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Comments 120601 to 120650:

120601. johnd at 02:29 AM on 22 April 2010
        Flowers blooming earlier now than any time in last 250 years
        michael sweet at 09:39 AM, you appear to be missing the point that soil moisture levels, which might surprise you, are tracked and well documented, are more dependant on total rainfall and it's distribution throughout the year than any slight changes in temperature. Whilst maximum and minimum temperatures may in some locations show slight changes, the other contributing factor, hours of daylight, and hours of darkness, also do not change from year to year despite the idea of many that daylight saving does give more daylight hours. As for long term trends in rainfall, for Australia generally, the last half of the 1900's were wetter than the first half, with the wettest period on record being during the mid 1970's, that possibly being the wettest period since first settlement. Despite the absence of weather data from the official BOM records, what records do exist indicate the 1800's being drier and more drought prone than the 1900's. So despite the most recent drought, and in spite of it, the indications are that the longer term trend for Australian rainfall are positive, and this will be the determining factor as to whether seasons advance or extend more so than any very minor changes in temperature. Global warming does not stop the natural cycles driven by other yet to be fully understood forces, and the next few decades of predicted and expected generally wetter conditions for much of Australia should provide much greater insight as scientists are now better prepared to poke, prod and measure than any time previous such a cycle occurred.
120602. garythompson at 02:08 AM on 22 April 2010
        The significance of past climate change
        john, as usual, a great post that is thought provoking and a joy to read. what was the reason for the MWP? there seems to be a new paper on this topic that points to this happening in the Indo-Pacific so it appears this event wasn't localized to Greenland. were we in a solar optimum at that point? i've heard the MWP debunked as a localized event but there are other papers such as this that show it happened other places on the Earth at the same time. I've also seen graphs of vostok ice cores showing we are due for another glacial period and i'm surprised i've never seen comments related to the fact that maybe we humans are counteracting that normal temperature decline wiht our GHG production. the up shot being, even if you subsribe to the AGW theory, it might not be a bad thing for the next 1000 years or so since plus 1 to 2 degrees C is easier to adapt to than negative 8 to 10 degrees C. forgive me if this has been already discussed ad nauseaum.
120603. angliss at 01:40 AM on 22 April 2010
        The significance of past climate change
        If you don't mind my asking, do you know what kind of engineers you were presenting to? In general, different engineering disciplines have different levels of understanding of advanced math, statistics, physics, chemistry, and so on. So what works for a room full of electrical engineers won't necessarily work for a room full of software engineers, mechanical engineers, nuclear engineers, or chemical engineers. Unfortunately, that means you'll need a few different presentations instead of just one, and you should ask the group that's sponsoring your presentation what the audience is likely to be before (and maybe ask the audience too and tailor your presentation accordingly).
        Response: They were mechanical engineers but let me be clear that I'm not commenting on their ability to understand past climate change but on my ability to explain it. The blank stares I receive are fairly universal. A university group once borrowed my info to write a short debunking flyer and I noticed they went with a completely different answer to the 'climate's changed before' argument - presumably they either didn't like or didn't understand my explanation (or thought they could do a better job). Hence I'm going back to the drawing board.
        
120604. theendisfar at 01:09 AM on 22 April 2010
        The significance of past climate change
        "See, this is the thing. In my presentation to the engineers, I did up this gorgeous little schematic of positive feedbacks, showing increased evaporation, more water vapor causing an increased greenhouse effect, more clouds, etc. Very colourful, I was very proud of it :-)" Do you have a link to this schematic? I am an engineer and would be pleased review it as well. I find your answer lacking since it has been dumbed down. It is, with all due respect, meaningless in 'simplified' form. What I am especially interested in is the detail of the positive feedbacks and whether you have satisfied the negative feedbacks sufficiently. Regards
        Response: Here's the slide I showed at the talk. Note - its purpose was just to introduce the concept of positive and negative feedbacks - that warming initiates a series of climate responses. It was not about accounting for every individual feedback (sea ice feedback is noticeably absent) - the general gist was to communicate that there are a myriad of different feedbacks which makes it difficult to work out the net feedback. But the way to cut through all that and calculate the net feedback without having to worry about the individual components was to look at past climate change.
        
        
        
120605. rawsnacks at 00:45 AM on 22 April 2010
        The significance of past climate change
        Seems like the question "why hasn't the climate changed over the millennia ought to garner some interest as well. It's been stable enough to grow stuff for a long time. Don't need esoteric statistics to see that.
120606. barry1487 at 00:45 AM on 22 April 2010
        The significance of past climate change
        My first thought was - do positive feedbacks kick in as strongly when the energy balance shifts towards cooling? My initial guess is "not so strongly", or, "negative feedbacks come into play more", judging by the slow cooling period compared to warming in the late quaternary ice ages. I don't know if covering this would dilute the message, but I think it would help give a more balanced assessment - skeptics scorn commentary that only talks about warming, for example. And I don't know if this goes beyond your intent, but it might be worth mentioning the rate of change now compared to past warming events. What you already have, though, is pretty clear I think. I'm not a scientist or an engineer, but it makes sense to me. (I am a fairly well-read layman, though)
120607. Alexandre at 00:25 AM on 22 April 2010
        The significance of past climate change
        nautilus_mr #10 I agree with you. Paleoclimatology is just one of the many lines of evidence to climate sensitivity. And if you pick one specific period -like the Medieval Warm Period- it's just one tiny fraction of this. So even if there had been a strong MWM... not much would change in the science.
120608. Alexandre at 00:19 AM on 22 April 2010
        The significance of past climate change
        chris #21 I would add in your response to Péter that this interglacial is remarkably stable when compared to the previous ones. So his assertion "temperature diminishes with temperature" has little supporting evidence. Besides, some events like PETM support a self-reinforced warming hypothesis.
120609. chris at 00:18 AM on 22 April 2010
        Where is global warming going?
        re: Berényi Péter at 01:38 AM on 21 April, 2010 mspelto at 00:46 AM on 21 April, 2010 says: The arctic in particular has had high air temperatures Berenyi Peter replies: "Come on. The "Arctic" has only one active GHCN station in Canada" so what Peter? There are lots of active Arctic temperature stations
120610. James Wight at 00:11 AM on 22 April 2010
        The significance of past climate change
        I assume this is intended to replace the text on the “Climate’s changed before” page. It seems like a good explanation to me – but then I understood the explanation on the original page (at least I think I did). I also think it’s worth including all the climate sensitivity info that was in the old version. I recommend that you keep your more detailed explanation and link to it from the new version. Also, is it really possible to derive solar activity from ice cores? I’m sure there are other proxies (carbon-14 comes to mind), but ice cores?
        Response: The more common method of working out past solar activity is using radiocarbon data from tree-rings. But Beryllium isotopes from ice cores are also a proxy for solar activity, going further back than tree-rings.
        
120611. chris at 00:05 AM on 22 April 2010
        The significance of past climate change
        Berenyi Peter, I suspect you say stuff that you know is wrong or illogic (but you say it anyway). (1) The Dansgaard-Oeschger events in your graphics are measurements of rapid temperature changes in Greenland cores. They are barely recognizable (and asynchronous) in Antarctic cores. Thus they are not representative of global warming/cooling events. (2) In fact these events are recognised likely to arise from major rapid shut down and restarting of the major ocean circulations (thermohaline circulation) that strongly participiates in bringing heat (or "thermal energy" if we're stil being pedantic about that!) from the equator to the high Northern latitudes. In other words they are indicative of major redistribution of Earth heat as opposed to global scale warming or cooling events. (3) Thus they have nothing to do with "climate sensitivity" which is the equilibrium response of the Earth's global temperature to changes in radative forcing. (4) The fact that D/O events (and similar large scale jumps/drops in high Northern latitude temperatures) aren't apparent in the Holocene part of the record you posted, is that these events only occur under conditions that major ice sheets occupy the high N. latitudes (that's part of the likely mechanism of the D/O events). Since we're in an interglacial period when these major ice sheets have melted away, we can't have D/O events. It's got nothing to do with temperature "being much more variable when it's cold" or "climate sensitivity diminishing with increasing temperature". One should really address these issue in terms of what we know!
120612. Berényi Péter at 23:38 PM on 21 April 2010
        The significance of past climate change
        It is a temperature reconstruction from a Greenland ice core (close to summit, at 72.6 N, 38.5 W, altitude 3200 m) for the last fifty thousand years. As you can clearly see, temperature is much more variable when it is cold. In other words: climate sensitivity diminishes with increasing temperatures.
120613. Ken Lambert at 23:35 PM on 21 April 2010
        Tracking the energy from global warming
        BP, HR and John Cook - great discussion, and lots of effort in posting the graphs - congrats on facilitating it John. A few points which my reading over the past year has produced: 1) Incoming radiation at TOA is generally quoted as TSI of 1366 W/sq.m divided by 4 = 341.5 /sq.m. The latest SORCE TIMS satellites give a figure for TSI of 1361.5W/sq.m - 4.5W/sq.m less. Divided by 4 this is 1.1W/sq.m less incoming at TOA than the accepted figure from previous satellites. This has been unexplained by the TIMS people since 2005. Check out their website: http://lasp.colorado.edu/sorce/data/tsi_data.htm To justify their -4.5W/sq.m lower figure, the TIMS people then produced an adapted Trenberth diagram of the total energy flux of the earth system using their reduced TSI/4 as the incoming radiation. I ran their graph past Dr Trenberth and he responded (he is a class act) that the TIMS graph did not make sense. Point: We don't have an accurate figure for TSI - only relative satellite figures for 30 years. The latest TIMS (4 satellites) read 4.5 W/sq.m low on previous numbers - so how do we know what incoming solar radiation figure 'balanced' the earth's outgoing longwave radiation in pre-industrial times and therefore what is the true 'equilibrium' temperature of the planet? 2)OHC - the von Schukmann paper has been introduced to the layman on this website. It is the only one which finds most of Dr Trenberth's missing heat down to 2000m. The sharp slopes of the bumps in von Schukmann's global OHC graph has been pointed out by BP and indicated huge rates of heat transfer down to 2000m in a matter of weeks to months. This hardly seems credible by air-water radiative or convective transfer nor even conduction of the warmed water to cooler water. The 'tiling' of the oceans and permanent tethered buoys reporting from the same tile at the same time would seem the only way to get an accurate snapshot of the whole ocean at Times 1 and 2 in order to calculate the change in OHC. The Argo buoys number 3255 for ocean area of 3.62E8 sq.km averages one buoy for every 111000 sq.km or a square of ocean 330km x 330km. There are practicaly no buoys above 60 degrees N or S latitude. I invite comment on the errors involved in one Argo buoy temperature column reading (not all reading down to 2000m) for on average every 111000 sq.km of ocean.
120614. perseus at 22:57 PM on 21 April 2010
        The significance of past climate change
        I tend to find the non-scientific mind has a poor conception of order of magnitude and probability. For example they are quite happy to imply that climate change happening now is natural by referring to climate change during an epoch perhaps hundreds of thousands or millions of years ago. All indications are that climate hasn't changed significantly for the best part of 10,000 years, so for it to suddenly change in the last 150 years just at the same time as mans influence on the biosphere has become significant, strongly implies this is the most likely cause. This is without any knowledge of greenhouse gases or other causes, it is a pure statistical explanation. The other more direct experimental evidence such as radiation exchange simply increases this probability further.
120615. Wadard at 22:39 PM on 21 April 2010
        The significance of past climate change
        I think you have the facts well explained, but there are a lot of them. Is an analogy helpful? Eg: Climate change history is like precedent in law - you have a good chance that a previous finding or two might establish where things stand 'when deciding subsequent cases with similar issues or facts'. Yes; the climate has always changed, man-made climate change is just a new precedent. Looking at 'precedents' or past forcings helps us with what might come next.
120616. aj1983 at 22:36 PM on 21 April 2010
        Climate's changed before
        He probably just wants to "enlighten" us with a link to his own blog. Anyway, a large part of the discussion is about PETM and AGW (with the link to resilient earth). A lot of it sounds like, if we extrapolate our CO2 emissions it would take forever to reach PETM concentrations, and PETM wasn't even caused by CO2 alone, so PETM cannot be used as an indication for the effect of CO2, so AGW does not exist. All the individual statements above are probably correct, except the conclusion. Think about it, have we seen any projections from IPCC showing a 6 -9 C global temperature rise? No. Oh, BTW it can also be found on that website that models can not fully reproduce PETM even if we use the CO2 concentrations at PETM, so models are WRONG! (It is understood why, because GCMs currently use bandwidth parametrisation instead of line-by-line CO2 absorption schemes (because of limited computer power) and will thus deviate if brought very far from their original (~300 ppm) state. This probably introduces a large error when going to extremely large (2000 ppm) CO2 concentrations. This PETM event can (in "skeptical" reasoning) even be used to say "look, even if we get a 3 C global temperature, it is all natural! Because in the near past of the Earth's history it has been 9 C warmer, and humans were not yet around!" And, using this reasoning and the paleo record, all climate variation will always be natural...
120617. Bart Verheggen at 22:29 PM on 21 April 2010
        The significance of past climate change
        The thing with this line of argument that your tackling is that it fails basic logic: Human activity of course didn't cause past climate changes, but that’s no evidence that it doesn’t now. Try that line of argument in a court of law against a arsonist, by saying that forest fires have always happened naturally; it won’t fly. Indeed, GHG had an important role to play in many past climate changes (even though their concentration changed without human involvement). Looking at the past actually strenghtens the evidence for a climatic effect of GHG.
120618. Spencer Weart at 22:28 PM on 21 April 2010
        The significance of past climate change
        An excellent presentation of past climate change is available online: Richard Alley, "The Biggest Control Knob: Carbon Dioxide in Earth's Climate History" at the Fall AGU meeting, see http://www.agu.org/meetings/fm09/lectures/videos.php To be sure this is for a scientist audience but the main points can be adapted for others... admittedly not easy. And of course, bear in mind that people have a hard time grasping knowledge that conflicts with what they want to believe!
120619. nautilus_mr at 22:28 PM on 21 April 2010
        The significance of past climate change
        I concur with #13. I think the first principle is explain what is causing warming now, then climate history comes in to a supporting role.
120620. Miriam O'Brien (Sou) at 22:21 PM on 21 April 2010
        The significance of past climate change
        How about this: Rather than list all the possible primary drivers (forcings), start by describing a couple of periods when the climate changed in the past from different forcings. For example, Milankovitch and volcanoes as the initial forcing. For each of the two periods in turn, describe in simple terms what the earth was like before the change (eg ice free Antarctica) and what it was like afterwards (eg lots of ice everywhere). Describe the forcing that led to the change (and define the terms - engineers most probably use slightly different jargon from climate scientists). Then move to today and show the evidence that the climate is changing (temperature, ice, oceans, sea levels etc). And explain that the forcings that caused the prior changes you discussed are absent, and the only primary driver or initial forcing operating today is CO2 / greenhouse gases. Then show how greenhouse gases also acted as a positive feedback, amplifying the changes you discussed in the two first examples (warming or cooling). You can deal with the 'but couldn't it be due to ...' in the question time / discussion - keep your detailed slides on hand for when specific questions are asked. If there are particular points you want to elaborate on (eg role of water vapour/clouds which some often ask about), you can probably do this during the discussion by saying, 'someone often asks me xyz' and then whip out your extra slides :). (As a broad (over?) generalisation, engineers are often clever, but their thought processes tend to be linear rather than lateral. Simple works best. One step after another, with a bit of repetition and reiteration of key points along the way. No offense meant to engineers, it's just an observation from working with groups of engineers in a variety of contexts.) The following publication is rather good, and will no doubt be more useful than my off the top of the head idea: CRED guide
120621. CBDunkerson at 22:17 PM on 21 April 2010
        The significance of past climate change
        I think part of the problem is that you are really conflating two different issues... which if separated might be phrased as; 1: 'Climate has changed in the past so how do we know humans are causing it now?' 2: 'How do we know that the climate change we are causing is going to be significant?' I think you can really handle the human causation question using CO2 alone (past correlations of CO2 and temperature, satellite and ground measurements confirming energy imbalance in CO2 absorption spectra, various proofs of increased CO2 levels being human caused, et cetera)... possibly following that up with explanation of why it ISN'T the Sun, cosmic rays, volcanoes, martian death rays, or whatever. All of which can be handled by showing lack of correlation - some match past changes, but none match the current. Once you have established CO2 as a major 'control knob' in determining temperatures then you can get into feedbacks amplifying that effect and what the historical record tells us about those. Basically, handle one issue at a time. Don't start talking about positive feedbacks before they've bought into CO2 increasing temperatures at all.
120622. nautilus_mr at 22:16 PM on 21 April 2010
        The significance of past climate change
        re #6 and #9: I get that argument sometimes and my response is that it wouldn't matter if there was either a more rapid or larger warming at some point in the distant past - there weren't billions of people living near the sea then. "The Planet" is not endangered - it is a small percentage of the planet's flora and fauna, plus a big percentage of its human beings. Of course, it's like asking for anesthetic at the dentist and being told you shouldn't have it because the dentist's grandfather had to suffer more than you!
120623. Marcus at 22:15 PM on 21 April 2010
        The significance of past climate change
        Thingadonta-how can you make such claims when global warming of +0.6 degrees has *already* occurred over the past 60 years, with nearly +0.5 degrees of that warming occurring in just the past 30 years?!?! The fact that virtually *every* natural climate change event in the past (with the exception of those caused by extremely massive natural disasters) has occurred at a rate of between 1/2 to 1/10th of the rate of recent change is simply further proof that nature is not the cause of the most recent climate change event. What humans are doing, by burning the accumulated & compressed CO2 storage of tens of millions of years of tree & plant life, is to effectively compress millions of years of geological activity into the space of just 250 years. To suggest that geo-engineering on this scale could *not* be the cause of rapid climate change simply shows how *weak* the contrarian argument actually is!
120624. nautilus_mr at 22:08 PM on 21 April 2010
        The significance of past climate change
        It may seem a bit off-beat, but I personally think paleoclimate more often than not is about red-herrings. While a number of false arguments try to use paleoclimate to deny AGW, I must admit I have never been convinced that the paleoclimate record is terribly useful to the debate. Fundamentally, there is nothing it gives us that is not more clearly communicated by contemporary data. For example, the "Hockey Stick" shows that the contemporary rate of warming diverges enough from the last few thousand years to raise a smoking gun type of question, but the graph itself is not an explanation -only a way of flagging an anomaly. Even if the hockey stick was proven wrong, it wouldn't matter - because arguments about medieval warming, past CO2 levels, higher ancient temperatures etc. all miss the point: In the contemporary world, we can identify the rate of global warming, the mechanisms of warming and the predicted (and confirmed) effects. Until there is a better explanation for the colossal body of evidence of the last 100 years, the opponents of the AGW thesis will try and drag our attention into the distant past, where the ground under any given argument is weaker.
120625. John Russell at 21:54 PM on 21 April 2010
        The significance of past climate change
        I would say that in my experience the key point to get across to sceptics is that during past climate changes there were no humans around to experience the effects. Consequently from today's human viewpoint past changes do not seem such a big deal. But the truth is they were huge. Although climate change of three, four degrees or more over tens of thousands of years would allow most plant and animal species to move, adapt or evolve to cope with that change; the more serious and/or sudden climate changes would cause huge extinction events. The problem, in explaining this, of course, is that such events seem no big deal to us today, looking back over millennia. So what, if large mammals -- which we're aware of only through scant fossil evidence -- once died, to be replaced by other equally unfamiliar species? On the other hand the current rapid Climate Change -- when humans are now one of our planet's larger animal species -- is a highly risky for both us and most of the other living species; though as an extinction event it will probably be no worse than many in the past. Arguably it's made worse by the unprecedented fact that humans are responsible for creating the problem this time. It would be interesting to conjecture (is it possible to know for sure?) the extinctions and changes to the nature of life on the planet as a result of past climate changes, and then extrapolate how the current climate change being instigated by humans could alter the nature of life on the planet today. Of course one of the problems in doing this is that global heating is only one of many serious issues now being caused by human influences on life's existence on our planet. Pollution; deforestation; industrial agriculture; fresh water diversion; resource depletion; over-population -- to name just some of the most obvious -- are all key components in the environmental timebomb we're creating.
120626. thingadonta at 21:50 PM on 21 April 2010
        The significance of past climate change
        I agree with pretty much all of what you say above except for one major point-the issue of the time scales involved. The past geological record indicates that changes on a global scale are invariably very slow. We're talking tens of thousands, to hundreds of thousands and even millions of years in the vast majority of cases. For something like acidification of global oceans by volcanoes, and indeed the majority of mass extinction events (except in rare cases of eg bolide impacts), that is the sort of time frame the geological record indicates is invariably required. To take a few examples, the output of greenhouse and other gases by Siberian Traps volcanism at the end of the Permian occurred on a major scale over several hundred thousand to several million years, and that is how long it took to cause major climate changes such as (possibly) acidifying the oceans, the collapse of coral reef ecosystems, and mass extinction. It was not a ‘rapid process’ when compared to the scale of human lifetimes. The break-up of the Gondwana supercontinent is likely implicated in eg the Mid-End Triassic mass extinction-continents do not break up 'rapidly'. This occurred over millions of years - with possible stress-related tipping points etc, as rift-related volcanism increased over very long time periods. Many other examples from the geological record indicate much the same thing, (eg oceans don't ‘acidify’ within short human timescales when similar amounts of c02 have been added to the atmosphere in the sort of time scales involved as is currently the case). This is also the major reason people such as the gradualist Charles Darwin were so skeptical of the presence of 'mass extinction' events in the geological record in the first place, and also I suspect why the person on the street is with current climate change and the extreme predictions around it as well. It's like worrying about continental drift changing the climate within this century. This is one of the major skeptical arguments, that major global changes such as those predicted by the IPCC to occur within the next century by human emissions of greenhouse gases will NOT occur, not so much because the concepts and theory is wrong, but because the scale of time involved is far too short, and that the geological record provides very good support for this contention. Academics and other pro AGW advocates get the concepts largely right, but get the time scales involved largely wrong.
120627. LauraM at 21:48 PM on 21 April 2010
        The significance of past climate change
        I think its important to mention the speed of climate change today vs the past.
120628. Marcus at 21:42 PM on 21 April 2010
        The significance of past climate change
        Every time I hear the "Climate changed naturally in the past, so humans can't be responsible this time around" I always respond by saying "so does this mean that 'because many forest fires start naturally, humans are *never* responsible for forest fires?'" The comments are equally nonsensical, yet it never ceases to amaze me how often the Contrarians try & push this illogical position!
120629. theendisfar at 21:23 PM on 21 April 2010
        The significance of past climate change
        John, In the past . . . What happened as Surface Temps rose, due to CO2 on occasion, with regards to the rates of convection and evaporation? Did they increase, decrease, or stay the same? If convection and evaporation rates increased as surface temps increased, did that cool the surface, heat the surface, or did the surface temps remain the same? Thanks
        Response: See, this is the thing. In my presentation to the engineers, I did up this gorgeous little schematic of positive feedbacks, showing increased evaporation, more water vapor causing an increased greenhouse effect, more clouds, etc. Very colourful, I was very proud of it :-) But I think I went into so much detail describing the positive feedback processes and the derivation of climate sensitivity, I think everyone had forgotten the point of the explanation by the time I got to the end.
        
        The basic point was to say that there are a number of feedbacks - both positive and negative. Finding the net feedback by adding up all the individual feedbacks is a complex job. But you can cut through all that in one fell swoop by looking at past change. By just comparing temperature change to changes in the energy balance, you determine the net feedback without having to know all the individual feedbacks.
        
        So I skipped all those details in this blog post in the effort of a simpler argument. But going through the explanation too fast leaves people wanting more details. Where to draw the line?
        
120630. Glenn Tamblyn at 21:18 PM on 21 April 2010
        The significance of past climate change
        VnceOZ Which bit of 'this' are you referring to? And why do you use a word like 'believe'?
120631. VinceOZ at 21:07 PM on 21 April 2010
        The significance of past climate change
        You don't really believe this do you?
        Response: It's not a question of belief - this is the state of the science as explained in the peer-reviewed literature. I go into more detail with peer-reviewed references at Climate's changed before - this was an attempt at a simpler, easier-to-understand explanation.
        
120632. JulianRGP at 20:42 PM on 21 April 2010
        The significance of past climate change
        I suspect that the argument has to proceed by easy steps. One step is to assert that it is not logical to exclude a new factor, without further examination. Before 1890, there were plenty of reasons for accidental deaths, but being involved in a motor car accident was not one of them - for obvious reasons. But we do not use that as an argument to say that car accidents should be ignored. In the case of CO2, it was not previously present in large quantities (unless you're going back before human history), but it now is and its projected increase in the time scale we're interested in will dominate other factors.
120633. Ari Jokimäki at 20:30 PM on 21 April 2010
        The significance of past climate change
        Few comments on some issues I think should be explained if you want this to be as simple as possible: - The role of greenhouse gases in the past climate (or where they come to the atmosphere) might need an explanation. - You should explain what positive feedback means and the factors which are positive feedbacks. - The part about CO2 being an external forcing might call for additional explanation - I don't think it's readily clear for someone not familiar with the issue.
120634. Richard482 at 17:34 PM on 21 April 2010
        Tree-rings diverge from temperature after 1960
        I think that this is the real reason for the decline in tree-ring data. An increasing amount of CO2 http://scienceblogs.com/pharyngula/2009/12/why_climatologists_used_the_tr.php
120635. Marcel Bökstedt at 15:34 PM on 21 April 2010
        Where is global warming going?
        HumanityRules> How would you expect to detect the energy in transit?
120636. James Wight at 15:13 PM on 21 April 2010
        Where is global warming going?
        I find the “missing heat” problem very interesting. I’m only a layperson, but I’m leaning towards the Arctic Ocean explanation. Since 2005, Arctic summer sea ice has declined dramatically. Less sea ice means that the ocean is able to absorb more heat. I’m guessing the Arctic Ocean on average is probably cooler than 4°C, so that might explain why the ocean hasn’t expanded more. If this explanation is correct, it would mean that ocean heat content measurements are biased for the same reason as HADCRUT global temperatures – inadequate coverage in the Arctic.
120637. HumanityRules at 14:18 PM on 21 April 2010
        Where is global warming going?
        12.mspelto There's a couple of practical problems with the idea that the extra energy is hidden. While it could be anywhere in the ocean that we don't measure there remains the important question of how did it get there. Everything was accounted for pre 2003 so in that time period it wasn't heading for these unknown energy stores. After 2003 it must have started being sequestered but it wasn't detected transitting any of the regions we do measure to make it to these mysterious energy stores. We should take readings in those difficult regions not yet covered by the bouys but is there really any reason to believe we'll find the lost energy?
120638. HumanityRules at 14:04 PM on 21 April 2010
        Where is global warming going?
        34.scaddenp The ocean doesn't just heat it also expands so there is a way of double checking the bouy data by using satellite data to measure sea level rise. For the present period (2003-2008) almost all the sea level rise is accounted for by melting land ice. That means very little thermal expansion, which means the energy is unlikely to be in the ocean. The bouy results are in agreement with the GRACE satellite data you don't just need to believe the bouy data. Secondly OHC was in line with expectations upto the mid 2000's before they began to diverge. So you have to believe that the data was fine and then became corrupted in some way. The reality is that the quality and coverage of the bouy ( and other ocean data) have only continued to improve a a time when we are meant to believe they have got worse. It's not just a matter of believing one or the other.
120639. HumanityRules at 13:11 PM on 21 April 2010
        Tracking the energy from global warming
        Trenberth wasn't kidding when he says figure 1 is heavily smoothed and simplified. The other thing that confuses me is that it is meant to in some way relate to this figure. Now I realise this is in some way also a simplified graphic. But with no volcanic activity since 2000 to give those great spikes then a simple increasing nett radiative forcing and energy budget should be on the cards but it obviously isn't. There is obviously an extraordinary amount we don't know when it comes to the natural variation in radiative forcing and energy budget.
120640. scaddenp at 12:08 PM on 21 April 2010
        Where is global warming going?
        33 - this "missing heat" comes about because of the discrepancy between OHC (heat stored) and TOA measurements (difference between incoming energy and outgoing energy). Heat leaving is measured so unless there is error in measurement, you can discount that. What do you trust most? The satellite measurements of heat imbalance or the buoy network of ocean temperature measurements? There is clearly an issue to be sorted out here. Its not about models - its about the heat balance.
120641. actually thoughtful at 10:55 AM on 21 April 2010
        Where is global warming going?
        Don't we have to give serious consideration to the idea that either 1) the heat is not there to be missing or 2) the heat is leaving the atmosphere? I would be satisfied to know that this "missing heat" comes from the 2000s "lack of warming" - this is tongue in cheek as everyone knows the world warmed - even during an el nino and the very low sunspot activity. So are we missing heat that IS there and it is just finding it? Or are we worried the models are wrong because they predict heat we can't find (so it could have never existed or left the envelope)? thanks.
120642. GFW at 09:44 AM on 21 April 2010
        Where is global warming going?
        Taking dscheidt's idea and running with it. Let's suppose we're trying to imagine a biological sequestration of 0.5 W/m2 over the whole planet via phytoplankton. Let's ballpark that as 1W/m2 over the most productive 70% of the ocean (therefore ~50% of the planet). Skipping a bit of math ... and charitably assuming that dead phytoplankton is nearly as nutritious (i.e. energy-laden) as pure sugar ... that's around 40g of excess material every 24 hours, in every square meter. So a patch of ocean 1000km by 1000km would create 40 mega-tonnes excess every day, which would be about 1.5 giga-tonnes per year. Scaling up to 50% of the planet's surface, that would be 300 Gt/y. Bearing in mind that this is excess, on top of "normal" it doesn't fit with estimates of the *total* biological rain over the entire ocean. which is on the order of 1 Gt/y
120643. Donald Lewis at 09:36 AM on 21 April 2010
        Where is global warming going?
        Here is my pass at the graph where area is proportional to magnitude. http://docs.google.com/present/view?id=d5sm6vp_50k3vzx2g3
120644. Glenn Tamblyn at 09:04 AM on 21 April 2010
        Where is global warming going?
        RSVP @25 The most recent figure I have seen are Murphy et al which go from 1950 to 3002 and give the total heat rise as around 1 *10^23 Joules. Thats around 3 Billion Hiroshima bombs. So thats what we are taking a percentage of.
120645. Riccardo at 08:35 AM on 21 April 2010
        Where is global warming going?
        dscheidt, the NASA image shows that there's an inverse correlation between phytoplankton productivity and temperature.
120646. Berényi Péter at 07:36 AM on 21 April 2010
        Tracking the energy from global warming
        #55 HumanityRules at 23:43 PM on 20 April, 2010 I also hunted down this presentation Thank you. It is useful. I have copied the 2000-2010 TOA radiation imbalance figure here. Also, I took NODC Global Ocean Heat Content for the same period, computed its derivative and made a figure. figure 1 figure 2 If all went well, the lower graph in figure 1 would be proportional to that of figure 2. It is clearly not, they are not even similar. Fluctuations in OHC as measured by floats are almost an order of magnitude larger than in net radiation imbalance at TOA as measured by satellites. Sometimes not even the sign comes out right.
120647. dscheidt at 06:53 AM on 21 April 2010
        Where is global warming going?
        Riccardo @ 26, Thank you for the links. You are correct that phytoplankton productivity has not been increasing during the period for which there is data [1998-2008]. Over that period the observed sea surface temperature hasn't increased. Indeed, in the Behrenfeld paper that you cited shows that there is a strong corollation between sea surface tempurature and ocean productivity. In short, if I understand Behrenfeld correctly, globally phytoplankton is behaving as expected with respect to temperature. Since we know that phytoplankton growth is endothermic the elevated levels of phytoplankton shown by Behrenfeld (with respect to pre-1998 levels) must be absorbing more energy than pre-1998 levels. The question is whether the amount of the negative feedback is significant. Of course, if the feedback was linear then one would expect to see a consistant divergence between temperature and missing energy, which we are not seeing. I suspect that it is, as it always seems to be with AGW, a more complex process. I'm not at all sure that the phytoplankton feedback effect is significant. I suspect that it's not. But I wanted to pose the question.
120648. hu? at 06:44 AM on 21 April 2010
        Trenberth can't account for the lack of warming
        Thank you for your response yocta, but your answer does not address my question. Where does Trenberth claim satellites indicate an energy imbalance? (not a sea level rise). There are two satellite data-sets discussed in the paper, CERES and GRACE. Which one does Trenberth refer to with this warming quote, in your opinion?
120649. Jacob Bock Axelsen at 06:25 AM on 21 April 2010
        Are we too stupid?
        embb A post ago you said that no one sees even the remotest chance for a trade war. Now it is "the lesser evil" and even real wars a possibility? Aren`t you a bit inconsistent? I claimed a tax and trade restrictions is not like a trade war. A trade war is the lesser evil as opposed to real war. I never denied the possibility of war. No inconsistency. I agree the type of fraud in the article does not affect the emissions. Still, a post ago you claimed there is no link between organized crime and emission trading... I doubted it. My bad. "Any asset market comprised of buying and selling non-physical, hard-to-measure goods is a con man’s dream."(...) Any game is a con man's dream. Strategies such as tit-for-tat amend that by stimulating cooperation through reciprocity. "An environment group slammed “false” carbon credit trading related to mainland China’s dams which allegedly *** undermines the Kyoto Protocol***, leading to a renewal of a carbon trading platform’s ban on the country’s hydroelectric power projects, reported South China Morning Post. " Apparently compliance can be checked in China. Contrary to what you persistently claim. If the US did not sign then most would agree that he did not become "bound by some tie" - as the act of signing means becoming bound to the agreement. So, there is no way for the US to defect on an agreement that was not signed. If USA signs it, they will come. If USA doesn't sign it, climate change will come. Cooperation or Defection. Take your pick. (...)are you suggesting the WTO fine the country that defects? Prison is of course meaningless in this context, so is tit for tat. I proved that taxes are always rigged to not be a dilemma. If there is no dilemma tit-for-tat will definitely beat all-defection. So US gets more money BY levelling the carbon tax on american companies and China gets a lot less by letting its companies become more competitive? In this case the 'prison time' can be substituted for 'trade restrictions'. You will see it makes sense. During the whole discussion I kept coming back to the point that the difference to the PD is that here we are not talking about individuals inside a state but about states with no organization above them. You keep coming back to explain trivial stuff about individuals. Unless you answer to my objections this is pretty much pointless. States, individuals - no matter. Tit-for-tat beats all-defection. No organization. No judge. No God. Just maths. they cooperated in Copenhagen? I missed that. Or maybe this wonderful change happened since December? If China, US and the rest of the world had signed a comprehensive deal to combat climate change it would have been wonderful? Absolutely. I was referring to the situation where a treaty to tax carbon emission was already in place. What is the point of even talking about game theory if you end up believing that the actors will not defect without any real analysis? I have never postulated that. It is the point of the post to analyse how to avoid defection. You must have missed that. Now, enough of what I know. What are your solutions to mitigate climate change? You must have something considering your clear stance.
120650. Riccardo at 06:17 AM on 21 April 2010
        Where is global warming going?
        As mspelto pointed out there's the big unknown of the Arctic and the Antarctic oceans, we don't know much about what's happening down there. But I would say we do not know much about global ocean circulation either. For example, we know that convective mixing in the Labrador Sea stopped for a while and then resumed. Does anybody know why? Also, scientists are still debating on the behaviour of the North Atlantic thermohaline circulation or the fate of Anarctic Deep Water. These are huge amount of heat (energy, to make suibhne happy ;)). Although the overall picture is clear, the details are missing. Trenberth has shown he does not belive the ocean heat content measurements much (see the email exchange with Pielke Sr.). With him, I'd not be surprised if that heat is in part "hidden" somewhere there.

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