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Unforced variations: Dec 2012

Filed under: — group @ 1 December 2012

A new meteorological season, perhaps some new science topics to discuss…

369 Responses to “Unforced variations: Dec 2012”

  1. 301
    Ric Merritt says:

    I have stopped reading Superman1. Boreholing would be a service.

  2. 302
    prokaryotes says:

    The problem i have with the AMEG approach is, that they do not call for emission cuts, carbon tax and biochar.

  3. 303
    perwis says:

    Lawrence Coleman @293

    While worst-case scenarios are important, they must be based in science, and not pure fantasy. You say that 2C would lead to an additional 7 meter SLR “from alaska, canada etc.” This is not based in science.

    The total amount of land-based ice left in Glaciers and Ice-caps outside Greenland and Antarctica is only about 0.15-0.37 m (see this post by Stefan Rahmstorf: ). Hence, ca 0.4 meter is clearly a worst-case scenario from Glaciers and Ice-caps.

    The thermostatic component for +2C warming (compared to pre-industrial) is less than 1 meter in year 3000 (see B1 scenario in Figure 3 in Goelzer et al 2012). In year 2300 it well below 0.5 meter according to Meehl et al (2012), which finds that RCP2.6 is associated with ca 0.15-0.25 meter SLR in 2300 (RCP2.6 yields ca +2C compared to pre-industrial in 2100 and ca +1-1.5C in 2300). Even RCP4.5 is ca 0.5 meter in 2300 (RCP4.5 yields +2.5-3.5C compared to pre-industrial in 2300) (See Supplementary Table 1 in Meehl et al (2012), which is available here: )

    It is the great ice sheets in Greenland and Antarctica that represent the elephant in the room. And this is where the models are most inadequate…


    Goelzer, H., Huybrechts, P., Raper, S. C. B., Loutre, M.-F., Goosse, H., & Fichefet, T. (2012). Millennial total sea-level commitments projected with the Earth system model of intermediate complexity LOVECLIM. Environmental Research Letters, 7(4), 045401. doi:10.1088/1748-9326/7/4/045401

    Meehl, G. A., Hu, A., Tebaldi, C., Arblaster, J. M., Washington, W. M., Teng, H., Sanderson, B. M., et al. (2012). Relative outcomes of climate change mitigation related to global temperature versus sea-level rise. Nature Climate Change, 2(8), 576–580. doi:10.1038/nclimate1529

  4. 304
    perwis says:

    Just a quick follow-up thought on the Hansen et al paper I referred to above. I have been looking forward to this paper and others in the forthcoming issue of Philosophical Transactions of the Royal Society A, based on presentations on a seminar on “Warm climates of the past – a lesson for the future?” at the Royal Society in October, 2011.

    James Hansen’s talk, together with all the others, are available as mp3:s here:

    Unfortunately, there are no powerpoint slides to go with the audio, but I guess that the previously mentioned paper by Hansen contains similar images that he discusses in his talk.

  5. 305
    sidd says:

    Thanks for the reference to the new Hansen paper. I see that they use a model by Russell et al. simplified to have an ocean depth of 100m, resulting in halving of oceanic poleward transport. This is done to reduce equilibration times. I am reading the Russell paper now, I see that the original model has more realistic deep ocean. Mention is made of a forthcoming paper by Russell which I look forward to. Another simplification is that the ice sheets have no internal dynamics, rather are surface properties of tundra. So I wonder if all essential physics is indeed included, or something dangerous has been left out.

    These quibbles aside, I like it ! Agree with the call for better paleo data.


  6. 306
    Superman1 says:

    Prokaryotes #302,

    “302.The problem i have with the AMEG approach is, that they do not call for emission cuts, carbon tax and biochar.”

    That’s true, but I think you have to address the ‘why’ as well as the ‘what’. There appear to be two reasons: one stated, one implied. On p.10 of the Strategic Plan, it is stated: “There is one thing that we do know can produce an appropriate amount of cooling power: the sulphate aerosol in the troposphere, as emitted from coal-fired power stations and from ship bunker fuel. This aerosol has offset CO2 warming by around 75% in the past century. There should be a temporary suspension of initiatives and regulations to suppress these emissions, while they are having a significant cooling effect in the Northern Hemisphere, unless human health is at risk.” I had a double-take when I first read this, but it does appear that they are promoting continuing certain types of fossil fuel combustion because of the cooling power of their sulphate aerosols.

    The implied reason is the predicament in which they find themselves. They truly believe there is a near-term problem in the Arctic that will prove irreversible unless addressed in the relatively near future. They also look at the world as it is, and see essentially no prospect for any real CO2 emissions reduction in the near or intermediate future. So, what are their options given the three-legged stool of technical/economic/sociopolitical that I defined in #297? Well, they can do nothing, and they see that as leading to near-term disaster. Or, they can propose some high-tech option that keeps the economy going and keeps people employed, as something that might be acceptable to the public.

    Would it address the underlying problem, as would the ’emission cuts, carbon tax and biochar’ you suggest, and other similar options? Obviously not! But, it seems to me they are really saying the only thing that would ‘sell’ is some near-term politically acceptable band-aid that gave us time to address the more fundamental problem. I also view their three proposals as ‘straw-men’. They need something tangible to bring to the table, and this is what they have generated. These proposals could serve as a starting point for more serious discussions, and hopefully the technical (and maybe even political) community could provide value-added with more serious enhancements. I think they’re really trying to get some action going at this point.

  7. 307
    prokaryotes says:

    Oh, i did not even knew this, lol – this is a bit nuts to try fire with fire.

    Sulfur dioxide (SO2) aerosols in the atmosphere are due mainly to increasing volcanic activity not from burning coal, according to NASA. Sulfur dioxide aerosols have a cooling effect and have recently been blamed for “hiding global warming.”

    The good thing about AMEG seems to me that they bring up the topic of Arctic Methane, but to opt for more coal and more aerosol spraying will not work. This is just to complex, with all the storms, precipitation patterns, methane from wetlands a current major player for methane uptake.

    The first step for any action is to enact the Carbon Tax – NOW! Then we need Biochar, Subsidies for clean tech, batteries …

  8. 308
    Hank Roberts says:

    Supe…1, that dead horse was pretty well beaten last summer.
    Try re AMEG and EPA on sulfate regulations. Coincidental?

  9. 309
    Hank Roberts says:

    Carbon held in fossil fuel companies’ reserves. (Courtesy of Carbon Visuals)

    That’s on the main page of today’s

    And ReCaptcha continues to win the Turing Test with
    “least tToBad”

  10. 310
    Chris Korda says:

    #301: “Boreholing would be a service.” #308: “Boring.”

    Hear, hear. Tolerance seems to be causing positive feedback. What’s the threshold for a quorum?

  11. 311
    David B. Benson says:

    Starvation Didn’t Wipe Out Sabertooth Cats

    I’ll take this as more evidence for the Clovis Comet.

  12. 312
    Lawrence Coleman says:

    AMEG Cooling techniques: I also cannot see this happening on a voluntary basis having seen a bit of the international legalities involved. There will be winners and losers, will the winners be able to compensate the losers adequately and by what means. People in Africa and India can’t eat money. The understanding of the physical processes in trying to manipulate climate on a subglobal scale, specific to a particular area or region will require complete understanding to even the smallest micro level. We are still struggling to understand the macro processes. So I also think forced implementation may unfortunately be the only way. Who does the forcing? By dictatorship or committee?. I believe that geoengineering of the climate will only happen when it truly positively HAS to happen and that will of course be far too late.

  13. 313
    Lawrence Coleman says:

    perwis: The total contribution by the arctic/antarctic regions is in the ball park of 21m sea level rise. Assuming a complete melt. I did say 2 millenia although I feel this length of time is way too optimistic. Kevin Anderson believes that from 0.8-2C will be sufficient. Don’t forget the poles are already experiencing a 4C increase and this rate is accelerating. It’s hard to base this on science when the science isn’t out yet and we are in uncharted territory unless you go back to the last interglacial period, but the mechanics then were not the same as now. There was far more flora (e.g rainforest) to soak up CO2. If you believe the IPCC arctica will be ice free in summer in 30+ years..should we believe that science??

  14. 314
    prokaryotes says:

    James Hansen and Makiko Sato

    Update of Greenland Ice Sheet Mass Loss: Exponential?
    26 December 2012

  15. 315
    sidd says:

    Hate to say this, but Hansen is doing numerology on GRIS projection. If he wants to expand this into a paper with ice dynamics i might take him more seriously.


  16. 316
    Jim Larsen says:

    290 Superman1 said, “a [written] debate, or some sort of exchange, among three experts”

    You aren’t getting the results you desire (I’m assuming) because you’re not picking venues appropriately. Though 290 is on topic and appropriate, I’m sure you were here for the discussion on Climate Dialogue’s first written debate amongst three experts, so…

    Did you submit your idea for a topic to Climate Dialogue first, and are submitting it here as a back-up?


    Did you feel that Real Climate would be a better place for such a thing? If so, why?

  17. 317
    Jim Larsen says:

    298 Superman1 asks, “However, clouds serve their own purposes, and arbitrarily removing them might have its own set of unintended consequences. Can we model this situation with sufficient accuracy to be confident we are not making the problem worse?”

    Your wording makes it sound like something with lasting consequences. Most GE projects are nearly instant-on and instant-off. I assume the timing for such an experiment would be to coincide with a big world surplus of food. Lots of safeguards and conditions ensuring any damage is minimal. Truly, can you imagine it not being so? Such a project would get more scrutiny than anything anytime anywhere. The risk, other than to the individuals in Region A who are harmed and those in Region B who benefit (when they’d swap destinies without the GE experiment), is primarily that the effort will have been wasted. Any harm beyond that is easily prevented simply by stopping the project.

    OTOH, it could be said that GE’s primary harm is psychological. If we can pretend that we can get away with burning everything, then many votes will be cast to do exactly that.

  18. 318
    Superman1 says:

    Jim Larsen #316,

    First time I’ve heard of Climate Dialogue. What is it?

    I’m indifferent to venue. If it were posted on Climate Progress, fine. I thought the debaters would be more amenable to Real Climate because of the scientific credibility of the monitors. In any case, we need the challenges to these somewhat different assertions about where we are relative to reversibility. I’m tired of reading these papers and hearing these videos where assertions go unchallenged.

  19. 319
    Superman1 says:

    Jim Larsen #317,

    “I assume the timing for such an experiment would be to coincide with a big world surplus of food. Lots of safeguards and conditions ensuring any damage is minimal. Truly, can you imagine it not being so?”

    I can only go by what the AMEG proposers state in their Strategic Plan: “The situation is so urgent that, unless appropriate action is taken within a few months, the window of opportunity will be lost.” That has little to do with the forerunner research, development, and testing that I’m used to before deploying such a complex system.

    The Plan states further: “The target should be to prevent a new record low of sea ice extent next year (2013). This involves providing sufficient cooling power into the Arctic to offset the warming which has built up as the sea ice has retreated.” Basically, they want to cool the Arctic. Given the heat influx laterally from both the warm atmosphere and ocean, which no doubt accelerated the melting the past few years, large regions would have to be cooled. The scale of the solution has to match the scale of the problem!

    I don’t view this as a small perturbation. Where are the models that can handle the very small physical points of injection and allow regional compatibility with global compatibility? I would suspect such models would take years to develop before they were tested and passed for reliability. The proposers want to deploy the system in months! This makes a Hail Mary pass look conservative!

    However, this proposal does give us an opportunity to do something constructive, rather than assemble another circular firing squad. One way to generate potential innovation is to start with some concept, identify the good and bad features, eliminate the bad ones, then build on the good ones. If enough people contribute to this process, sometimes really good ideas can result. We have a proposal on the table from AMEG; what are the positive and negative features? What needs to be eliminated; what needs to be added? Prokaryotes started to do this in #307. How can we expand this further?

  20. 320
  21. 321
    Jim Larsen says:

    318 Superman1,

    Cool. Perhaps you’d enjoy the RealClimate discussion on ClimateDialogue’s first debate, which was on arctic sea ice and included Walt Meier, Judith Curry, and Ron Lindsay. It’s an interesting discussion with lots of good thoughts and ideas on how ClimateDialogue might fine-tune their process.

  22. 322
    Jim Larsen says:

    319 Superman1 said, “I can only go by what the AMEG proposers state in their Strategic Plan: “The situation is so urgent that, unless appropriate action is taken within a few months, the window of opportunity will be lost.” ”

    We know that arctic ice recovers easily when conditions are appropriate. Sea ice has no tipping point and little memory. Sea ice’s “window of opportunity” could be as wide as when winter sea ice still forms. That’s a mighty wide window.

    We also know permafrost and clathrates are well-protected. Like an adobe house which stays cool through a hot day, it takes a long time for a pulse of warmth to reach permafrost. 2013’s heat will be clathrate-felt decades from now as a tiny blip it almost notices.

    It’s a tipping point, but the time scale is geologic. Plus, buried ice melts at different rates at different depths and surface conditions. Add in chimneys et al and the signal is blurred like crazy, like a zillion little carbon valves each doing its own thing.

    From our viewpoint, it’s a long slow slide that gets ever steeper. The further along you get, the more extreme GE you’d have to do if you want to restore a semblance of initial conditions. This is especially true since whatever you do will be delayed in action. GE can restore sea ice quickly, but there’s absolutely nothing we can do about the delayed heat we’ve sent down towards the buried ice.

    So what if we miss the deadline and the plan slips a year? I didn’t read the proposal and would guess the principals don’t paint the ramifications as bleak as you seem to propose – that the fate of the world hangs on what we do in the next few months. Hmm, care to buy my slightly used Mayan calendar?

  23. 323
    Superman1 says:

    Jim Larsen #321/Hank Roberts #320,

    Thank you for pointing me towards Climate Dialogue. When I saw Bart’s name, I remembered the thread about his venture. In fact, I had a couple of comments on that thread.

    I have read the official remarks of the three invited presenters, and some of their responses to public comments. I suspect my views on what you call an ‘interesting discussion’ differ from yours.

    There are three metrics of interest in evaluating the Climate Dialogue discussion: choice of topic; selection of presenters/discussants; motives of monitors/sponsors. The central issue/topic of interest has three major components: does global warming/climate change exist; if so, what fraction is attributable to anthropogenic forcing; what can we expect if present trends continue. Why did the flagship discussion not address this central problem? Arctic ice cap loss is a potential symptom of climate change. There are many other symptoms that could have been selected, such as Greenland ice loss, Antarctic ice loss, floods/storms in Europe, droughts in SW, two hurricanes in NY in two years, etc? But, why would one select a symptom, rather than the problem and its causes?

    In the medical world, a disease is characterized by many symptoms. One would not think of focusing on a specific symptom in analyzing a disease. Rather, one focuses on a ‘signature’ of symptoms to characterize a disease, that unique weighted pattern of symptoms reflective of the disease. One tracks the ‘signature’, not merely any specific symptom.

    Climate change is characterized by the increased frequency and magnitude of what were once considered ‘extreme’ events. We have had hurricanes stronger than Sandy hit the NY/NJ area. Sandy was a Cat 1; I remember a hurricane in 1944 that demolished Heinz’s Pier in Atlantic City. We have had droughts in the SouthWest before; the dustbowl in the 30s. We have had extreme heat waves before. What makes these events unique to climate change is their increasing frequency and magnitude. Once in a century storms are occurring once on a decade or sooner. That should have been the focus of the flagship issue, but instead, a symptom, with its higher variability, was chosen for the focus.

    All the presenters were funded by the USA government. If they had been funded by e.g. the Koch Bros., there would have been a hue and cry about selective bias. Why; because grantees/contractors/employees tend to promote the views with which their sponsors are comfortable. And, the somewhat similar conclusions the presenters reached were those with which the climate change action-free USA government would be very comfortable. ‘Yes, there might be a problem, but we have time, and we really need more research.’ For any credibility, there should have been two, or preferably three, different funding sources, including one or more McPherson types with no external funding.

    Finally, the motives of the monitors. They were selected by the Dutch government to perform a task. I know very well how the USA government selects such people to head panels or workshops: good scientists, but sufficiently reliable to produce the results that protect the government. I doubt the Dutch government uses different criteria. And, it worked. The result would put a gleam in the eye of any government that wanted to justify its inactivity on climate change, and delay its actions far into the future.

  24. 324
    perwis says:

    Sidd @315

    Regarding Hansen & Sato’s note (link in @314 above): The fitting of exponential curves against the recent data of ice sheet mass loss found in Sheperd et al (2012) is a simplistic approach, and perhaps not sufficiently justified. However, they also suggest some arguments for non-linear mechanisms that could come into play (these are found in the Appendix of the note, which is an excerpt from Hansen & Sato 2012).

    Hansen & Sato provides at least five arguments in favour of exponential ice sheet loss:

    1. BAU scenarios have a “climate forcing that is increasing at a rate dwarfing any known natural forcing”. (p. 4)

    One implication being that historical maximum glacier speeds during recent times (e.g. the methodology used by Pfeffer et al 2008) are not necessarily indicative for the maximum speeds at the end of the century. Sounds plausible to me.

    2. “As warming increases, the number of ice streams contributing to mass loss will increase, contributing to a nonlinear response that should be approximated better by an exponential than by a linear fit.” (p. 4)

    It seems plausible that more ice streams in the great ice sheets will be activated in a warming climate, and the contribution will therefore be more than linear.

    3. “Some Greenland ice stream outlets are in valleys with bedrock below sea level. As the terminus of an ice stream retreats inland, glacier sidewalls can collapse, creating a wider pathway for disgorging ice.” (p. 4)

    This also sounds plausible. For example, the Jakobshavn Isbrae has a deep trough more than 1000 meter below sea level stretching more than 60 km into the ice sheet, the Pine Island Glacier has a trough more than 250 km (Thomas et al 2011). I have not seen any modelling that takes into account the effect that Hansen & Sato describes. Perhaps someone can point me to such studies?

    4. In Antarctica, “large portions of the ice sheet are buttressed by ice shelves that are unlikely to survive BAU climate scenarios” (p. 5).

    The removal of ice shelve buttressing gives a highly non-linear acceleration. For example, the recent acceleration of the Pine Island Glacier looks exponential (see Figure 2 (d) in Thomas et al 2011), and the modelled acceleration after an ice-shelf breakup is even greater (see Figure 4 in Thomas et al).

    5. Most of the West Antarctic Ice Sheet and large part of the East Antarctic Ice Sheet are grounded below sea level (corresponding to about 20-25 meter of SLR), making it vulnerable to rapid collapses.

    These are four strong arguments, at least prima facie, for assuming a supra-linear contribution from the great ice sheets in Greenland and Antarctica. Will it be exponential during the course of the 21th century and with what exponent? This is hard to say, but Hansen & Sato’s arguments at least provide reasons to seriously investigate the possibility of greater than linear acceleration of SLR.

    This is in stark contrast with the prevailing approaches to SLR projections, which seems to be based mainly on linear assumptions.

    For example, the IPCC AR4 calculations of ice-sheet dynamics, which Alley et al (2008) calls “back-of-the-envelope approaches” are based on the assumption that if “ice-flow ‘contribution were to grow linearly with global average temperature change’, an additional 0.1-0.2 m of sea-level rise would result” (p. 1061).

    Another example is Rignot et al (2011), which gives yet another linear extrapolation and finds that “At the current rate of acceleration in ice sheet loss, starting at 500 Gt/yr in 2008 and increasing at 36.5 Gt/yr2, the contribution of ice sheets alone scales up to 56 cm by 2100.”

    If anything, I am sceptical of the dominant linear extrapolations of ice sheet dynamics, which may perhaps be due to “scientific reticence” (Hansen 2007) or “Erring on the side of least drama” (Brysse et al 2012)…

    (List of not obvious) References:

    Alley, R. B., Fahnestock, M. & Joughin, I. (2008). Supporting Online Material for Climate change. Understanding glacier flow in changing times. Science, 322(5904), 1061–2. doi:10.1126/science.1166366

    Brysse, K., Oreskes, N., O’Reilly, J., & Oppenheimer, M. (2012). Climate change prediction: Erring on the side of least drama? Global Environmental Change. doi:10.1016/j.gloenvcha.2012.10.008

    Hansen, J. E. (2007). Scientific reticence and sea level rise. Environmental Research Letters, 2(2), 024002. doi:10.1088/1748-9326/2/2/024002

    Rignot, E., Velicogna, I., Van den Broeke, M. R., Monaghan, a., & Lenaerts, J. (2011). Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise. Geophysical Research Letters, 38(5), 1–5. doi:10.1029/2011GL046583

    Thomas, R., Frederick, E., Krabill, W., Manizade, S., & Martin, C. (2009). Recent changes on Greenland outlet glaciers. Journal of Glaciology, 55(189), 16.

  25. 325
  26. 326
    John Pollack says:

    Perwis @324

    In addition to the non-linear factors you mention, isn’t it also true that the flow viscosity of glacial ice would decrease with rising temperature in the ice? Or is this small enough to be neglected?

  27. 327
    Lawrence Coleman says:

    Re Jim Larsen: Sea ice does and can bounce back if it’s only due to favourable weather conditions on the surface but what about the melting from below? When the surface waters are consistantly at 0C or higher how can ice form? That to me that constitutes a tipping point. Even during the arctic winter the warm currents from the south are mixing with the cold.

  28. 328
    Lawrence Coleman says:

    Superman: I’m getting a little bored with Jim Hansen’s famous dice analogy which he drags out every interview but it does plainly illustrate the change in climate over the past 40-60 years. Before- post CC the dice had one side blue (below average temp) one side red (above ave. temp) and 4 sides white (usual temps). Now in 2012 it’s 4.5 sides red, 1 side white and 0.5 sides blue..(these are taken from global climatic events) quite a change in 40 years! You should see the bell’s unrecognisable.

  29. 329
    prokaryotes says:

    Re, perwis: “Some Greenland ice stream outlets are in valleys with bedrock below sea level. As the terminus of an ice stream retreats inland, glacier sidewalls can collapse, creating a wider pathway for disgorging ice.”

    I find this interesting in regards to ice flow…
    Flow of Ice Across Antarctica

  30. 330
    sidd says:

    Mr. perwis: There seems to be some confusion here.

    1)By exponential i mean the sea level height h=h0*exp(t/tau) where tau is the time constant. Hansen exhibits two exponential projections with 5 and 10 yr doubling time. (tau is simply related to the doubling time). These are not better fits than the linear fit as Hansen himself says.
    2)by supralinear i mean any polynomial increase above first order:
    h=h(i)*t^i, summed over i, where at least one h(i) is nonzero for i>1
    3)I see no current data supporting exponential rise in sea level contribution from GRIS, or WAIS. I do see data supporting supralinear rise.
    4)Hansen himself warns that exponential rise in sea level contribution cannot persist, will be self limiting.
    5)The reasons 1)-4) you mention all plausibly support supralinear rise. But a calculation must be done explicitly including these effects. Curve fitting is of no avail without physics. So I think Gregoire is a much better treatment than this GRIS projection from Hansen.In short, put in the ice dynamics like Gregoire and the climate models like Tedesco, shut up and calculate. Hansen is not lacking in wits or resource. He can do much better than curve fitting, that’s why I find his note disappointing.
    6)(personal opinion) I am beginning to think, in light of the Tedesco treatment, that SMB will be as large a contribution to GRIS mass waste as calving and submarine melt. And of course it might rain on GRIS. But in the case of WAIS, not so. For example PIG is 40 Km wide compared to JI at 4Km and Thwaites is wider, the submarine exposure to warm ocean is an order of magnitude larger, and air temperature increase is is not nearly as large as on GRIS. So WAIS will melt from below.

  31. 331
    Patrick 027 says:

    On the first day of Christmas (I meant to have this done a few days ago) my search engine gave to me

    Atmospheric circulation and climate change, focus on Earth, AGW, extratropical storm tracks and extratropics in general, but with exceptions

    I. mostly Science articles directly addressing such matters
    II. background info and resources
    -A. textbooks and websites, general, including some Earth/Planetary system stuff (for comparison)
    -B. some more atmospheric/oceanic dynamics textbooks and websites
    -C. a series of mostly peer-reviewed articles, and a few websites, roughly organized by topic (PS ‘THM93’ and the ‘CPRW'(1-4,maybe 5) papers will not be elaborated on much here; they will get more attention in part III)
    III. my own attempt at a brief introduction that will help in understanding the above (I will take a break after I and II before getting to this).

    In quotes, unless stated otherwise, emphasis is mine.

    Most of these (in I. and II.) I have only skimmed or read the abstract and/or looked at the graphs (so don’t assume that a lack of tag or (signalling that climate change is addressed somewhere somehow) means I wouldn’t have recommended it or … etc. – also, I had a particular set of interests (extratropical storm tracks, wave propagation, synoptic and planetary scale dynamics) and goals (articles that can be used to introduce oneself to a topic, and/or that provide mechanistic explanations) and choices to ‘recommended’ reflect that. Also I probably haven’t been consistent in applying it so take it with a grain of salt – for example, in part I). I will probably never read through it all, but I have read through some and plan to read through some more. But I wanted to get this list together and post it sooner rather than later or never.

  32. 332
    Patrick 027 says:

    Here’s part I:…

    especially recommended (also apply to a few at the beginning where I didn’t specifically say so?)

    Especially recommended!
    climate change – and background information
    Allison Wing, 12/11/09: Extratropical Storm Tracks.
    (climate change pp. 9-10, 11-12, and starting again (I think) on p.14;
    p.12: “O’Gorman and Schneider (2008) found that the eddy kinetic energy scales linearly with the mean available potential energy and that the mean available potential energy depended on the vertically integrated meridional temperature gradient. McCabe et al. (2001) and Yin (2005) also noted that the higher tropopause would mean a deeper baroclinic zone and that some system could utilize this increased supply of available potential energy aloft.” – just one of the points brought up.
    also, p.12: increased H2O vapor leads to increased latent heat release, which may make extratropical storms stronger, but increased H2O vapor can/could increase horizontal latent heat flux, making storms more effective in poleward heat transport, tending to decrease number and/or strength/size? (“smaller“) of eddies.)

    Bengtsson, Lennart, Kevin I. Hodges, Erich Roeckner, 2006: Storm Tracks and Climate Change. Journal of Climate, 19, 3518-3543.
    (from the abstract: “The statistical distribution of storm intensities is virtually preserved under climate change using the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario until the end of this century.“; did not find more intense storms (tropical or extratropical); find a “minor reduction” in the number of weaker storms; significant regional changes; poleward shift, more clearly in Southern Hemisphere – Southern Hemisphere storm track shifts “associated with zonal SST gradient” changes “in particular” the Southern Hemisphere.)
    (nice maps)

    Bengtsson, Lennart, Kevin I. Hodges, Noel Keenlyside, 2009: Will Extratropical Storms Intensify in a Warmer Climate? Journal of Climate, 22, 2276-2301.
    (end of abstract:

    For the twenty-first century, changes in the distribution of storms are very similar to those of previous study. There is a small reduction in the number of cyclones but no significant changes in the extremes of wind and vorticity in both hemispheres. There are larger regional changes in agreement with previous studies.

    The largest changes are in the total precipitation, where a significant increase is seen. Cumulative precipitation along the tracks of the cyclones increases by some 11% per track, or about twice the increase in global precipitation, while the extreme precipitation is close to the globally averaged increase in column water vapor (some 27%). Regionally, changes in extreme precipitation are even higher because of changes in the storm tracks.

    interesting figures!)

    Paul A. O’Gorman, 2010: Understanding the varied response of the extratropical storm tracks to climate change. PNAS 2010 ; published ahead of print October 25, 2010, doi:10.1073/pnas.1011547107
    (part of abstract:

    I show that the southern storm track intensifies in the multimodel mean of simulations of 21st century climate change, and that the seasonal cycle of storm-track intensity increases in amplitude in both hemispheres. I use observations of the present day seasonal cycle to confirm the relationship between storm-track intensity and the mean available potential energy of the atmosphere, and show how this quantitative relationship can be used to account for much of the varied response in storm-track intensity to global warming, including substantially different responses in simulations with different climate models. The results suggest that storm-track intensity is not related in a simple way to global-mean surface temperature, so that, for example, a stronger southern storm track in response to present-day global warming does not imply it was also stronger in hothouse climates of the past.



    Francis, J. A. and S. J. Vavrus (2012), Evidence linking Arctic amplification to extreme weather in mid-latitudes, Geophys. Res. Lett., 39, L06801, doi:10.1029/2012GL051000.
    (was discussed here previously (16, 69-70, 75, see also 20 and 208-212 @ )

    I’ve seen (the links for) a couple of related youtube videos in comments at RC before; I’m not sure if these are the exact same ones:

    16:04 Does Arctic Amplification Fuel Extreme Weather in Mid-Latitudes?

    1:24:25 Weather and Climate Summit – Day 5, Jennifer Francis

    especially recommended (the next several)

    Rivière, Gwendal, 2011: A Dynamical Interpretation of the Poleward Shift of the Jet Streams in Global Warming Scenarios. J. Atmos. Sci., 68, 1253–1272.

    The role played by enhanced upper-tropospheric baroclinicity in the poleward shift of the jet streams in global warming scenarios is investigated. Major differences between the twentieth- and twenty-first-century simulations are first detailed using two coupled climate model outputs. There is a poleward shift of the eddy-driven jets, an increase in intensity and poleward shift of the storm tracks, a strengthening of the upper-tropospheric baroclinicity, and an increase in the eddy length scale. These properties are more obvious in the Southern Hemisphere. A strengthening of the poleward eddy momentum fluxes and a relative decrease in frequency of cyclonic wave breaking compared to anticyclonic wave breaking events is also observed.

    Then, baroclinic instability in the three-level quasigeostrophic model is studied analytically and offers a simple explanation for the increased eddy spatial scale. It is shown that if the potential vorticity gradient changes its sign below the midlevel (i.e., if the critical level is located in the lower troposphere as in the real atmosphere), long and short wavelengths become respectively more and less unstable when the upper-tropospheric baroclinicity is increased.

    Finally, a simple dry atmospheric general circulation model (GCM) is used to confirm the key role played by the upper-level baroclinicity by employing a normal-mode approach and long-term simulations forced by a temperature relaxation. The eddy length scale is shown to largely determine the nature of the breaking: long (short) wavelengths break more anticyclonically (cyclonically). When the upper-tropospheric baroclinicity is reinforced, long wavelengths become more unstable, break more strongly anticyclonically, and push the jet more poleward. Short wavelengths being less unstable, they are less efficient in pushing the jet equatorward. This provides an interpretation for the increased poleward eddy momentum fluxes and thus the poleward shift of the eddy-driven jets.


    Barnes, E.A., and D.L. Hartmann, 2011: Rossby Wave Scales, propagation and the variability of eddy-driven jets, J. Atmos. Sci. , 68, 2893-2908.

    The eddy-driven jet is located in the midlatitudes, bounded on one side by the pole and often bounded on the opposite side by a strong Hadley-driven jet. This work explores how the eddy-driven jet and its variability persist within these limits. It is demonstrated in a barotropic model that as the jet is located at higher latitudes, the eddy length scale increases as predicted by sphericalRossbywave theory, and the leadingmode of variability of the jet changes from a meridional shift to a pulse. Looking equatorward, a similar change in eddy-driven jet variability is observedwhen it ismoved equatorward toward a constant subtropical jet. In both the poleward and equatorward limits, the change in variability froma shift to a pulse is due to themodulation of eddy propagation and momentum flux. Near the pole, the small value of beta (the meridional gradient of absolute vorticity) and subsequent lack of wave breaking near the pole account for the change in variability, whereas on the equatorward side of the jet the strong subtropical winds can affect eddy propagation and restrict the movement of the eddy-driven jet or cause bimodal behavior of the jet latitude. Barotropic quasilinear theory thus suggests that the leading mode of zonal-wind variability will transition from a shift to a pulse as the eddy-driven jets move poleward with climate change, and that the eddy length scale will increase as the jet moves poleward.

    see also? Barnes Hartmann 2012 The Global Distribution of Atmospheric Eddy Length Scales
    related?? – Fyfe Lorenz 2005 Characterizing Midlatitude Jet Variability: Lessons from a Simple GCM)

    Barnes, E.A., and D.L. Hartmann, 2012: The Global Distribution of Atmospheric Eddy Length Scales. Journal of Climate, 25, 3409-3416.
    DOI: 10.1175/JCLI-D-11-00331.1
    (in press version:
    Barnes, E.A., and D.L. Hartmann, 2012: The Global Distribution of Atmospheric Eddy Length Scales. J. Atmos. Sci. , , in press. )
    immediately after abstract:

    Eddies play an important role in defining the largescale circulation, and their scale predominantly determines their propagation and dissipation (Hoskins et al. 1983). Kidston et al. (2010) demonstrated that the Coupled Model Intercomparison Project phase 3 (CMIP3) general circulation models (Meehl et al. 2007) exhibit a robust increase in zonal eddy length scale in future climates, and they suggest that this increase contributes to the predicted poleward migration of the midlatitude jets with increased greenhouse gases. Barnes and Hartmann (2011) present an alternative possibility, demonstrating that a poleward shift of the midlatitude jet can cause an increase in eddy size in a barotropic model, consistent with spherical Rossby wave theory.

    Understanding eddy scales is clearly important to understanding future atmospheric circulation changes and pinpointing cause and effect. …


    Barnes, E.A., D.L. Hartmann, D.M.W. Frierson, and J. Kidston, 2010: The effect of latitude on the persistence of eddy-driven jets. Geophys. Res. Lett., 37, L11804, doi.10.1029/2010GL043199.

    An asymmetry in the persistence of the eddy‐driven jet is demonstrated, whereby the equatorward‐shifted (low‐phase) jet is more persistent than the poleward‐shifted (high‐phase) jet. The asymmetry is investigated by stirring the nondivergent vorticity equation on the sphere and is shown to arise due to the sphericity of the earth, which inhibits poleward wave breaking when the jet is at high latitudes. This spherical effect becomes increasingly important as the mean jet is positioned at higher latitudes. The persistence of the annular mode decreases as the mean jet moves closer to the pole due to the decreased persistence of the high‐phase state, while the low‐phase state exhibits similar persistence regardless of the jet position. These results suggest that with the expected poleward shift of the jet due to increasing greenhouse gases, the annular mode’s total persistence will decrease due to a decrease in the persistence of the high‐phase.

    (see eq. 3 p.3/5)

    Barnes, E.A., and D.L. Hartmann, 2010: Testing a theory for the effect of latitude on the persistence of eddy-driven jets using CMIP3 simulations. Geophys. Res. Lett., 37, L15801, doi:10.1029/2010GL044144.
    (focusing on Southern Hemisphere; from abstract: Earth’s sphericity inhibits wave breaking on poleward side of jet, decreasing wave-mean flow feedback, widens the jet and makes the jet less “self-sustaining”; SAM is less persistent when jet is shifted poleward, and models with jets at too-low latitudes may exaggerate poleward shift in response to global warming.)

    Barnes, E. A. and D. L. Hartmann (2012), Detection of Rossby wave breaking and its response to shifts of the midlatitude jet with climate change, J. Geophys. Res., 117, D09117, doi:10.1029/2012JD017469.
    (in press form: )
    (changes in anticyclonic and cyclonic wavebreaking associated with climate change and poleward jet shift in the Southern Hemisphere:

    A Rossby wave breaking identification method is presented which searches for overturning of absolute vorticity contours on pressure surfaces. The results are compared to those from an analysis of isentropic potential vorticity, and it is demonstrated that both yield similar wave breaking distributions. As absolute vorticity is easily obtained from most model output, we present wave breaking frequency distributions from the ERA-Interim data set, thirteen general circulation models (GCMs) and a barotropic model. We demonstrate that a poleward shift of the Southern Hemisphere midlatitude jet is accompanied by a decrease in poleward wave breaking in both the barotropic model and all GCMs across multiple climate forcing scenarios. In addition, it is shown that while anticyclonic wave breaking shifts poleward with the jet, cyclonic wave breaking shifts less than half as much and reaches a poleward limit near 60 degrees S. Comparison of the observed distribution of Southern Hemisphere wave breaking with those from the GCMs suggests that wave breaking on the poleward flank of the jet has already reached its poleward limit and will likely become less frequent if the jet migrates any further poleward with climate change.

    offhand, I don’t know if the cyclonic and anticyclonic wave breaking events mentioned are generally poleward or if there are any equatorward breaking events as well…)


  33. 333
    Patrick 027 says:

    Zelinka, M.D. and D.L. Hartmann, 2012: Climate Feedbacks and their Implications for Poleward Energy Flux Changes in a Warming Climate, J. Climate , 25, 608-624.

    Feedbacks determine the efficiency with which the climate system comes back into equilibrium in response to a radiative perturbation. Although feedbacks are integrated quantities, the processes from which they arise have rich spatial structures that alter the distribution of top of atmosphere (TOA) net radiation. Here, the authors investigate the implications of the structure of climate feedbacks for the change in poleward energy transport as the planet warms over the twenty-first century in a suite of GCMs. Using radiative kernels that describe the TOA radiative response to small perturbations in temperature, water vapor, and surface albedo, the change in poleward energy flux is partitioned into the individual feedbacks that cause it.

    This study finds that latitudinal gradients in the sum of climate feedbacks reinforce the preexisting latitudinal gradient in TOA net radiation, requiring that the climate system transport more energy to the poles on a warming planet. This is primarily due to structure of the water vapor and cloud feedbacks, which are strongly positive at low latitudes and decrease dramatically with increasing latitude. Using the change in surface fluxes, the authors partition the anomalous poleward energy flux between the atmosphere and ocean and find that reduced heat flux from the high-latitude ocean further amplifies the equator-to-pole gradient in atmospheric energy loss. This implied reduction in oceanic poleward energy flux requires the atmosphere to increase its share of the total poleward energy transport. As is the case for climate sensitivity, the largest source of intermodel spread in the change in poleward energy transport can be attributed to the shortwave cloud feedback.

    (see also (both below in the H2O section):
    Muller and O’Gorman 2011
    Held and Soden 2006 )

    especially recommended
    Graff, Lise Seland, J. H. LaCasce, 2012: Changes in the Extratropical Storm Tracks in Response to Changes in SST in an AGCM. J. Climate, 25, 1854–1870.

    A poleward shift in the extratropical storm tracks has been identified in observational and climate simulations. The authors examine the role of altered sea surface temperatures (SSTs) on the storm-track position and intensity in an atmospheric general circulation model (AGCM) using realistic lower boundary conditions.

    A set of experiments was conducted in which the SSTs where changed by 2 K in specified latitude bands. The primary profile was inspired by the observed trend in ocean temperatures, with the largest warming occurring at low latitudes. The response to several other heating patterns was also investigated, to examine the effect of imposed gradients and low- versus high-latitude heating. The focus is on the Northern Hemisphere (NH) winter, averaged over a 20-yr period.

    Results show that the storm tracks respond to changes in both the mean SST and SST gradients, consistent with previous studies employing aquaplanet (water only) boundary conditions. Increasing the mean SST strengthens the Hadley circulation and the subtropical jets, causing the storm tracks to intensify and shift poleward. Increasing the SST gradient at midlatitudes similarly causes an intensification and a poleward shift of the storm tracks. Increasing the gradient in the tropics, on the other hand, causes the Hadley cells to contract and the storm tracks to shift equatorward. Consistent shifts are seen in the mean zonal velocity, the atmospheric baroclinicity, the eddy heat and momentum fluxes, and the atmospheric meridional overturning circulation. The results support the idea that oceanic heating could be a contributing factor to the observed shift in the storm tracks.


    especially recommended (includes STRATOSPHERE)
    Butler, Amy H., David W. J. Thompson, Ross Heikes, 2010: The Steady-State Atmospheric Circulation Response to Climate Change–like Thermal Forcings in a Simple General Circulation Model. J. Climate, 23, 3474–3496.
    tropical troposphere warming: poleward shift in extratropical storm tracks; weaker stratospheric Brewer-Dobson circulation (opposite to what happens in most climate change experiments)
    polar stratospheric cooling: poleward shift in extratropical storm stracks – “very” sensitive to forcing’s “level and depth”; stratospheric Brewer-Dobson circulation weakens in midlatitudes, strengthens at high latitudes “because of anomalously poleward heat fluxes on the flank of the polar vortex.
    polar surface warming: equatorward shift in extratropical storm tracks
    responses to forcings in general: some differences between equinox and winter, nonlinear responses (sum of responses to individual forcings not equal to response to all forcings together)

    (my speculation following abstract only: so maybe we have poleward shift, followed by equatorward shift when most arctic ice loss occurs (in ~winter +/-), followed by continuing poleward shift?)

    especially recommended
    Butler, Amy H., David W. J. Thompson, Thomas Birner, 2011: Isentropic Slopes, Downgradient Eddy Fluxes, and the Extratropical Atmospheric Circulation Response to Tropical Tropospheric Heating. J. Atmos. Sci., 68, 2292–2305.
    (tropical tropospheric latent heating, eddy fluxes of PV, heat (which is like PV at the surface))
    (see also Schneider 2006 because of isentropic slopes?)



    especially recommended
    Simpson, Isla R., Michael Blackburn, Joanna D. Haigh, 2009: The Role of Eddies in Driving the Tropospheric Response to Stratospheric Heating Perturbations. J. Atmos. Sci., 66, 1347–1365.
    (compares different distributions of stratospheric heating, including one that is implied (in the abstract; haven’t read it through) to correspond to solar effects)
    (interesting graphs; jet and storm track shifts, index of refraction (see p. 1356, equation 4))

    A simplified general circulation model has been used to investigate the chain of causality whereby changes in tropospheric circulation and temperature are produced in response to stratospheric heating perturbations. Spinup ensemble experiments have been performed to examine the evolution of the tropospheric circulation in response to such perturbations.

    The primary aim of these experiments is to investigate the possible mechanisms whereby a tropospheric response to changing solar activity over the 11-yr solar cycle could be produced in response to heating of the equatorial lower stratosphere. This study therefore focuses on a stratospheric heating perturbation in which the heating is largest in the tropics. For comparison, experiments are also performed in which the stratosphere is heated uniformly at all latitudes and in which it is heated preferentially in the polar region. Thus, the mechanisms discussed have a wider relevance for the impact of stratospheric perturbations on the troposphere.

    The results demonstrate the importance of changing eddy momentum fluxes in driving the tropospheric response. This is confirmed by the lack of a similar response in a zonally symmetric model with fixed eddy forcing. Furthermore, it is apparent that feedback between the tropospheric eddy fluxes and tropospheric circulation changes is required to produce the full model response. The quasigeostrophic index of refraction is used to diagnose the cause of the changes in eddy behavior. It is demonstrated that the latitudinal extent of stratospheric heating is important in determining the direction of displacement of the tropospheric jet and storm track.

    especially recommended
    Simpson, Isla R., Michael Blackburn, Joanna D. Haigh, 2012: A Mechanism for the Effect of Tropospheric Jet Structure on the Annular Mode–Like Response to Stratospheric Forcing. J. Atmos. Sci., 69, 2152–2170.
    (refraction, critical line, momentum flux, equatorial stratospheric heating, effects of eddy phase speeds)
    see also
    Barnes, E.A., D.L. Hartmann, D.M.W. Frierson, and J. Kidston, 2010, and
    Barnes, E.A., and D.L. Hartmann, 2010

    For many climate forcings the dominant response of the extratropical circulation is a latitudinal shift of the tropospheric midlatitude jets. The magnitude of this response appears to depend on climatological jet latitude in general circulation models (GCMs): lower-latitude jets exhibit a larger shift.

    The reason for this latitude dependence is investigated for a particular forcing, heating of the equatorial stratosphere, which shifts the jet poleward. Spinup ensembles with a simplified GCM are used to examine the evolution of the response for five different jet structures. These differ in the latitude of the eddy-driven jet but have similar subtropical zonal winds. It is found that lower-latitude jets exhibit a larger response due to stronger tropospheric eddy–mean flow feedbacks.

    A dominant feedback responsible for enhancing the poleward shift is an enhanced equatorward refraction of the eddies, resulting in an increased momentum flux, poleward of the low-latitude critical line. The sensitivity of feedback strength to jet structure is associated with differences in the coherence of this behavior across the spectrum of eddy phase speeds. In the configurations used, the higher-latitude jets have a wider range of critical latitude locations. This reduces the coherence of the momentum flux anomalies associated with different phase speeds, with low phase speeds opposing the effect of high phase speeds. This suggests that, for a given subtropical zonal wind strength, the latitude of the eddy-driven jet affects the feedback through its influence on the width of the region of westerly winds and the range of critical latitudes on the equatorward flank of the jet.

    Haigh, Joanna D., Michael Blackburn, Rebecca Day, 2005: The Response of Tropospheric Circulation to Perturbations in Lower-Stratospheric Temperature. J. Climate, 18, 3672–3685.

    A multiple regression analysis of the NCEP–NCAR reanalysis dataset shows a response to increased solar activity of a weakening and poleward shift of the subtropical jets. This signal is separable from other influences, such as those of El Niño–Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO), and is very similar to that seen in previous studies using global circulation models (GCMs) of the effects of an increase in solar spectral irradiance. The response to increased stratospheric (volcanic) aerosol is found in the data to be a weakening and equatorward shift of the jets.

    The GCM studies of the solar influence also showed an impact on tropospheric mean meridional circulation with a weakening and expansion of the tropical Hadley cells and a poleward shift of the Ferrel cells. To understand the mechanisms whereby the changes in solar irradiance affect tropospheric winds and circulation, experiments have been carried out with a simplified global circulation model. The results show that generic heating of the lower stratosphere tends to weaken the subtropical jets and the tropospheric mean meridional circulations. The positions of the jets, and the extent of the Hadley cells, respond to the distribution of the stratospheric heating, with low-latitude heating forcing them to move poleward, and high-latitude or latitudinally uniform heating forcing them equatorward. The patterns of response are similar to those that are found to be a result of the solar or volcanic influences, respectively, in the data analysis.

    This demonstrates that perturbations to the heat balance of the lower stratosphere, such as those brought about by solar or volcanic activity, can produce changes in the mean tropospheric circulation, even without any direct forcing below the tropopause.

    especially recommended
    Miller, R. L., G. A. Schmidt, and D. T. Shindell, 2006: Forced annular variations in the 20th century Intergovernmental Panel on Climate Change Fourth Assessment Report models. J. Geophys. Res., 111, D18101, doi:10.1029/2005JD006323.
    (troposphere-stratosphere coupling, GHG, anthropogenic aerosol, and volcanic forcing, models vs. observations)

    We examine the annular mode within each hemisphere (defined here as the leading empirical orthogonal function and principal component of hemispheric sea level pressure) as simulated by the Intergovernmental Panel on Climate Change Fourth Assessment Report ensembles of coupled ocean-atmosphere models. The simulated annular patterns exhibit a high spatial correlation with the observed patterns during the late 20th century, though the mode represents too large a percentage of total temporal variability within each hemisphere. In response to increasing concentrations of greenhouse gases and tropospheric sulfate aerosols, the multimodel average exhibits a positive annular trend in both hemispheres, with decreasing sea level pressure (SLP) over the pole and a compensating increase in midlatitudes. In the Northern Hemisphere, the trend agrees in sign but is of smaller amplitude than that observed during recent decades. In the Southern Hemisphere, decreasing stratospheric ozone causes an additional reduction in Antarctic surface pressure during the latter half of the 20th century. While annular trends in the multimodel average are positive, individual model trends vary widely. Not all models predict a decrease in high-latitude SLP, although no model exhibits an increase. As a test of the models’ annular sensitivity, the response to volcanic aerosols in the stratosphere is calculated during the winter following five major tropical eruptions. The observed response exhibits coupling between stratospheric anomalies and annular variations at the surface, similar to the coupling between these levels simulated elsewhere by models in response to increasing GHG concentration. The multimodel average is of the correct sign but significantly smaller in magnitude than the observed annular anomaly. This suggests that the models underestimate the coupling of stratospheric changes to annular variations at the surface and may not simulate the full response to increasing GHGs.

    Hartmann, D. L., J. M. Wallace, V. Limpasuvan, D. W. J. Thompson and J. R. Holton, 2000: Can Ozone Depletion and Global Warming Interact to Produce Rapid Climate Change? Proc. Nat. Acad. Sci., 97, 1412-1417.

    The atmosphere displays modes of variability whose structures exhibit a strong longitudinally symmetric (annular) component that extends from the surface to the stratosphere in middle and high latitudes of both hemispheres. In the past 30 years, these modes have exhibited trends that seem larger than their natural background variability, and may be related to human influences on stratospheric ozone and/or atmospheric greenhouse gas concentrations. The pattern of climate trends during the past few decades is marked by rapid cooling and ozone depletion in the polar lower stratosphere of both hemispheres, coupled with an increasing strength of the wintertime westerly polar vortex and a poleward shift of the westerly wind belt at the earth’s surface. Annular modes of variability are fundamentally a result of internal dynamical feedbacks within the climate system, and as such can show a large response to rather modest external forcing. The dynamics and thermodynamics of these modes are such that strong synergistic interactions between stratospheric ozone depletion and greenhouse warming are possible. These interactions may be responsible for the pronounced changes in tropospheric and stratospheric climate observed during the past few decades. If these trends continue, they could have important implications for the climate of the 21st century

    … H2O in the STRATOSPHERE:

    Maycock, Amanda C., Manoj M. Joshi, Keith P. Shine, Adam A. Scaife, : The circulation response to idealized changes in stratospheric water vapor.
    Journal of Climate 2012 ; e-View

    Observations show that stratospheric water vapor (SWV) concentrations increased by ~30% between 1980 and 2000. SWV has also been projected to increase by up to a factor of two over the 21st century. Trends in SWV impact on stratospheric temperatures, which may lead to changes in the stratospheric circulation. Perturbations in temperature and wind in the stratosphere have been shown to influence the extratropical tropospheric circulation. This study investigates the response to a uniform doubling in SWV from 3 to 6 ppmv in a comprehensive stratosphere-resolving atmospheric-GCM. The increase in SWV causes stratospheric cooling with a maximum amplitude of 5-6 K in the polar lower stratosphere and 2-3 K in the tropical lower stratosphere. The zonal wind on the upper flanks of the subtropical jets is more westerly by up to ~5 m s−1. Changes in resolved wave drag in the stratosphere result in an increase in the strength of tropical upwelling associated with the Brewer-Dobson circulation of ~10% throughout the year. In the troposphere, the increase in SWV causes significant meridional dipole changes in the midlatitude zonal-mean zonal wind of up to 2.8 m s−1 at 850 hPa, which are largest in boreal winter in both hemispheres. This suggests a more poleward storm track under uniformly increased stratospheric water vapor. The circulation changes in both the stratosphere and troposphere are almost entirely due to the increase in SWV at pressures greater than 50 hPa. The results show that long-term trends in SWV may impact on stratospheric temperatures and wind, the strength of the Brewer-Dobson circulation and extratropical surface climate.



  34. 334
    Patrick 027 says:


    especially recommended
    climate change
    Scaife, Adam A., Thomas Spangehl, David R. Fereday, Ulrich Cubasch, Ulrike Langematz, Hideharu Akiyoshi, Slimane Bekki, Peter Braesicke, Neal Butchart, Martyn P. Chipperfield, Andrew Gettelman, Steven C. Hardiman, Martine Michou, Eugene Rozanov, Theodore G. Shepherd, 2012: Climate change projections and stratosphere–troposphere interaction. Climate Dynamics, 38, 2089-2097.
    DOI 10.1007/s00382-011-1080-7
    (from abstract: many extratropical regions: increases in winter rain, flooding; stratospheric circulation has significant regional effects; changes consistent with stratospheric winds affecting growth rate of baroclinic eddies through depth of troposphere, “A change in mean wind structure and an equatorward shift of the tropospheric storm tracks relative to models with poor stratospheric resolution allows coupling with surface climate. Using the Atlantic storm track as an example, we show how this can double the predicted increase in extreme winter rainfall over Western and Central Europe compared to other current climate projections.“)



    especially recommended
    climate change
    Booth, James F., Shuguang Wang, Lorenzo Polvani, 2012: Midlatitude storms in a moister world: lessons from idealized baroclinic life cycle experiments. Clim Dyn, ?, ?.
    DOI 10.1007/s00382-012-1472-3
    (I’ve only looked at this a little tiny bit, but p. 3/16 indicates cartesian geometry and constant f; I’d be curious what corrections would be found for spherical effects)
    (abstract, emphasis mine:

    The response of midlatitude storms to global warming remains uncertain. This is due, in part, to the competing effects of a weaker meridional surface temperature gradient and a higher low-level moisture content, both of which are projected to occur as a consequence of increasing greenhouse gases. Here we address the latter of these two effects, and try to elucidate the effect of increased moisture on the development and evolution of midlatitude storms. We do this with a set of highly controlled, baroclinic lifecycle experiments, in which atmospheric moisture is progressively increased. To assess the robustness of the results, the moisture content is changed in two different ways: first by using different initial relative humidity, and second by varying a parameter that we insert into the Clausius-Clapeyron equation. The latter method allows us to artificially increase the moisture content above current levels while keeping the relative humidity constant. Irrespective of how moisture is altered, we find that nearly all important measures of storm strength increase as the moisture content rises. Specifically, we examine the storm’s central pressure minimum, the strongest surface winds, and both extreme and accumulated precipitation rates. For all these metrics, increased moisture yields a stronger storm. Interestingly, we also find that when moisture is increased beyond current levels, the resulting storm has a reduced horizontal scale while its vertical extent increases. Finally, we note that for moisture increases comparable to those projected to occur by the end of the twentyfirst century, the actual amplitude of the increases in storm strength is relatively modest, irrespective of the specific measure one uses.

    (the part about vertical vs horizontal extent doesn’t surprise me (not that any of it does))

    Schneider, T., P.A. O’Gorman, and X. J. Levine, 2010: Water vapor and the dynamics of climate changes. Rev. Geophys., 48, RG3001,
    (H2O vapor dynamic effects = latent heating;
    majority of abstract, emphasis mine:

    Contrary to widely held beliefs, atmospheric circulation statistics can change non-monotonically with global-mean surface temperature, in part because of dynamic effects of water vapor. For example, the strengths of the tropical Hadley circulation and of zonally asymmetric tropical circulations, as well as the kinetic energy of extratropical baroclinic eddies, can be lower than they presently are both in much warmer climates and in much colder climates. We discuss how latent heat release is implicated in such circulation changes, particularly through its effect on the atmospheric static stability, and we illustrate the circulation changes through simulations with an idealized general circulation model. This allows us to explore a continuum of climates, constrain macroscopic laws governing this climatic continuum, and place past and possible future climate changes in a broader context.


    Dettinger, Michael
    Atmospheric Rivers
    (slide 13/26 – AR vs PE ?)
    (slide 24 refers to climate change)

    Muller, C. J., P. A. O’Gorman, 2011: An energetic perspective on the regional response of precipitation to climate change. Nature Climate Change, 1, 266-271.
    (most of abstract:

    This energetic perspective reveals that changes in temperature, greenhouse gases, aerosols, solar forcing and cloud feedbacks can all affect the global average rate of precipitation5,7–11. Local precipitation changes have conventionally been analysed using the water vapour budget, but here we show that the energetic approach can be extended to local changes in precipitation by including changes in horizontal energy transport. In simulations of twenty-first century climate change, this energy transport accounts for much of the spatial variability in precipitation change. We show that changes in radiative and surface sensible heat fluxes are a guide to the local precipitation response over land and at large scales, but not at small scales over the ocean, where cloud and water vapour radiative feedbacks dampen the response. The energetic approach described here helps bridge the gap between our understanding of global and regional precipitation changes. It could be applied to better understand the response of regional precipitation to different radiative forcings, including geo-engineering schemes, as well as to understand the differences between the fast and slow responses of regional precipitation to such forcings.


    Held, Isaac M., Brian J. Soden, 2006: Robust Responses of the Hydrological Cycle to Global Warming. J. Climate, 19, 5686–5699.
    (H2O water vapor abundance shaped by Clausius-Clayperon relationship, H2O evaporation rate shaped by energy fluxes. One is larger than the other. Consequences for circulation.)
    (it gets easier to summarize if you wait longer after reading it)
    (PS I’d add – unless they address this – it’s been ~ 2 years since I read it, but anyway – with increasing greenhouse (LW) forcing having some effect at the surface (not generally equal to tropopause or TOA levels), the convective energy flux should tend to increase ?. H2O vapor especially adds to that effect over some range of temperatures, until saturation at a temperature higher than present (when net LW surface cooling approaches zero) – provided sufficient RH (presumably low RH just delays the effect?). H2O also absorbs some SW radiation, so beyond that point, H2O would reduce SW heating of the surface and thus reduce convective heat flux from the surface. Cloud LW feedback …? albedo feedback in general, except that associated with atmospheric solar heating, would increase convective heat flux when it is positive. The fraction of convective heat flux that is latent heat tends to increase with temperature, so that would tend to peak after the peak in total convective heat flux. Would there necessarily be a peak if it were solar forcing, or would H2O LW saturation at the surface with increasing H2O SW absorption and … scattering? (clouds aside) … just slow the increase in convective surface cooling? Convection regionally can be larger than otherwise given some regions where convection heats the surface.)

    Shiu, C.-J., S. C. Liu, C. Fu, A. Dai, and Y. Sun (2012), How much do precipitation extremes change in a warming climate?, Geophys. Res. Lett., doi:10.1029/2012GL052762, in press.

    Daily data from reanalyses of the European Centre for Medium-Range Weather Forecasts (ECMWF) and the National Centers for Environmental Prediction (NCEP) are analyzed to study changes in precipitation intensity with respect to global mean temperature. The results are in good agreement with those derived from the Global Precipitation Climatology Project (GPCP) data by Liu et al., [2009], providing an independent verification for large changes in the precipitation extremes: about 100% increase for the annual top 10% heavy precipitation and about 20% decrease for the light and moderate precipitation for one degree warming in the global temperature. These changes can substantially increase the risk of floods as well as droughts, thus severely affecting the global ecosystems. Atmospheric models used in the reanalysis mode, with the benefit of observed wind and moisture fields, appear to be capable of realistically simulating the change of precipitation intensity with global temperature. In comparison, coupled climate models are capable of simulating the shape of the change in precipitation intensity, but underestimate the magnitude of the change by about one order of magnitude. The most likely reason of the underestimation is that the typical spatial resolution of climate models is too coarse to resolve atmospheric convection.




    *** (Paleoclimate, high latitude amplification)
    Lee, Sukyoung, Steven Feldstein, David Pollard, Tim White, 2011: Do Planetary Wave Dynamics Contribute to Equable Climates? Journal of Climate, 24, 2391-2404.
    DOI: 10.1175/2011JCLI3825.1

    Viable explanations for equable climates of the Cretaceous and early Cenozoic (from about 145 to 50 million years ago), especially for the above-freezing temperatures detected for high-latitude continental winters, have been a long-standing challenge. In this study, the authors suggest that enhanced and localized tropical convection, associated with a strengthened paleo–warm pool, may contribute toward high-latitude warming through the excitation of poleward-propagating Rossby waves. This warming takes place through the poleward heat flux and an overturning circulation that accompany the Rossby waves. This mechanism is tested with an atmosphere–mixed layer ocean general circulation model (GCM) by imposing idealized localized heating and compensating cooling, a heating structure that mimics the effect of warm-pool convective heating.

    The localized tropical heating is indeed found to contribute to a warming of the Arctic during the winter. Within the range of 0–150 W m-2 for the heating intensity, the average rate for the zonal mean Arctic surface warming is 0.8˚C per (10 W m-2) increase in the heating for the runs with an atmospheric CO2 level of 4 × PAL (Preindustrial Atmospheric Level, 1 PAL = 280 ppmv), the Cretaceous and early Cenozoic values considered for this study. This rate of warming for the Arctic is lower in model runs with 1×PAL CO2, which show an increase of 0.3˚C per (10 W m-2). Further increase of the heating intensity beyond 150 W m-2 produces little change in the Arctic surface air temperature. This saturation behavior is interpreted as being a result of nonlinear wave–wave interaction, which leads to equatorward wave refraction.

    Under the 4 × PAL CO2 level, raising the heating from 120 W m-2 (estimated warm-pool convective heating value for the present-day climate) to 150 and 180 W m -2 (estimated values for the Cretaceous and early Cenozoic) produces a warming of 4˚–8˚C over northern Siberia and the adjacent Arctic Ocean. Relative to the warming caused by a quadrupling of CO2 alone, this temperature increase accounts for about 30% of the warming over this region. The possible influence of warm-pool convective heating on the present-day Arctic is also discussed.


    Sabato, Jude S., 2008: CO2 Condensation in Baroclinic Eddies on Early Mars. J. Atmos. Sci., 65, 1378–1395.
    (cites Fantini 2004)


    Hartmann, D. L. and K. Larson (2002), An important constraint on tropical cloud – climate feedback, Geophys. Res. Lett., 29(20), 1951, doi:10.1029/2002GL015835.

  35. 335
    Hank Roberts says:

    Why are so many trees falling? (Seattle weather blogger Cliff Maas)

    “… my hypothesis is that we had a wet, snowy period with consistently cool, but not super cold, temperatures in a range that promoted sticky snow. No major wind events to blow off snow. No pineapple express warming. It all game together in a very unusual way, causing massive snow loading on trees. Another contributor might be the mild temperatures that have left the ground unfrozen and thus less able to hold the trees in place. …”

  36. 336
    sidd says:

    Mr. Perwis:

    I should have pointed out that the following projection is supralinear in my terminology, since they include a t^2 term

    “Another example is Rignot et al (2011), which gives yet another linear extrapolation and finds that “At the current rate of acceleration in ice sheet loss, starting at 500 Gt/yr in 2008 and increasing at 36.5 Gt/yr2, the contribution of ice sheets alone scales up to 56 cm by 2100.”

    Mr Patrick 027 writes:

    “Most of these (in I. and II.) I have only skimmed…”
    “I will probably never read through it all, …”

    Sir, you are discourteous. Many decades ago, I sometimes used to receive letters that had a postscript:

    “Dictated, but not read”

    Your post elicits the same response in my mind. If you feel that we should pay attention to your compendium of links, might you be gracious enough to read the articles first ?


  37. 337
    Edward Greisch says:

    AMEG: GeoEngineering [GE] with sulfur compounds really turns me off because they oxidize to form sulfuric acid. We have been trying really hard to get H2SO4 out of our air. Other GE: Covering the Arctic ocean with ping pong balls must be some kind of pollution.

    To rephrase my question, is AMEG just another fringe group that belongs in the borehole? I am well aware that RC has pronounced methane hydrates and melting tundra to be minor issues, at least for now. Does AMEG damage the cause by being a fringe group or is there no such thing as bad publicity?

  38. 338
    Superman1 says:

    Jim Larsen #322,

    “I didn’t read the proposal and would guess the principals don’t paint the ramifications as bleak as you seem to propose – that the fate of the world hangs on what we do in the next few months. Hmm, care to buy my slightly used Mayan calendar?”

    Read the proposal; I basically just quoted from it.

  39. 339
    prokaryotes says:

    sidd – “shut up and calculate. Hansen is not lacking in wits or resource. He can do much better than curve fitting, that’s why I find his note disappointing.”

    North Carolina’s senators, however, have tried to stop state-funded researchers from releasing similar reports. The law approved by the senate on 12 June banned scientists in state agencies from using exponential extrapolation to predict sea-level rise, requiring instead that they stick to linear projections based on historical data.

    Apparently Hansen is not alone with this “fitting” or what you call it. And then there are abrupt developments to expect, which suggest extreme developments to come. Then consider his track record on projections. Even with all the really conservative IPCC estimates on 2100 SLR, he was on this and each year the “general consensus” is further coming in line with what Hansen had calculated much earlier.

    Kinematic First-Order Calving Law implies Potential for Abrupt Ice-Shelf Retreat

    And then there is this:
    The researchers estimate that 50 per cent of the West Antarctic Ice Sheet (1 million km2) and 25 per cent of the East Antarctic Ice Sheet (2.5 million km2) overlies preglacial sedimentary basins, containing about 21,000 billion tonnes of organic carbon. Team leader, Professor Wadham said: “This is an immense amount of organic carbon, more than ten times the size of carbon stocks in northern permafrost regions.

  40. 340
    Superman1 says:

    Edward Greisch #337,

    ” is AMEG just another fringe group that belongs in the borehole?”

    According to the Collins Dictionary, a ‘fringe group’ is defined as ” a group that is on the periphery of a larger organization because its views are more extreme than the majority”. Not necessarily a negative connotation. If the mainstream is going in the wrong direction, it may be a positive connotation.

    Two academics listed in AMEG are Stephen Salter and Peter Wadhams. Salter has a background in wave energy conversion and cloud albedo enhancement, and Wadhams has been making ice measurements in the Arctic for decades. Both appear to be highly credible. They see the collapse of the Arctic as we speak, with the potential for unknown damage. The Strategic Plan comes across to me as an act of desperation by well-meaning people who are seeing no action being taken to contain the damage. The proposal is obviously flawed, as a few posters have already pointed out. Tell me, what other choices do they have to get something done?

    “I am well aware that RC has pronounced methane hydrates and melting tundra to be minor issues”

    On Arctic ice and related issues, I would give higher priority to Wadhams’ views.

    [Response: We have asked for, and not received, any backing for Wadham’s views for an exponential fit to the ice volume. This is the sole ‘evidence’ for his prediction of an ice free summer in 2015, but that is not in any way convincing to most everyone else, and so, yes, this prediction (and the dramatic consequences that are supposed to follow) is ‘fringe’. Sometimes fringes are right, but in science they dominate by the weight of evidence, not authority. – gavin]

  41. 341
    Hank Roberts says:

    Operation Icebridge, Dec. 2012 — here’s the developing large crack in the ice stream mentioned above:

  42. 342
    Patrick 027 says:

    Re 336 sidd – I understand the sentiment, but I read the abstracts I provided, and didn’t ask anyone to read any farther – actually didn’t ask anything at all. I hope to read more; if someone else does too, great, if not, well I certainly understand why. It’s there for those who want it. That was the intent. Sorry for the misunderstanding.

  43. 343
    Patrick 027 says:

    … oh, I guess you took the word ‘recommendation’ as unconditional and complete, as in ‘you must read this whole thing regardless of your interest’. Well I didn’t mean it that way. Okay, done.

  44. 344
    Jim Larsen says:

    323 Superman1 asked, “why would one select a symptom, rather than the problem and its causes?”

    Ahh, Engineering attempts to engage in Public Relations….

    Cuz the goal is to have the public give a damn. The public is on a 1 hour news cycle, so unless it’s happening RIGHT NOW, it’s, like, whatever.

    Biggest melt ever. Hollywood-style exaggeration but it’s real life reported (or not) in real time.

    Not that it lit the public’s fuse, but I think the topic was spot on perfect for an initial post made at that time.

    The lesson here is clear. If you want to make a political difference, forget PACs. Invest in mass media and leverage your voice.

    Seriously, the analogy for Climate Change is exercise. Ya know you oughta do it. Ya know you’ll be better off. You’ll feel better, more energy, yada yada yada….

    But skipping today won’t hurt, and exercising today will do so little as to be no good (0.2 pounds?? woo.) and won’t be near as much fun as that bag of chips…

  45. 345
    Jim Larsen says:

    323 Superman1 said, “I suspect my views on what you call an ‘interesting discussion’ differ from yours.”

    Probably. You head straight for the prey. I see around corners.

    S1 asked, ” what fraction is attributable to anthropogenic forcing; what can we expect if present trends continue. Why did the flagship discussion not address this central problem?”

    In the battle for a scrap of desert amongst the descendants of two brothers who worship the same god in slightly different ways (Palestinians and Jews), the actual sitting at a table in the same room – the arrangements, the tiniest detail which might suggest superiority of morals or power had to be addressed. That sort of thing takes decades….

    It was/is a friggin kindergarten stupid family squabble.

    Skeptics VS Warmists. Yep, we’re right. So? We still have to get to the table.

    So a symptom we all can see. Something which God has Revealed (to continue the religious analogy). By finding agreement in something, it sets the tone for finding agreement in larger issues, and it eliminates wiggle room. Things we disagree on are often best left for later. Find another thing we can agree on. Eventually, the mosaic we create with such agreements will lock in the truth for things we could never directly resolve.

    S1 said, “Once in a century storms are occurring once on a decade or sooner. That should have been the focus of the flagship issue, but instead, a symptom, with its higher variability, was chosen for the focus.”

    They’re both symptoms. The drought is more local, which helps PR, but the sea ice is less controversial, which helps agreement. The model for success isn’t Our Side beating The Evil Opposition to death, but building a new consensus with the mindset that EVERYONE at the table is TRULY INTERESTED in finding the REAL truth. (The caveat is that many feel the best place to find the REAL truth is in THEIR beliefs. That’s not immoral. We cherish folks who do works through faith.)

    S1 went into a funding rant….

    dude. Chill.

    The “Alarmist” argument (which I often agree with) wasn’t missing by intent. At least two Alarmists were asked to participate. One never responded. The other accepted, and then backed out due to lack of time.

    324 perwis quoted, ” “As the terminus of an ice stream retreats inland, glacier sidewalls can collapse, creating a wider pathway for disgorging ice.”

    yeah, but adding 5 miles of fjord just makes it HARDER for ice to get from the receded glacier to the ocean. Woo if it’s wide. I know that the ice/water interface can enlarge, but disgorgement has got to be hindered by retreat. (Here’s where I hope somebody fills in what I’m missing)

    327 Lawrence C, I agree completely. I’m no expert and can’t quantify, but as the ocean waters increase in temp, one would have to target colder and colder surface air temperatures to achieve whatever September ice extent is desired. I’m sure that the “instantness” would slow down too. With a warm Arctic Ocean and warm waters flowing in from a warm world, it could take years of induced brutal winters to cool the system back to a semblance of normal.

    338 S1 said, “Read the proposal; I basically just quoted from it.”

    No thanks. I mostly just wanted to know if your stance reflected theirs. If so, your excerpts were plenty.

    342 Patrick,

    Perhaps a better leading synopsis? I got the impression of a ton of stuff tossed in my direction with nary a clue as to why or what. That there was “1000 pages” sitting in front of me might have contributed to my failure. Whether I was typical or not, I briefly pseudo-scanned and got nada.

  46. 346
    Jim Larsen says:


    I am getting “could not open socket” on perhaps 2/3rds of my submissions. It fixes itself without changes. I’m on OS X 10.4.11

  47. 347
    Patrick 027 says:

    Re Jim Larsen @ 346 – had the same problem last night.

    @ 345 – thanks for the feedback. I think I tend to expect that stuff will take up fewer lines than it actually does. Perhaps I was too focussed on getting it posted before one more day passed. I’ve been working on this since I think early November, and actually even earlier than that. Part I was supposed to be about climate change specifically so some of my tags were gratuitous; also, except for the Wing paper, the ‘especially recommended’ should have been dropped; I started out knowing that I wanted to tag some sources with that label but over time I perhaps over or under-used it; it would have been better just to put the citations in bold as an attention-grabber.

    I don’t want to stop anyone from digging in, but I wanted to eventually post a brief intro into some subject matters that would make these articles more understandable. The problem is, there’s a few i’s to dot and t’s to cross on my side before I’m ready to do that, and I just didn’t want to sit on all these articles until I had time to read through them more. At least I’ve got the abstracts under my belt now.

    Also, when I do try to write an ‘intro to planetary fluid dynamics’, I’m going to want to provide citations, and that’s the boring, tedious part (for me), so I figured it might go faster (for me) to post a list of articles first; I could always refer back to those postings at a later time. Having the list put together should help me avoid reading a bunch of stuff and then typing about it having forgotten what came from where.

    As for those articles which I don’t anticipate reading beyond the abstract, I think they still serve a purpose in:

    1 Some are cited by the articles that I will go through, and it’s nice to have the citations and links there already in case I need them.

    2 While one must be careful about taking things out of context, I thought I might use some things as reference material where I’d read the parts that provide what I’m interested in. Case-in-point: Vasavada, Ashwin R., Adam P. Showman, 2005: Jovian atmospheric dynamics: an update after Galileo and Cassini. Rep. Prog. Phys., 68, 1935-1996.
    – I don’t anticipate getting through the whole thing any time soon (because gas giants aren’t the focus), but there were about ten pages in there which provides a nice summary of how eddies can form and drive jets (quasi-/__-geostrophic turbulence, Rhines scale, forcing and dissipation) and a really neat diagram with a page (1967) that gave me a much better understanding of how/why Taylor columns would fit in Earth’s outer core (than I got from Karato – nothing against Karato; great (geology) book) – which I realize is going off on a tangent but why explain PV and then strictly limit yourself to thin-shell stably-stratified fluids?
    – also, there are some websites that provide information which I already know a lot, so I’d just be reading parts of them.

    3 It provides an awareness of the issues to see that their are articles about particular things. I think this can motivate interest in learning about those things from the other sources (those sources which are better for introductory purposes or have a bigger-picture outlook).

    And of course once I had a list put together I wanted to post it.

    PS I wasn’t going to post quoted abstracts for everything in part II; I just figured it made sense to do that for part I (I see I forgot one).

  48. 348
    Superman1 says:

    Jim Larsen #345,

    “n the battle for a scrap of desert amongst the descendants of two brothers who worship the same god in slightly different ways (Palestinians and Jews), the actual sitting at a table in the same room – the arrangements, the tiniest detail which might suggest superiority of morals or power had to be addressed. That sort of thing takes decades….”

    This is ‘superficiality’ carried to new heights! The above diversions are meant for public consumption only. The central problem is that each side would like to gain control of the full territory. The Israelis would like to cover the West Bank and Gaza Strip with new settlements, and have the Palestinians emigrate to other Arab states. The Palestinians would like to send the Israelis back to Europe (the main group), and turn the whole region into a Palestinian State. Until those fundamental issues change, the superficialities will dominate the news.

    We had the same problem in Korea and Vietnam. The Paris Peace talks in Vietnam, and similar talks in Korea, were delayed, according to the Press, by differences on the shape of the table and who sat where. The central problem was neither side was ready to surrender or negotiate, so they engaged in these superficialities.

    In climate change, we have a similar problem, but with an added dimension. Rather than recognize the inherent addictive nature of the problem, we focus, as you did repeatedly, on the need for public information and political action. If the problem were lack of information, then the solution would be dissemination of information. But, if the problem is addiction to intensive use of cheap fossil fuel energy, then the solution is not merely provision of information, but addressing the addiction head-on. But, it’s so much more convenient to blame the cartels than the addicts.

  49. 349
    perwis says:

    MODERATOR: I also get the same socket errors and could not post at all yesterday.

    sidd @330

    I am not saying that Hansen & Sato sufficiently justifies the hypothesis that mass loss will follow an exponential curve. However, the arguments they provide give reason for concern that mass loss will be accelerating, at some faster-than-linear pace. Of course, exponential developments are a very special case, and it would be interesting to read more justification from Hansen regarding the hypothesis of exponential mass-loss of the great ice-sheets.

    It is correct that Rignot et al:s projection is supra-linear (it is accelerating ice-loss), but they assume a linear acceleration. It is not far-fetched to assume that ice-loss will be accelerating more in the end of the century under BAU-forcings. Will it be exponential? Maybe not, but can we rule it out?

    Hansen & Sato also points out that recent sea level projections are primarily based on linear assumptions. Notably, this include the “back-of-the-envelope” calculations for ice dynamics in IPCC AR4, expert judgments such as Pfeffer et al (2008) or Katsman et al (2011) (see my discussion in post # 324), as well as the the semi-empirical methods by Vermeer & Rahmstorf (2009) and others (Rahmstorf, Perrette & Vermeer (2011) say that “a non-linear response of ice sheets could make semi-empirical projections overestimate or underestimate the true future sea level rise.”). I would argue that the linear assumtions are not justified based on the exatcly the kind of phenomena that Hansen & Sato (2012) highlights.

    The billion-dollar question is if the current ice-sheet models are any better. My understanding is that the forthcoming AR5 sea level projections rely on ice-sheet models for estimating the future contribution from ice-dynamics (which is where the main uncertainty is, see my post #303 above).

    I read Hansen & Sato’s recent note and their brief discussion of this in Hansen & Sato (2012) as yet another warning of scientific reticience regarding sea level rise and that current methods for sea level projections probably does not sufficiently capture the scale and speed of the loss that can occur over short periods of time (this century) due to non-linear responses of the great ice-sheets in Greenland and Antarctica.

  50. 350
    Superman1 says:

    Jim Larsen #345,

    “The “Alarmist” argument (which I often agree with) wasn’t missing by intent. At least two Alarmists were asked to participate. One never responded. The other accepted, and then backed out due to lack of time.”

    Okay, so if you’re scheduled for major surgery, and the first two anesthesiologists the surgeon requests back out, you’d go ahead with the surgery anyway? What was the rush for the dialogue without a balanced team?

    On to a more fundamental issue. I have been promoting the viewpoint that the major roadblock to combating climate change is the effective ‘addiction’ of the energy consumer to cheap and plentiful fossil fuel-supplied energy. That seems not to be resonating on this site. Instead, the focus appears to be ‘let’s target the media for not getting the correct info to the public, and the energy companies for their media and political influence’. Now, if I believed info restriction or undue political influence were the major roadblocks, then I would agree that the focus on the media or the politicians is appropriate. But, if the consumer is the major roadblock, and the consumer drives the politicians, then the focus on the politicians has it backwards, and can never solve the problem. Any politically-driven mandates on heavy energy use restriction, or politically-driven taxes/penalties on heavy fossil fuel use will go nowhere without public acceptance. So, it seems to me from first principles that the energy consumer is the central problem, and solutions can only come when the energy consumer is willing to forego his ‘addiction’. This could either be voluntary or involuntary.

    Now, if this message is not being received, it seems to me there are three potential major causes: there is a problem with the transmitter, there is a problem with the transmitting medium, there is a problem with the receiver, or any combination of the above. So, where are the main problems? Do you disagree with the fundamental message presented above? If so, tell me how the politicians could institute the required harsh changes without the consent of the energy consumer? Any other comments would be appreciated as well.