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Comments 45351 to 45400:

45351. Tom Curtis at 00:12 AM on 17 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Dikran Marsupial @28:

       1)  How couild Michel possibly know that there was a scientific concensus on any particular theory by his definition?  The only way to determine it would be by an exhaustive survey of all relevent experts (and no such exhaustive surveys exist in any field) or an exhaustive survey of all relevant literature including non-peer reviewed literature.  His definition is clearly intended only to turn "There is no scientific consensus on climate change" into a trivial truth with no more information content than informing people that all bachelors are unmarried.  Presumably the next step will be an equivocation so as to confuse people into thinking there is no scientific consensus as defined in the paper (and wikipedia).

       2)  It is informative, however, to look at some of the fields in which it is known that their is no consensus (by Michel's definition).  These include not only the fields heavilly disputed on ideological grounds such as climate science and biological science, but also such theories as relativity, geocentrism, and even the theory that the Earth is not flat. The failure of even heliocentrism and the theory that the Earth is round to command a concensus by Michel's definition shows just how pointless it is.  

45352. Kevin C at 00:05 AM on 17 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       HJones: Your paraphrase of my statement misrepresents my statement which you quote directly below it. Further, you disregard my subsequent paragraph which clarifies the issue.
       
       It's really very simple: The study distinguished between papers which do not address the question of the human contribution to global warming, and papers which addressed the question and were undecided on the answer. To argue that papers which do not address the question should be counted as 'undecided' in quantifying the level of consensus is preposterous.

45353. HJones at 23:45 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Kevin C @19,

       A new survey of over 12,000 peer-reviewed climate science papers by our citizen science team at Skeptical Science has found a 97% consensus in the peer-reviewed literature that humans are causing global warming.

       I believe that the openning statement to this post is in disagreement with your response to JRT256.  You state that the article clearly states that the 97% is only for papers that took a position

       Secondly, the paper is very clear that the 97% consensus is among papers which stated a position.

       The openning state is at-best misleading, and needs to be corrected.

45354. Dikran Marsupial at 23:31 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Michel, Wikipedia describes scientific concensus as "Scientific consensus is the collective judgment, position, and opinion of the community of scientists in a particular field of study. Consensus implies general agreement, though not necessarily unanimity. "

       This seems pretty reasonable to me.  If you describe "consensus" as being "reached when nobody expresses his or her opposition to one view", then there is no concensus on any scientific topic as there is no field in which there are no dissenters from the mainstream view. This means that either the word "concensus" is meaningless in a scientific context, or your definition of "concensus" is not appropriate.

       Can you name a scientific topic on which there is concensus according to your definition? 

45355. cRR Kampen at 22:58 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Michel, look at the top left of this page below 'Most used climate myths', number 4 (guess that one will be updated :) ).

45356. Composer99 at 22:55 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Michel:

       First, on what basis should we accept your definition of consensus over the implicit/explicit definition/denotation used in the paper?

       Second, minuscule proportions of contrarians notwithstanding, consensus absolutely does exist in other areas of science: special/general relativity, quantum mechanics, plate tectonics, evolution, germ theory of disease, to name a few.

       Third, that humans are causing global warming is not an opinion. Based on the available evidence it is a settled fact.

45357. bert at 22:20 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       John, Dana,

       In to your paper, ‘endorsement’ comes in three different ways:
       A. Explicit, with quantification;
       B. Explicit, without quantification;
       C. Implicit.

       However, your paper (nor the supplementary info) doesn’t provide a proper breakdown of the various groups. Can you enlighten on this? In particular the results for group A respectively B.

       Thanks in advance,

       Bert Amesz

45358. JvD at 21:59 PM on 16 May 2013
       A Detailed Look at Renewable Baseload Energy
       

       @JasonB. You write:

       "Ignoring the fact that naval nuclear reactors are much more expensive per kWh, is it "propaganda" to point out that the levelised cost of electricity of new nuclear power is extremely sensitive to the load factor?"

       They are not much more expensive. Typical navy nukes such as are installed on nuclear aircraft carriers cost around 7 ct/kwh, according to US Navy own figures (look it up yourself plz, I forget the source). This is expensive compared to stationary, commercial NPP's, but not *much more* expensive. Also, building such plants on land instead of in limited space on ships will allow some cost reductions. In fact, the first ever NPP to supply electricity to the grid was a beeched naval nuke built in the '50's at Shippingport, I memory serves.
       
       "You seem to be confusing generation power with storage capacity, which is surprising for someone trying to lecture others. "a few dozen extra GW of storage" makes no sense."

       I'm hoping you practice reading comprehension. When we are talking about storage, tow kinds of capacity are relevant: storage capacity, and power capacity. When I say: GW of capacity, I'm referring to power capacity. When I say GWh of capacity, I'm referring to storage capacity. This is normal practice in power engineering communications. No reason to initiate a quibble over this. If anything, you are exposing your own lack of routine in discussing these kinds of issues.

       "The Nordel power system has a storage capacity of about 120 TWh (and I have seen reports that there is the potential to expand it to as much as 205 TWh) and the UCTE grid has another 57 TWh, for a total of 177 TWh. (Link)

       That's enough storage (note the units) to power the EU-27 for 177,000 GWh/363 GW = 487 hours = 20 days = nearly three weeks with no other electricity generation at all — no wind, no solar, nothing. Nordel alone actually has enough for nearly two weeks."

       Yes the storage is enough for this, but there is no power capacity to deliver 300 GW (as you confirm) much less absorb the 2000 GW of power that the Greenpeace EU renewables fleet will be delivering for storage. If the pumped hydro cannot absorb 2000 GW, then that pumped hydro can play no role in reducing curtailment of renewables. If the capacity to absorb renewable power is limited to 100GW, then, in worst case, 1900 GW of renewables will need to be curtailed during a windy, sunny day in Europe. This is my point, and you are not addressing it.

       Please address how the Greenpeace-proposed 2600 GW of renewables for Europe will not be regularly and significantly curtailed, using your own figure of 363 GW average power usage if you want.

       "Now, in order for it to be able to do that, obviously three things need to happen:

       1. Big interconnects between Scandinavia and Europe so the power can be efficiently transferred back and forth. (Hence NORD.LINK, NorNed, NorGer, HVDC Norway–UK, Scotland–Norway interconnector, etc.)

       2. The existing hydro-electric dams upgraded to pumped storage so they can pump water back up into the reservoir when electricity is cheap, thereby storing it (rather than simply relying on nature to replenish the dams).

       3. Install more and larger generators so the peak power output can be increased (current max. for Nordel is 46 GW because that's all they need at the moment)."
       
       On point 1. This can be done, and is already done. Extra links have already been built, and more will be built. No problem here.

       On point 2. This is not a minor exercise problem, because the number of locations suitable for this is much smaller than mere hydropower. To covert to pumped storage, you need an upper lake AND a lower lake. I recollect a Scnandinavian research estimate of about 100 GW of capacity that could be built across Scandinavia in suitable locations. Of course, as you rightly point out, more GW could be installed at the same site, although the storage time and load factor would decrease and hence the economics.

       On point 3. Additional GW's cannot be added endlessly to any particular pumped storage site, because GW's are also limited by water flow rates that need to conform to ecological and safety regulations. That is why scandinavian authorities work with the ~100 GW max potential figure for power capacity of pumped hydro in Scandinavia, which estimate already includes optimism about ecological feasibility. More certain is the availability of a few dozen extra GW's that would cause limited and perhaps acceptable ecological damage.

       "Then why don't you read it? Your source is talking about breeders."

       I am very much aware my source is talking about breeders and fast reactors. Only the breeder reactor (or the fast reactor) is relevant to the discussion of inexhaustible energy supply. I (perhaps falsely) assumed this to be self-evident. Thermal uranium reactors cannot be part of an inexhaustible energy supply for obvious reasons.

       Anti-nuclear propaganda has several import main ambitions, one of which is to convince the public that fast reactors, breeders and fast breeders are not commercialisable. They are half-right. The commercial argument for such reactors is based mainly on the improvement of uranium usage efficiency. But as long as uranium prices are as low as they are today, fast reactors or breeders are not commercial. Typically, nuclear energineering experts use the rule of thumb that a breeder or fast reactor will always be at least 20% more expensive than a once-through reactor. This is too much to justify only on the basis of the uranium fuel savings at current uranium prices. There is an important caveat to this though. The Russians have been developing their fast reactor BN-xxx series for decades, and have recently started exporting commercial versions. These reactors are competitive because the Russians have been able to leverage the cost benefit of the specific low-pressure reactor design they are using. So although the reactor is more expensive to build, it is far cheaper to operate and maintain, which, apparently, allows them to compete with traditional once through thermal reactor designs like the AP1000 and EPR.

       Anyway, I'm sorry if I did not state clearly enough that when discussing te eon-scale energy supply picture, the once-through thermal uranium fuel fuel cycle is utterly irrelevant. Therefore, it is completely superfluous to assess the longevity of the uranium (and thorium) resource bases by assuming only once-through thermal uranium reactors, because you will automatically conclude that uranium is not sufficiently abundant to support eon-scale nuclear power. Perhaps that is why anti-nuke advocates always insist on assuming only once-through thermal reactors will ever be built, because otherwise they will be forced to concluded that uranium and thorium supplies are inexhaustible on the scale of eons.

       For additional information, one can review the various long-term nuclear power strategy reviews that are available from different sources. All of these sources conclude that fast reactors and breeders will be built in force from around the middle of the century, or whenever uranium price development calls for it, or whenever the populations demands a solution for nuclear waste. I assume you know that all virtually all very long lived nuclear waste can be burned as fuel in fast reactors, so fast reactors may eventually be fast-tracked if populations demand cheap and effective solution to nuclear waste. 

       Concerning load following, the French have long augmented several of their NPP's for improved load following, so this is not limited to naval NPP's. EPR and AP1000 both support 5%/min. load following per standard design.

       Concerning the lack of commercial fast reactors or breeders, please refer to my explanation that current low uranium prices do not call for commercialisation of fast reactor or breeders today. Initial R&D on fast reactors and breeders was initiated during a time when uranium supplies were thought to be limited enough to warrant the R&D. But as recently as the '60 and '70 it became clear that uranium supplies were abundant enough to leave fast reactors and breeders to the future. I remember having already explained this in a previous post on this thread.

       Thank you,

       JvD

45359. Michel at 21:48 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Majority is given when, out of a group of consulted people, more votes are given to one view than to other ones.
       Unanimity happens when all voting people positively chose one view, without any exception.
       Consensus will be reached when nobody expresses his or her opposition to one view.

       All of this happens in opinion polls or formal votes, but not in science.

       So, what is the fuss about grading scientific papers in the way they convey [or not] opinions?

        

45360. gws at 21:04 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Thank you and congratulations to John and the team for this effort and the resulting paper and excellent post here.

       While there is -- so to say -- nothing new here, i.e. the consensus was present 20 years ago and so was the (successful) denial ot it, there appears to be a difference when looking into the mainstream press: the spread of this "news" is somewhat astonishing.

       I think the denier reaction may therefore provide a good study case of the pschycological effect and response to being told that you are in denial. It has already started ...

45361. shoyemore at 20:13 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Congratulations to the Skeptical Science team!

       The paper has also made an impact around some news sites, I hope that grows.

       www.ft.com/intl/cms/s/0/28d54536-bd7b-11e2-a735-00144feab7de.html

45362. JvD at 20:12 PM on 16 May 2013
       A Detailed Look at Renewable Baseload Energy
       

       @michael sweet. You said:

       "Yet every night France has to export substantial amounts of their nuclear power since their generation capacity is greater than their baseline usage. Why is it good for France to export nuclear but bad for Germany to export renewables? Provide citations to support your wild claim that wind and solar facilities only last 15 years. I previously noted several nuclear plants that have been withdrawn from service because of maintenance issues. Your 100 year claim is simply false."

       France exports this electricy for profit, whereas Germany exports their electricy far below cost. Politicians in my country (Netherlands) are takign note of this, and considering reducing the ambition for build out of wind/solar in The Netherlands precisely because The Netherlands is already benefitting from near-free (or even negative cost!) solar/wind power from Germany oftentimes. Of course, the solar/wind power we get from Germany is not really free. Far from it. But it's costs are paid by German citizens, rather than the buyer of the electricy. This suits The Netherlands just fine. Especially since we have a lot of natural gas power plants which can deal relatively well with deep load following. But it is a false comfort. Once the German population decides it wants to stop subsidizing solar/wind energy, The Netherlands will not be able to import near-free subsidized German power anymore. We will have to start paying the cost of energy again ourselves. So the Netherlands can never rely on Germany for providing us some of its excess renewable power in future.

45363. MarkR at 20:08 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       18. Ed Davies, it would depend on the statement of the result in the abstract. I don't remember encountering one that did not discuss the impacts in a way that was translatable to the question are we causnig most of the recent global warming?

       e.g. if someone found a very large negative feedback then the abstract would put it in context in terms of climate sensitivity or impact on warming estimates, as the abstract is supposed to provide background. A large negative feedback would likely lead to a small climate sensitivity and would therefore be a rejection by the definitions in Table 2 of the paper.

       But if they found a small negative or positive feedback without specifying the overall effect on warming, then it would be put as no position.

       We were cautious here, tending towards 'no position' in our ratings. This is confirmed by the scientists' responses compared with ours: more than half of our 'no position' abstracts were rated as 'endorsement' by the scientists who actually wrote the papers! A few 'no positions' were rated as 'rejection' by the authors too, but on average the scientists rated 0.6 classifications closer to endorsement than we did, on the 7-point classification scale.

45364. JvD at 20:04 PM on 16 May 2013
       A Detailed Look at Renewable Baseload Energy
       

       @Tom Curtis. you wrote:

       "1) Fail safe design, so that in the complete breakdown of power supply and or mechanical systems the reactor shuts down safely; and

       2) No net environmental impact for ore to waste. The idea here being that uranium ore is a naturally occuring low level environmental hazard. That fact allows a straightforward definition of safe disposal of nuclear waste. That is, if radiation count at the surface of a waste disposal site is no greater than at the original ore body, and the waste is stored in a way that is proof to leeching and as expensive to reprocess as the original ore, then waste disposal has no net environmental impact and can be considered safe.

       Do you agree that these are reasonable constraints on the nuclear industry?"

       I agree. Furthermore, these constraints should count for all energy industries. What we need is a level playing field. So if there is for example a gas pipeline break that kills people (which happens all the time, in all countries using natural gas) then clearly all natural gas pipelines worldwideneed to be shut down immediately until there is a thorough review of their safety, and full list of recommendations to improve safety to the minimum level of nuclear power, just as what was done in Japan and Germany after Fukushima. Otherwise there is no level playing field. It won't do to consider deaths due to natural gas explosions, wind turbine blade tossing, people falling of their roofs while cleaning solar panels, etc as somehow different from deaths due to radiation accidents. All these deaths are known and they should be treated equally.

       Concerning the safe storage of wastes, we know from the Oklo uranium deposits (which contain numerous natural nuclear reactors) that radioactive products from nuclear fission are contained by such geologies. So returning HLW to such mines is a first indication that safe storage of fission products is easy and in existence. We can engineer storage facilities that are even better than the naturally occuring nuclear waste storage sites that have been found at Oklo, but it is nonsense to suppose that 'there is no solution to nuclear waste' Clearly, there is. Even nature itself - with no engineered radiation barriers - does a very good job.

       Concerning fail-safe reactor esign. The modern AP1000 and EPR NPP's contain many of such features. Most 4th generation reactor design are even safer still, because they don't rely on passive, non-energised safety systems, but rather on reactor physics that require no safety systems at all, passive or active.

45365. Kevin C at 19:52 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       JRT256:

       So, I was curious as to how the study would classify a paper which stated either that we don't know how much of the warming was caused by human activity or that stated a percentage which was less than 50% of it as being caused by human activity.

       A 'we don't know' paper would be counted as taking a position but uncertain (category 4b). A 'less than 50%' paper would be counted as an explicit rejection of the consensus (category 7).

       Ed Davies:

       One question, how would a paper which accepted the basic chain of human emissions -> more CO₂ in the atmosphere -> warming -> positive feedbacks (water vapour, etc) but then proposed that there were large negative feedbacks which cancel out most of the effect be counted?

       You would have to look in the database for the answer on individual papers - the study criteria were based on past warming. Low sensitivity has implications for past warming. Is depends how this is handled in the abstract (or the paper for self ratings).
       

45366. Kevin C at 19:45 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       JRT256: Your post raises several distinct questions, which need separate answers.

       The study examined the abstracts of 12,464 papers and about a third of them endorsed the fact that humans are causing global warming.  Yet the papers conclusing is that there is a 97% consensous.  I am sorry, but that just doesn't make sense.

       Firstly, only a third of the abstracts stated a position on whether mankind was the principle cause of recent warming. However the author self-ratings, based on the whole paper, increased this proportion to two thirds.
       
       Secondly, the paper is very clear that the 97% consensus is among papers which stated a position.
       
       Finally, your confusion is based on a false assumption that every paper which mentions global warming is trying to test whether global warming is occuring and is man made. But many papers with the appropriate keywords in the title only deal with parts of the question. For example a paper on measuring the global warming signal in the instrumental temperature record may say nothing about the cause. Thus it is expected that a significant proportion of the papers will have no position on the question. Including such papers is as meaningful as including all the papers on the colours of butterfly wings.

       It sounds to me like most papers are scientifically proper and did not take a postition on political issues.

       Whether human activity is causing the majority of recent warming is not a political question, it is a scientific question. The question 'what should we do about it' is a political question.

45367. Ed Davies at 19:41 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Excellent work. One question, how would a paper which accepted the basic chain of human emissions -> more CO₂ in the atmosphere -> warming -> positive feedbacks (water vapour, etc) but then proposed that there were large negative feedbacks which cancel out most of the effect be counted? I'm thinking of the UAH guys and Richard Lindzen who, as I understand things, have views like this.

       (Read this article and your Guardian post but not the main paper - sorry if this is covered in the paper.)

45368. Dikran Marsupial at 19:18 PM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Dr Tung I'm sorry, but you have not answered my question.  It may be your opinion that there is a systematic underprediction by the CMIP3 models, but if you want others to agree with your opinion you need to be able to provide adequate justification for that opinion.

       As scientists (I am also a scientist) we do indeed pay special attention to the systematic discrepancies between model and observation; however as scientists we should not stop at observing a visual discrepancy.  The human eye is rather too good at seeing "systematic features" in signals where in reality there is only noise, which is why we have statistics to provide an objective test for our hypotheses (even if only a sanity check).  So at the very least, a scientist should determine whether there is adequate evidence that the apparent discrepancy actually is systematic, rather than being merely an artefact of the noise (in this case internal unforced climate change).  My question was intended to help you to explain the evidence for a systematic discrepancy, and so far you have provided none.  I still have an open mind on this, but I require evidence.

       Note I wouldn't go as far as to say that the models give good hindcasts of 20th century climate (in absolute terms), just that their hindcasts are as accurate as we have reason to expect.  If someone can show that the plausible magnitude of the effects of unforced internal variability is substantially smaller than the spread of the model runs, then there may be an argument that the accuracy of the hindcasts falls below that we could reasonably expect.  The problem is that we have only one realisation of the observed climate, with ever changing forcings, so it is difficult to see how we can estimate the magnitude of unforced internal variability without using models in much the way they are currently used.

       At the end of the day, there needs to be an element of self-skepticism in good science, in this case, the null hypothesis should be that the apparent discrepancy is due to internal variability and the onus is on yourself to demonstrate that this is implausible, as it is your claim that a systematic discrepancy exists.  That is conventional scientific practice.

45369. Rob Painting at 19:16 PM on 16 May 2013
       Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
       

       R Gates - There are two aspects to ocean warming; increased greenhouse gas content of the atmosphere warms the cool-skin layer of the ocean and lowers the thermal gradient through that layer. Less heat (from sunlight) leaves the ocean and the surface ocean grows warmer over time. That's why the oceans are warming despite a reduction in solar radiation over the last 3 decades.

       Secondly; the oceans are not passive. They have changed in response to warming, and also have a large natural variability component. Were this not so, only the surface oceans would warm, the surface layers would stratify, and surface warming would be occurring much faster than it is. The recent acceleration of ocean heat content is exaggerated due to the negative phase of the Pacific Decadal Oscillation happening on top of the long-term ocean warming trend. At some stage we are likely to see a return to the positive phase - so ocean warming will slow down.

       Current observations are consistent with paleodata from warm intervals in Earth's ancient past. The equator-to-pole and, surface-to-deep ocean temperature gradients were reduced when compared to modern-day. This implies stronger transport of heat to the deep ocean and polar oceans than is going on today, and suggests the observations are tracking in that direction. 

       I believe a lot of the confusion stems from readers not understanding how the oceans really operate - Coriolis Effect, ocean gyres, Ekman transport, and so on. Working on fixing that. 

45370. JRT256 at 19:15 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       I am trying to get this straight.  The study examined the abstracts of 12,464 papers and about a third of them endorsed the fact that humans are causing global warming.  Yet the papers conclusing is that there is a 97% consensous.  I am sorry, but that just doesn't make sense.  It sounds to me like most papers are scientifically proper and did not take a postition on political issues.
       
       IAC, the issues in the anthropogenic global warming hypothesis are considerably more complex than just yes or no.  This has become even more the case in the last few years as the earth's average surface temperature doesn't seem to increase -- at least for now.  This will clearly result in more papers trying to explain this fact on subjects such as climate sensitivity, as well as whether or not CFCs caused more warming than originally thought, radiation of heat into space as earth's effective temperature increases, and whether the saturation of absorption of EMR by CO2 in the atmosphere actually fits the logrithmic curve.  Papers on these subjects as well as recent ones already publised on water vapor feedback will be the interesting ones and they may not be found by a survey such as this.
       
       I also note that it is clear that some global warming has clearly been caused by human activity.  So, I was curious as to how the study would classify a paper which stated either that we don't know how much of the warming was caused by human activity or that stated a percentage which was less than 50% of it as being caused by human activity.

45371. MarkR at 19:15 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       I think it's important to remember the specific question we asked: are we causing most recent global warming?

       Logically, this means there is also a strong consensus that the rise in CO2 is man-made, the greenhouse effect is real etc. The 'skeptics' that say otherwise are backed up by basically no research that was good enough to pass peer review.

       The evidence for man-made global warming is far too strong to throw out, but on some of the other details we might find more interesting answers if we get the chance to expand this sort of analysis.

45372. cRR Kampen at 17:42 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Zapped onto CNN this morning (local Dutch time) to find John Cook talking to me about this survey, great :)

45373. MS1 at 16:32 PM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Dear Prof Tung,

       thank you for this impressive posting and the valuable comments. As you mentioned Rahmstorf/Forster, I think their paper failed due of the assumption that the ENSO index is linear to the global temperature effect of the ENSO process. Such linearity is a basic prerequisite of a linear regression. The reason for the non-linearity is mainly due to El Nino warm water pools drifting out of the ENSO index region and continuing to warm for years, though no longer measured by the ENSO index. Detrended AMO appears to be the better choice, PDO may be another good choice IMHO.

45374. bill4344 at 16:04 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       I'll buy that T-shirt, by the way. (With maybe a bit less text)

       That's a strong graphic.

45375. KR at 14:47 PM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Tom Curtis - Also worth noting are data discrepancies during the war years, and during the change-over from bucket/engine-room/buoy measures of ocean temperatures. I'm not convinced that all of those data issues for the 1940's have been resolved. 

45376. dana1981 at 14:44 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Yes, the paper is all over the media.  More coverage than we even expected, which is awesome.  We can't even keep up with all the articles!

       The he/she mistake actually originated in the Reuters article.  Innocent enough – you only talk with people over the internet, they never actually see you, and Dana could be either gender.  I've emailed Doyle at Reuters about the mistake as well.

45377. KR at 14:43 PM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Tom Curtis - Quite right, dates (and variability) are not exact. Just keep in mind that while the ENSO represents a major portion of the climate variability, it doesn't cover all of it. However, the 1915-1935 La Nina's and the 1935-1945 El Nino have a significant effect on short term temperature slope over that range. 

       I would not at all be surprised by significant black carbon influences - without satellite measures in the WWII period, it would be difficult to say how much BC was present due to basic fire effects during war years. To estimate that would require extrapolating war damage to black carbon production, and I am not aware of any work in that respect. 

       Does anyone know of relevant papers?

45378. chriskoz at 14:20 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       skywatcher@8

       I've sent an email to Peter Hannam today at 14:00AET (Sydney) requesting the correction. Will see how long this simple fix takes him.

       Everyone in climate blog circles (I guess also most climate scientists) know Dana. But pupolar press editors still don't know him and make big gaffes about him. It's like AGW scientific concensus vs. lack of public awareness about it.

45379. Tom Curtis at 14:17 PM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       KK Tung @34, here is Fig 9.5 A of AR4 overlaid with HadCRUT4 running 12 month mean along with the trends from 1900-1960 and 1910-1940:

       

        Clearly both trends are greater than that of the multimodel mean over equivalent periods.  That being said, the 1900-1960 trend clearly lies above the data from 1945 on, suggesting that it has been dragged up by the 1937-1946 temperature excursion.  It is fair to say, therefore, that the multimodel mean accurately predicts temperatures in the early and mid twentieth century except from 1937 to 1946.  Given that the world was in a state of war durring that period (remembering not just WW2, but Spain, Manchuria and the Sino-Japanese wars) it is at least plausible that the excursion is either an artifact of reduced temperature measurements or the result of unusual and as yet undetermined forcings resulting from the devestation of modern warfare.

       Of course, if the appropriate trend comparison is 1910-1940, such possibilities will be inadequate to explain the discrepancy.  However, for 1910-1940 to be the appropriate period of analysis, we need an independent reason for distinguishing that period.  Without that independent reason, focusing on an interval starting with an unusual low and ending with an unusual high in tempertures is just another game of cherry picking.

       You will argue, no doubt, that the existence of the AMO give sufficient reason to focus on that interval.  I would disagree.  You have not established the existence of an AMO prior to the twentieth century, and your reason to consider the twenteith century AMO independent from known forcings comes down, in the end to the 1940s temperature discrepancy.  Consequently, the is not evidence of a globaly influental AMO, but only that something occurred in the 1940s which is not yet adequately explained.  The AMO is one candidate explanation among others.  Indeed, the lack of a regular, influental AMO prior to the twentieth century makes it, IMO, a very weak alternative explanation.  So weak that it is in danger of being merely ad hoc.

45380. Tom Curtis at 13:53 PM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       KR @36, the cool aberation from 1907-1914 at least partially overlaps the strong El Nino event starting in 1910, and hence is not entirely explained by ENSO.  Likewise the warm aberation from 1937-1946 is longer, and starts earlier than the major El Nino of 1940-1943.  (Dates determined by eye so not exact.)  Consequently while ENSO may partially explain these aberations, there remains something to be explained once we have accounted for ENSO.  I personally am inclined to think that Black Carbon forcing durring the war years has been underestimated, but obvoiously that is just a guess.

45381. Rob Honeycutt at 13:22 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Yeah, I'm really glad we did the self-rating thing.  It removes any notion that the results are just the SkS rating being biased.  In fact, it shows that the SkS ratings were very conservative in their judgement.

45382. DSL at 13:14 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Let the whining begin.  Congratulations, people!  The self-ratings results are a slap upside the head of the Watts-bots.

45383. Miriam O'Brien (Sou) at 13:12 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       You can't argue with the evidence.  Looks to be an excellent effort all around.  Congratulations to John, Dana and all the authors and everyone who worked so hard to bring this to fruition.  Also to the donors.

       I see it's popping up all over the mainstream press.  It's having a solid impact.

45384. skywatcher at 13:11 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       Awesome work everyone, very impressive indeed. Also a nice article in The Age, but someone should maybe tell them Dana's a bloke!
45385. Bob Loblaw at 12:54 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Yes, congratulations are in order. A team of volunteers, contributing significant amounts of their personal time - an accomplishment to be proud of. And to get such a large number of scientists to participate by rating their own papers - that in itself is an indication of the respect that active climate scientists give to the team and the leadership of John Cook.

       And kudos to the rush of SkS readers that provided the funds (10 hours!) to make the paper Open Access. Readers that were obviously willing to put their money where there eyes are...

45386. Bob Loblaw at 12:41 PM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       KK Tung @34: " As a scientist we pay special attention to the systematic discrepancies between model and observation, and I see a systematic underprediction of the observed warming rate in the early part of the twentieth century by the CMIP3 models. "

       [Refering to the graph presented by KR @23]

       Other than your eye, what basis do you have to say that it is a systematic underprediction? Exactly how are you determining which part of the observations represent systematic behaviour, and which part represent random behaviour? (Note that I am asking a somewhat rhetorical question: from what I've read in the posts and your comments, my impression is that you have determined that the observations have systematic behaviour because you've assumed that the behaviour you see is systematic.)

       GCM simulations, by their nature, will have random variations over time, if you start them from slightly different initial conditions. Each simulation represents a realistic sequence, but any one of them will be possible. The observations only represent one sequence. It's like rolling dice: you can have one sequence of numbers originating from rolling the dice 100 times, and a computer model "throwing" dice via a random number generator. When you compare the two, you don't expect an exact match. Doing 20 computer simulations and averaging them will give a sequence closer to the middle, but the observations can still fall anywhere in the expected range for a single sequence. (The analogy isn't the best - rolling dice is purely random, with no systematic pattern in the trend over time.)

       It is simply a mistake to think that the ensemble model mean is what nature is supposed to do: even with a perfect model, nature could follow any one of a large number of different sequences from the model. The correct thing to do, if the observations fall wihtin the range of the individual model runs, is to accept that there is little else you can say about the comparison.

       You simply can't expect the non-stochastic behaviour of the model (average of a number of runs) to follow the stochastic nature of a single run (or observations). If you try to do so by adjusting the model, you are fitting to the noise. In such a case, fitting to a different sequence (e.g., a different time period) with different noise will require different adjustments to the model - and it won't mean anything because the underlying physics is still the same and you've just taken noise and interpreted it as signal.

       ...which appears to be exactly what you are doing with your study: you have mistaken noise for signal, and see a pattern that you think means something, but the pattern is just an artifact of the particular sequence of noise in the data.

       I, like others here, remain unconvinced.

45387. KR at 12:24 PM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       scaddenp - Indeed, which makes the 2000-2012 "slowdown" accompanied by more of a balanced ENSO distribution (ending in significant La Ninas) far more understandable; the expected effects of short term variations against recent history.  

45388. Doug Bostrom at 12:17 PM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       A huge amount of work; well done!

       It's remarkable to see in black and white numbers how isolated contrarians have made themselves.

45389. scaddenp at 12:12 PM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Interesting graph KR. I note too though there is an unually large no. of EN events from 1975 to 2000 which would imply observed warming about background levels.

45390. KR at 11:25 AM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Dr. Tung - Given the large number of La Nina events from ~1915-1935, followed by a decade long El Nino state centered around 1940, the first qualification of the IPCC report should apply:

       Differences between model and observations should be considered insignificant if they are within:

       1. unpredictable internal variability (e.g., the observational period contained an unusual number of El Niño events),

       2. ...

       

       [Source]

       I believe that unusual run of ENSO is a more than adequate reason for a slightly higher slope than non-ENSO modelling in the beginning of the 20^th century - without invoking huge internal variations inconsistent with ocean heat content. I consider your claims of poor focing/climate modelling in the early 20^th century unfounded. 

45391. Tom Curtis at 10:55 AM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Congratulations to John Cook and the SkS team for this important paper.  I know how much work was involved and the team that carried it out have done a marvelous job.

       Moderator Response:

       [JH] You were an integral part of the SkS team and made major contributions to the TCP effort. Thank you for that as well.

45392. Rob Honeycutt at 10:50 AM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       But they are very very noisy!  

45393. Alexandre at 10:23 AM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Albatross at 09:26 AM on 16 May, 2013

       I agree with you that this disagreement among 'skeptics' should be more stressed. They are:

       1) a very heterogeneous group, with conflicting theories among them

       2) a very tiny minority, as shown here (again)

       3) not backed up by evidence

45394. Alexandre at 10:19 AM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Man, this was fast. Congrats to all co-authors and volunteers.

       About the skeptics, I think a more accurate sentence would be 

       We fully anticipate that some climate contrarians will move the goalposts by saying "we don't dispute that humans cause some global warming."

       I'll add this paper to the Wikipedia article on Global Warming (Portuguese version).

       PS: SJI link is incomplete and not working.

45395. KK Tung at 09:56 AM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Correction to my post 26: 1700s should be 1800s.

       Moderator Response:

       [Sph]  Original comment revised to help avoid confusion.

45396. KK Tung at 09:54 AM on 16 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       In reply to post 31: "So the question I would like Dr Tung to answer is "Exactly how close to the multi-model mean would you expect the observations to lie in order to give a good hindcast of 20th century temperatures, and how would you justify this estimate of the magnitude of the unforced component?"" 

       The ensemble mean, especially multi-model ensemble mean, should reveal only the forced response.  The difference should be accounted for by the unforced variability (if we assume that the models' forced response is correct).  Although there is quite a bit of inter-model scatter, about 0.3 C, as often happens when you have an ensemble of different models with different levels of quality, one can see in AR4's Figure 9.5 a difference in slope between the red curve and the black curve.  I hear what some of you are saying about the fact that the difference still lies within the scatter, and therefore there is no need for an unforced variability and that the AR4 models are doing well simulating the historical data in the early twentieth century as well.  As a scientist we pay special attention to the systematic discrepancies between model and observation, and I see a systematic underprediction of the observed warming rate in the early part of the twentieth century by the CMIP3 models. This just my opinion. You do not need to agree with me on this.

45397. Albatross at 09:26 AM on 16 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       Congrats to everyone involved!  Undertaking this research clearly required an immense amount of work and dedication, not to mention enduring an illegal hack on the SkepticalScience website (the stolen material which fake skeptics were [and are] only too happy to disseminate, is evidence that ethics and morality are extremely low on the list of priorities of fake skeptics).

       Regardless, this independent study by Cook et al. (2013) corroborates previous research, and once again underscores the fact that anthropogenic warming is indeed a theory, with multiple independent lines of evidence have lead to this consensus (consilience in fact).

       In stark contrast, the radical 3% cannot even seem to agree on what to disagree about, they are in a state of chaos, have an alarming propensity to engage in conspiracy ideation and routinely contradict each other and even themselves.  The spectrum of positions held by this fringe element range from those who deny the existence of the so-called greenhouse effect, to self proclaimed "lukewarmers" and fake skeptics.  Indeed, this fringe element seem even more disorganized than those who deny the theory of evolution.

       Climate "skepticism" is in disarray, hardly surprising given that their position/beliefs are based on ideology and politics and not on sound physics.

45398. scaddenp at 07:24 AM on 16 May 2013
       The last time carbon dioxide concentrations were around 400ppm: a snapshot from Arctic Siberia
       

       William, in that past period there has been time for full equilibrium to be established. 8C warmer is consistant with estimates of ECS. It takes 1000s of years for ice sheet to melt but when gone, your albedo is reduced. Ditto for ocean equilibrium. Noone disputes that climate has changed in the past without human influence. That statement is just rhetoric and verging on sloganeering. The important point is that climate has changed in the past for well understood reasons and those causes dont apply now. With different milankovich forcings, interglacials were at different temperatures. However, consider that in pliocene, milankovich cycles were still happening but glacial werent. Why? CO2 too high.

       Because fires can start naturally, does that mean you cant charge someone for arson?

45399. Rob Honeycutt at 07:13 AM on 16 May 2013
       The last time carbon dioxide concentrations were around 400ppm: a snapshot from Arctic Siberia
       

       William @ 23...  The fact that atmospheric CO2 has radiative properties that cause the planet to warm does not have to be re-examined in each and every paper that discusses it.  This is a fact that has been well established for over 100 years.

45400. William Haas at 07:07 AM on 16 May 2013
       The last time carbon dioxide concentrations were around 400ppm: a snapshot from Arctic Siberia
       

       So according to this article there is more evidence of huge changes in climate that could not possible be caused by man.  It talks about CO2 levels about what they are today but with temperatures as much as 8C higher.  (-snip-).  This paper is consistent with the idea that some of the past interglacial periods were much warmer than the current one.

       Moderator Response:

       [DB] Sloganeering snipped.

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