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Comments 44951 to 45000:

44951. JasonB at 12:56 PM on 24 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       There is a reason why the email asked the original authors whether their paper endorsed such a simple, "common speech" statement without definitions of each word — it's so that their answer can be reported to the general public in the same terms.

       Actually, there was one definition: "human activity (i.e. anthropogenic greenhouse gases)". This narrowing of "human activity" to just anthropogenic GHGs allows them to state that the consensus relates to GHGs without anyone being able to muddy the waters by claiming that some scientists might have been talking about other activities like land clearing.

44952. Riduna at 12:54 PM on 24 May 2013
       Matt Ridley's misguided climate change policy
       

       Climate sensitivity is found by the IPCC to be ~3.5C, a value confirmed by paleoclimate studies undertaken by Hansen and others and is widely accepted. Dr Otto et al, using data covering a relatively short period (too short?) has found that sensitivity appears to be significantly lower.

       Ridley concludes from this that public policy on curbing anthropogenic carbon emissions is misplaced, damaging and should be slowed. He comes to this conclusion without accurately quantifying and estimating the effect of slow feedbacks over next 87 years of this century or their capacity to fully off-set the Dr Otto's findings by 2100.

       Those feedbacks include loss of albedo, methane and carbon dioxide emissions trapped in and under permafrost and increased water vapour due to atmospheric warming. Nor can we ignore increasing ocean heat content and the likelihood of its release to the atmosphere, accelerating feedbacks.

       The speed with which feedbacks are now developing is more likely to increase rather than lower the rate of global warming. To interpret the findings of Dr Otto et al as indicating that we may have a decade or so longer in which to curb anthropogenic emissions is, in my view, the height of folly.

44953. Eric (skeptic) at 12:13 PM on 24 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       R Gates, I think my question also applies to SSW, but it may not.  It appears that models have improved a lot in coupling the stratosphere to the troposhpere.  The theory of SSW includes many factors including solar plus feedback with weather in the troposphere and ozone in the stratosphere.  The feedback with the troposphere could include some changes due to a decreased tempeature gradient from global warming but generally the gradient is so large during these events it is hard to imagine an impact from that long term trend.  Also difficult because those events are relatively rare.

       Chris, that makes sense although I'm not sure of the implications for the positioning and strength of the polar jet. 

44954. JasonB at 10:27 AM on 24 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       nealjking,

       In my view, it has to be understood as "common speech"

       Precisely. There is a reason why the email asked the original authors whether their paper endorsed such a simple, "common speech" statement without definitions of each word — it's so that their answer can be reported to the general public in the same terms.

       Consider the fact that laws are full of such undefined terms, like "reasonable". Probably the most famous of these is the phrase "guilty beyond reasonable doubt". The reason that they don't tell you, as a jury member, how you are "supposed" to interpret that is precisely because they want you to bring your own definition to the table. Get a large enough group of people together and the opinion of the majority will be an effective "poll" on what the word is supposed to mean.

       Likewise, ask a few thousand scientists whether or not their papers endorse the proposition that human activity is causing global warming and you can be sure that the majority are going to interpret that in the same way as the majority of the populace. It doesn't matter if a few scientists here and there have odd interpretations, or a few members of the public have odd interpretations, overall they will agree.

       The only exception to this rule is when the scientists have a reason for systematically interpreting it differently to the general population, and in this case it could well be true, because these scientists are climate scientists, and they can hardly be unaware of the IPCC's statement of consensus, which is that "human activity is very likely causing most of the current GW". Given that, it is entirely reasonable to assume that those scientists answered an even stronger interpretation of the statement than what the general population would assume it to mean, but this possibility does no favours to those who wish to nitpick.

       The bottom line is that several thousand scientists, when asked to asses their own papers —  so there was no need for them to try to interpret what they wrote, they knew exactly what they were trying to say —  responded by claiming that 97.2% of those that addressed the question at hand endorsed the statement that human activity is causing global warming.

       This is profound for two reasons: 1) It shows that a large number of scientists, independently interpreting both the meaning of that phrase and their own papers, arrived at the same level of endorsement as Cook et al did looking only at their abstracts, and 2) it did so while at the same time enormously growing the percentage of papers that actually addressed the question, that Cook et al were forced to categorise as "neutral". Incredible.

       Arguments over whether levels 2 or 3 endorse the proposition that humans are the "dominant" cause, or a "signficant" cause, or "> 50%", are seriously missing the point, just like those insisting that "reasonble" be precisely defined. If the scientists wanted to convey lesser degrees of human involvement, they could have chosen level 5, or level 6, or level 7, depending on how it was conveyed in their paper. The fact that the overwhelming majority of them didn't speaks volumes. Levels 2 and 3 cannot be read in isolation, and the fact that both have the worse "endorse" in the title cannot be ignored.

44955. KK Tung at 07:18 AM on 24 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       In reply to post 104 on the relevance of the recent hiatus to the present thread on the Tung and Zhou (2013) paper:  That paper offered one possible explanation for the observed hiatus observed since 2005, as due to a recurrent internal variability. Therefore it is relevant (thank you, Dikran, for pointing this out in post 105). There are many other suggestions, including coal burning in the emergent economy of China (Kaufmann et al. [2011] ), increases in stratospheric water (Solomon et al. [2010] ), or increases in “background” stratospheric aerosol (Solomon et al. [2011] ). I in no time suggested that ours is the only explanation.  The most recent explanation is that the heating from the greenhouse gas induced radiative imbalance goes into the deep ocean.  There are two timely paper by Jerry Meehl and his co-workers: One is published in 2011 in Nature Climate Change,vol 1, page 360-364, entitled : "Model based evidence of deep ocean heat uptake during surface temperature hiatus periods". The other is currently under consideration at J. Climate, entitled "Externally forced and internally generated decadal climate variability associated with the Interdecadal Pacific Oscillation".  They are very relevant to our current thread.
       

       Meehl et al used CCSM4 model run with a future scenario (RCP4.5), which does not have oscillatory variations in the forcing or dips such as those by volcano eruptions. With smooth forcing, the 5-member ensemble mean model global mean temperature is also smoothly increasing.  However the individual members show variability about the mean of around 0.5 K from peak to trough.  These papers are not about how good the model is in comparison with observation.
       

       From an energy balance standpoint, the top of the atmosphere radiative imbalance driven by the anthropogenic forcing should be accounted for mostly by the heat uptake in the oceans, as land and ice have much lower heat capacity.  In the model this heat budget can be done exactly.  Meehl et al defined the hiatus period as when the surface temperature has a negative trend even in the presence of increasing radiative driving. They found that during the hiatus period, the composite mean shows that the upper ocean takes significantly less heat whereas the ocean below 300m takes up significantly more, as compared with the non-hiatus period.  The second paper compares hiatus periods with accelerated warming periods, and finds the opposite behavior: the upper ocean takes up more heat and the deeper ocean much less.
       

       The question is, what causes some periods to have more heat going into the deep ocean while some other periods the heat staying more in the upper ocean?  I suggest that this is caused by the internal variability that we were discussing earlier.  Our previous exchanges hopefully established the viewpoint that we should view the ensemble mean as the forced solution and the deviations from the ensemble mean by each member as internal variability.  There are no hiatus periods in the forced solution under the CCSM4 RCP4.5 experimental setup.  In fact this solution is smoothly increasing in its global mean temperature.  It is the internal variability, possibly associated with variations in the deep overtuning circulations in the oceans, which determines when a portion of the heat should go to the deep ocean and show up as warming hiatus,  and when it should stay near the surface, and show up as accelerated warming. ENSO, which we generally view as internal variability, also has this kind of vertical distribution variability in the oceans: In La Nina, the upper ocean is cool while the heat goes to the deeper ocean, and opposite behavior in El Nino.
       

       The CCSM4 is known to have internal variability that is faster than in the observation.  Instead of having hiatus periods of about 2-3 decades in the observation its cooling periods last 1-2 decades.  This may possibly be caused by too rapid a vertical mixing in the ocean but I do not know for sure.  The Interdecadal Pacific Oscillation (IPO) that was discussed by Meehl et al is the low frequency portion of the Pacific Decadal Oscillation (PDO). In the observation the IPO cooling periods coincides with the cooling periods of the AMO, which led me to suspect that the IPO is just the Pacific manifestation of the AMO, which is caused by the variations of the Atlantic Meridional Overturning Circulation.
       

       
       

44956. From Peru at 06:41 AM on 24 May 2013
       Matt Ridley's misguided climate change policy
       

       "committed climate change damage of $2.4 trillion, or over 3% of the global gross domestic product"

       Well, this cost depends on the social discount rate r (among a lot of other variables) the lower the social discount rate, the higher the cost:

       Present value(cost) of pollution = Σ (future damage of year i)/(1+r)ⁱ......(summed over i; i is the number of years in the future)

       But the social discount rate is a function of economic growth:

                                                   r = δ +γ g,

       Where:

       • r is the discount rate
       • δ is the so-called "rate of impacience"
       • γ is a parameter called " aversion to intertemporal inequality"
       • g is economic growth

       [source: Christian Gollier, Pricing the future:The economics of discounting and sustainable development, Toulouse School of Economics, 2011]

       δ is set to zero for intergenerational timescales, leaving r as just a function of γ and g.

       Now if the economy is seriously damaged by climate disasters, g will turn smaller, lowering the discount rate and so raising the present value of future damages.

       I don't know how low can the discount rate fall. So:

       Could it fall below zero, making the present value of damages to skyrocket?

       Is this subtle effect accounted when the cost of CO2 is calculated?

44957. John Hartz at 06:38 AM on 24 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       @Barry 201:

       Speaking for myself, I do not find it terribly useful for you to define one gneral term, i.e., academic merit, with another general term, i.e., quality of scholarship. What is generally accepted set of standards which are associtaed with these terms? (Source please.)

       In your opinion, which of the standards were violated by Cook et al 2013?  

       Do you believe that the editors of Environmental Research Letters deliberately ignored  certain standards when they published Cook et al 2013?

44958. Chris Colose at 06:19 AM on 24 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       Eric #9

       
       The mechanisms behind jet changes (strength, latitudinal shifts, etc) are still pretty hot topics in dynamical meteorology.  I tend to agree, however, that increases in the upper tropospheric pole-to-equator temperature gradient may be more important than the (fairly shallow) decrease in surface pole-to-equator temperature gradient. 

       In fact, because the tropopause slopes downward as you move poleward, if you are floating at a fixed level in the atmosphere near the tropical tropopause you are initially in a region of strong warmer (the "hotspot") but if you moved polewards at that level, you'd eventually end up in a region that was cooling in a global warming scenario.  That has a lot of implications for dynamics, since gradients in wind velocity are directly proportional to horizontal temperature gradients.

44959. MA Rodger at 06:10 AM on 24 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years?
       

       So where to look for evidence of AMO warming beyond the shores of the N Atlantic?

       My first thought was that if AMO was going to effect temperatures anywhere, it would be the UK. Indeed, the CET was invoked within T&Zh13. So I compared CET with the SST for the surrounding seas (45-65N, 20W-10E) with nomad3 providing monthly SST data - 1981 to date. The two temperature profiles are re-based for comparison and graphed below. with AMO also plotted (although AMO is of course subject to a de-trending).

       The divergent record is evidently CET not the SST which suggests that during these divergent periods, AMO is not in any way a dominant influence in CET. So are divergent periods infrequent such that the period 1988-2004 is the norm where SST & CET can be married together?

       

       A de-trended CET for the period of Enfield's AMO index (1856 to date) is next up for comparison being graphed below. Divergence appears the normal state here, with the two indices have little in common. I would conclude that the CET record does not support the suggestion that AMO drives UK temperatures.

       
       Still. It's early days. There may yet be that local variation is swamping the signs of the AMO driving UK temperatures. And the UK is not the whole globe.

44960. Dumb Scientist at 05:56 AM on 24 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       As I discussed in part 2 of the post, the MLR analysis follows the arguments laying out the evidence in favor of the AMO being mostly natural. [KK Tung]

       Again, I don't think that's the issue. Removing the AMO to determine anthropogenic warming would only be justified if detrending the AMO from 1856-2011 actually removed the trend due to anthropogenic warming.

       The MLR analysis cannot stand on its own as evidence. If that were what we did in our PNAS paper, then our arguments would have indeed been circular.

       Those arguments aren't sufficient to support your claim that ~40% of the warming over the last 50 years can be attributed to a single mode of internal variability. Especially because Isaac Held and Huber and Knutti 2012 used thermodynamics to conclude that all modes of internal variability put together couldn't be responsible for more than about 25% of the warming.

       Similarly, as you have done here, you assume the hypothetical case that the AMO is anthropogenically forced, but you do a MLR assuming it is instead mostly natural and remove it.

       Actually, Dikran's analysis defines the AMO as 40% anthropogenic and 60% natural. So it is mostly natural.

       But again, I think the key point is that linear detrending doesn't remove the nonlinear anthropogenic trend from the AMO.

44961. KR at 05:46 AM on 24 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Dr. Tung - I would agree that the identification of the AMO is critical for attribution analysis. I would disagree on the AMO index you used. 

       You used the CET as an AMO proxy - however the CET is equally vulnerable to aliasing (hiding) the global warming signal. Frequency analysis in this case is suspect, as the sum forcings in the 20th century (GISS forcings here), when averaged out by climate response times, have a frequency similar to that of the AMO observations - and are therefore not directly separable using just time series analysis. 

       ---

       I am in addition greatly disappointed that you have (as yet) failed to respond to my points regarding the Ting et al 2009 analysis (time/spatial principal component analysis supporting the Trenberth Shea 2006 detrending method, not linear detrending) or to ocean heat content thermodynamic constraints (upper limits on contributions from internal variation), as raised here. Either of these points indicate a much different anthropogenic contribution to current temperatures. 

44962. MA Rodger at 04:57 AM on 24 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years?
       

       Dikran Marsupial @62.

       I can agree almost fully with your comment. Perhaps the use of Occam's razor needs wielding with care so it doesn't become Occam's broom (sweeping stuff under the carpet, out of sight).

       The point with the 'chipping away' idea is that just as CAN BE is distinct from IS, so it is also distinct from IS NOT. Thus, while our inabilities in removing the AGW signal from AMO would seemingly present an insurmountable problem for the T&Zh13 method, the question of how much of recent global warming is AMO and not AGW will remain unanswered.

       So I'm thinking of looking to see if there are signs of AMO warming beyond the N Atlantic, or signs of non-AMO warming. A tiny bit of harmless analysis. But frankly analysis that I feel should have been done already. Perhaps it has & I missed it. Perhaps not.

44963. KK Tung at 04:42 AM on 24 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Regarding the Matlab code result of Dikran mentioned in post 106 and by DumbScientist earlier:

       I am frustrated that I have not been able to get my point across despite a few attempts, as you continue to focus on a technical procedure, the multiple linear regression analysis (MLR).  As I discussed in part 2 of the post, the MLR analysis follows the arguments laying out the evidence in favor of the AMO being mostly natural.  The MLR is then used to see the possible impact it may have on the deduced anthropogenic warming rate assuming that the AMO is mostly natural.  The MLR analysis cannot stand on its own as evidence.  If that were what we did in our PNAS paper, then our arguments would have indeed been circular.

       I also mentioned in part 2 of my post that one could legitimately claim that use of either the Enfield AMO index or the Trenberth and Shea index is ciruclar, if that is the entirety of the evidence that you presented.  Similarly, as you have done here, you assume the hypothetical case that the AMO is anthropogenically forced, but you do a MLR assuming it is instead mostly natural and remove it.  You can then demonstrate that the resulting anthropogenic response is wrong.  That is, it is different than you originally assumed to be true.  Conversely, if you consider the hypothetical case that the AMO is mostly natural, but you do not remove it, you would also get a wrong anthropogenic response in the end.  This you could have known even before you do the Matlab calculation.

44964. rockytom at 04:21 AM on 24 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       John, another fantastic article with the best graphics I've seen integrated with the text.  I wish we (John Cook and I) had had the graphics when writing our textbook (Climate Change Science: A Modern Synthesis) as we certainly would have included at least some of them (with permissions, of course).

44965. KK Tung at 04:09 AM on 24 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       In reply to post 106 by Dikran: The effect of offsetting on the perceived spread of models has been underdiscussed in literature.  I agree with what you said about it here, and I would encourage you to develop it into a publishable paper.   The procedure of offsetting with a baseline is needed for model projections because projection is different from a prediction.  In a prediction of ,say weather for the next few days, today's measured weather is our baseline, and such a baseline is assimulated into the model.  The model attempts to predict both the forced and unforced response.  Due to chaos, models start to deviate after today, and after two weeks, the prediction becomes mostly useless. But it is useful for a week or so.

       The IPCC projections of future climate change is different.  The model is initiated in the preindustrial period, 1850-1870, runs about 150 years in the 20th century simulation (when what is to be simulated is known), and then runs forward under different scenarios of future emissions.  There is no hope of doing a prediction of both the forced and unforced response over such a long period.  Instead it is hoped that the forced response of the climate is simulated with the ensemble mean of the model runs.  If, in the presentation of the results, all models are offset against their initial condition at 1850-1870.  The intermodel spread is rather large, even during the period of 20th simulation, where the observed response is known before hand. This is caused by systematic errors in each model. This intermodel spread is reduced by offsetting each model's ensemble mean by its own climatology in a specified period, say 1980-1999, as used in Chapter 10 of AR4. It reduced the intermodel spread during the period of offset, and also for a decade or so after that.  AR4 uses different offsetting period in different chapters, and there is no consensus on how to do it. You have found that a longer offsetting period makes the pre-2000 results less anomalous.  On the other hand, for the purpose of evaluating projections to the future, perhaps it may be fairer to the models to offset it with the lates known data.  That is, year 2000 for AR4 projection and year 2005 for the CMIP5 projection.  We however do not know what the observed forced response is, but since AR4 models have simulated the observed 20th warming quite well with forced (ensemble mean) solutions, it may not be a bad idea to offset the model prediction at year 2000 for AR4 projection with the observation at year 2000, and then attribute the subsequent deviation of the model ensemble mean from the observation to the presence of internal variability. Have you tried it yet?

44966. R. Gates at 03:34 AM on 24 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       Wow, fantastic post. Lot's a great information.  One bit of information, perhaps advanced but very important for understanding a negative AO index at certain times of the winter and the havoc it can bring to lower latitudes.  Sudden Stratospheric Warming events (SSW's) where air is descending over the pole form the upper stratosphere and even the mesosphere bring of course high pressure over the pole, warming, and often times a very negative AO index.  These SSW events in essence "open the freezer door" on the Arctic and shunt this very cold air down to lower latitudes.  The normal winter westerlies turn to easterlies as the Polar Vortex is often shattered, and you get real nasty weather at lower latitudes.  Looking back historically, very negative AO events in the winter are highly correlated with these very disruptive SSW events.

       But again, a great article!

44967. nealjking at 03:00 AM on 24 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       s_gordon_b:

       You wrote:

       "Categories 2 and 3 are too ambiguous - as defined in table 2 - to equate to the consensus that humans are not only a cause of industrial era global warming but the dominant cause since the middle of the last century (at least). Am I not reading that right? And if so, shouldn't only those abstracts that take an unambiguous stand on the consensus of dominant human causation be counted and the others excluded in the same way that abstracts that take no stand at all were excluded?"

       From looking at the paper, what I find as the first statement of the consensus (in the abstract) is: “Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming.” So the definition of the consensus position is that “humans are causing global warming”. But how is this to be understood?

       In my view, it has to be understood as "common speech": When the proverbial “man in the street” asks the question, “Are we (humans) causing global warming?”, he is NOT necessarily asking, “Is the degree of responsibility for global warming that is due to human activity greater than 50%?” or "Is human activity the dominant cause of global warming?" He is asking something much closer to, “Is human activity contributing to global warming big enough that we ought to be doing something different?” And I believe most scientists would agree with this understanding of the AGW issue: Not that the human contribution is necessarily greater than 50%, but rather that it is important enough that we should be seriously thinking hard about whether we want to change what we are doing, on a global scale.

       My understanding of the Levels of Endorsement (LOEs) 2 & 3 is that they indicate agreement, explicit or implicit, with the spirit of the underlined statement above, which I regard as a filled-out "common speech" version of the statement in the abstract.

       Therefore, I have no doubts about including LOEs 1 - 3 together as indicating support for the AGW consensus.

44968. barry1487 at 02:39 AM on 24 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       John Hartz,

       What exactly do you mean when you use the phrase, "academic merit"?

       Quality of scholarship..

44969. Dumb Scientist at 02:33 AM on 24 May 2013
       Has the rate of surface warming changed? 16 years revisited
       

       jdixon @27: Sure, just return it when you're done so I can use it again. ;)

44970. John Mason at 02:04 AM on 24 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       Eric - interesting question. I'll have a read of those papers and get back to you in a few days. However one point I would make is that because the Tropopause is such a strong temperature inversion, convective heat transfer between the troposphere and stratosphere is effectively blocked. I would therefore suggest the troposphere plays the main role.

44971. jdixon1980 at 01:46 AM on 24 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       Wow that's a lot of info without having to buy a meteorology textbook - will have to look this one over a few times to absorb it.

44972. Eric (skeptic) at 01:15 AM on 24 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       Good article.  My main question is about how this explanation fits with prior explanations of changes in AO.  For example: <A HREF="ftp://psrd.hawaii.edu/engels/Stanley/Textbook_update/Science_297/Moritz-02.pdf">ftp://psrd.hawaii.edu/engels/Stanley/Textbook_update/Science_297/Moritz-02.pdf</A>  The explanation in this 2002 paper seems to be that GHG cooling of the lower stratosphere leads to an increased vertical gradient and a stronger polar jet.  The explanation above seems to focus on the decreased horizontal temperature gradient causing a weaker jet.  Is one gradient more important than the other?  My opinion is that the 1950-present chart above appears to be mostly natural variation.

       A question specific to Sandy is that the left turn came not just from blocking but from Sandy phasing with a strong short wave riding on the deeply diving longwave jet. I'm not sure why there would be any natural or GHG-induced trend in the strength of the short waves because their strength seems to depend on local temperature contrasts that greatly exceed any of the trends in wide scale temperature contrasts from GHG or natural cycles.

       Finally, Andrew Freedman has a good perspective on climate change and tornadoes <A HREF="http://www.climatecentral.org/news/making-sense-of-the-moore-tornado-in-a-climate-context-16021">http://www.climatecentral.org/news/making-sense-of-the-moore-tornado-in-a-climate-context-16021</A> with a focus on strong tornadoes only.

44973. jyyh at 01:03 AM on 24 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       Thanks for this informative post. I find it's a bit sad case that scientific articles like this one get pretty quickly buried in other kinds of articles on politics, opinions and rebuttals of denialist bullshit. After reading this, I remembered there was a good article on SkS about Sudden Stratospheric Warmings breaking the polar jet stream just recently... after some 10 minute searching I wasn't sure of it anymore. Eventually I found it. It's here :-D :  http://neven1.typepad.com/blog/2013/04/sudden-stratospheric-warmings-causes-effects.html

       I might some day (or week or two) go through the entire archives of climatology blogosphere to seek these kinds of articles I've found clear and approachable to my level students of climate, but as of yet this hasn't happened. I'll note here if I get to it. Thanks again.

44974. jdixon1980 at 00:31 AM on 24 May 2013
       Has the rate of surface warming changed? 16 years revisited
       

       DS @21 I like the water sloshing analogy better than the "flywheel" or the yo-yo because of the built-in illustration of measurement at a single location - I assume you don't mind if I borrow it?  

44975. Rob Honeycutt at 00:27 AM on 24 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       s_gordon_g...  Instead of trying to over interpret the exact wording, take a step backward and look at big picture.

       ~97% of the research supports AGW.

       ~3% of the research rejects AGW.

       The way you're approaching it, you're completely missing the forest for the trees.  This is a common "skeptic" tactic when faced with data they don't like.

44976. John Mason at 23:04 PM on 23 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       Chris, I'll split up your many questions and attempt to answer them in bold type:

       Polar jet stream, is maybe a bit confusing sicne the southern antarctic oscillation is also a polar jet stream?

       Yes, there is also a southern polar jet, but this post is specifically with regard to the Northern Hemisphere.

       Polar air intrusion during the winter because of the higher jet stream amplitude. The UK will likely expereince much more pronounced floods, with Jet Stream blocking patterns, when the rain system just keeps sitting there.

       This can be the case but more typically from a blocked pattern in summer - when it's warmer then the air can contain more moisture. Winter blocks tend to produce pronounced cold spells.

       What about downward bursts/microburst?

       These are features associated with high-precipitation thunderstorms and so occur in highly unstable atmospheric environments - an approaching upper trough with its attendant PVA will encourage mass ascent of air, but downbursts are storm-scale features.

       Greenland is according to Jennifer Francis a prime spot for blocking patterns to occur, see Sandy - caused 90 degree turn.

       Yes WRT Greenland, with stubborn high pressure over it and linking down to the Azores High being a good example of a blocked setup. The upper pattern played a part WRT Sandy's course, but I'm not sure of the exact figure without looking it up.

       Where exactly is the Jet Stream, if not with the Jetstreaks?

       See the diagrams up-post

       Are these visible from the ground - do they come with clouds or is this different?

       Cirrus can occur within jetstreaks and is obvious as it's moving rapidly. But in general no.

       In regards to tornadoes and Jet Stream:“As with hurricanes, I think frequency needs to be separated from intensity.Climate change increases the available energy for tornadoes through a warmer and moister atmosphere. Wind shear decreases in the global mean, but this might be irrelevant locally when the jet stream dives southward like it did last weekend across the Plains.“I believe there is evidence that the strongest tornadoes are getting stronger. They are certainly getting longer and wider.” - James B. Elsner, an atmospheric scientist at Florida State University Humid air and the Jet Stream help to fuel more intense thunderstorms/tornadoes

       Joe Romm has a post-Moore, OK, review of tornado climatology at Climate Progress:

       http://thinkprogress.org/climate/2013/05/21/2040221

44977. Dikran Marsupial at 21:31 PM on 23 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years?
       

       MA Rodger The degree to which Prof. Tung's method over- or under-estimates the true anthropogenic component depends on both the true "noise" (the variation not due to the factors explicitly included in the model - note this is not necessarily the same as the residuals from the regression) and on the nature of the non-anthropogenic factors. As linear and quadratic detrending are correllation based methods, they are highly susceptible to any correlation or anti-correlation between the anthropogenic and non-anthropogenic components of the AMO.  Similarly any flaw in the detrending of the AMO that is correllated or anti-correlated with the noise in the observations may be exploited by the regression procedure.

       Essentially Prof. Tung's regression approach appears only to be workable if we can eliminate the anthropogenic influence on AMO exactly without attenuating any of the non-anthropogenic component.  We can't do this unless we already know what exactly the anthropogenic influence on AMO actually is.  I don't think this is "chipping away"; if my analysis turns out to be correct (and I have no problem with being wrong - it is part of normal scientific procedure!) then the whole regression procedure is invalid and hence does not support the conclusion. 

       Even when valid, regression methods can only really show that something CAN BE explained by something else, not that something IS explained by something else.  We really need physics to determine whether AMO actually does influence GMST. The work of Foster and Rahmstorf shows that we don't need AMO to explain the "hiatus" as it CAN BE explained using ENSO etc.  Occam's razor suggests we shouldn't needlesly introduce new elements if an existing theory already explains the observations already; however that doesn't mean that AMO has no effect on GMST.

44978. Dikran Marsupial at 21:04 PM on 23 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Prof Tung writes

       "When the observation is below the model ensemble mean, I tentatively suggest that the explanation could be that there is an internal variability that is in a cool phase in the observation but is not (and should not be) in the model ensemble mean."

       Yes, I think that the majority of SkS readers would agree that the ensemble mean is probably the best method we currently have for estimating the forced response of the climate system and that any difference between the observations and the ensemble mean can be explained as being due to the unforced response due to sources of internal climate variability.  This is of course, provided the difference is approximately within the spread of the ensemble (in reality this is probably an underestimate of the true uncertainty due to the small number of model runs and the limited number of models).

       "The point I made previously was why we need it now during the hiatus period and not during the period of accelerated warming."

       I do not agree with this statement.  There are multiple sources of internal climate variability, which include for example ENSO and plausibly AMO.  Most of the time these will be acting to warm or cool the climate essentially at random, and so most of the time might be expected to largely cancel out.  This is why the ensemble mean, while being an estimate of only the forced response, is still a reasonable point estimate of the observed climate.  However, sometimes multiple sources of internal variability may temporarily align in direction, causing the observed climate to stray away from average conditions.  Under such circumstances one would expect the observations to stay reasonably close to the forced response most of the time, but for there to be occasional periods of little or no warming, or conversely more warming than expected. 

       Easterling and Wehner (2009) investigated this issue in some detail and found that

       "...periods of no trend or even cooling of the globally averaged surface air temperature are found in the last 34 years of the observed record, and in climate model simulations of the 20th and 21st century forced with increasing greenhouse gases. We show that the climate over the 21st century can and likely will produce periods of a decade or two where the globally averaged surface air temperature shows no trend or even slight cooling in the presence of longer-term warming."

       In other words, we should expect to see the occasional "hiatus" ocurr due to internal climate variability, the models predict that they will happen if you wait long enough, but being chaotic phenomena the models cannot predict when they will happen.  As far as I can see, there is little evidence that the models need internal variability more in recent years than they did before.

       It is also worth noting that the issue to do with baselines may look as if the observations were more central in the spread of the models during the baseline period as baselining removes any offset between timeseries exactly within the baseline period, but only approximately outside.  Some of these offsets will be due to random rather than systematic differences, so the apparent uncertainty of the models in the baseline period will be lower than outside the baseline period.  This effect will be smaller the longer the baseline period, as shown in my earlier post, but I suspect it does contribute to the observations looking less "anomalous" during the pre 2000 years than perhaps they should.   

       I think it is very important to be highly skeptical of phenomenon that seem obvious from a visual inspection of the data.  The human eye is very prone to seeing patterns in noise that don't actually mean anything.  We should be reticent in claiming that there has been a real hiatus until there is statistically significant evidence for that assertion.

       Incidentally, as Dumb Scientist points out, I have also made two posts in the previous thread addressing the issue of circularity, which seems to suggest that the regression method proposed does involve circularity.  The posts are here and here.  If you are a MATLAB user, I can send you the scrips used to perform the analysis.

44979. MA Rodger at 20:39 PM on 23 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years?
       

       Dikran Marsupial @57.

       Assuming your method holds up, you have illustrated that by subtracting the AMO signal from global temperature to reveal the AGW, you can be also inadvertantly be subtracting a significant amount of AGW. Your "Question 2" @16 thus stands now with evidential support.
       Commendable stuff but....
       The question that would perhaps follow would concern whether the proportions shown within the example you present (ie that 33% of the AGW signal is lost by subtracting AMO in this manner) are sensitive or insensitive to the situation. Will it always be about 33% or will it sometimes be much more, or less.

       
       And I am far more sceptical about T&Zh13., I feel this chipping away is not the best approach. Indeed I remain sceptical that there can be any significant contribution to the global temperature anomaly from AMO.
       One point I would make runs as follows - If global temperature wobbles 0.3ºC peak-to-peak due to AMO (as T&Zh13 asserts) and if 67% of this is resulting naturally from AMO (ie if we factor in the suggested finding @57  = 0.2ºC) then how much energy will be required to wobble the global temperature that amount? With TRC=2ºC (this is one place where contrarians would find high Climate Sensitivity useful), the global wobble would require a forcing equatable to 10% of 2xCO2 or 0.37Wm^-2 or an energy flux of 6ZJ pa. If this energy flux originates solely in the N Atlantic (ie if it is a direct energy output of the AMO), it will incur significant losses as it spreads out around the world. If the AMO has some deliverable other than 'heating of the climate' then the T&Zh13 thesis has some explaining to do.

       
       

       I think I will go in search of my 6+ZJ pa. It is rather a large quantity to go unnoticed.

       I suppose my feeling on all this is that the AMO is simply an ocean waggling like a continent and is driving zip. But such comment here is pure speculation. And I am prepared to admit as much.

44980. Dikran Marsupial at 20:36 PM on 23 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       MA Rodger It seems to me that Prof. Tung has introduced the "hiatus" largely as a way of establishing the existence of internal variability, although I think the majority of SkS readers will already accept that without the need for it to be stated explicitly. 

44981. MA Rodger at 20:21 PM on 23 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       KK Tung @97.

       The thesis we discuss (Tung & Zhou 2013) specifically addresses multidecadal episodes of warming and cooling. This "hiatus period" you now discuss has been evident within the temperature record for less than a decade. Given the present short duration of this "hiatus period," given the many other points presented within Tung & Zhou 2013, is it helpful to our discussion to introduce yet another topic into this discussion? Indeed, why is the "hiatus period" relevant?

       So far the two posts on this thesis have encompassed (1a) The shape of the net anthorpogenic forcing profile. (1b) Sea ice as a driver of AMO, (2a) AMO in climate models. (2b) AMOC evidence. (2c) Pre-industrial AMO data. (2d) Remnant anthropogenic signal in AMO. (2e) Using AMO as a "forcing."
       So far, most of these topics remain poorly addressed, if addressed at all. I would suggest adding a fresh item to this discussion (ie introducing the "hiatus period" ) which does not appear entirely relevant is the opposite of what we should be attempting.

44982. Dikran Marsupial at 19:45 PM on 23 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years?
       

       As an update to my previous post on Prof Tung's method, I've now investigated quadratically detrending the AMO signal to remove the anthropogenic influence, using:

       X    = [ones(size(T)) T T.^2];
       beta = (X'*X)\X'*AMO;
       AMOd = AMO - X*beta;
       
       

       This doesn't work either, but this time it over-estimates the anthropogenic forcing, although the error is smaller than for the linear detrending.

       

       The reason this doesn't work either is both subtle and interesting.  Ideally the detrending would eliminate the quadratic anthropogenic component leaving only the sinisoidal natural component.  However, the sinusoidal component has a linear trend, being positive in the first half of the time series and negative in the second.  So when we quadratically detrend the raw AMO signal, we can erase both the anthropogenic component AND the linear component of the natural signal.  However the linear component of the natural signal slopes downward and that of the anthropogenic signal upward, so this cancels out to a degree, and the resulting quadratically detrended AMO signal has an upward linear trend.

       

       We defined the synthetic AMO signal as

       AMO = 0.4*anthro + 0.6*natural;

       so if we exactly remove the anthropogenic component, the correctly detrended AMO signal is just 0.6*natural (blue).  However if we use simple quadratic detrending, we get the AMOd signal shown in red.  The green line just shows the difference between the two.

       The problem is now that the component shown in green is correllated with the anthropogenic component of the observations, so a quadratically detrended AMO still acts as a proxy or alias for BOTH the natural and anthropogenic components of the observations, which means that you can't use this method for attribution either.

       
       The bottom line is that it seems that Prof. Tung's method only gives the correct answer if the anthropogenic component is exactly removed from the AMO signal before performing the regression.  Adding the trend of the residuals does not solve this problem.  Of course we can only exactly remove the anthropogenic component from AMO if we already know what it is, so using this method to estimate the anthropogenic component of the observations does require circular reasoning...  provided I have not misunderstood the method, of course!

44983. johncl at 18:40 PM on 23 May 2013
       On the value of consensus in climate communication
       

       I do believe the main problem for many now is not to accept that there is global warming happening, but that its caused by humans - as it implies that they are themselves guilty of it. Also, its very easy for people to put blame to others even if they believe humans are the cause of it. "Its the Chinese and all their coal plants!". So here in Norway there is constantly comments from people about e.g. electrical cars being bad because they are fueled by coal electricity - even though Norway has 99% of its electricity from hydro power. The general idea is that, if its not good for the general average over the whole globe, its not good for us as well. But this idea is rather silly in my opinion, and in most cases its rather impossible to change peoples view on this since its so securely rooted in the trandition of the fossil fuel car being the best choice. It doesnt help that Norway also gets its current wealth from oil as well.

       The same odd argument is also used against building more windmills in Norway, because we already have enough hydro power. So its indeed like a snake biting its own tail, as many people seem to be unable to have more than one thought in their heads at one time. I do believe the more you are able to see things in a wider perspective your views will slowly creep towards more liberal viewpoints and are able to see the bad things about free market policies and the effect of e.g. globalism. Also there is general disconnect from nature in the way that we treat consumables as things that magically appears in the shelves. In general people need to be educated about the carbon footprint of anything we buy, almost to the point where every good has a carbon footprint estimate printed on its label. But with e.g. the clothes industry not even wanting to inform the public about which factories their goods are made in - its clear that the "truth" of globalism is one they would rather be kept secret since its generally bad publicity the moment another building collapses or is known for using child labour. So we need education of the masses that every choice we make in consumption is also a moral choice about the implication of globalism, its carbon footprint and human suffering that results from it.

       I am very thankful that John Cook and SkeptialScience is keeping up with spreading the message and I was very happy to see the consensus research even presented in mainstream media here in Norway as well. The discussions in the comment fields were just littered with "AGW is BS" and all kind of denial ofc. But those comment fields are also a place were we should be active and promote real science information and preferably with links to sources, which is one the denialsphere often lacks as its generally based on feelings and not facts. Unfortunately when they do seek "facts" for themselves they very easily end up on WUWT and other denial sites because it seems they have been able to flood the search databases with classical spam link methods for getting high on the search results. Its easy to see this if you search for "global temperature" for images and see where those images lead to. So its indeed an information battle going on here to get real information. Good transparent research like this consensus project is definitely what we need more of.

       To quote a song by Peter Gabriel: "Turn up the signal, wipe out the noise!".

44984. Chris8616 at 18:27 PM on 23 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       A link between reduced Barents-Kara sea ice and cold winter extremes over northern continents

       The recent overall Northern Hemisphere warming was accompanied by several severe northern continental winters, as for example, extremely cold winter 2005–2006 in Europe and northern Asia. Here we show that anomalous decrease of wintertime sea ice concentration in the Barents-Kara (B-K) seas could bring about extreme cold events like winter 2005–2006. Our simulations with the ECHAM5 general circulation model demonstrate that lower-troposphere heating over the B-K seas in the Eastern Arctic caused by the sea ice reduction may result in strong anticyclonic anomaly over the Polar Ocean and anomalous easterly advection over northern continents. This causes a continental-scale winter cooling reaching −1.5°C, with more than 3 times increased probability of cold winter extremes over large areas including Europe. Our results imply that several recent severe winters do not conflict the global warming picture but rather supplement it, being in qualitative agreement with the simulated large-scale atmospheric circulation realignment. Furthermore, our results suggest that high-latitude atmospheric circulation response to the B-K sea ice decrease is highly nonlinear and characterized by transition from anomalous cyclonic circulation to anticyclonic one and then back again to cyclonic type of circulation as the B-K sea ice concentration gradually reduces from 100% to ice free conditions. We present a conceptual model that may explain the nonlinear local atmospheric response in the B-K seas region by counter play between convection over the surface heat source and baroclinic effect due to modified temperature gradients in the vicinity of the heating area. Link to Source This study was submitted Nov. 2009.

        

       Keywords:
       Arctic sea ice;atmospheric circulation;nonlinear dynamics

44985. Chris8616 at 18:24 PM on 23 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       NAO

       Timeseries of the winter (December to March average) of the Jones et al. NAO index, updated to the winter of 2011/12. Note the upward trend from the 1960s to the early 1990s, but also that the trend has not been sustained and has significant year-to-year variability superimposed on it. Note also that the winter 2009/10 had the most negative NAO index measured during the almost 190-year record.

       

       Another pathway for temperature chaneg in the northern polar region is freshwater flux from increased thaw in the siberian region, which changed the Arctic curretn setup NASA video arctic ocean current Though freshwater can isolate sea ice

       A new wind regime is another change in the nothern hemispheric aquatic environment, which is ratehr chaotic i guess. The new winds will cause coastel erosion and there seems to be an uptake in more intense storms in the arctic, which happen to break up sea ice chunks of the size 1300 km length (happened a few days ago and in Februar similar).

        

       

       .

       "As we lose all the summer ice, the response in the fall may plateau somewhat (although Arctic Amplification will continue via the other factors), but as ice in the other seasons declines, we should see the response become stronger all year long"

        

       Maybe we get kind of permanent blocking pattern, without the ice. 

44986. Chris8616 at 17:53 PM on 23 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       Polar jet stream, is maybe a bit confusing sicne the southern antarctic oscillation is also a polar jet stream?Polar air intrusion during the winter because of the higher jet stream amplitude. The UK will likely expereince much more pronounced floods, with Jet Stream blocking patterns, when the rain system just keeps sitting there.What about downward bursts/microburst? Greenland is according to Jennifer Francis a prime spot for blocking patterns to occur, see Sandy - caused 90 degree turn.Where exactly is the Jet Stream, if not with the Jetstreaks? Are these visible from the ground - do they come with clouds or is this different?In regards to tornadoes and Jet Stream:“As with hurricanes, I think frequency needs to be separated from intensity.Climate change increases the available energy for tornadoes through a warmer and moister atmosphere. Wind shear decreases in the global mean, but this might be irrelevant locally when the jet stream dives southward like it did last weekend across the Plains.“I believe there is evidence that the strongest tornadoes are getting stronger. They are certainly getting longer and wider.” - James B. Elsner, an atmospheric scientist at Florida State University Humid air and the Jet Stream help to fuel more intense thunderstorms/tornadoes
44987. s_gordon_b at 15:04 PM on 23 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       I'm having a problem interpreting this study. The banner conclusion is that "among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming." But in the Results section it states: "To simplify the analysis, ratings were consolidated into three groups: endorsements (including implicit and explicit; categories 1–3 in table 2)..." This is where I'm experiencing a disconnect. Categories 2 and 3 are too ambiguous - as defined in table 2 - to equate to the consensus that humans are not only a cause of industrial era global warming but the dominant cause since the middle of the last century (at least). Am I not reading that right? And if so, shouldn't only those abstracts that take an unambiguous stand on the consensus of dominant human causation be counted and the others excluded in the same way that abstracts that take no stand at all were excluded? 

44988. scaddenp at 13:51 PM on 23 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       I think this confounds physical and statistical modelling but I will look at the paper. The success of more recent techniques (like F&R) would strongly suggest that this paper is mistaken. The indices might be an imperfect measure of the large scale process, but they are good enough for predicting unforced variation in global temperature due to ENSO.

44989. DSL at 13:48 PM on 23 May 2013
       On the value of consensus in climate communication
       

       I don't have much to say.  Kahan's points are fair, but they're also academic.  No actual model for communication is given, other than a link to a page that has, near the bottom, something useful--the ambivalent partisan approach or mode.  Cook makes good points as well, but he's responding to a game being played behind the curtain, one that Kahan never really addresses.  Indeed, that game should be fully recognized in any strategy for moving the public on this issue.  The other players are trained in rhetoric and have absolutely nothing to lose.  It's as if they play the game with a full deck and science is limited to no face cards (and aces count as 1). 

       
       Detailed, practical approaches need to be available to anyone who is willing to enter "the trenches."  The "ambivalent partisan" mode is one I try to emulate, with a few additions.  More powerful than ideology is the need to remain valuable, and that need is amplified when the discussion is public.  No one wants to be dismissed out of hand--to be categorized, labeled, boxed, stamped as innocuous.  I will only once in a blue moon use any sort of label, including "denier," when I speak with people in a general public forum on this issue.  I ask questions, and not questions that have a rhetorical edge, but well-explained questions that invite the interlocutor to express a speculative opinion.  No ivory tower.  I try to give uncertainty when it exists.  It's better to provide and discuss uncertainty than it is to leave it out.  Tom Curtis is very good at that, and I think to the consternation of a few other SkS regulars.  Also, as Kahan points out with the example of Hayhoe (though he gums it up with academic jargon), it's better to step into someone's else's castle and recognize it as a valid construct than it is to remain in your own castle and stand at the battlement throwing taunts and unexplained bits of heavy science.  I've had good success with this general approach (a variety of private FB messages/emails thanking me not for explaining things but for doing it in a way that wasn't antagonistic.  I often get the "I'll respond to you because you seem like a reasonable person."  That's the response I aim for.).
       
       

       Ultimately, the Cook study is only valuable to me as a conversation starter and a casual debunking of the "there is no consensus" myth.  I think Kahan doesn't understand that there are a great many people who don't understand the greenhouse effect and who are susceptible to suggestions that AGW is something different than the greenhouse effect.  That's really what the consensus is all about for me as I find myself discussing it in various places.  People aren't sure what points of the theory the consensus is providing agreement on, and so they respond to it as they do to every other article talking about global warming.  In other words, the consensus doesn't mean anything specific.  It's like how the word "catastrophic" is used in professional "skeptic" circles--it means whatever you need it to mean at the moment.

       A bit rambling.  Sorry.  I started out with my two cents and it turned into a pfennig, a pence, and half a yen (to revise it).

44990. jmorpuss at 11:40 AM on 23 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       Nice John

       One thing I thought might add more understanding to your post would be to include some sort of acknowladgement and recognition for this natural interaction process. http://en.wikipedia.org/wiki/Electric_force I tried a site search but could not find any reference to Coulomb's Law so link is provided.

44991. MS1 at 10:30 AM on 23 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       #46 scaddenp at 08:54 AM on 17 May, 2013

       "MS1 "I think their paper failed " really?... If the ENSO index was substantially flawed or there was significant non-linearity, this isnt born out by the success of their prediction. If you believe that the prediction can be improved significantly by other indexes or method, then show us."

       ---------------------

       Compo et al 2010 have addressed this issue.

       http://www.esrl.noaa.gov/psd/people/gilbert.p.compo/CompoSardeshmukh2008b.pdf

       "Because its [ENSO's] spectrum has a long low frequency tail, fluctuations in the timing, number and amplitude of individual El Nino and La Nina events, within, say, 50-yr intervals can give rise to substantial 50-yr trends..."

       "...it also accountd for an appreciable fraction of the total warming trend..." (see figure 9b )

       "...It [The Pacific decadal oscillation or the interdecadal Pacific oscillation] is strongly reminiscent of the low-frequency tail of ENSO and has, indeed been argued to be such in previous studies (e.g. Alexander et al 2002, Newman et al 2003, Schneider and Cornuelle 2005, Alexander et al 2008)..."

       "...In this paper, we have argued that identifying and removing ENSO-related variations by performing regressions on any single ENSO index can be problematic. We stressed that ENSO is best viewed not as a number but as an evolving dynamical process for this purpose..."

44992. Dumb Scientist at 10:26 AM on 23 May 2013
       Has the rate of surface warming changed? 16 years revisited
       

       Farmer Dave @24: Last year I noted that the deep ocean's heat capacity is much larger than the cryosphere's. So I think Kevin C was right to focus on the warming deep ocean purely on thermodynamic grounds.

       I mentioned melting land and sea ice not because of their total effect on surface temperatures, but because those independent measurements also confirm that the climate is still gaining heat, even over the last 16 years. Here are relevant links and a short movie.

44993. JasonB at 09:50 AM on 23 May 2013
       Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
       

       barry,

       Rather than going round and round in circles arguing over definitions, let's make this concrete:

       Earlier you claimed that there is a difference in meaning between the wording in the graphic and the wording in Dana's example of a paper that would be classified as endorsing the consensus ("we are the cause" vs "we are causing").

       I propose a test: Can you give any examples of abstracts that were rated as level 2 or level 3 that you feel do not endorse the statement in the graphic?

       If your argument is correct, there should be papers that you feel do not support the claim and based on the number of them we can ascertain the impact that would have on the results.

       Note that unless you're going to do an exhaustive search, you need to count how many papers you looked at as well as how many examples you found. This is so we can get a percentage that can be used to estimate the impact. You can also propose what you view as the "correct" classification for the examples you find.

       Until then, this argument is merely academic.

44994. william5331 at 09:47 AM on 23 May 2013
       Has the rate of surface warming changed? 16 years revisited
       

       Being completely unscientific and speaking anthropogenically, Gaia is fighting back and keeping the temperature constant.  A sort of light switch phenomenon.  Look out when we have pushed the switch beyone Gaia's capacity to thermo-regulate.  The next time we have an El Nino should be interesting.  Sept 15, 2016 likewise.

44995. Farmer Dave at 09:32 AM on 23 May 2013
       Has the rate of surface warming changed? 16 years revisited
       

       Dumb Scientist @2

       I agree with your question about the impact of ice melting on reducing the rate of air temperature increases. I presume that earth energy balance models include the latent heat required to achieve all the ice melting we have seen over the last few years. Does anyone know of any estimates of the effect the melting has had on moderating changes in sensible temperature over, say, the last decade?

44996. william5331 at 09:26 AM on 23 May 2013
       2013 SkS News Bulletin #13: Alberta Tar Sands and Keystone XL Pipeline
       

       You have to agree with the article on Canada.  Even if the heads of their government officials are so far up where the sun doesn't shine that they can't recognize the disaster they are helping to cause, at least they could be accute business men.   Why on earth would Canada send raw oil, only just separated from the sand, to the USA for them to make most of the profit.  As the writer says, Canada is seeing precious little benefit from the exploitation of it's resource.  They should be pipeing or trucking refined petrol, diesel and other products to the US.  As far as her ecological record goes, look at how she has destroyed her east coast fisheries resources through glaringly faulty science and through bowing to the very short term interests of her fishing companies.  They behave like grasshoppers rather than ants (aesop fables) and show zero intestinal fortitude.  They went so far as to try to shift the blame onto the seals for the decline in their fisheries resources and actually subsidized seal hunters when the immages of the slaughter of baby seals trashed the fur market.  If you want an account of the stupidity of successive Canadian governments, get Sea Of Slaughter by Farley Mowat.

44997. Rob Honeycutt at 08:59 AM on 23 May 2013
       It's satellite microwave transmissions
       

       grindupBaker...  I'm really unclear on what you're attempting to say.

44998. Esop at 08:57 AM on 23 May 2013
       A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming
       

       Brilliant article. Very informative!

44999. Dumb Scientist at 08:55 AM on 23 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Mod: please delete #99. Dunno why it came out empty...

45000. Dumb Scientist at 08:54 AM on 23 May 2013
       The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
       

       Just to be clear, my comment #96 didn't refer to Dikran's comment #95 above. I linked to Dikran's comment on another page which is much more interesting.

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