or satelite. They are based on assumptions about climate physics, and simulate the consequence of those assumptions. If you want to show that the models are not accurate, then you need to show that the error of the models is larger than the internal variability of the climate. However, we can't measure the variability of the climate, no matter how good our instuments are, as there is only one stochastic realisation of true climate physics available (i.e. the observed climate on Earth). The best estimate we can get is the spread of the model ensemble, so we are back to the consistency argument again. Note if the climate models were perfect, the spread of the model runs would be a perfect characterisation of the internal variability. So any attempt to discuss the accuracy of the models without reference to the inherent uncertainty is fundamentally misguided. "You claim climate science is about making accurate LONG term predictions. These predictions need some accuracy to them in order to be useful as science." Yes, but we only know if they are accurate in hindsight, and we can only assess the accuracy of hindcasts with respect to the inherent uncertainty of the observations (not just the measurement error, but the uncertainty due to "weather noise"). Can you demonstrate that current climate models give inaccurate hindcasts (or forecasts of long term trends for older models)? "What is your iconic climate model prediction that has proven accurate by the test of time? When was that prediction made?" How about this one "Is that climate model still in use?" Of couse not. Steam locomotives are still capable of pulling carriages, but are no longer used due to a sequence of incremental improvements mean we can now do better. Climate models are no different, but the basic principles uesd now are the same as they were 30 years ago. "Disequilibrium" is indeed an odd term, and a bit of a non-sequitur as nobody mentioned it. The climate spends most of its time in a state of approximate, but not exact equilibrium, with the occasional flip between glacial and interglacial (equilibrium) states. "There is no real objective evidence that warmer is not better." It is the fact that there will be change that is the problem, as that will require adaption, which has economic and societal costs associated with it. If you live in Amsterdam or Bangladesh, you might argue that there is obvious evidence that warmer is not better, at least for you. "How do you think we should plan to stop China and the rest of the developing countries from using coal and burning wood? War? " Does that affect the science or whether the models are accurate? No. HTH (Hope That Helps) Dikran
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  22. "Science is not about rhetoric, it is about logical argument." Regarding the conduct of science, you are spot on. However, given the population we have now, rhetoric is still necessary to convince the population that they should be concerned about climate change. Blaming science education, while true in a reductionist sense, will not get the results you want. If science wants to win this battle, it needs to understand the tools the opposition is using, VERY EFFECTIVELY, against you. WHY are people being persuaded by a, by all accounts, small group of deniers? They appear to be very politically astute and seem to be pushing people's buttons in a way that they respond. I'm no marketing maven but I know there is science out there on how to persuade people of things - will hard science understand that they need to power of soft science?
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  23. dcwarrior It is true that rhetoric often has a greater effect on public opinion than science, however it is vital to clearly distinguish between scientific arguments and rhetoric in our responses. If someone makes a specious scientific argument, then it is best answered by a straight scientific response, and that is what SkepticalSciece does so well. What we shouldn't do is respond to specious scientific arguments by engaging in rhetoric ourseves. If we do that we run the risk of being seen as dishonest and lose the trust of the public (and indeed we would deserve to lose it) when our rhetoric is exposed for what it is. Of couse scientists need to understand rhetoric, but (IMHO) only to better advise journalists and politicians to argue for the scientifically justified political and economic action and to expose the flaws in the arguments of the opposition.
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  24. This comment should be tidied and then upgraded to a blog post; it's a marvelously clear explanation, the double-pendulum employment and graphic beautifully illustrates the difference between weather and climate.
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  25. Doug @10 Thanks for the visual depiction. While that information wards off the sense that the battle is lost, it doesn't actually show improved understanding of climate scientists. Over the duration of the graph, the pro-science group (3 left most spheres) lost 4%, while the anti-science group gained 4%). This was during an El Nino event, so the outcomes of the current and future warmings were on display. 70/30 feels comfortable. 66/34 feels much less so (even though it is "only" a 4% swing.
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  26. DM at #23 I don't think good and persuasive writing and argument are separate from facts or scientific reasoning. They are an integral and possibly neglected part of it. If a judge, your daughter, your Ph.D review committee or the public has been confused by someone's mis-stating or obfuscation of the facts, simply stating the facts again won't be persuasive in any of those forums. True, any political effort must follow the science rather than the other way around. But simply trying to ignore that you have to write and argue persuasively will just get the pro-science side in more trouble. And, I assume they know your tactics - some of the denier memes may be counting on the fact that you will retreat into "objective" statements of the science in hopes that the public won't be able to tell the difference between their gobbledegook and your science.
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  27. Actually Thoughtfull I think of it as something like "unnatural variability." Social scientists are trying to better tease out the effect of the email hacking event and heavy snowfall in some regions last winter. There are not enough numbers to say for sure but it seems to me there are at least some hints of effects from those in the statistics. I also wonder if the publicity around the 2007 Arctic ice anomaly influenced the 2008 numbers. I'm left to imagine the situation may be largely static in terms of trends, something that fits with what scientists have learned of ideology being the gatekeeper controlling integration of information into our worldview.
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  28. "How about this one" Wallace Broecker concluded: "Our efforts to understand and EVENTUALLY to predict these changes need to be redoubled" Science is about prediction based on mathematical models. Broecker was not claiming he had high confidence in a quantitative model. His paper was much more qualitative in nature. A good model would define a function that twenty years into the future that would contain all the variables needed to make the prediction. Solar variability, CO2 and other GHG, volcanic activity, etc. Then, the twenty years of data is plugged in to see if the model from 20 years in the past can produce a prediction that is 90% accurate. If that can be done for many years without a need to constantly add more factors to the model in order to improve its accuracy, then Climate science will have arrived at the magical 4.5 level of confidence. I predict that will not actually happen for at least another 50 years. In the mean time, over the next twenty years, the IPCC predicts developing nations emissions of CO2 will dwarf current levels and thus allow climate scientists to have increasing amounts of CO2 to better test their climate models.
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  29. nhthinker, How about this one: "The bottom line? Scenario B is pretty close and certainly well within the error estimates of the real world changes. And if you factor in the 5 to 10% overestimate of the forcings in a simple way, Scenario B would be right in the middle of the observed trends. It is certainly close enough to provide confidence that the model is capable of matching the global mean temperature rise!"
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  30. Erik, you beat me to it. " A good model would define a function that twenty years into the future that would contain all the variables needed to make the prediction." Why do we need models this good anyway? Governments constantly make decisions and major investments on models from economists, transport analysts and dozens of others. How often do any of them produce anything as good as Hansen?
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  31. nhthinker As I have explained "90% accuracy" is pretty much a meaningless phrase in terms of climate prediction as accuracy can only be assessed relative to the internal variability of the climate as this is the cause of an irreducible uncertainty in any prediction (i.e. it doesn't go away even if the model is perfect). You asked for a model that had proven accurate, and I gave you Broeker's as an example. Dismissing his quantitative prediction of 20th century warming (even though it was accurate) because Broeker wasn't confident is merely moving the goalposts. How about Hansen's 1988 predictions, which get the post 1988 trend broadly correct (scenario B was closest to the observed emissions etc)? "A good model would define a function that twenty years into the future that would contain all the variables needed to make the prediction. Solar variability, CO2 and other GHG, volcanic activity, etc" The models used for climate prediction already do include all of those things. "Then, the twenty years of data is plugged in to see if the model from 20 years in the past can produce a prediction that is 90% accurate. " That sort of thing is already routinely done (see e.g. here), except that as I have pointed out the "90%" accuracy bit is a meaningless criterion (you have to look at the error bars of the prediction, some of that is an irreducible uncertainty that would affect any prediction, no matter how good the model). IIRC the IPCC report has a chapter on model evaluation (I'll check when I am next in the office). Perhaps if you comment on the failings of the assessment activities described there we could have a more concrete discussion?
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  32. If a science has lots of models, which even the advocate is not confident in its predictive ability, then the science is clearly not reached a 4.5 to 5 level of confidence. If scientists start saluting a model that produces 90% long range results, then the science is reaching the 4.5 to 5 level. Broeker's analysis was directionally correct. I do not know anyone that is claiming CO2 has no impact: the primary issue is the accuracy of the level of impact. The advocates here seem to fall into the fortune teller's trap. There will always be some accurate prediction of of future events, especially when you have thousands of predictions to choose from. Much of the politics of the issue focus on taking extreme predictions out of context to intentionally scare people. The emphasis for a science to reach the stature of a 4.5 to 5 standard needs to be cold and calculating aspects of the math involved. From Gavin Schmidt's article on Hansen's predictions: But can we say that this proves the model is correct? Not quite. Look at the difference between Scenario B and C. Despite the large difference in forcings in the later years, the long term trend over that same period is similar. The implication is that over a short period, the weather noise can mask significant differences in the forced component. This version of the model had a climate sensitivity was around 4 deg C for a doubling of CO2. This is a little higher than what would be our best guess (~3 deg C) based on observations, but is within the standard range (2 to 4.5 deg C). Is this 20 year trend sufficient to determine whether the model sensitivity was too high? No. Given the noise level, a trend 75% as large, would still be within the error bars of the observation (i.e. 0.18+/-0.05), assuming the transient trend would scale linearly. Maybe with another 10 years of data, this distinction will be possible. However, a model with a very low sensitivity, say 1 deg C, would have fallen well below the observed trends. I'm curious if Gavin Schmidt thinks Climate science has reached the predictive ability of medical science. I kind of doubt it based on what he wrote in the article. Anyone here with enough connections to ask him?
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  33. nhthinker at 21:08 PM on 3 August, 2010 Making too much of the comparison between the predictive abilities in medicine and climate science is pretty fruitless. One can address such comparisons but we should be much clearer specifically on what we are talking about. Your "fortune teller" jibe is way off base. If we consider models and their predictive abilities (and the Gavin Schmidt quote), we can be much more specific: We have a high degree of certainty that enhancing the greenhouse effect will cause the Earth to warm all else being equal, and have rather strong evidence based on analysis of historical [CO2]/temperature relationships that the climate sensitivity (equilibrium Earth temperature response to doubling [CO2]) is at least 2 oC. The most likely value based on our understanding is 3 oC and there is lesser likelihood that it is above 4.5 oC. Those values are pretty well constrained by a large body of evidence. Since climate models are parameterized according to our best understanding we are not surprised that they have so far done pretty well predictively. A major uncertainty (that Dr. Schmidt is referring to) is the various elements of the climate system, especially the oceans, which result in inertia in the response to forcing. Thus we have higher certainty about the amount of eventual warming, than the temporal progression of warming, although the reasonable success of current models (and even Broecker's 35 year old back-of-the-envelope calculation) indicates that we have a pretty good understanding of the essential energy balalnce of the climate system. One could argue that this compares favourably with many aspects of medicine. If one considers a diagnosis of cancer, for example, and considers an expert prognosis, the predictive elements are not a million miles from those involved in predictive climatology. The specialist may well have a high degree of certainty about the outcome (e.g. a cancer that is a high mortality), but will be less certain about the temporal progression of the response. S/he might be able to give 1 year, 3, yr, 5 yr chances of survival, but there will be a range of possible projections that involve interperson variability (genetics, lifestyle, personality) and other contingent happenings. Much in the way that the a climate projection might be completely scuppered by an unpredictable series of massive volcanic eruptions, so the medical prognosis might be scuppered by unanticipated future events (the patient might be run over by a bus)...
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  34. Another good model prediction here ("Quantifying the uncertainty in forecasts of anthropogenic climate change", 1999/2000), particularly Figure 3. This was referred to in a recent GUARDIAN article.
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  35. Re: nhthinker Loth as I am to do so, I am forced to point out that nnthinker is engaging a rhetorical, rather than scientific argument, in which I am not that keen on participating. DC is right, scientists do need to know about rhetoric; IMHO it needs pointing it out, but it is best just to stick to the science otherwise and not be drawn into the same tactics (I hope I have managed that here). For example, asking for an example of an accurate climate prediction "What is your iconic climate model prediction that has proven accurate by the test of time?" and then when some examples are given, replying "The advocates here seem to fall into the fortune teller's trap. There will always be some accurate prediction of of future events, especially when you have thousands of predictions to choose from. Which rather transparently shows that there was little genuine interest in the answers. There is certainly an element of "having your cake and eating it as well". There is also the point that I have explained more than once that "90% correct is a meaningless term, and nhthinker is still using that term and has not attempted to engage in the point that the internal variability of the climate means that the accuracy of a prediction is not so easily measured as that phrase suggest. The quote from Gavin Schmidt is rather curious, in that in a couple of occasions it mentioned the internal variability ("weather noise") that I raised, here "The implication is that over a short period, the weather noise can mask significant differences in the forced component." and here "Given the noise level, a trend 75% as large, would still be within the error bars of the observation (i.e. 0.18+/-0.05), assuming the transient trend would scale linearly" In other words, the weather noise in the data is large enough over such a period that the model could be very different and still be consistent with the observasions (note it is the error bars of the obervaions he mentions, not of the models). The highlighted bit "Is this 20 year trend sufficient to determine whether the model sensitivity was too high? No." Doesn't say that the model is wrong, just that there isn't enough data to be confident of detecting an error (as the "weather noise" is too large). Which was pretty much what I was trying to explain. Regarding "Broeker's analysis was directionally correct.", that is a little disingenuous as he predicted global warming of 0.8 degrees over the 20th century, and the GISS data show a warming of about 0.82 (judging from the plot). I'd say that was rather more than merely "directionally correct". If you want to know Gavin Schmidt's views, why not ask him? If you don't want to email him, you could always post a comment on RC marked "FAO Gavin Schmidt". That will be my last response to nhthinker (chorus: phew! ;o) until he actually engages with the point that "weather noise" means that it is not possible to achieve an arbitrary level of accuracy, even if your model is perfect.
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  36. As an engineer, I understand all about noise. Noise can be averaged out if what is being looked for is long term trends. If the noise can not be averaged out for the time frames you are concerned with, then you can't make supportable claims about the accuracy of the underlying signal. Best judgement in the 70s was CO2 doubling would be 2 to 4 degree C change. It was also contemplated that the Earth's response to elevated CO2 would be linear or that it might trigger some damping response or multiplying effect within the complex interworkings of atmosphere clouds and oceans in addition to the nonlinear effect in the polar regions. How much have those numbers "tightened up" in the last 45 years? Maybe not at all. How much have we learned about the other effect of increase CO2 or increased temperature as to whether their exists the probably of additional damping or mulitplying effects of sustained higher temperature? Not much, because the changes to the environment (our experiment) is so slow. Repeatability is critical to good scientific confidence. That is what it takes to be a hard science. Climate science is no where near established enough to make repeatable hundred year predictions. I find it humorous that those advocates here will not concede that sciences that involve controlled repeatable tests and relatively short time scales are inherently more reliable than sciences that only involve one object under test and the scientists are too impatient to propose a model and then wait until it is proved out by the data and instead constantly tweak the model much faster than the experiment actually runs. Medical science involves plenty of different independent objects to test and time scales where the scientific impatience does not play as large of role. Is there anyone on this forum that claims to be a climate scientist and would also claim that Climate science rivals medical science in term of its certainty of its hypothesized models tested by repeatable trials by independent scientists? The answer is no scientist worth his salt would ever make such a claim. They might claim climate science certainty is good enough, but it is no where in the same league as medical sciences or physics. The people on this board seem to have forgotten some fundamental principles of science. Those that separate the hard sciences from the softer sciences. There are still huge things to discover about climate science. I totally agree with
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  37. Simple examples that you can begin to doubt - dear “student”: “7. The new CO2 (as shown by its isotopic signature) is mainly from burning fossil fuels.” - The same "isotopic signature" have respiration, especially soil respiration. “8. Therefore the global warming currently occurring is anthropogenic (caused by mankind) [how? hypothesis 2a and 2b? - see Real Climate - discussion: G.S. + E.S. contra R.P. s.].” In Poland it is a proverb: "The devil [is what is most important] is in the details ..." But you doubted until the end - the “dear student” - in the alleged consensus, let us give voice a “prominent of the man” of the IPCC, a prominent scholar whose works (especially one), I cite here many times. He will answer the question you: “So what’s all the fuss about, then?” Atte Korhola , the Professor of Environmental Change, the UN IPCC (IPCC is the creator of "consensus"), he present: “... various reasons, so they desperately look around for anything they can to perhaps put off having to FACE REALITY.” (February, 2010). ... and "face reality" according to him is this: “The mistakes demonstrate that IPCC has taken on too much when TRYING TO CRAM the entirety of diverse climate research in one book and force it INTO CONSENSUS. [namely: the pursuit of consensus is a major mistake IPCC ...]” “However, science develops all the time and reduction of scientific ambiguity is NOT REALISTIC.” “UNREASONABLE EXPECTATIONS [These are 1-8 claims above?] are placed in the IPCC report. The report is being read as if it were a HOLY BOOK [“holy book” = “consensus”], and details presented in it are taken as truths CARVED IN STONE.” “HOWEVER, SCIENCE DEVELOPS ALL THE TIME AND REDUCTION OF SCIENTIFIC AMBIGUITY IS NOT REALISTIC. [ie: these 1-8 assertions + 9 - dominant negative effects GW; and are too detailed to give a strong consensus, at best it can be a MOMENTARY consensus - with many VERY significant: "but ..."]” "The evaluation of climate change should be continuous, and it should genuinely allow for DIFFERING VIEWS. [How can this be reconciled with the above -“professor “ - understanding of consensus?]” Consensus, consensus building ("style", the IPCC - that is, de facto proposed above - "Professor"), by Korhola, ignores the fact that: “... the issue of climate change has proved increasingly complex ...” “... the ambiguity of the models increases ...”; ... and leads to the emergence of: “... mistakes and exaggerations ... “ - „... for example, regarding the Himalayan glaciers, destruction of the Amazon rain forest, collapse of the grain crop in Africa, and the link between climate change and natural disasters ... [I'd loved - whit the most important - the spread of malaria ...]” ...and yet the logical (and most important) component of the consensus (by IPCC) is: „... and poses significant risks for a broad range of human and natural systems …” ... and becoming the logic: even when the based claims are true, but the conclusions are false, the “whole” must be regarded as false ...
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  38. Arkadiusz Semczyszak There is very little room for any doubt that the rise in atmospheric CO2 is anthropogenic. An even more straightforward argument than isotopic concentration can establish this, it is called the mass balance argument. The increase in the amount of new CO2 in the atmosphere each year is only about 45% of anthropogenic emissions (this is known as the "airborne fraction"). This demonstrates that the natural environment must be a net sink of CO2 as the "missing" 55% of our emissions has to go somewhere (there has to be conservation of mass). Essentially, if the natural environment were a net source of carbon dioxide, then the observed annual rise in atmospheric CO2 would be grater than anthrpogenic emissions as both man and the environment would be contributing to the rise, but that is observed not to be the case. Now if you can show how the natural environment can be the source of the excess CO2, whilst at the same time the annual rise being less than anthropogenic emissions, THEN there may be reason to doubt. Ferdinand Engelbeen has an excellent webpage on this topic. Appologies if I have misunderstood your point.
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  39. What you see in the proposed by Dikran Marsupial website (and what follows)? The figure of CO2 concentration on the former as an example d13C - sponges, we can see that from about 1820 years to the present rate of growth of pCO2 is very similar (slightly faster than the circa 1950). Furthermore, studies of sponges - presented here, include only the LIA (LIA began in 1315-1320 was not until 1550) and the last of CWA. Author proposed by Dikran Marsupial website writes: “There are only two fast main sources of CO2 to the atmosphere, besides the burning of fossil fuels: oceans and vegetation.“ “That is because every year about 150 GtC of CO2 (somewhat less than 20% of the CO2 content) is exchanged between the atmosphere and the oceans/vegetation.” “Over longer periods, humans continue to emit (currently about 8 GtC) CO2. The accumulation over the last years thus is 8 + 5.3 + 4.3 + 3.5 + 2.8 +... or about 40 GtC from the emissions over the past 30 years. That is only 5% of the current atmosphere... Some conclude from this that humans are only responsible for 5% of the CO2 increase and thus, as far as that influences temperature, also only for 5% of the temperature increase. But that is a wrong assumption...” “Thus at maximum, the influence of temperature on the current increase is 0.7 ºC x 8 ppmv/ºC = 5.6 ppmv of the about 100 ppmv increase since the start of the industrial revolution.” In theory, precisely, but ... the author writes nothing about the soil respiration. This is not surprising, even though the update 10.07.2010, the author is not based on all the major recent surfaces. This item: Bond-Lamberty, B. and Thomson, A.: A global database of soil respiration data, 2010, not in his surfaces. The authors write there, like this: “We find that the air temperature anomaly (the deviation from the 1961–1990 mean) is significantly and positively correlated with changes in RS. We estimate that the global RS in 2008 (that is, the flux integrated over the Earth’s land surface over 2008) was 98 ± 12 Pg C and that it increased by 0.1 Pg C yr-1 between 1989 and 2008, implying a global RS response to air temperature (Q10) of 1.5.”; The increase in our emissions is similar to the increase of soil respiration (0.1 Pg C yr-1). These so Dikran Marsupial sentence: “... but that is observed not to be the case ...” is false. It should be noted that the standard error of estimation of the current soil respiration is 12 GtC - it is about 4 GtC bigger than our “about 8 GtC”. If only for this example shows that is right Korhola, that: “reduction of scientific ambiguity is not realistic.”
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  40. Sorry to be references - instead: "Surfaces"; I read about the changes of SST hence the confusion ...
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  41. Arkadiusz Semczyszak You appear to be missing my point, the mass balance argument proves beyond any reasonable doubt that the natural environment (including soil respiration) is a net sink of carbon dioxide, and hence is opposing the rise in atmospheric CO2, not causing it. If the natural environment were a net source, then the annual rise in atmopsheric CO2 would be greater than annual anthropogenic emissions, but that is not the case, we know that from the observations. Whether soil respiration is giving out more carbon than it recieves in biomass from dead trees and animal dung etc. each year is irrellevant. The point is we know the natural environment as a whole is a net sink, and hence the observed rise in atmospheric CO2 is anthropogenic. "The increase in our emissions is similar to the increase of soil respiration (0.1 Pg C yr-1). These so Dikran Marsupial sentence: “... but that is observed not to be the case ...” is false. " No, that is not correct, simply because soil respiration is not the only component of the natural carbon cycle. From Ferdinand's webpage: The blue is total anthropogenic emissions (land use and fossil fuel use), the red line is the annual increase in atmospheric CO2 as measured at Mauna Loa. For conservation of mass, we know that dC = E_a + E_n - U_n where dC is the annual change in atmospheric CO2, E_a is anthropogenic emissions, E_n is "natural" emissions and U_n is "natural" uptake. Of these, we can directly measure dC and E_a, so rearranging, we have E_n - U_n = dC - E_a This is the green line, which gives total net emissions into the atmosphere from all natural sources (including soil respiration). As you can see, it is always negative, demonstrating that the natural environment is a net sink, and is hence opposing the atmospheric rise, not causing it. The data is shown here it can all be downloaded from the Carbon Dioxide Information Analysis Center CDIAC, the specific datasets you need are: anthropogenic emissionshere and Mauna Loa data here. Do feel free to check Ferdinand's plot checks out - as indeed I did.
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  42. “Whether soil respiration is giving out more carbon than it recieves in biomass from dead trees and animal dung etc. each year is irrellevant.” And what about the detritus Tundra? But there is often in arrears for more than 10 thousand. years, and the NPP is negligible. Arctic could upset the balance of CO2. “Thus, modest global change scenarios resulting in a 1 to 2 deg C increase in mean temperature would have the most significant effect on the 60 g C/m2 year respired by tundra.” “Soil respiration has been shown to be strongly influenced by temperature (Lloyd and Taylor 1994, Fang and Moncrieff 2001) - Duke Uniwersity Allison Thomson: “Previous climate change research shows that Arctic zones have a lot more carbon locked away than other regions. Using the complete set of data collected from the studies, the team estimated that the carbon released in northern -- also called boreal -- and Arctic regions rose by about 7 percent; in temperate regions by about 2 percent; and in tropical regions by about 3 percent, showing a trend consistent with other work.” “The increase in carbon dioxide given off by soils -- about 0.1 petagram (100 million metric tons) per year since 1989 -- won't contribute to the greenhouse effect unless it comes from carbon that HAD BEEN LOCKED AWAY OUT OF THE SYSTEM FOR A LONG TIME, such as in Arctic TUNDRA.” “In addition, removing only 10 percent of the boreal-Arctic data points was enough to invalidate the statistical significance of the boreal-Arctic result. Together, the results support the idea that more boreal data on regional climates is needed to reach statistical relevance.” “This analysis could not distinguish whether the carbon was coming from old stores or from vegetation growing faster due to a warmer climate. But other lines of evidence suggest warming is unlocking OLD CARBON, according to the researchers.” "We identified an area where WE NEED TO DO MORE WORK," said Thomson. But do not You, You already know ...
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  43. And my "perennial" question: why these fluctuations year on year increase of CO2 at a dose? from 0.5 to 5 ppmv, even as there is no volcanic eruptions, what is changing so quickly?
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  44. Arkadiusz Semczyszak El-Nino is the likely cause of the annual fluctuations in the rise in CO2, IIRC largely becuase of the effect it has on the productivity of the terrestial biosphere. The correllation between temperature and the rate of increase in atmospheric CO2 is well known, and often the source of incorrect skeptic arguments, such as the one dealt with here.
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  45. Arkadiusz Semczyszak said "And what about the detritus Tundra?" Again, you are missing the point. The observations show beyond reasonable doubt that the natural environment as a whole is a net carbon sink, and therefore is opposing the rise in atmospheric CO2, not causing it. It is irrellevant if soil respiration is increasing if some sink elsewhere in the natural carbon cycle is strengthening sufficiently to take up the extra carbon from soil respiration (the observations show that this must be ocurring - even if we don't know the detail of exactly where the carbon is taken up). You have to look at the big picture. So, if the natural environment is the cause of the observed rise in atmospheric CO2, why is the observed rise smaller than anthropogenic emissions. If you can't answer that question, maybe it will help you to understand why increased soil respiration does not (by itself) imply doubt on whether the rise is of anthropogenic origin.
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  46. #38: "The increase in the amount of new CO2 in the atmosphere each year is only about 45% of anthropogenic emissions (this is known as the "airborne fraction"). ... Ferdinand Engelbeen has an excellent webpage on this topic" My congratulations to Engelbeen for a strong bit of work. I've been playing with a slightly different way of showing this strong connection between atmospheric CO2 increase and CO2 emissions. The US EIA has a wealth of data on CO2 emissions from fossil fuels by fuel type, by country, etc. These data can be turned into "annual world emissions of CO2 in Gtons". From MLO monthly CO2 concentrations, compute the annual high (Mar-Apr-May) and annual low (Sep-Oct-Nov) for each year. Form a delta CO2 (in ppm/yr) from these seasonal extrema; plot together with the world emissions: The right hand scale is emissions in Gtons; the left hand scale is ppm CO2/yr. A smoothed curve of the composite of the spring and fall extrema is shown; with the exception of the big dip in 1991, this graph is an extraordinary match to the emissions curve. What caused that drop in the rate of CO2 increase? Robock 2003 and others have established that the violent eruption of Mt. Pinatubo led to a short term cooling and diffusion of sunlight which in turn led to a profound increase in plant growth over the following few years. More plant growth, more CO2 taken out of the atmosphere. Note however, that the annual change in atmospheric CO2, even at the bottom of the dip, is still positive. Note also that the rate of CO2 increase quickly recovers its upward trend; as CO2 emissions continue to increase, we should be seeing 2.25-2.5 ppm/yr fairly soon.
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