RealClimate

Climate science from climate scientists...

You are here: Home / Climate Science / Unforced variations 3

Unforced variations 3

by

Here’s an open thread for various climate science related discussions, to prevent more off-topic clutter everywhere else. We have some good posts coming up, but if you want to discuss something you read in the media, saw in a press release or just wanted to ask about, this is the time.

Some interesting things we’ve seen recently include discussions on the epistimology of climate modelling, Andy Dessler’s adventures in debate land and his new paper on water vapour trends, and a review of trends in the Columbia glacier. Have at it.

Addendum: Kevin McKinney has beaten us to the mention of this, but another recent article of importance is a thorough review of the state of knowledge of drought, past and future, by Dai.  The article is open access here.

Reader Interactions

573 Responses to "Unforced variations 3"

  1. Interesting paper:
    http://icesjms.oxfordjournals.org/content/65/3/296.full
    Oxford Journals
    Life Sciences
    ICES Journal of Marine Science
    Volume65, Issue3
    Pp. 296-301.
    Plankton, from the last ice age to the year 3007
    E. C. Pielou

    “… Currently, predictions emphasize one or the other of two contrasted alternatives: abrupt cooling caused by a shutdown of the thermohaline circulation (the “ocean conveyor”) or abrupt warming caused by copious outgassing of methane. Both arguments (the former from oceanographers and the latter from geophysicists) are equally persuasive, and I have chosen to explore the methane alternative, because I am familiar with an area (the Beaufort Sea and Mackenzie Delta) where outgassing has recently (2007) been detected and is happening now: in the Arctic Ocean and the Canadian Arctic Archipelago, where disappearance of the ice will affect currents, temperature, thermocline, salinity, upwelling, and nutrients, with consequent effects on the zooplankton….”

  2. Since Jim’s discussion continues in more than one thread, don’t miss Gavin’s inline response to Jim:

    [Response: You have misunderstood the comment completely. I was referring to a specific calculation which requires an fully equilibriated simulation. Most experiments – and this includes all transients for the next few decades – do not require this and so coupled models are routinely used. – gavin]

    xref: https://www.realclimate.org/?comments_popup=5308#comment-190909

    Jim, please, get a blog.
    If you do that, people be more patient and helpful, at greater length, in one coherent discussion.
    Scattering this through various RC topics is giving people the wrong impression about your thinking.
    Getting it together — would be a good move.

  3. 550 adelady

    Having never had anything you might call forests makes Australia a prime candidate for growing new forests, but that depends on big changes to water distribution.

    They figured this out along the Nile 10,000 years ago; so with the Tigris and Euphrates Rivers.

    There was not much growing in the California Central Valley for a million years or so, since it dried up as part of the Pacific Ocean. (Rough description of geologic age.)

    Trees balance burned coal on a roughly ton for ton basis. So it would be ok to use some of that tax money from BHP and Rio Tinto to help get the project going.

  4. Jim Bullis (#541),

    > vertical mixing by hurricanes, storm surges, etc

    There seems to be interesting work being done on this: Might tropical cyclones, by cooling the surface and mixing heat down, be a major driver of poleward heat transport, and could this be a positive feedback to global warming? E.g.:

    Sriver, Ryan L., and Matthew Huber. 2007. Observational evidence for an ocean heat pump induced by tropical cyclones. Nature 447, no. 7144 (May 31): 577-580. doi:10.1038/nature05785.

    Herweijer, Celine, Richard Seager, Michael Winton, and Amy Clement. 2005. Why ocean heat transport warms the global mean climate. Tellus A 57, no. 4 (8): 662-675. doi:10.1111/j.1600-0870.2005.00121.x.

    Here’s a recent one:

    Sriver, Ryan L., Marlos Goes, Michael E. Mann, and Klaus Keller. 2010. Climate response to tropical cyclone-induced ocean mixing in an Earth system model of intermediate complexity. Journal of Geophysical Research C: Oceans 115 (October 20): 9 pp. doi:201010.1029/2010JC006106.

  6. 554 CM

    Thanks for good stuff to study.

    I think you are using the term “positive feedback” differently than the control system sense, where ‘positive’ means things go crazy.

    Cooling the surface and mixing heat downward is how a negative feedback works to keep things from going crazy.

    The terminology is completely crazy, since your sense of the word ‘positive’ fits with normal people’s use of the word; not the way engineers defined it for their purposes. I think the climate scientists grudgingly go with the engineers on this one, but only because Bode was at Bell Labs, and that has to count for something. (See Chris Colosse definitions a few weeks ago.)

  7. 554

    The first two references seem to disagree with each other and the third link does not work for me.(Is there another option.)

    I am unclear about how the vertical mixing occurs, but the Sriver reference uses measured data to come to conclusions, so I am inclinded to put that first in credibility.

  9. 558 David B. Benson,

    At least you have the direction right.

    In control system theory, all inputs are amplified, but the negative feedback serves to bring the summing point to near zero. In general, positive feedback results in instability since the amplifier provides a high gain amplification of whatever is at the summing point.

    This being the origin of the term, it seems to me that definitions otherwise are a bit like 6th grade science.

    True, nobody owns words, but when a supposed science adapts well established terminology from another field, it is not very good science when they use it inconsistently. A definition is never wrong, but when used inconsistently with the way it is used by others, especially when those others might be important to bring into the club, that definition can be called ‘not useful’. I think that the real scientists understand how important it is to communicate to the people who bring solutions to the table.

    When you provide advise, please remind yourself that you have no idea of my background. That does not mean I do not appreciate it when you provide useful information.

  10. Confusion about the meaning of feedback is really quite ubiquitous, so we shouldn’t castigate Jim Bullis for getting it all wrong.

  11. Jim, re: my #554,

    Oops, sorry. The correct DOI for Sriver et al. 2010 is 10.1029/2010JC006106 and you’ll find it here:
    http://www.agu.org/pubs/crossref/2010/2010JC006106.shtml

    I’m using “positive feedback” in the ordinary climate science sense, as discussed most recently on Chris Colose’s threads. The first reference I gave surmises that increased tropical cyclone activity, by mixing down heat, may lead to increased poleward ocean heat transport, which may lead to a rise in global mean temperature. This is based on the argument in the second reference, that ocean heat transport moistens the subtropical atmosphere, reduces subtropical and mid-latitude low cloud, and melts high-latitude sea-ice, thus amplifying global warming by enhancing water vapor and albedo feedbacks. Hence although the tropical sea cools locally in the wake of a cyclone, globally the planet warms. (The third reference finds the main impacts to be confined to the Pacific Ocean.) This may not be a very precise precis — I haven’t had the time to read these carefully.

  12. 561 CM

    The first reference says, “Our results indicate that tropical cyclones are responsible for significant cooling and vertical mixing of the surface ocean in tropical regions. Assuming that all the heat that is mixed downwards is balanced by heat transport towards the poles, we calculate that approximately 15 per cent of peak ocean heat transport may be associated with the vertical mixing induced by tropical cyclones. Furthermore, our analyses show that the magnitude of this mixing is strongly related to sea surface temperature, indicating that future changes in tropical sea surface temperatures may have significant effects on ocean circulation and ocean heat transport that are not currently accounted for in climate models.”

    I see nothing here about ‘may lead to a rise in global mean temperature’. That seems to be your conjecture.

    I see this as a process where vertical mixing is described such that ‘heat is mixed downwards’. It is my reasoning that heat mixed downward is a way that heat is removed from the atmosphere.

    The authors announce cooling and vertical mixing, but then make unwarranted suppositions on the implications of that. I look for observed data and rational discussions of the implications. What goes beyond this I tend to ignore.

    Heat mixed downwards will affect global heat transport according to how changes in deep temperatures impact the global circulation system. Whether it ultimately adds to heat held deep in the ocean, and therefore stays out of the climate, is not addressed by the authors. I say this is the interesting question.

  14. In short form ‘going crazy’ equates to ‘becoming unstable and starts to oscillate’.

    If the climate system gets to the point that it acts unstably and starts to oscillate, we all would need to run and hide.

    I did not need to read the Wikipedia explanation to know this. Actually, I built a regenerative short wave radio receiver in the 8th grade. But in developing amplifiers for control systems, that was considered an utter failure of design.

  15. Jim Bullis, Miastrada Co. @564 — Too bad nature is a utter failure then because that is approximately how it works. And no, nature is not a control system. And yes, it has been oscillating for the last 2.58 million years, due to changes in orbital elements, not due to internal instabilities per se.

    However, both ENSO and AMO are quasi-periodic oscillations said to be internal variability. There are more examples.

  16. Replication and due diligence, Wegman style

    http://deepclimate.org/2010/11/16/replication-and-due-diligence-wegman-style

    Next, I’ll look at Wegman et al’s “reproduction” of McIntyre and McKitrick’s simulation of Mann et al’s PCA methodology, published in the pair’s 2005 Geophysical Research Letters article, Hockey sticks, principal components, and spurious significance). It turns out that the sample leading principal components (PC1s) shown in two key Wegman et al figures were in fact rendered directly from McIntyre and McKitrick’s original archive of simulated “hockey stick” PC1s. Even worse, though, is the astonishing fact that this special collection of “hockey sticks” is not even a random sample of the 10,000 pseudo-proxy PC1s originally produced in the GRL study. Rather it expressly contains the very top 100 – one percent – having the most pronounced upward blade. Thus, McIntyre and McKitrick’s original Fig 1-1, mechanically reproduced by Wegman et al, shows a carefully selected “sample” from the top 1% of simulated “hockey sticks”. And Wegman’s Fig 4-4, which falsely claimed to show “hockey sticks” mined from low-order, low-autocorrelation “red noise”, contains another 12 from that same 1%!

    Finally, I’ll return to the central claim of Wegman et al – that McIntyre and McKitrick had shown that Michael Mann’s “short-centred” principal component analysis would mine “hockey sticks”, even from low-order, low-correlation “red noise” proxies . But both the source code and the hard-wired “hockey stick” figures clearly confirm what physicist David Ritson pointed out more than four years ago, namely that McIntyre and McKitrick’s “compelling” result was in fact based on a highly questionable procedure that generated null proxies with very high auto-correlation and persistence. All these facts are clear from even a cursory examination of McIntyre’s source code, demonstrating once and for all the incompetence and lack of due diligence exhibited by the Wegman report authors.

  17. Jim Bullis #562,

    (sigh) Well, I read the whole thing, summarized the part of their conclusions that I thought had a particular bearing on your argument and that you might find surprising, and explained how it fits with the paper you thought contradicted it. Here is the concluding paragraph in full:

    Our analysis suggests that changes in global cyclone frequency, duration and/or intensity are closely related to the amount of heat pumped into—and available to be subsequently transported by the oceans. This relationship may have implications for changes in heat transport associated with past and future climate change. Extrapolation of our results suggests that future increases in tropical temperatures may result in increased dissipation, mixing, heat storage, and eventually heat transport. Moreover, this positive response in transport might feed back on climate by redistributing heat poleward, diminishing the Equator-to-pole temperature gradient, and raising global mean temperature. We have provided some evidence that cyclone-induced mixing is a fundamental physical mechanism that may act to stabilize tropical temperatures, mix the upper ocean, and cause polar amplification of climate change. It is not included in the current conceptual or numerical models of the climate system. Better representation of cyclone winds and the associated mixing in
    climate models may help to explain the still-vexing questions posed by past climates.

    In a nutshell, these people are saying, like you, that tropical cyclones mix down a lot of heat. Like you, they’re giving thought to the effects this might have on global warming, given that warming oceans are expected to make more intense cyclones. But they’re arguing that if anything (big if so far), this would tend to amplify global mean warming, not reduce it.

    You should be interested in their reasons for thinking so, since unlike you (and me), they are experts doing active research in the field. They may be wrong, but they’re likely to have thought this through a lot more carefully than you have. For instance, they have thought about where the heat would go after it’s mixed down below the mixed layer and before it has any chance of reaching the deep ocean.

    But sure, if you like, please feel free to ignore anything in a paper that strikes you as counter-intuitive. I’ll feel free to treat your opinions on science accordingly.

  18. Read critically,

    Authors of report say, “We have provided some evidence that cyclone-induced mixing is a fundamental physical mechanism ”

    This is the actual result of their work. And it is interesting.

    However, that this ” –may act to stabilize tropical temperatures, mix the upper ocean–” includes the word ‘may’ though it could be probable since it is relatively obvious result of a mixing mechanism.

    But then, “cause polar amplification of climate change” is a huge leap since the equatorial mixing is not even quantified as to depth, so that the coupling to the thermohaline circulation is not even a topic of the paper. So we have no idea how much heat gets to the poles due to this mixing. And we have no reason to think this would couple to the atmosphere if it did get there. What about, if it simply caused ice to melt?

    They absolutely have not, from their own words, shown evidence that this would “–cause polar amplification of climate change.”

    However, I spot with interest that they say about this mechanism, “–It is not included in the current conceptual or numerical models of the climate system.” So the fact that these people are active in the field is relevant to their knowledge of such things, or would seem to be.

    But further it indicates they have no idea what they are talking about when they make the seemingly obligatory conclusion about climate change.

    I hasten to add, I did not read the whole report, but simply go on the abstract, but here I only analyze the words you quoted.

    But then you, CM, tell me that the authors thought about where the heat would go once it got below the mixed layer. Getting mixed below the mixed layer is a little perplexing, sort of self contradictory wouldn’t you say? But you don’t tell me what they thought.

    I did not opt to pay $26 to read the rest of this paper since it did not sound particularly useful beyond what was in the abstract. Do you recommend I do that?

    Sigh yourself. There has to be some discrimination in what we choose to study in depth. There should be a rule that people providing references should read them first.

  19. Anonymous Coward, from yours at the Science Narrative and Heresy topic

    anonanon,

    Was that a job offer to run a tree plantation?

    Ah yes, eucalyptus, a fine tree when people want yield. The railroad folks thought so 100 years ago, so they brought these from Australia with the intent of using the wood for railroad ties.

    My eucalyptus plantation (6 in my backyard planted 40 years ago) rapidly yielded more firewood than I needed, and that was not great since it quickly gummed up the chimney.

    Dense eucalyptus growth turned a part of the Berkeley Hills into a firestorm a few years ago.

    That is my impressive resume for eucalyptus management.

    No? Maybe I should find someone to help on this.

  20. Jim Bullis, Miastrada Co. @568 — Almost alwaays you can find a copy of published paers freely available on authors’s websites.

  21. One of the most common fallacies held sacred by denialists is that CO2 concentrations of 384 ppm are too low to have any impact on the climate.

    The caffeine content of popular energy drinks, such as Monster and Rockstar is 200 ppm or less. The average human body holds 10 gallons of water, so consuming a 12 oz energy drink would result in a caffeine concentration of approximately 4 ppm in the body.

    Therefore, according to denialist logic, consuming 96 12oz energy drinks couldn’t possibly have an effect on the human body because the concentration of caffeine would be too low.