archive-org.com » ORG » R » REALCLIMATE.ORG

Total: 1481

Choose link from "Titles, links and description words view":

Or switch to "Titles and links view".
  • Climate Science « RealClimate
    4 January 2016 This is a second post related to the new Marvel et al 2015 paper The first post dealing with the substantive content is here What with AGU15 going on and a little bit of overlap in content with Shindell 2014 NASA wasn t particularly keen to put out a press release for the paper but we did get a web special put out on Friday Dec 18th the last day of AGU and a few days after the paper appeared online I ve been involved with many similar releases for papers and it is always a struggle to concisely say why a paper is interesting while not overselling it or being too technical which is why only a small fraction of papers get press releases at all As we ve previously remarked about other people s press releases eg Stainforth et al or Willerslev et al properly calibrating the aspect of a release that will get picked up by the media can be tricky and so it proved in this case More References K Marvel G A Schmidt R L Miller and L S Nazarenko Implications for climate sensitivity from the response to individual forcings Nature Climate Change 2015 http dx doi org 10 1038 nclimate2888 Comments pop up 28 Marvel et al 2015 Part 1 Reconciling estimates of climate sensitivity Filed under Aerosols Climate modelling Climate Science Greenhouse gases Instrumental Record IPCC gavin 4 January 2016 This post is related to the substantive results of the new Marvel et al 2015 study There is a separate post on the media blog response The recent paper by Kate Marvel and others including me in Nature Climate Change looks at the different forcings and their climate responses over the historical period in more detail than any previous modeling study The point of the paper was to apply those results to improve calculations of climate sensitivity from the historical record and see if they can be reconciled with other estimates But there are some broader issues as well how scientific anomalies are dealt with and how simulation can be used to improve inferences about the real world It also shines a spotlight on a particular feature of the IPCC process More References K Marvel G A Schmidt R L Miller and L S Nazarenko Implications for climate sensitivity from the response to individual forcings Nature Climate Change 2015 http dx doi org 10 1038 nclimate2888 Comments pop up 30 Older Entries Newer Entries Site Google Custom Search Recent Comments What is the best description of the greenhouse effect Jim Eager What is the best description of the greenhouse effect Patrick Eriksson What is the best description of the greenhouse effect Kevin McKinney Anti scientists Carbomontanus What is the best description of the greenhouse effect Spencer Marvel et al 2015 Part III Response to Nic Lewis SteveS What is the best description of the greenhouse effect Chris Colose Blizzard Jonas and the slowdown of the Gulf Stream System doiknow What

    Original URL path: http://www.realclimate.org/index.php/archives/category/climate-science/page/2/ (2016-02-13)
    Open archived version from archive

  • RealClimate » Blog Archive » Marvel et al (2015) Part III: Response to Nic Lewis
    is smaller than ECS MEA15 used the wrong iRF and ERF values for F 2xCO2 MEA15 shouldn t have used ocean heat content data or should have done so differently The regressions in MEA15 in the iRF case should have been forced to go through zero The linearity of the different forcings is only approximate Point 1 is a misunderstanding of the concept of climate sensitivity and in any case would apply to every single paper being discussed including Lewis and Curry and Otto et al It has nothing to do with whether those papers give reliable results Point 2 begs the question entirely why do analyses of transient simulations under estimate ECS Point 3 is worth discussing in more detail and we do so below Point 4 on the OHC misunderstands that MEA15 were trying to assess whether real world analyses give the right result Using TOA radiative imbalances instead of ocean heat uptake which cannot be directly observed with sufficient precision would be pointless But there are different ways to treat the OHC and we return to that below Point 5 is easily tested and found not to matter in the slightest as could easily be inferred from the graphs Point 6 is freely admitted to indeed we already wrote a paper on that exact issue Marvel et al 2015a It makes no difference to our conclusion since the breakdown into single forcings is in order to explain the fact that the historical all forcing runs have a lower slope than the GHG or CO 2 responses and for that the accuracy of the linearity assumption is totally adequate In making his points Lewis makes a number of errors that all go the way of making his points superficially more plausible He conflates different model versions fully interactive

    Original URL path: http://www.realclimate.org/index.php/archives/2016/02/marvel-et-al-2015-part-iii-response-to-nic-lewis/%5C (2016-02-13)
    Open archived version from archive

  • Marvel et al (2015) Part 2: Media responses « RealClimate
    case you had to read six paragraphs down to get the message people would care about and even argue heatedly about which could have sparked headings like Global Warming From CO2 Likely Lowballed Instead the web special opened with Estimates of future global temperatures based on recent observations must account for the differing characteristics of each important driver of recent climate change which sounds a bit ho hum if not well duh The whole second paragraph was taken up with definitions and so on The heading Examination of Earth s Recent History Key to Predicting Global Temperatures didn t seem to be on point at all 5 patrick says 5 Jan 2016 at 8 04 AM it is always a struggle to concisely say why a paper is interesting while not overselling it or being too technical Very well observed Ditto paragraph 2 I appreciated the release very much and was glad to have it Disinformers saw fossil fuels and cooling together in the same sentence and they popped like bovine methane They would not have read the next two sentences or cared to comprehend the whole paragraph You clarify it they ll blur it on purpose It s the method And it s the full extent of their capacity But this does point out the need for educating about aerosols both to further understanding of climate science and to protect human health as the case may be I appreciated the topical December 7 image in the release especially because I was looking at how the BBC World Service More or Less trivialized and obscured a good recent paper by Rohde and others on the health effects of pollution notably around Beijing notably from particulate matter of less than 2 5microns etc They also obfuscated probabalistic statements about flooding events What they did was they made a hash they pretended it was ice cream and they put a cherry on top Thank you CM for all of your remarks It s a dilemma no doubt whether to try to do more with the release which suits people like me or to do less to minimize potential handles for disinformers to grab The abstract is brief and clear on what the paper is about and the release linked that plus some supplementary materials 6 CM says 5 Jan 2016 at 10 57 AM Patrick 5 Good point about the picture which matters I ve also been told that the reading most people take away from a newspaper story is the heading and the picture caption The caption did a very good job using the current interest story in the picture to make the study s point about the unequal geographical impact of aerosols or so I thought 7 patrick says 5 Jan 2016 at 3 07 PM CM 6 Copy Press release team please copy Thanks for your informed perception I subscribe to all of your remarks On top of everything pun intended I can now characterize what the BBC World Service has been doing thanks to remarks by CM at 4 It s the cherry on the hash fallacy So NASA GISS press release team don t pull back The good news is the world wants press releases and you have the credibility Comments from the experimenters are a good thing An informal edge is o k 8 MA Rodger says 6 Jan 2016 at 12 51 PM The post in describing the nonsense from the Express Daily Rail and also scientific chaos mild confusion solved by plucky researchers as being newsworthy perhaps misses the idea that newspapers TV channels can be institutionally in denial The BBC s Roger Harrabin has facebooked on this in recent days Are the BBC climate change deniers as well as featuring on a Radio 4 complains programme on the same subject linked on Facebook and 5 mins from 15 30 back in December A TV journo is a bit different to a print journo but Harrabin is pointing to the small amount of time available to put a TV story across perhaps 110 words But the journalist is not in control of what the editor allows to be put on air and his words may be edited down to fit the space by the journo or by the editor and probably in a rush Simply the news is part of the media It is entertainment Thus we get The Terminator at Paris COP21 And we don t get mention of AGW with every climate weather story just as sunrise goes without mention on the media for days on end But the sunrise is not the subject of denial mis information A typical problem occurred 5 1 16 when the BBC TV evening news gave a short item on the UK s December weather being of record warmth and record wet The 300 word version is posted on line here but that wasn t what appeared on the telly which was very short The recordness of December s weather was drowned out by saying it was only since 1910 rather than since records began And the causes were given but with zero climate change comment Instead we got only El Nino the Jetstream All this from memory the on line version was off line by the time I got to look there Folk like Harrabin at the BBC are properly signed up to AGW but reluctant to bombard the audience with AGW at every turn My previous resistance to the inevitable climate mention on every flood news story remains he says But beyond that the editors presenters at the BBC do show signs of being less sighed up and the message while not overtly denialist does not prevent a denier taking a denialist message from the coverage That of course is wrong But when there are folk involved in the process that do not see denial as a problem as well as folk who are more concerned with the entertainment factors than the denialist problem an institutionally denialist outcome should be no surprise Newspapers are more word hungry than TV but otherwise the same applies I would also suggest with the Express the Daily Rail other right wing papers that they are likely to see a bit of down right denialism as good for business Such is their readership 9 Kevin Malone says 6 Jan 2016 at 7 05 PM late to comment but here goes as a biologist working on salmon issues in the Pacific Northwest I cannot emphasize enough that when trying to communicate complex issues to the Public points have to be easily understood and presented using terms examples they understand etc In reading Real Climate and climate change type articles I am always amazed how poorly this field communicates info to the Public My pet peeve is where the expected change in temperature is almost always presented in degrees C and not F I would guess that 80 percent of the US population could not define C or convert it to F The same knowledge level applies to anything dealing with the metric system Secondly when talking to the Press you need to talk like Bill Nye the Science Guy not Albert Einstein In my experience you can never assume that what you believe to be common knowledge is actually that The Press and Public have short memories and are not involved in the issue on a day to day basis Yes at one time they may have known about aerosols but that may have been two years ago and they moved on to other topics This one of the major reasons that businesses etc provide Press releases that clearly describe salient take home points and also if they are well done provide info on what the report etc doesnt say The Press generally spends little time questioning these releases and lots of time simply repeats whats stated As scientists we generally write our papers recognizing what the scientific critiques weaknesses may be and trying to address these in the paper The same effort should be given to thinking about how vested interests will use the information presented in the paper 10 t marvell says 7 Jan 2016 at 11 54 AM Responsible reporters would contact GISS to make sure they understand things There is contact info in the press release Did the Express and Mail reporters do that Did any other reporters 11 Hans Kiesewetter says 8 Jan 2016 at 3 15 AM KM 9 Indeed Communication is difficult It starts with understanding your public I have difficulties understanding degrees F In my part of the world not US 95 is not able to convert F to C without some kind of conversion tool General comment Thanks for the combination of a technical post part 1 and a separate communication post part2 I like that 12 AntonyIndia says 8 Jan 2016 at 11 19 PM What is your comment on Nicholas Lewis review of your article on climateaudit org http climateaudit org 2016 01 08 appraising marvel et al implications of forcing efficacies for climate sensitivity estimates Response Mostly confused but there are a couple of points worth following up on Should have the relevant sensitivity tests available next week gavin 13 Phil says 9 Jan 2016 at 6 34 PM t marvell 10 I engaged the Daily Mail over their misreporting of the Cryosat2 paper in July 2015 documented by Jim Hunt here During my communication with the Mail I suggested that since they had gone so badly wrong with their calculation they contact the authors for clarification Their response back contained phrases like UCL researchers say So I forwarded it to Rachel Tilling lead author and asked her did you say these things Her answer was unequivocal the UCL team that published the paper had not been contacted by the Mail and they UCL team did not and would never have said the things that the Mail in their private email to me claimed they did Quite who the UCL researchers the Mail did talk to a Classics PhD in the post room perhaps were who knows The whole idea that the Mail may be responsible reporters seems laughable they appear to have an agenda and will print anything they can find or interpret that supports it 14 Halfkidding says 9 Jan 2016 at 7 42 PM The herd or tribal instinct of humans is being magnified by modern communications One complexity is that people can instantly become members of many tribes via modern communications If one understands that news organizations are a tribe then one can understand that selecting to work for one and then being selected requires one to abide by the tribes rules Among the most important rules in news organizations is to always demonstrate neutrality In order to appear neutral one must give equal credence to all or more typically both sides of an argument or debate hat tip to Jay Rosen Look him up A sample https www youtube com watch v ms548AkFP5s It is probable that most every working writer for major print organizations and writers of copy for news readers know that AGW is a fact That has nothing however to do with their job as journalists and reporters The tribe requires neutrality 15 sue says 10 Jan 2016 at 3 43 AM Gavin The obvious error is that they thought it was news that aerosol emissions have partially cancelled out some of the warming one would expect with greenhouse gas emissions Now if this was the 1980s they might have had a point but the fact that aerosols are an important climate forcing have a net cooling effect on climate and in part arise from the same industrial activities that produce greenhouse gases has been part of mainstream science for 30 years Isn t 30 yrs ago in the 80 s 1985 86 16 Hank Roberts says 10 Jan 2016 at 10 54 AM For Sue about climate science aerosols and the 1980s https www aip org history climate Winter htm Gavin s description of the timeline is consistent with the history there That s a link into Spencer Weart s frequently updated online History of Global Warming also found on every RC page in the right hand sidebar under Science Links where it s abbreviated cryptically as AIP Discovery of Glob Warm The big government s at the time were still considering whether a preemptive nuclear first strike might be a good strategy the idea that World War III could be won in a few days or a week and without a lot of collateral damage or not Aerosols were arguably a concern and still very much news as the issue become mainstream science You had to be there 17 Ray Ladbury says 10 Jan 2016 at 11 33 AM Dudes they don t call it the Daily Fail for nothing 18 Paul K says 12 Jan 2016 at 5 24 AM Gavin You say that Nic Lewis is confused I am also confused In fact I think that anyone who says that they are not confused by Marvel et al is just failing to understand the situation Completely independently from Nic Lewis I set up a non parametric convolution model of GISS E2 R This uses the step forcing data from the published CO2 instantaneous quadrupling experiment to define the unit step forcing responses for temperature and net flux The temperature and net flux responses for any arbitrary forcing series can then be forward modeled by convolution of the forcing data with the unit impulse response or by superposition of the incremental forcing values with the unit step response Analytically the integrals yield an identical result Numerically they give 3 sf accuracy with a TS of 6 months First test was to see whether GISS E2 R conforms to a linear system since this is one of the important assumptions made in Marvel et al Using the concentration vs forcing data from Hansen 2005 and Hansen s value of 9 27 for Fi for 4xCO2 I derived with high order accuracy since it is not log linear the forcing vs time profile for the 1 p a experiment and then used this to predict the temperature and net flux evolution of the 1 p a experiment The temperature and net flux predictions match almost perfectly with the published data lending support for the view that GISS E2 R conforms to a linear system The TCR predicted by the emulation model is 1 376 deg K vs a published TCR of 1 4 I then predicted the 20th century historical run using the Fi iRF values from Miller as used in Marvel et al Without any efficacy corrections i e Weighted efficacy 1 0 this yields temperature and net flux predictions for the 20th Century historic run which correspond very closely with the published values The only clearly evident correction required is to the volcanic efficacy where the GCM response is slightly lower than the emulation model Overall this would lend strong support for the view that using Hansen s forcing data Fi basis very little is required in terms of total weighted efficacy correction to the historic mix of forcings Miller stated that the GISS E2 R CO2 forcings were almost identical to those from GISS E These are the forcings I have used in the above analysis On the other hand Marvel et al uses a value of Fi for 2xCO2 which is almost 10 lower than Hansen s value Since my system is linear the use of the lower Fi value would rescale my results pro rata but would still not justify the massive adjustment to TCR implied in Marvel et al It would be truly helpful if we could have a clear statement from GISS on what the Fi Fa and ERF forcings really are in GISS E2 R over a range of CO2 concentrations as per Hansen 2005 It is impossible to reconcile Miller s statements with the values used in Marvel et al Only with these data is there any chance of testing the Marvel et al conclusions Even with the values cited in Marvel I cannot reproduce her results So yes I am confused 19 Patrick says 13 Jan 2016 at 11 43 AM I cordially invite you guys to the OCEAN TUNNELS group on Facebook to solve earths global warming problem here https www facebook com groups 1548937018758434 Ocean Tunnels offer us a way out of this quagmire of which there seems to be no other solution to So instead of dilly dallying around for decades on end lets put an end to it once and for all 20 Edward Greisch says 15 Jan 2016 at 6 14 AM 13 Phil and everybody else There is no point in trying to correct a provoker Punching the tarbaby just gets you more stuck in the tar You can do your best to word your paper carefully but in the end your only recourse is to not communicate with such people They are purely looking for a way to cause trouble emotional trouble if possible As journalists they are also looking for a way to create controversy as a method of selling newspapers The more you try to correct them the more newspapers they can sell So your job is to put them out of business by making controversy as difficult to find as possible Make your paper sound like a very boring history As we found over the past half century we have today found the same old thing Aerosols bla bla bla provoker A person who provokes a troublemaker English Wiktionary 21 patrick says 16 Jan 2016 at 6 26 AM 20 Edward Greisch Not really Not always You have to be good Really good It s a particular calling And it s a great service for example https twitter com climatehawk1 status 683838014909321216 The disinformation dissected here is logging 283

    Original URL path: http://www.realclimate.org/?p=18953 (2016-02-13)
    Open archived version from archive

  • Reflections on Ringberg « RealClimate
    this in AR5 but the connection to ECS estimates was weak 21 Chris Colose says 2 Apr 2015 at 1 12 PM Hi Tim 18 good to see you here I know you know this but for everyone else Brian Rose et al also has a pretty elegant paper here on the time evolution of sensitivity in this context 22 Thomas Frölicher says 2 Apr 2015 at 1 36 PM A quick follow up on Tim s comment 18 which might be of interest Mike Winton Jorge Sarmiento and myself have published a follow up study showing that even if emissions stop the Earth could warm for centuries using GFDL s ESM2M model We show that this occurs in spite of a decline in radiative forcing that exceeds the decline in ocean heat uptake a circumstance that would otherwise be expected to lead to a decline in global temperature when using the simple energy balance model described in the post http www nature com nclimate journal v4 n1 full nclimate2060 html 23 Russell says 2 Apr 2015 at 1 39 PM Gavin should try to see to it that the Erice organizers get to hear both sides of the story at future climate related workshops there schmoozing by Singer s cohort has turned it into a sort of Sicilian Heartland Conference in recent years with predictible op ed fallout in Europe 24 Matthew R Marler says 2 Apr 2015 at 3 18 PM Thank you for the post I am glad that you highlighted the complications of the cloud feedback My three questions for today 1 Do you or most people or anyone other than me distinguish the warming of the surface from the warming of the middle and upper troposphere I ask because transfer of energy from upper troposphere to space is mostly by radiation whereas most of the transfer of energy from the surface to the atmosphere and space is by non radiative transfer advection convection and evapotranspiration A single governing equation for all seems a priori a simplification too far If you think of the system as being in steady state at least approximately instead of equilibrium and if you think of the effect of CO2 increase to be a change from one steady state to another it would not necessarily be the case that the temperature increase of the surface middle troposphere and upper troposphere to be the same This is a phramacokinetic view if you increase the infusion rate of a drug until a new steady state has been achieved you would not necessarily have equal increases in the concentrations in the plasma and in the target organ A paper by Laliberte et al earlier this year in Science Magazine looked at energetic constraints on steady state related to increased water vapor 2 If the surface were to warm by 1C how much would the advective convective evapotranspirative and radiative energy transfer from the surface increase You can also add in the rate of transfer from the ocean surface to the deeps 3 At the ocean surface where H2O is nearly always evaporating and the wind seldom stops blowing completely for long what really happens when the power of the DWLWIR increases by about 1 or less 25 Chris Dudley says 2 Apr 2015 at 5 11 PM Thomas 22 There are a number of papers showing this kind of behavior though not necessarily for the same reason but when emissions stop at a range of concentration level it is the higher concentration stopping points that fail to cool or warm as you describe Your stopping point is around 4xCO2 which would make it a high stopping point 26 S Molnar says 2 Apr 2015 at 7 26 PM Re Ray Ladbury s comment 19 I could point out that Bohr and Einstein didn t generally use airplanes to get together but it s certainly true that the scientific community is much more geographically diverse these days Still ships can be reasonably efficient with respect to carbon sails and given the abundance of stories about shipboard encounters in the old days I wonder if both science and the arts haven t lost a valuable venue for fruitful meetings I would also add that the problem extends to academics in general including the tendency towards online courses as a substitute for in person courses Yes they can reach a wider audience and you don t have to put on trousers to attend but it s just not the same 27 Steve Fish says 2 Apr 2015 at 7 29 PM Re Comment by Matthew R Marler 2 Apr 2015 3 18 PM 23 Matthew it is my understanding that all heat loss from the earth to space is by radiation Water vapor from evapotranspiration has to rise upward until the lapse rate causes condensation back to water Thus latent heat is stored until it can be released and then subsequently radiated to space and this process is slower than radiation from the surface The earth is contained in the very efficient thermos bottle of space Steve 28 Jef says 2 Apr 2015 at 7 41 PM Similar question to Matthew s albeit much more layman Clouds and aerosols shade the surface but is there not still heat trapped in the atmosphere above them but below the GHGs in the higher atmosphere In fact isn t the solar radiation warming the clouds and aerosols and therefore the atmosphere directly Thank You Jef 29 Pete Dunkelberg says 2 Apr 2015 at 9 38 PM Matthew R Marler If you have a supercomputer in the basement perhaps Gavin will send you the code for a GCM and you can see for yourself that there is more to it than A single governing equation 30 Matthew R Marler says 3 Apr 2015 at 1 06 AM 27 Steve Fish Water vapor from evapotranspiration has to rise upward until the lapse rate causes condensation back to water Thus latent heat is stored until it can be released and then subsequently radiated to space and this process is slower than radiation from the surface See more at http www realclimate org index php archives 2015 04 reflections on ringberg comment page 1 comment 628048 my comment at 24 contains an error I ask because transfer of energy from upper troposphere to space is mostly by radiation whereas most of the transfer of energy from the surface to the atmosphere and space is by non radiative transfer advection convection and evapotranspiration See more at http www realclimate org index php archives 2015 04 reflections on ringberg comment page 1 comment 628048 It should say transfer of energy from the surface to the atmosphere whence radiated to space is by non radiative transfer etc I apologize for the error Now about this this process is slower than radiation from the surface The energy flow estimates in Stephens et al show a greater rate of transfer from the surface to the upper troposphere by non radiative than by radiative means Which mechanism is faster at any particular time and place depends on the circumstances then and there thundercloud build up and rainfall versus cool sunny day for example 31 Thomas Frölicher says 3 Apr 2015 at 2 00 AM Chris the model also warms at lower atmospheric CO2 stopping points Keep in mind that there are studies using simple models see Pierrehumbert 2014 suggesting that when climate sensitvity becomes very high there would be warming after emissions have ceased In our paper I argue that we can not rule out the possibility that there may be long term commited warming in AOGCMs at even lower climate sensitivity I think the TCR ECS ratio or realized warming fraction is key here to understand the long term climate response 32 Carrick says 3 Apr 2015 at 9 35 AM Isaac Held has a nice discussion of the time dependence of climate sensitivity relating to the figure that Gavin showed above here One of the papers he references is Winton 2010 33 Matthew R Marler says 3 Apr 2015 at 10 28 AM 29 Pete Dunkelberg there is more to it than A single governing equation Of course there is Gavin wrote this There were two major themes that emerged across a lot of the discussions the stability of the basic energy balance equation that defines the sensitivity See more at http www realclimate org index php archives 2015 04 reflections on ringberg sthash Btx3NkIK dpuf He went on to explain that lambda should not be treated as a constant but otherwise focused on a single balance equation Then he went on to the complexities of cloud feedback one of my long term favorite topics It does not require a copy of computer code to realize that the use of a single balance equation is likely to lead to inaccurate answers Consider the paper by Laliberte et al in Science Magazine earlier this year about the thermodynamic constraints imposed by increasing the water vapor content of air it is the first paper I have seen looking at the climate system as approximately a steady state rather than an approximate equilibrium Thought of that way there have to be a lot of energy flux balance equations 34 Steve Fish says 3 Apr 2015 at 11 13 AM Re Comment by Matthew R Marler 3 Apr 2015 1 06 AM 30 Matthew to clarify what I said All heat that leaves the earth from the surface or the atmosphere is by radiation All The portion from evapotranspiration is relatively small and slower because of the delay prior to being radiated while the heat remains latent There are many illustrations of these processes such as this one by Chris Colose https chriscolose files wordpress com 2008 12 kiehl4 jpg w 480 h 350 Steve 35 Pete Dunkelberg says 3 Apr 2015 at 3 03 PM Mathew R Marler apologies if I misunderstood you I thought you might be thinking of a single equation for more than just sensitivity You started with Do you or most people or anyone other than me distinguish the warming of the surface from the warming of the middle and upper troposphere Yes of course There is at first a single defining equation for sensitivity but then things happen Now I think I understand your question better 36 Chris Colose says 3 Apr 2015 at 3 23 PM Steve Fish not my figure but thanks The short and lazy answer to Matthew Marler s question about the column energetics that bring the system back to equilibrium is that GCMs do of course represent evaporation sensible heating etc in ways that are undoubtedly imperfect e g via bulk formulas that transfer energy down gradient of temperature or humidity differences between the surface and air aloft but they are free to evolve in climate change scenarios in ways that are physically self consistent For example one cannot increase evaporation precipitation arbitrarily since energetic limitations come into play this comes up in discussions of the hydrologic cycle in global warming experiments where global mean precipitation evaporation increase rather slowly certainly more slowly than the column water vapor amount But at least to first order why can we usefully adopt a top of atmosphere TOA perspective to determine surface temperature even though the surface energy budget must also close in equilibrium and which includes many different non radiative terms To begin with remember that CO2 or whatever causes some net change in the TOA energy budget perhaps by reducing the outgoing longwave radiation OLR by 8 W m2 instantaneously like a quadrupling of CO2 an imbalance that must gradually shrink in time After sufficient time evolves we reach a new equilibrium defined by a near zero net TOA radiative imbalance the figure in the post shows that this evolution may not follow a linear track but ignore this for now Thus the eventual zero anomaly can be split up into a forcing and an equal but opposite flux arising from all the processes in the column that conspire to bring it back to equilibrium The partitioning of these processes is a bit artificial For example we can ask what the flux change would be if the column warmed uniformly by the same amount as the surface warming in the vertical holding all else fixed We call that a Planck feedback As Matthew correctly intuits this uniform warming doesn t actually happen so we can ask how the flux would change owing to departures from vertical uniform warming by subtracting off the surface temperature anomaly along the whole dT z curve We call that a lapse rate feedback One can similarly construct a feedback analysis by perturbing the humidity holding all else fixed etc There are many ways to partition all of the column adjustments that must eventually act to counteract the imposed radiative forcing Another way to do this is to allow the specific humidity to evolve in a way that keeps the relative humidity fixed thus eliminating a water vapor feedback from the analysis and re defining the feedback owing to the temperature adjustment in the column However this partitioning is done we are ultimately interested in determining 1 the new T z curve and 2 Ts given the T z curve Number 1 is not as unconstrained as it might seem As Matthew noted radiation is not an efficient vertical energy transfer process in the troposphere This is because the troposphere is very opaque and so the temperature gradient that would need to exist for the troposphere to be in radiative equilibrium would be far steeper than in reality Such a lapse rate is dynamically unstable and so the column convects Radiation is thus always destabilizing the troposphere and convections acts to move energy upward until a stable lapse rate is obtained corresponding to an appropriate adiabat this is why we have a troposphere and one can identify tropospheres more generally by virtue of their temperature structure following such a curve This is true in climate change as well so to first order one can determine any point along the T z curve by knowing the temperature at one point Problem 2 depends on the nature of your surface budget but as a starting point we can assume that the surface budget is acting to keep surface temperatures close to the temperature of the air right above the surface This replaces all of the complicated terms in the surface budget with the assumption that Ts is equal to the lowest level atmospheric temperature This works especially over moist surfaces So evaporation doesn t control sea surface temperatures but it does couple that surface temperature to the overlying air temperature but importantly one needs to satisfy the TOA budget to determine what that temperature is i e it wouldn t be correct to assume there s an upper bound on SSTs after which evaporation is so efficient that the temperature can t increase much more There s situations where one can t just get away with a TOA perspective assuming the surface budget to be dragged along in the process if you re over a changing desert surface or polar region etc The vertical structure of warming and stability of the polar atmosphere comes up in discussions of mechanisms behind arctic amplification It turns out there s many complicated physical and dynamical processes wrapped up in some of the feedbacks we identify from a TOA perspective particularly the lapse rate feedback I haven t made an attribution statement about everything that must occur to keep the lapse rate what it will eventually be Ming Cai and Jianhua Lu have made attempts at reformulating our framework to think more explicitly about such things but it hasn t quite caught on perhaps more because of its elegance necessity but I don t speak for everyone Like most things there s not a single correct way to think about all this but the TOA framework is exceptionally useful precisely because we can write things like OLR Ts due to the way the whole column behaves as a result of all the dynamics processes occurring but in ways that don t necessarily require detailed accounting of them all Obviously when you move up the hierarchy of model complexity such simple explanations must be replaced by the simulation of processes That s how we move forward and build credible answers but the underlying framework of how a planet s temperature is determined has been securely intact for well over 50 years Manabe and Wetherald a good entry point 37 Frank says 3 Apr 2015 at 4 20 PM Gavin wrote The variation in climate sensitivity in models seems to be dominated by the simulations of low clouds which are a net cooling to the climate which have a tendency to disappear as the climate warms Whether this can be independently constrained in the observations is unclear According to Isaac Held climate models predict that the relative humidity over oceans will have to rise about 1 a 5 increase in 1 RH to suppress surface evaporation which would otherwise rise at 7 degC and create a surface energy imbalance because DLR increases with warming nearly as fast as OLR This causes me to speculate that an increase in boundary layer humidity could increase the likelihood of clouds at the top of the boundary layer In the past haven t boundary layer clouds been considered to be one of the weak points of AOGCMs http www gfdl noaa gov blog isaac held 2014 06 26 47 relative humidity over the oceans 38 Jim Eager says 3 Apr 2015 at 5 14 PM Steve Fish you need to revise that statement to All heat that leaves the earth to space is by radiation Heat leaves the surface by radiation conduction convection and evapotranspiration latent heat 39 Matthew R Marler says 3 Apr 2015 at 5 54 PM 34

    Original URL path: http://www.realclimate.org/index.php/archives/2015/04/reflections-on-ringberg/ (2016-02-13)
    Open archived version from archive

  • Climate Sensitivity Week « RealClimate
    but on the chance that they do worth posting them here Thanks for providing this opportunity 6 John L says 22 Mar 2015 at 6 41 PM Looks like a very interesting workshop As an interested amateur one issue that I hope is clarified is how to numerically combine different lines of evidence IPCC famously gives a likely 1 5 4 5 interval for the ECS But it is very hard to understand how such large interval can be derived from the evidence IPCC itself gives Palaeosens gives a likely 2 2 4 8 CMIP5 models is in the range 2 1 4 7 and the uncertainties in inter annual feedback observation analysis is mainly from cloud feedbacks which is said to be likely positive Dessler has claimed that it is very unlikely to be below 2 from this analysis Each line of evidence has to be expert judged for its bias and structural uncertainty i e how much to increase its variance and when combining the level of independence has to be judged as well Using conservative values of the judged parameters you may get say 1 5 4 5 likely intervals for each of the three methods above Combining you get perhaps conservatively a 1 5 4 5 very likely interval Remains the modern time period energy balance analysis which as I understand it tends to include lower values But combining two intervals is not done by taking the average or an interval that includes both intervals For example combining an 1 5 and an 2 5 3 5 normal distributed interval results in an interval narrower than 2 5 3 5 This means that the energy balance methods line of evidence cannot really increase the 1 5 4 5 very likely interval and certainly not to IPCC s numbers I ve also learned from this blog that these methods tend to have a low bias and give only weak constraints of ECS This is further confirmed by that the Charney report gave a similar estimate as IPCC AR5 which simply is not reasonable considering the huge amount of research and new data since 1979 OK you may argue that the Charney report underestimated the uncertainties but then you have to do that explicitly Finally another intuitive confirmation is the high certainty in the attribution statement of warming contributions which is difficult to reconcile with such large uncertainties for ECS http www realclimate org index php archives 2013 10 the ipcc ar5 attribution statement 7 James C Wilson says 22 Mar 2015 at 7 06 PM ARGO GRACE NOAA MSU and the boreholes permit analysis of the internal energy of the climate system over the last 30 or more years The hiatus does not appear in internal energy of the climate system This finding highlights the need to understand the various cycles that impact heat transfer from the oceans to the atmosphere and back It looks like these efforts are gaining some traction Looking at GAST since 1880 one sees some famous plateaus that have been ascribed to aerosol and internal variability ocean cycles How does the discussion of climate sensitivity deal with this information Average over the ups and flats Emphasize the steep parts of the curves Thanks Chuck 8 Thomas says 22 Mar 2015 at 8 48 PM One plea Is that what feedbacks and system latencies have been included in a given sensitivity value be clearly stated We have things like instantaneous response Charney short term sensitivity Include other feedbacks and or thermal reservoir timescales and yet higher sensitivities are expected So just labeling a distribution as sensitivity is seriously incomplete as the details matter 9 Jan Galkowski says 22 Mar 2015 at 11 08 PM Doesn t climate sensitivity in the classical sense depend upon temperature and the feedbacks that rely upon it Accordingly is this sensitivity discussion limited to just CO2 doubling holding all else constant And what reference temperature is the sensitivity calculated against Oughtn t a sensitivity develop along RCPs like other things do And I presume there ll be discussions of both ECS and TCS too no Finally I hope the work of Nathan Urban and colleagues is well represented in the discussions especially their Bayesian methods Frankly some of the lobbing of criticism I ve read back and forth over these questions seem to me to be byproducts of questionable methods I mean land ECS is not the same as ocean ECS and so to answer in part a comment made elsewhere here when they are combined you do get multiple bumps Accordingly representing them as a Gaussian can distort 10 jyyh says 23 Mar 2015 at 12 21 AM I ve deliberately kept all talk of climate sensitivities out of my shares at social media Locally knowing what the global sensitivity to whatever forcing is not too important as the earth warms at different rates depending on the latitude and partly of the location combination of the longitude and latidtude The topics to be covered include how sensitivity is defined and whether it is even meaningful Spoiler yes it is you say and it might be asked whether using such a number that s not even defined exactly in scientific communications is useful yeah let s have all the countries negotiating have a different equation to calculate the sensitivity to see if they can agree on something That said no doubt such a workshop on poorly defined concepts is a great opportunity to meet with people having different ideas on how to approach the politicians who might use active hearing protectors after hearing the word climate ref Florida F e 1 very obvious error in the image on the feedbacks is the part on vegetation killing a plant does not take decades but might happen in a single season due drought etc That said you have a good workshop The planting season for this year was delayed a bit by the cool burst last week so I should have some free time to follow it Apple trees need pruning though 11 Russell says 23 Mar 2015 at 12 56 AM Let s hope estmates converge preferably before the century is out 12 R Bodman says 23 Mar 2015 at 5 03 AM 1 Eli But distribution for ECS is not gaussian changing spread may well be an asymmetric change so the mean will change and the mean is maybe not best estimator anyway in a skewed distribution median and mode will be lower 4 Ray I think you may be referring to ECS estimate from different approaches complex models and simple energy balance models energy balance calculations Complex models have been fairly consistent with ECS as an emergent property of 3 or so But note these are typically from only a small number of model realisations Simple models are very different and are more like an effective sensitivity and may well lack some of the nonlinear dynamics regional processes that occur in the real world and in a more limited way in the complex models 13 Andy Revkin says 23 Mar 2015 at 6 10 AM Gavin or others Do you know if anyone s done a plot of the shifts in sensitivity range curves over time through the 5 IPCC reports To me this seems in many ways to be more of a known unknown than an area in which some analytical breakthrough will clarify things in time for policy relevance 14 Ray Ladbury says 23 Mar 2015 at 9 37 AM R Bodman and Jan Galkowski Yes I realize that My puzzlement stems from the way estimates have evolved over time e g that the 5 to 95 range expanded in the most recent IPCC analysis I noted that during the same period the distribution had bifurcated into a lower mode and an upper mode This bimodality was not evident when I did a similar analysis 4 or 5 years ago It would appear that the definition of sensitivity is not consistent from one analysis to the next I think this is important as denialists will seize on the lower mode to argue for inaction while the consequences could be dire indeed if in fact the upper mode comes closer to the truth 15 Racetrack Playa says 23 Mar 2015 at 11 37 AM Here s an interesting paper that is referenced in some of the listed publications Meraner et al 2013 Robust increase in equilibrium climate sensitivity under global warming GRL https hal inria fr hal 01099395 document They conclude based on study of CMIP5 model output that equilibrium climate sensitivity ECS is not a fixed quantity as temperatures increase the response is nonlinear with a smaller effective ECS in the first decades of the experiments increasing over time They attribute this increase in ECS to enhanced tropical water vapor feedback and a rise in the height of the tropopause This also tends to support the general concept that changes in the tropics 30N 30S are the primary drivers of global climate change processes in the North Atlantic and North Pacific seem to respond to changes in the tropics not the reverse i e the concept of climate controlled by a global oceanic conveyor belt driven by a North Atlantic gear mechanism can probably be discarded However the ECS doesn t seem to capture biogeochemical feedback processes that could either add or subtract forcing agents from the atmosphere although most of the feedbacks appear positive release of organic carbon trapped in permafrost of methane clathrates in shallow Arctic waters and drought related conversion of forests to grasslands or deserts The most cited article on the permafrost subject think Siberian methane blowhole craters seems to be this one Schuur et al 2008 Vulnerability of Permafrost Carbon to Climate Change Implications for the Global Carbon Cycle http www polartrec com files resources article 37588 docs pnw 2008 schuur001 pdf 16 Eli Rabett says 23 Mar 2015 at 12 56 PM R The point remains whatever measure of central tendency you use the estimates of central tendency are all over the place mean mode median and that means you have to be foolhardy or Nic Lewis Judith Curry to narrow the probability of outliers 17 Susan Anderson says 23 Mar 2015 at 1 22 PM I hope an effort will be made to clarify the issues for us interested laypeople OTOH I m not sure that is possible It is all over the map because it is all over the map The inclusion of the Curry Lewis paper makes me curious Is there a possibility that open mindedness could become a two way street there I am very interested in the Ladbury query as well 18 Ray Ladbury says 23 Mar 2015 at 1 57 PM Eli I agree that central tendency becomes a fraught concept whenever you are dealing with a pathological distribution However a thick tailed pathology is telling you something fundamentally different than a multimodal distribution Multiple modes usually reflect a heterogeneous population This raises the possibility of whether people even know what they are talking about when they discuss sensitivity The fact that this has gotten worse in the last 5 years rather than better is not comforting 19 Rob Nicholls says 23 Mar 2015 at 6 19 PM Apologies if off topic a question I have is why TCR is sometimes said to be more policy relevant than ECS I can understand that approaching equilibrium takes a long long time while TCR gives a better measure of what will happen over the next few decades and that technology and society may be very different in 200 years time but on the other hand I thought nations had agreed to try to limit global warming to less than 2 degrees C overall and not just to limit it to less than 2 degrees C by 2100 20 John L says 23 Mar 2015 at 7 22 PM 18 Ray if there are two different types of methods that consistently gives two different mean values then logically at least one of them must have a bias But naturally one must first adjust for best estimate judgement of model bias before combining evidence For example some scientists Shindell Dessler etc argue that the energy balance methods have a low bias If we assume that they are right and additionally that the bias is about 1K then a mean at 2 0 means that there is no bimodal problem and no contradiction in that sense I think some people seem to do the mistake of interpreting each paper naively from its given nominal mean For example if someone publishes a paper with a simplified model that assumes no feedbacks giving a mean ECS at 1 2K this will not push the combined estimate downwards regardless of what will be written on the skeptic blogs I m happy to be corrected by Gavin or others if I m wrong otherwise I think that I showed in comment 6 that one big reason for lack of improved interval over time is the analytical mistake of not using a formal procedure from basic statistics for combining evidence instead relying on vague intuition That you must subjectively judge some parameters does not mean that the mathematics doesn t apply It is not possible to decide exactly which value is correct but some domain expert average might be the best bet but you can give a range which it reasonably must be into therefore it is possible to nicely encapsulate the subjectivity in a formal mathematical model 21 Jan Galkowski says 24 Mar 2015 at 12 14 AM Ray Ladbury Assuming I understand you correctly WHY should multimodality in distribution be an indication of pathology Indeed all things being possible it should be expected and unimodality a happy circumstance for analysis Ditto the Gaussian a result from combining the effects of a great many individual phenomena all about equivalent in effect Rather I should think if the multimodal unimodal tension is too much to bear the resolution should be sought in for what use the posterior density so derived will be put I doubt policymakers are as interested in the ECS TCS for the oceans or by extension the globe as they are for land Yet the ECS TCS for land always trends higher and that little contingency is curiously ignored I don t understand why in these semi technical forums people seem adverse to handling descriptions of ECS up to the details of Professor Ray Pierrehumbert s Section 3 4 2 PRINCIPLES OF PLANETARY CLIMATE page 163ff Surely there the effects of temperature and feedbacks are fully considered Or are readers allergic to differentials 22 CM says 24 Mar 2015 at 10 57 AM Jan Galkowski 9 21 land ECS is not the same as ocean ECS and so when they are combined you do get multiple bumps What ECS is defined in terms of global mean temperature change not separately for land and ocean The different bumps come from different approaches to estimating that one global quantity You must be talking about a different beast 23 Matthew R Marler says 24 Mar 2015 at 11 57 AM Here is my calculation of climate sensitivity which has been intelligently disputed at Climate Etc by Pat Cassen It s what you might call far out According to the theory a doubling of the CO2 concentration will result in an increase in the power carried by the downwelling long wave infrared radiation DWLWIR up from approximately 346 W m 2 for simplicity I am rounding to the unit place and suppressing the uncertainty by 4 W m 2 2 and the Earth surface will warm until the sum of the upwelling long wave infrared radiation UWLWIR the latent heating of the troposphere LH and the sensible heating of the troposphere SH has increased by 4 W m 2 How much surface warming might that be I illustrate by calculating the increase due to a 0 5C increase in surface temperature UWLWIR is proportional to T 4 2 with emissivity constant so the increase in UWLWIR assuming that the global mean surface temperature is equal 288K works out to delta U 288 5 288 4 398 398 2 8 W m 2 LH results from the hydrologic cycle cloud formation and precipitation The review by O Gorman et al 3 reports that a 1C increase in global mean temperature will result in a 2 7 increase in the precipitation rate the lower values are results of GCM output and the upper values are results from regressing estimated annual rainfalls on annual mean temperatures Using the value 4 a 0 5C increase in global mean temperature will produce an increase of 2 of 88 W m 2 1 8 W m 2 The increase in SH can be estimated from a result reported by Romps et al 4 Their main result was an increase in the cloud to lightning ground strike rate by 12 per 1C increase in mean temperature over the US east of the Rocky Mountains The most important result for this presentation was the estimate of a 12 increase in the power of the process that generated lightning and that estimate was not confined to the US east of the Rockies Up to a constant of proportionality the power of the process generating the lightning was calculated as CAPExPR where CAPE is convective available potential energy 5 and PR was precipitation rate Precipitation rate was used in the calculation rate not because of the latent energy in the water vapor but because the precipitation rate was treated as proportional to the rate of transfer of air with water vapor mixed in from the surface to the upper cloud level and the fraction of each kilogram of air that was water vapor was treated as constant That result depended on the modeled lapse rate and difference between the interior and exterior of the

    Original URL path: http://www.realclimate.org/index.php/archives/2015/03/climate-sensitivity-week/ (2016-02-13)
    Open archived version from archive

  • The mystery of the offset chronologies: Tree rings and the volcanic record of the 1st millennium « RealClimate
    African monsoon and the flow of the Nile Geophys Res Lett 33 L18711 doi 10 1029 2006GL027665 3 Aslak Grinsted says 19 Feb 2015 at 1 52 PM Interesting and provocative post I come from an ice core lab and am provoked by this post I am not directly involved in any ice core dating work Here s what provokes me zero uncertainty In this respect it is extremely unlikely that any of the tree ring data used in this exercise is incorrectly dated The argument is based on independent datings But how independent can they be if they are all based on the same type of data I am convinced that the tree ring dating is really good but no uncertainty whatsoever sounds too good to be true 4 Russell says 19 Feb 2015 at 2 45 PM Among the sick elephants in the room is the palaeoepidemiology of epidemic plant diseases Tree growth rings may also record the evolving virulence of blights and pests from plant viruses to wind born insects rendering dendrochronology even more difficult to deconvolute 5 Jonny McAneney says 19 Feb 2015 at 4 18 PM This is why independent replication is so important for example the Irish Oak English oak and German oak chronologies were all constructed independently of each other using trees from many different locations and they are found to correlate extremely well over many millennia This minimises any local effect from disease or predation One can also correlate trees globally through specific events such as the AD536 540 signatures or indeed their radiocarbon signature For example the recent discovery of excess radiocarbon at AD 774 Miyake et al 2012 appears in the correct place as a hemispheric signal from Japan to Siberia Germany Ireland and Western USA see Jull et al 2014 and reference within https www academia edu 6896755 Excursions in the 14C record at AD 774 775 in tree rings from Russia and America This is the power of dendrochronology and replication and global correlation allows us to ignore any sick pachyderms see also Buntgen et al 2014 http www nature com nclimate journal v4 n6 full nclimate2240 html message global remove Response Since you mention Buntgen et al 2014 and the AD 774 event I would also refer readers to our piece last year in Nature Climate Change Missing tree rings and the AD 774 775 radiocarbon event It is a challenge to the dendrochronological community and we look forward to any future related developments Mike 6 Jonny McAneney says 19 Feb 2015 at 5 24 PM Alan you will be pleased to know that we recognised your work and did indeed cite your publication regarding your AD 939 date of Eldgja in our paper Jonny 7 Jonny McAneney says 19 Feb 2015 at 5 53 PM Aslak I can understand why you as an ice core worker would be provoked by the paper As scientists it is in our nature to bristle at the thought of a zero uncertainty measurement but as I have mentioned above though the agreement in tree ring chronologies are really very good and do lead to precisely dated events One can check any chronology through comparisons of independently replicated By this I mean that for example dendrochronologists in Belfast construct a chronology using statistical methods and interpretation to match ring patterns within their own lab In Germany dendrochronologists will do their own work on their own trees with their own analysis and interpretation If one then compares the two chronologies one will find that key signatures are dated to the same date with zero uncertainty Further more all these chronologies are anchored to the present by living trees So even though they are effectively measuring the same data they do so independently of each other So you can guarantee that if a ring is dated to AD 536 then it is AD 536 Uncertainties can come about in the felling date of trees where there is incomplete sapwood but when constructing long chronologies absence of sapwood is not important if you have enough tree rings to form a statistically significant overlap with the rest of your chronology If I have a tree sample and it has 200 rings on it but incomplete sap wood then while there is uncertainty in the year the tree was felled there would be no uncertainty in the age of each existing ring when cross dated with a master chronology 8 Jonny McAneney says 19 Feb 2015 at 5 55 PM Wili I certainly do not have the experience or knowledge to answer your question but perhaps an ice core expert would be able to help 9 Hank Roberts says 19 Feb 2015 at 6 42 PM In hindsight this also tho the authors presume the 934 date but what physics would connect that date for an eruption with hot summers in China in the following four years But in 939 sudden cold Eldgjá eruption starting around 934 AD was investigated An extremely hot summer was reported in 934 AD hundreds of people died of the intense heat Snowless and possibly also mild winters probably occurred successively following the Eldgjá eruption until 938 AD In 939 AD cold weather set in abruptly and lasted for about 3 years whereas peak cooling occurred in 939 AD Climatic Change June 2006 Volume 76 Issue 3 4 pp 443 457 10 Jun 2006 The Possible Climatic Impact in China of Iceland s Eldgjá Eruption Inferred from Historical Sources Jie Fei Jie Zhou Not saying there s anything unique about that study just noticed while poking around Can other work be read as supporting the 939 date even where the authors didn t say so at the time in hindsight Little surprises 10 Hank Roberts says 19 Feb 2015 at 7 35 PM a cosmic event that happened in 774 775 caused the production of enough Carbon 14 to throw off the chronology by hundreds of years This is seen in the close examination of Carbon in the tissue of trees placed in a tree ring chronology illustration Greg Laden s blog 7 29 2014 11 Hank Roberts says 19 Feb 2015 at 9 53 PM blush Fei and Zhou are well discussed in http www clim past net 11 105 2015 cp 11 105 2015 pdf and I ll tiptoe back to the peanut gallery where I belong Fascinating I ll learn more if I write less 12 jyyh says 20 Feb 2015 at 1 07 AM delete As a lighthearted note I ll ask the obvious that is why haven t we heard about this through WUWT before Seven years is a hugely long time period and this gamma ray burst you re talking about might be the final proof of the influence of ancient aliens on the psyche of medieval man A lot of history can be rewritten in the lost seven years Have we finally traced the origins of climate conspiracy to correct time in history Did Charlemange and Pope Adrian I wipe out the memories of 7 years of all the people by using alien tech This revelation could lead to a whole new chronology of mankind all together I mean what do we know about the effects of gamma ray bursts of cosmic origin to the psyche of contemporary man let alone the medievalists delete Interesting article thanks I ve sometimes thought that global cataclysms like the largest volcanic eruptions would disrupt the glacial records by many years like Oruanui eruption c 26500bp as these would induce unrecorded behavior in weather and other things f e the huge ash deposits might decrease the albedo so much a local melting event happens In addition there s of course the possibility of no snow on the drilling site losing a layer here and there and on some sites there could be additional layers if there s a normal melting event before the winter snowfalls I guess I d imagine these would be much more common during the HCO Holocene Climate Optimum and thus I ve been assuming these ice core chronologies are just advisory what would be the proper period for the N S seesaw is to me very much an open question But its useful to have a reference chronology in science and in history to make it easier for making cross discipline research 13 jyyh says 20 Feb 2015 at 1 38 AM the 14C spike in 773 14 has been attributed to a comet collision http www ncbi nlm nih gov pmc articles PMC3893640 this would connect to the later date increases quite well if the numbers on amounts match part of the comet could have splintered high in the atmosphere producing a fallout of the said radioisotope during next few years 14 Thomas P says 20 Feb 2015 at 4 53 AM How do varve data lake sediments fit into this 15 Jonny McAneney says 20 Feb 2015 at 5 54 AM jyyh regarding the comet impact hypothesis This was a nice idea but it doesnt hold up to scrutiny If one reads the paper http www ncbi nlm nih gov pmc articles PMC3893640 See more at http www realclimate org index php archives 2015 02 the mystery of the offset chronologies tree rings and the volcanic record of the 1st millennium more 18139 one can see the authors datingis not very tight which is crucial They date their coral using thorium radiometric dating and get a date of AD 783 14 They then note that it is the layer 7 years below this that has the 14C anomaly making the date 776 14 years then they arbitrarily move it to 773 to coincide with the beginning of the 14C excess in Japanese cedar This date of AD 773 then seems to coincide with an entry in Chinese records of the comet impact with it stating that the impact occurred in the 7th year of Dai Zong As best that I can make out the accepted date for Dai Zong beginning his reign is 762 or 763 meaning that the 7th year of his reign is between 768 770 depending upon whether the 7th year is inclusive So unless the authors of the paper are privy to other information then I cant see how the two events coincide Furthermore this paper The Solar Cosmic Ray Origin for the Rapid 14C Increase in AD775 http www cbpf br icrc2013 papers icrc2013 1149 pdf states the following with respect to the chinese chronicle In the evening on the Chinese lunar calendar day of 11 Dec 774 i e 17 Jan AD775 in the east and above Moon there were more than ten bands of white lights like the spread silk penetrating and covering eight grand constellations named in Chinese corresponding to the sky composed of Taurus Auriga m Gemini q Cancer l Orion V Orion e Taurus d Hydra and a Leo and the lights were ceased gradually after middle night as recorded in the Old Tang Book a Chinese Chronicle 7 The auroras described are actually located in a wide region from east to west and from north to south in Earth s northern hemisphere The records indicated clearly that time to see auroras is most probably from 5 00 6 00 PM to 1 00 2 00 AM therefore the event lasted about 8 hours In Tang dynasty the natural abnormal events were observed and recorded by qualified officers so the records are highly trustable and the work was conducted in the Tang capital Xian which is located in a geomagnetic latitude at lower twenties The low geomagnetic latitude indicates that the solar particles which caused very strong auroras are very intense and with higher energies We also know that there was another large 14C excess again in 993 994 but less intense about 0 6 the energy flux of the 774 775 event but that the flux was similar to the 774 755 event http www nature com ncomms journal v4 n4 full ncomms2783 html So if we look to historical records we see the following events suggesting aurora displays worthy of note Annals of the Four masters M992 19 The colour of fire was in the heavens till morning Annals of Ulster U992 4 A remarkable manifestation on St Stephen s night the sky appearing blood red Thomas Short 992 In November for three Nights successfully the heavens seemed bloody 993 On the 7th of the Calends of January at one a Clock in the Night suddenly Light Shined out of the N like mid day it lasted an Hour but the Sky turning red the Night returned Usoskin and Kovaltsov 2014 http arxiv org abs 1401 5945 have also shown that the comet impact hypothesis is untenable In a nut shell to generate the amount of excess radiocarbon observed the comet would have to be massive at least tens of kilometres if not 100 km in size If such an impact occurred we would not be here to discuss it So I dont think that 773 is the date of a comet impact and that the Sun is the likely culprit for the 14C excess Usoskin et al 2013 http www aanda org articles aa abs 2013 04 aa21080 13 aa21080 13 html 16 Jonny McAneney says 20 Feb 2015 at 5 57 AM Thomas P I havent been privy to any varve data but it is an interesting question Someone here might have an answer though 17 Hank Roberts says 20 Feb 2015 at 9 34 AM Aside et al and Usokin explain much by It s The Sun but I note they re said to have discovered a new kind of sunspot according to Watts Up With That Feb 22 2014 Guest Post by Willis Eschenbach and a hockey stick rapid recent increase of solar influence on climate http adsabs harvard edu full 2005ESASP 560 19U Looking for ways to prove rather than disprove a hypothesis leads one into strange places 18 jyyh says 20 Feb 2015 at 9 44 AM thank you for the very detailed response yes agree that auroras visible during the early evening would be a result of hugely energetic particles 19 Hank Roberts says 20 Feb 2015 at 10 28 AM Broken link above can t make a working link to Usoskin s hockey stick paper It is SAO NASA Astrophysics Data System ADS Title Solar activity over the last 1150 years does it correlate with climate Authors Usoskin I G Schüssler M Solanki S K Mursula K Journal Proceedings of the 13th Cambridge Workshop on Cool Stars Stellar Systems and the Sun held 5 9 July 2004 in Hamburg Germany Edited by F Favata G A J Hussain and B Battrick ESA SP 560 European Space Agency 2005 p 19 Bibliographic Code 2005ESASP 560 19U 20 vukcevic says 20 Feb 2015 at 5 02 PM Hank Roberts Usoskin is here http www aanda org articles aa pdf 2014 02 aa23391 14 pdf 21 Hank Roberts says 20 Feb 2015 at 8 01 PM Solar activity over the last 1150 years does it correlate with climate Shorter it did until the past 30 years when climate got warmer faster while the solar activity diminished For JJ et al that s that global warming activity always in the same direction emerging in the past several decades from the background variation noise that goes up and down 22 Thomas says 21 Feb 2015 at 4 33 PM So let us assume for the purposes of discussion that the ice core dating is seven years too long Doesn t this imply that seven years were somehow double counted Could this happen as a result of some extreme weather event creating an extra ice horizon which is mistakenly taken as an annual layer It would seem odd if geographically separated ice cores contained the same skips wouldn t it Anyone care to comment 23 C Lott says 22 Feb 2015 at 3 04 PM The dating problem may relate to the changing ratios of Carbon isotopes Atmospheric bomb tests created a spike max at 1963 of Carbon 14 Fossil fuels make things date older and bombs make things date younger Are the trees Radiocarbon Dated Response Other way around Tree ring chronologies are used to calibrate the radiocarbon time scale gavin 24 Jonny McAneney says 23 Feb 2015 at 4 27 AM Thomas if we are correct in our hypothesis then only the ice core workers would be able to assess why independent ice cores exhibit similar offsets in their dating One can always speculate many different scenarios to explain such an offset but we suspect that it may be something to do with a methodological issue of replication rather than a global weather issue though the latter would be really interesting if this were the case 25 Jonny McAneney says 23 Feb 2015 at 4 28 AM Dendrochronologically derived dates do not rely on radiometric dating In fact it is actually the other way around When we make a tree ring chronology we begin with measuring the tree ring pattern of living growing trees That way we have a solid correct anchor date i e the year that living tree was sampled So we map out the tree ring pattern of those living trees then we look to historical timbers such as those used in construction of buildings It doesn t matter if we do not know the date of construction of the building since we need only look at the ring patterns in the timbers and then cross match it to our living tree patterns Then we try to extend the chronology backwards in time by trying to find older and older timbers moving from historical timbers to archaeological and otherwise naturally preserved timbers e g bog timbers The above describes the process for the likes of European oak but when it comes to some

    Original URL path: http://www.realclimate.org/index.php/archives/2015/02/the-mystery-of-the-offset-chronologies-tree-rings-and-the-volcanic-record-of-the-1st-millennium/ (2016-02-13)
    Open archived version from archive

  • Aerosols « RealClimate
    overview and update of some of the most discussed model observation comparisons updated to include 2012 I include comparisons of surface temperatures sea ice and ocean heat content to the CMIP3 and Hansen et al 1988 simulations More Comments pop up 152 On sensitivity Part I Filed under Aerosols Climate modelling Climate Science IPCC Paleoclimate gavin 3 January 2013 Climate sensitivity is a perennial topic here so the multiple new papers and discussions around the issue each with different perspectives are worth discussing Since this can be a complicated topic I ll focus in this post on the credible work being published There ll be a second part from Karen Shell and in a follow on post I ll comment on some of the recent games being played in and around the Wall Street Journal op ed pages More Comments pop up 104 Some AGU highlights Filed under Aerosols Arctic and Antarctic Climate impacts Climate modelling Climate Science gavin 8 December 2012 Here a few of the videos of the named lectures from last week that are worth watching There are loads more videos from selected sessions on the AGU Virtual Meeting site the AGU YouTube channel has quite a lot more from past meetings too All well worth the time More Comments pop up 62 Older Entries Newer Entries Site Google Custom Search Recent Comments What is the best description of the greenhouse effect Jim Eager What is the best description of the greenhouse effect Patrick Eriksson What is the best description of the greenhouse effect Kevin McKinney Anti scientists Carbomontanus What is the best description of the greenhouse effect Spencer Marvel et al 2015 Part III Response to Nic Lewis SteveS What is the best description of the greenhouse effect Chris Colose Blizzard Jonas and the slowdown of the Gulf Stream System doiknow What is the best description of the greenhouse effect James Powell Unforced Variations Feb 2016 Jim Galasyn With Inline Responses Marvel et al 2015 Part III Response to Nic Lewis SteveS Marvel et al 2015 Part III Response to Nic Lewis steve s Marvel et al 2015 Part III Response to Nic Lewis Andrew Kerber Blizzard Jonas and the slowdown of the Gulf Stream System Hank Roberts Blizzard Jonas and the slowdown of the Gulf Stream System doiknow Marvel et al 2015 Part III Response to Nic Lewis MartinM Anti scientists Don McKenzie Marvel et al 2015 Part III Response to Nic Lewis Matt Skaggs Anti scientists mikeworst New On line Classes and Models Marcus Pages Acronym index Data Sources Categories Climate Science Aerosols Arctic and Antarctic Carbon cycle Climate impacts Climate modelling El Nino Geoengineering Greenhouse gases Hurricanes Instrumental Record IPCC Oceans Paleoclimate Sun earth connections Communicating Climate Reporting on climate skeptics Extras Attic Comment Policy Contributor Bio s FAQ Glossary In the News Reviews Supplemental data Tutorials hydrological cycle Open thread RC Forum Scientific practice statistics The Bore Hole Books Contributors Highlights Dummies Guide to the latest Hockey Stick controversy El Nino Global

    Original URL path: http://www.realclimate.org/index.php/archives/category/climate-science/aerosols/page/2/ (2016-02-13)
    Open archived version from archive

  • And the winner is… « RealClimate
    What would you like to wager 11 Chris says 18 Nov 2015 at 9 48 AM You may have won the bet but we ve lost the game 12 Jim Baird says 18 Nov 2015 at 9 57 AM Stefan thank you for your response at 1 The consensus is La Niña conditions brought about the slowdown These conditions stacked warm water in the eastern Pacific driving the thermocline down to a depth of about 300 meters Once the trade winds subsided however in 2013 this stacked warm water sloshed back to the east and to the surface with the result 2014 and 2015 have successively been the warmest years ever recorded Very little of the stacked heat was mixed and diluted in the ocean abyss below the thermocline and as a result when it came back to the surface it was able to drive temperatures off the coast of North America 3 degrees higher than normal The oceans are the repository of 93 percent of the heat of global warming and since warm water rises most of the heat sits near the surface while the temperature at depth approaches the freezing point of water This differential makes the oceans particularly tropical waters the largest battery on the planet When heat flows from a warm source to a cold sink through a heat engine just as when electrons flow from the negative to the positive terminal of a battery energy is produced It is estimated the oceans have the capacity to produce 14 terawatts of primary energy through ocean thermal energy conversion or OTEC or about the same amount of energy as is currently derived annually from fossil fuels NOAA estimates the ocean battery is being charged at a rate of about 330 terawatts each year and since there is no draw down of this charge we are experiencing the escalating consequences of global warming Due to the low thermodynamic efficiency of a heat engine operating within the temperature range offered by the oceans OTEC requires the movement of about 20 times more heat to the deep than the 14 terawatts of power the oceans are capable of producing In other words virtually all of the heat the ocean battery is currently accumulating is either converted to work or moved to deep water with this process In support of this premise in the late 1970s a team from the Applied Physics Laboratory of Johns Hopkins University estimated that the surface water temperature of the oceans and therefore the lower atmosphere would be reduced by 1 degree Celsius each decade through the production of 5 terawatts of OTEC power The relocation of this heat to the deep would be benign due to the large thermal capacity of water It is estimated that in spite of all the heat they are absorbing at depths from 500 to 2000 meters the oceans are warming by about 002 degrees Celsius every year and in the top 500 meters they are gaining 005 degrees The benefit of this ocean heat absorption is noted by Levitus who pointed out that if all of the heat the oceans absorbed to a depth of 2000 meters from 1955 2008 which raised their temperature by an average of 09 degrees Celsius was instantly transferred to the lower 10 kilometers of the atmosphere that layer would be warmed 36 degrees Celsius My point is we have not tried to apply the knowledge gained in the 50 studies you refer to so what is the point of them 13 Urs Neu says 18 Nov 2015 at 11 14 AM If we assume or are confident that the reduced warming is for the main part due to La Nina conditions and is probably supported by a decreasing solar cycle amplitude as well as some increase in volcanic aerosols it is not astonishing that climate models even with initialized runs do not accurately forecast such a decadal evolution All the mentioned influences are not included in the models climate model runs normally are based on constant solar and volcanic forcing on the one hand and are not able to forecast the ENSO evolution over more than about half a year Unfortunately this might lead us to the insight that for decadal predictions the missing knowledge of the evolution of the solar cycle volcanic forcing and ENSO will remain an important problem and make decadal projections of global temperature nearly useless unless climate models will be able to forecast ENSO for a couple of years 14 Barton Paul Levenson says 18 Nov 2015 at 12 54 PM Nemesis 9 the past participle of catch in English is irregular caught instead of catched 15 Tim McDermott says 18 Nov 2015 at 6 47 PM Jim Baird 12 I see two troubles with OTEC First is that it has not proven to scale into the terawatt range The demonstration plants are all in the 100 MW range their efficiency is in the 3 range and they tend to get shut down after a year of two The history of OTEC reminds me of fusion power which has been 20 years away for my entire life For me the more serious problem with OTEC is what will it do to the oceans if it is deployed widely Dumping tens of terawatts into the deep ocean will change currents likely generate new upwellings of deep water and cause changes that are unlikely to be foreseen without modeling what happens with large hotspots in the deep ocean 16 Mark E says 19 Nov 2015 at 1 59 AM Jim Baird pushes OTEC because of personal ties to the technology according to his own posts on the subject here and elsewhere Tim thank you so much for articulating the concern about rapidly transporting surface BTUs into the deep Anthropocene Age to be sure 17 Dimis Poulos says 19 Nov 2015 at 9 31 AM both papers made an attempt to better the estimations of climate variability but if you are interested in the real climate you should follow my research Since 2005 I have documented and described the variability while the last two years I have reached way beyond to detailed descriptions of the mechanisms involved 18 Jim Baird says 19 Nov 2015 at 12 15 PM TM 15 Dumping tens of terawatts into the deep ocean will change currents likely generate new upwellings of deep water Hansen et al recently pointed to increased sea ice melt acting as an insulator to warmer deep waters shutting down ocean circulation leading in turn to further ice melting and rapid sea level rise http phys org news 2015 09 eyes oceansjames hansen sea html jCp So moving tropical heat to the deep is more likely to preserve thermohaline circulation than halt it As well as sapping the energy of tropical storms OTEC also would decrease sea level rise 3 ways First it short circuits the movement of heat towards the poles and the effect Hansen suggests The coefficient of thermal expansion of sea water is also greatly reduced at 1000 meters as compared to at the tropical surface and finally the production of hydrogen as an energy water carrier to get offshore power to market is a transference of ocean volume to the land As to upwelling Munk in his paper Abyssal Recipes calculates that the return rate of heat moved to the abyss is about 4 meters per year which would hardly be a problem and a certain amount of upwelling would be beneficial to phytoplankton considering increasing thermal stratification is cutting them off from the nutrient rich waters they need to survive Better I am sure that the atmosphere is deprived of half of its source of oxygen Mark E your concern about anyone making a profit from addressing the problem let alone years of their own effort is laughable Better I am sure that the fossil fuel industry continue to make money hand over fist 19 Kevin McKinney says 19 Nov 2015 at 6 48 PM 18 Jim I don t claim any great understanding of these things but OTEC would be deployed largely in the tropics because that s where the needed temperature differential is while Hansen et al seems to be talking about effects that are happening in actually driven by effects in the polar regions So your comment that So moving tropical heat to the deep is more likely to preserve thermohaline circulation than halt it doesn t make a lot of sense to me Just saying I m remaining agnostic on the virtues or vices of OTEC 20 Jim Baird says 20 Nov 2015 at 11 30 AM Kevin 18 The net heating imbalance between the equator and poles drives an atmospheric and oceanic circulation that climate scientists describe as a heat engine In our everyday experience we associate the word engine with automobiles but to a scientist an engine is any device or system that converts energy into motion The climate is an engine that uses heat energy to keep the atmosphere and ocean moving Evaporation convection rainfall winds and ocean currents are all part of the Earth s heat engine NASA http earthobservatory nasa gov Features EnergyBalance page3 php Essentially this is the second law of thermodynamics in action heat flowing from the wamr equator where it is accumulating to the cold poles where it is radiated to space What Hansen says is the fresh water melt acts as a blanket that prevents the radiation to space and thus the heat accumulates again mostly at the equator which warms all the more compounding the problem What I claim is the abyss is an even greater cold sink than the poles and that heat flowing there a heat pipe is required because warm water is buoyant through other kinds of heat engines can in part be converted to power and would no longer be available to move to the poles where it may be producing the effect Hansen claims Some like Tim at 14 suggests this could also shutdown the thermohaline circulation because it is tropical heat that drives the process As NOAA points out however the oceans are accumulating about 330 terawatts of excess energy every year We would be lucky to come close to converting and sequestering that much heat in the depths after decades of building out the OTEC fleet and since the thermohaline has been operating for eons it would continue to work if we took out only the heat accumulating due to climate change As it turns out this would produce about exactly the amount of energy we currently get from fossil fuels I also put this option up against nuclear or fission which increases the heat load on the oceans and all that goes with that 21 Susan K says 23 Nov 2015 at 3 11 PM I m not a climate scientist but don t temperature rises follow rising CO2 levels pretty loosely I thought there was a century level connection not an annual one so a decade or two here or there doesn t mean its stopped OTOH with all the efforts to slow CO2 levels with more renewables and all the countries that say they have reduced CO2 emissions since Kyoto with EU cap and trade with the RGGI cap and trade in Northeast US China incredible GWs of renewables added even from the slowdown in economic activity from 2008 recession etc I m actually more surprised at the robotic ly even trajectory of CO2 rise every year That s the one I d have thought hoped was leveling off just a bit globally by now But no impact yet 22 Keith Woollard says 23 Nov 2015 at 9 45 PM To the anonymous responder to my 8 Because that s what you said Here is the bet and the whole thrust of your post The bet we propose is very simple and concerns the specific global prediction in their Nature article If the average temperature 2000 2010 their first forecast really turns out to be lower or equal to the average temperature 1994 2004 we will pay them 2500 If it turns out to be warmer they pay us 2500 This bet will be decided by the end of 2010 We offer the same for their second forecast If 2005 2015 turns out to be colder or equal compared to 1994 2004 we will pay them 2500 if it turns out to be warmer they pay us the same The basis for the temperature comparison will be the HadCRUT3 global mean surface temperature data set used by the authors in their paper Response You are right had they accepted the bet that would have been the decisive data set and we would have won the bet by that as well For a comparison with reality though I d take the currently best data and that definitely is not HadCRUT3 any more and neither HadCRUT4 given their treatment of the large data gap in the Arctic which we have extensively discussed on this blog stefan 23 Nemesis says 24 Nov 2015 at 1 13 AM Barton Paul Levenson 14 Nemesis 9 the past participle of catch in English is irregular caught instead of catched Hey thx a lot nice catch I m still learning so I stumble over those irregular verbs occasionally Herzliche Grüsse aus Deutschland 24 Keith Woollard says 24 Nov 2015 at 2 28 AM and adding to my 22 how can it make no difference http www woodfortrees org plot hadcrut3gl from 1994 plot gistemp from 1994 plot hadcrut3gl from 1994 trend plot gistemp from 1994 trend Response Because they predicted a cooling and all observational data sets show further warming just somewhat different amounts stefan 25 Kevin McKinney says 24 Nov 2015 at 9 54 AM Jim 20 I m OK with the heat engine terminology and am well aware how insolation drives large scale circulation patterns thank you However I think you are wrong about this What Hansen says is the fresh water melt acts as a blanket that prevents the radiation to space and thus the heat accumulates again mostly at the equator which warms all the more compounding the problem The fresh water is in circumpolar regions and so far at least we don t see ocean circulation shutting down Moreover if we did and if OTEC were indeed deployed at large scale in the tropics any large scale effect on SSTs would presumably be in the direction of decreased thermal gradients That s the wrong sign to be helping circulation 26 Jim Baird says 24 Nov 2015 at 12 00 PM Kevin 24 Freshwater injected onto the North Atlantic or in both hemispheres shuts down the AMOC from Ice melt sea level rise and superstorms evidence from paleoclimate data climate modeling and modern observations that 2C global warming is highly dangerous http www atmos chem phys discuss net 15 20059 2015 acpd 15 20059 2015 pdf page 20081 Tropical and Southern Hemisphere warming is the well known effect of reduced heat transport to northern latitudes in response to the AMOC shutdown Rahmstorf 1996 Barreiro et al 2008 page 20086 same paper I could be wrong Perhaps Stefan could clarify 27 Kevin McKinney says 24 Nov 2015 at 9 32 PM 22 23 how can it make no difference Well this lower or equal to makes it kinda Boolean By Hadcrut3 Keenlyside et al lose by GISTEMP they lose worse but there s no penalty for losing worse 28 Silk says 25 Nov 2015 at 7 55 AM Susan 21 If you are interested AR5 IPCC Working Group 3 Technical Summary will give you the breakdown in emissions But in short rich countries have reduced their emissions a little bit very poor countries have not seen much of a change but previously poor and now rapidly growing economically countries have increased emissions massively due to huge increases in demand for energy This IS NOT to say that the rich countries shouldn t be taking steps to reduce emissions Rather that these steps have been weak AND that we need serious effort to stop the grow in emissions in in particular China and India and then decarbonise these these and other countries This is an enormous technical and social problem Technical in that there are technical ways to reduce emissions massively better vehicles renewables nuclear insulation heat pumps etc but challenges remain and short term costs are higher than not giving a damm and social in that it s not just a technology fix People will have to change attitudes to things like saving energy eating meat and what things we tax or don t tax IMHO 450ppm CO2 will be significantly overshot there s no indication global emissions will peak any time soon but there s still masses to play for The difference between BAU and actually doing what is feasible given political will is huge I d take 2 7 degrees now if you offered it 29 Steven Sullivan says 25 Nov 2015 at 2 29 PM Science trumps Nature 30 Kevin McKinney says 25 Nov 2015 at 3 16 PM 26 Jim those quotes seem to me to support what I ve been saying ie the cause of the potential circulation changes is in the high latitudes You propose to address that with a remedy applied in the tropics It s not clear to me at least that the causality runs both ways Am I missing something 31 Chris Colose says 25 Nov 2015 at 6 27 PM Just to play pessimist Is the whole exercise futile not just premature The internal variability is just too important unless the forcing is very large on this high frequency timescale volcanoes Especially you re interested in the spatial structure especially e g DJF higher NH latitudes Just low signal to noise even if you know the phase of some mode that exhibits a multi decadal timescale at the

    Original URL path: http://www.realclimate.org/index.php/archives/2015/11/and-the-winner-is/ (2016-02-13)
    Open archived version from archive



  •