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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 52951 to 53000:

  1. Nuccitelli et al. (2012) Show that Global Warming Continues
    Probably a silly question, but one I have all the same. According to GISSTemp there hasn't been much movement either way in global surface temps (basically flat since 2003). We also know that from 2005-2010 we saw the deepest solar minimum in satellite records. My question: what can cause the oceans to keep warming (as shown in the 2002-2008 line in the table in the article) when the accumulated heat sources decreased? Source: http://data.giss.nasa.gov/gistemp/2011/
  2. Jerry Mitrovica: Current Sea Level Rise is Anomalous. We've Seen Nothing Like it for the Last 10,000 Years
    dr2chase - You might also research geological records of ice sheet extent; there is a lot of data available on extents, although the thickness of the ice sheets is still a point of discussion.
  3. Philippe Chantreau at 09:26 AM on 12 October 2012
    Nuccitelli et al. (2012) Show that Global Warming Continues
    Congrats on the publication! Good to see that the SkS team not keeps up with the science but even adds to it.
  4. Nuccitelli et al. (2012) Show that Global Warming Continues
    From Peru @21 - a pre-published version is linked in the post where it says Nuccitelli et al. (2012).
  5. Jerry Mitrovica: Current Sea Level Rise is Anomalous. We've Seen Nothing Like it for the Last 10,000 Years
    dr2chase - As I indicated, I would expect more information as isostatic and gravitational effects are disentangled with regional sea level proxies. That should include the possibility of determining mass distributions in both glacial and interglacial periods, depending on the number and certainty of those sea level proxies. I am looking forward to those papers.
  6. Nuccitelli et al. (2012) Show that Global Warming Continues
    Is there somewhere a pre-published version of the paper? (most physics papers are pre-published in Arxiv)
  7. Jerry Mitrovica: Current Sea Level Rise is Anomalous. We've Seen Nothing Like it for the Last 10,000 Years
    KR@16, yes, that's the state of the ice now. But in the paleoclimate record, what was the state of the ice just before sea level started rising multiple meters per century?
  8. Nuccitelli et al. (2012) Show that Global Warming Continues
    chriskoz @19 - 0.62 is just the conversion factor between J/yr and W/m2. For the radiative imbalance see Table 1 in the paper and post. Our results are in the same ballpark as Hansen and a number of previous radiative imbalance studies. In the ballpark of 0.5 W/m2, depending on exactly what timeframe is considered.
  9. Nuccitelli et al. (2012) Show that Global Warming Continues
    Dana@17, That number (Ftoa = 0.62Wm-2) coincides with the best estimate of the TOA radiative imbalance (I remember Jim Hansen said it was 0.5Wm-2). Looks like those numbers mean the same, at least to me. Can it be considered some confirmation, that TOA flux calculated from OHC changes (by large the main heat sink on the planet) and from radiative imbalance fall into the same ballpark?
  10. Nuccitelli et al. (2012) Show that Global Warming Continues
    "SkS being an outlet of the League of Evil Scientists." Wha??? Where's my sticker, then?...;) I tend to think yours, and others, opinions are correct. If (snort..."if"...) Watts resorts to that, I see it as just more rhetorical rope with which to hang himself. I do 'sense a disturbance' in the (bloggers') Force that suggests the tide is truly turning towards science. It might be wishful thinking, however...
  11. Jerry Mitrovica: Current Sea Level Rise is Anomalous. We've Seen Nothing Like it for the Last 10,000 Years
    dr2chase - See the USGS reference on this topic. Potential (m) / Location 64.80 / East Antarctic ice sheet 8.06 / West Antarctic ice sheet 0.46 / Antarctic Peninsula 6.55 / Greenland 0.45 / All other ice caps, ice fields, and valley glaciers 80.32m Total In other words, Greenland and Antarctica are the primary repositories of land ice, and the source of past multi-meter changes in sea level. I expect that Mitrovica and company will be putting out a number of papers on specific attributions based upon relative sea level change fingerprints in the near future.
  12. Nuccitelli et al. (2012) Show that Global Warming Continues
    DMCarey @15 - to convert from J to W/m2 you first get the change in energy over time (i.e. Joules per year converted to Joules per second = Watts), then divide by the surface area of the Earth to get W/m2. There's a formula in the paper (click the Nuccitelli et al. 2012 links in the above post for a free copy). Ftoa = 0.62[d(OHC)/dt] Where OHC is in Joules per year and Ftoa (top of the atmosphere flux) is in W/m2. Converting years to seconds and dividing by the Earth's surface area yields a convenient factor of 0.62.
  13. Jerry Mitrovica: Current Sea Level Rise is Anomalous. We've Seen Nothing Like it for the Last 10,000 Years
    AndrewDoddsUk@5, Would be lovely to know what ice was available to melt when we had meters-per-century rise. That's one part of the puzzle I'm unclear on; was this large chunks of the northern ice caps running off into the ocean? (that is, would the max rate be proportional to the length of the glacier faces onto the oceans?) Did sea level rise trigger some large positive feedback? Was it just plain *melt*? (wouldn't that require an extraordinary amount of heat delivered to white ice?)
  14. The Economic Damage of Climate Denial
    funglestrumpet notes: The more of those ugly wind turbines we have peppering our once beautiful landscape Others have pointed that wind turbines are a fair sight more attractive than, say, coal mines, but I would suggest most of the fixtures of modern fossil-fuel civilization are also unpleasant compared to wind farms. At the city where I live (Ottawa, Ontario), our old-school shopping centres near the city centre (Rideau Centre & St Laurent centre) are hideous concrete blocks. The building where I work is a squat metal box. The main highway through town (provincial highway 417) is a long strip of pavement marring the landscape. How are wind farms any uglier than most of the modern accountrements of affluence?
  15. Nuccitelli et al. (2012) Show that Global Warming Continues
    #9 MarkR - thanks, see it now...
  16. Nuccitelli et al. (2012) Show that Global Warming Continues
    I'm afraid I have to agree with Noesis; Watts will very likely be unable to find any fault in the paper itself (excellent work, it should be noted), and as such will perpetuate something along the lines of SkS being an outlet of the League of Evil Scientists. It's a pity that in the absence of a legitamite rebuttal, attacks on character are called upon instead. I am curious though, I often see heat content changes expressed in matters of W/m2, but I am not familiar with how the conversion is done save from Btu. How exactly does one convert Joules to W/m2 for instance?
  17. Nuccitelli et al. (2012) Show that Global Warming Continues
    Congratulations to the SkS team!
  18. Shapiro et al. – a New Solar Reconstruction
    Falkenherz, To add to DSL's point about your "very likely" comment... if you made that statement in good faith, believing it to be a valid and tenable position, then you need to step back and to realize how (subtly) warped your view has become as a result of propaganda. There are a hundred (thousand?) trivial little details like this one that you have probably completely and uncritically accepted without even knowing it. Any scoffing dismissal of mainstream science, dripping with venom and disdain, is quite honestly the position of a 21st century moron, someone who wants to enjoy all of the fruits of our modern civilization while living within it like a savage. Your current position is one of a stone age aborigine who believes a camera will steal his soul, and he won't believe otherwise until the tribal shaman (in the form of an un-degreed blogging ex-TV-weatherman?) assures him otherwise. It's up to you to go back and delete these twisted preconceptions from your mental image of climate science. You need to do that before you can proceed and actually understand. On the other hand, if you did not make the "very likely" statement in good faith...
  19. Nuccitelli et al. (2012) Show that Global Warming Continues
    Congratulations on the paper. I suspect Watts will merely ignore the paper unless forced to acknowledge it's existence, and if forced to address it, he'll dismiss it out of hand with an ad hominem and a link back to some other previous post that attacks Skeptical Science.
  20. Nuccitelli et al. (2012) Show that Global Warming Continues
    T'will be interesting to see how Wattsy spins this one: kinda amazed he hasn't yet, at least as of this morning (10/11/12). congrats to all for hard work, diligence, and the wherewithal to keep up this good and important work.
  21. Shapiro et al. – a New Solar Reconstruction
    Falkenherz: "to quote the infamous wording of IPCC, 'very likely'." This is the kind of comment, Falkenherz, that suggests you're not as open-minded in your approach as you've claimed. The IPCC's wording is only "infamous" among the Heartland group and its adherents. The general public rarely encounters the actual language of the IPCC (how many people outside of the online climate "debate" just up and decide to read the SREX?). It was attacked because it was an inherently soft target: there was no way for the IPCC to use language that could not be attacked. If they had used numerical values for confidence and certainty, they would have been attacked (in presentation to the general public) for trying to quantify certainty (which, to the general public, seems impossible). Had they expressed any sort of absolute certainty, they would obviously have been attacked for being unscientific (science does not deal in absolutes). What would you have them do? Or are you just satisfied to re-hash the attack, an attack that serves absolutely no purpose within the context of the current argument but does act semiotically to place you within a certain group from which you've previously attempted to divorce yourself? Further, if you really want to understand this, then you're going to have to do the math to some extent. There are free spreadsheet programs with useful functions, if you don't have Excel. There are other resources to help you as well. Science of Doom is basically an online textbook. It has taken me four years (spare time, after the babies go to bed) for me to work out the details well enough to not feel like a complete idiot when I open my mouth.
  22. Nuccitelli et al. (2012) Show that Global Warming Continues
    Yes, congrats on a great article. I'm always trying to find ways to express scientific info to a more general public. Wiki shows the energy released from the Hiroshima bomb to have been ~6 x 10^13 joules. Adding the figures for heat increase in the top 700 meters and from 700-200 meters gets me, eyeballing it, about 25 x 10^22 joules. So can I tell students and others that the amount of heat GW has added to the top ~2000 meters of ocean is roughly equivalent to 4 billion Hiroshima bombs? (And this all since ~1972!?) Please check my maths and other assumptions. Do we have updates on the OHC levels since 2008? Thanks ahead of time for any corrections/pointers...
    Moderator Response: [DB] Glenn shows in this post that the amount added from 1961-2011 (133 Terawatts) is equivalent to 2 Hiroshima bombs a second. Continually since 1961.
  23. Climate time lag
    Falkenherz, The article does not "jump." It introduces a key concept, radiative imbalance, and then relates it to the problem. It is, in fact, the crux of the above post. I agree that it could be clarified, but you can't expect every blog post to qualify and explain every single detail within it. At some point you have to say "gee, radiative imbalance, I don't quite understand that, maybe I should go read up on it and then come back and re-read this article again." Or, you could invite a lengthy stream of comments, all of which explain it to you, and yet...
    I believe these are two totally different things...
    1) Don't say "I believe." There is no "believe" in science. There is "I understand" and "I don't understand." If you say the latter, then you have more to learn. Period. Your statement is also an insult to all of the people who have posted responses to you and tried to explain it to you. Basically what you are saying is that you still don't understand and don't want to be bothered, you'd rather stick with your initial and wrong misconception. And they both are and are not two totally different things. They are different in that one (radiative imbalance) is the cause of the other (temperature change with a lag). But you can't separate them. Climate lag is not a magical fairy effect imposed by the cosmic climate-lag equation of ∂T = ΕWr⁰Ng. It is a manifestation of the fact that radiative imbalances are small compared to the heat capacity of the earth, and so that imbalance must be maintained and constant over a long period of time for a forcing to have a noticeable effect on global mean temperature. If the forcing is not large enough or not constant, there is no detectable change. If there is a detectable change, it is not linear. You need to go study radiative imbalance and understand this before you can continue. You cannot choose to skip this simply because you want to "keep it simple." That's like saying traffic signs and stop lights are too complicated. You're a new driver. It's hard enough to steer and press the gas and brake pedals, so you want to be allowed to drive around for a few weeks without paying attention to those bothersome traffic signs and laws. They just get in your way.
  24. Shapiro et al. – a New Solar Reconstruction
    Falkenherz, First, please, you appear to have skimmed the article, or at best read it without complete comprehension. Please re-read the article several times, and when you hit something you are not absolutely sure of, go do some more research on it. But remember, the point of the article is to discuss whether or not the Shapiro reconstruction is valid, not how TSI correlates to temperature.
    ...shouldn't that just mean "faster"?
    No. Why would you think that? If the NH warmed "faster" then it would get further and further out of balance with the global mean. How could that physically work?
    Are there any...?
    What do you mean? There must be global reconstructions against which to compare the NH reconstruction, otherwise no one could state any factor at all.
    ... 0,4 and not 0,8 Degree, as IPCC states...
    Citation, please. Is this supposed IPCC statement about the northern hemisphere or the globe? To 2000, or 2007? Using 1880 as a baseline, or some other point? Was this an observed or projected value? Did you get this from an actual IPCC report, or from some blog that is itself misrepresenting a statement by the IPCC?
    At the same time, TSI was raising by 6 W/m2...
    If you accept the Shapiro reconstruction, which is the entire point of this article. That reconstruction is an outlier with problems explicitly explained in the OP. Don't cherry pick the data that best fits your hypothesis. That's bad science.
    How is that possible?
    (a) You're still not understanding climate lag and (b) it's probably not, which is sort of the point (that reconstruction is suspect... a 6 W/m2 increase in such a short period has all sorts of problems), and (c) as has been repeatedly explained, there are other factors in climate, and solar variation is only one (and one that in all probability does not vary greatly over time).
    How is that possible?
    See the answer above.
    How is that possible?
    See the answer above.
    ...maybe we can nevertheless and at least do a more general comparison of TSI and temperature levels...
    Yes, we can, we have, and when we do, it seems that the correlation is very, very weak, unless you consider all of the other factors (aerosols, volcanic activity, GHGs, albedo changes) simultaneously. Which is why we have climate models, and which is why trying to sort things out with just 2 variables (TSI + GT) and one constant (climate lag) is never, ever, ever going to lead to anything of any value.
    ... we see very rough correspondence between average GT and TSI.
    Over very long time scales when using the Shapiro reconstruction, which has been called into question, and which is at odds with other solar reconstructions. So why do you uncritically cling to it? This entire post is about the issues with Shapiro, and yet you have adopted it as fact and are attempting to use it to sort out your own misconceptions of climate. Doesn't that strike you as a silly approach?
    Jump-conclusion: Everything seems to be "normal" at first glance?
    Long answer: it shows that in the recent past the primary driver of climate, i.e. the only factor that was able to vary consistently for a long enough time to affect climate (i.e. fractionally drop or rise for hundreds of years) has been the sun. Other factors like albedo changes, volcanic activity, natrual aerosols etc. have not been strong enough or long lived enough to, over the long term in the past thousand years, greatly affect climate. But GHG are not small in their effect, and they are not short lived. They'll be in the atmosphere for hundreds to thousands of years, and their forcing dwarfs even the Shapiro reconstruction of TSI changes. So what does that tell you? Short answer: Key (wrong) words in your statement/question are "seems", "normal" and "first glance". No. You can't eyeball this stuff and get it right, there is no "normal", and first glances are always, always deceiving. You are starting from a very, very, very bad point with all of this, the assumption that the answer is as simple as that hot thing you see in the sky, and a mythical lag like the way you have to wait for the fuel pump to fill your gas tank. At the same time you are ignoring the science that describes all of the other factors, simply because it's too complicated and you want to start "easy." There is no easy. Please make some effort to actually learn the subject, all of it, and stop playing games and wasting everybody's time by taking a too simplistic approach to the subject.
  25. Nuccitelli et al. (2012) Show that Global Warming Continues
    Congratulations! Would any of the testing be at location(s) where ocean circulations would be indicated or is deep water too shallow?
  26. Nuccitelli et al. (2012) Show that Global Warming Continues
    #8 DrYew, the caption explains that it is OHC increase. I agree that the y axis label could be labelled 'heat content change' to make it clearer.
  27. Shapiro et al. – a New Solar Reconstruction
    The main argument of the article is to take the difference of north globe temperature level from 1500 to 1800 (+0,15 Degree) and compares this to the same difference in TSI levels of 6 W/m2. This infers tome the question whether it is the chicken or the egg we are looking at first. Since we are right where I want to be, namely comparing the relation of long-term TSI to long-term global temperature (GT), I have some observations/questions: First, on the temperature data used here: It is stated that the Ljungqvist reconstruction exhibits larger temperature changes than the planet as a whole by a factor of approximately two. Based on my limited school knowledge about oceanic and continental climate, shouldn't that just mean "faster"? Are there any global reconstructions which show that this factor of 2 is indeed true? Also, I eyeball that the temperature difference between 1880 and 2000 is 0,4 and not 0,8 Degree, as IPCC states for the whole globe. So could it even be smaller instead of larger temperature changes, by the factor of two? Second, on comparing the curves: At 1700, temperature jumps up by 0,4 Degree, after it fell about the same about before, in the course of almost a century. Behold, the End of the Maunder Minimum (MM). At the same time, TSI was raising by 6 W/m2 (from 1360 to 1366 W/m2). This seems to be a direct feedback, without any climate lag, from TSI to GT. How is that possible? GT then stays more or less the same level for two centuries until 1900. TSI drops in between almost back to the value from the MM. How is that possible? We see another jump up of GT, roughly from 1900 to 1960, by almost the same amount as after the MM; 0,4 Degrees. TSI was raising about 4 W/m2 in that time, again, apparently no lagged response time of GT. How is that possible? My jump-conclusion: Short term relations of TSI to temperature are not possible without heavily taking into consideration all other possible forcings. Seems to make no sense otherwise. Third, not being able to correlate curves on a short-term timescale, maybe we can nevertheless and at least do a more general comparison of TSI and temperature levels: As to the medieval warm period, as well in the antique, we see very rough correspondence between average GT and TSI. High level TSI corresponds to high level temp. Temp seemed at those times roughly to be at the same level as today. And the same applies for TSI! Jump-conclusion: Everything seems to be "normal" at first glance? (Of course, an "unnormality" would be there if temp rises further in the next decades, which is, to quote the infamous wording of IPCC, "very likely".)
  28. Climate time lag
    John, I would welcome that. In my opinion, some clarification would be good. Talking about global temperature being submitted to a "climate" lag is one thing, and my discussion was focusing on that. But the article jumps midway into talking about an inceased radiative imbalance. I believe these are two totally different things, and this could be clarified. Bob, my approach is rather to go from simple to more complicated. It's the natural learning process this way. gws, a lot of work, and believe me when I say I do not understand Math formulas (as I have for example no clue what a multiplier to a multiplier in brackets minus something should tell me in the end). The conclusion is of course nothing new. I was aware that most of part of the response was already before 1960; that's why we were talking about a trailing-off, and I was trying to focus on what level of difference we are actually looking at in order to determine the scale of trailing-off we should take into account. BTW, in the Saphiro article, which Sphaerica linked to, I can do a lot of observations which show that directly comparing TSI to GT on a under-100-year scale makes absolutely no sense. Sometimes you see an almost direct response, sometimes none at all. I am trying to comment that over there. My bottomline for the climate lag article here; it should probably explain how "radiative imbalance" is calculated without resorting to global temperature, as the latter seems to greatly mislead.
  29. Nuccitelli et al. (2012) Show that Global Warming Continues
    Could you just explain the zero level on the axis? Heat content can be neither zero or negative so I assume there's a false origin - which makes it appear as if HC has doubled since 1995. cheers jonathan
  30. Cornelius Breadbasket at 19:17 PM on 11 October 2012
    Nuccitelli et al. (2012) Show that Global Warming Continues
    You have worked so hard on this. Very well done.
  31. Nuccitelli et al. (2012) Show that Global Warming Continues
    Well done indeed, team!
  32. Nuccitelli et al. (2012) Show that Global Warming Continues
    A milestone if ever there was one. Congratulations! Now keep 'em coming.
  33. Nuccitelli et al. (2012) Show that Global Warming Continues
    Excellent work as always, Dana! You rock!!
  34. Nuccitelli et al. (2012) Show that Global Warming Continues
    Hey, what's up with you people? You didn't trumpet it. You didn't wind up the press. You didn't get your minions to start babbling questionable assumptions. You let actual working climate scientists get involved. What's up with that? Congrats, all. Not surprising, so I won't add any exclamation marks.
  35. Nuccitelli et al. (2012) Show that Global Warming Continues
    Congratulations to the authors! This is not going to be the first peer-reviewed paper that the SkS team produces... It is going to be interesting to see what excuses the fake skeptics are going to contrive to try and dismiss or downplay this solid refutation of DK12. It would not surprise me if at the same time, the fake skeptics fail to recognize or cede the serious problems with DK12 that undermine its entire premise.
    Response: [JC] "This is not going to be the first peer-reviewed paper that the SkS team produces"

    Well, it is the first. Whether it's the last peer-reviewed paper that SkS produces is another matter :-)
  36. Daniel J. Andrews at 13:24 PM on 11 October 2012
    Nuccitelli et al. (2012) Show that Global Warming Continues
    I saw this via twitter, and wanted to say congratulations there, but figured it would appear here where I could say it. So "Congratulations!" for getting published and for the work itself. Very nicely done indeed. Hope you all are still flying high on this.
  37. Jerry Mitrovica: Current Sea Level Rise is Anomalous. We've Seen Nothing Like it for the Last 10,000 Years
    jyyh@12, Jerry explains that in great details starting from 25:00. Re-watch it.
  38. Update from Easton Glacier: Climate Crocks on Ice
    We saw a glacier in Alaska this summer that had retreated ~500 ft. In a year.
  39. Same Ordinary Fool at 04:33 AM on 11 October 2012
    Jerry Mitrovica: Current Sea Level Rise is Anomalous. We've Seen Nothing Like it for the Last 10,000 Years
    Icarus @9 "He [Mitrovica] and others working on the same problem start with the equivalent of four "fingerprints" all laid down atop each other: they know how much sea levels have risen during the past century - or in some cases, several centuries - at various inhabited locations. From these observed changes, their work is to isolate the distinct impact - of the melting of the West Antarctic Ice Sheet; the Greenland Ice Sheet; other glacier systems including that in Alaska; and thermal expansion...In this way they are able to make an indirect observation of precisely how much volume and mass each ice sheet has lost." (Harvard Magazine) "Localization" effects can be determined from the difference between the video's Greenland effects map based on a uniform 1mm equivalent (of meltwater to cover the world's oceans) and another Greenland effects map with the same amount of meltwater located where the melting actually took place, based on best estimates. (Oceanography, pp32-34, Figure 4) Conceivably this might also be done with separate oceans. I bet Jerry Mitrovica could solve it, if he had enough grad students.
    Moderator Response: [DB] Fixed Link.
  40. Climate time lag
    Seems to me that the OP would benefit from an update that incorporates the some of the detailed comments being made in response to Falkenherz.
  41. Climate time lag
    KR, indeed. That is why I commented that this is Falkenherz's "thought experiment". As the long time lag dominates, the picture is not too far off, but as was commented here before, the shorter air-T time lag has additional effects that make it more realistic.
  42. Climate time lag
    A single lag time is insufficient to describe the observed climate response (as in Bob Loblaw's post, the model shouldn't be too simple). Tamino has an excellent post on this, Fake Forcing, where he examines attempts to use single lags - attempts that require ad hoc, physically unsupported tweaks to come even close; the "fake forcings". On the other hand, if you consider a two-box model, two time lags, roughly corresponding to the responses of atmosphere and oceans, you can replicate climate behavior quite well. That model (lags in Taminos example of 2 and 45 years, respectively) fits observations quite well without modifications, and has the added benefit of being based on physics. It also directly provides an estimate of climate sensitivity using purely instrumental data, of 2.4C/doubling of CO2, well within IPCC estimates. Sliding time-lines back and forth for visual matching (which also neglects the fact that the climate responds to all forcings, not just one, and that analysis should be measured by statistics, not the "eyecrometer") is equivalent to using a single-box model - that's just too simple to describe observed climate behavior.
  43. Climate time lag
    continued Multiply the above picture with the actual TSI impact (aka smaller 1 W/m2) and you understand why the TSI impact is so small. What about CO2? I created a simple model of atmopheric CO2 concentrations (from 280 to roughly 395 ppm) following an exponential increase with constantly increasing growth rate (see, e.g., Tans et al., Atmos. Environ. 43(12), 2009); not exact, but an ok first guess. I then used the Myhre formula (forcing = 5.35*ln(C/C0), which gives a 3 K climate sensitivity for doubling CO2, and a 1.7 W/m2 value for the 395 ppm end point) to calculate the changes in forcing over time, then repeated the incremental integration as above. For comparison purposes to TSI, I further assumed that the atmospheric CO2 increase suddenly stopped at 400 ppm. The resulting graph looks like this: Image and video hosting by TinyPic Note, again, that the T increase is in lock-step with the driver increase (here: [CO2]) as long as the increase is maintained, thus a close correlation between CO2 and T is expected as long as only CO2 is driving the system. But note that in this case, much more warming is in the system, with "only" 0.7 K realized by the time the CO2 forcing stops, with another 0.5-0.6 K in the "pipeline". Not bad for a simple box model I would say. I was suprised myself. I will supply the R code for this to the moderator, or post it here if desired. One other thing: The difference in physical forcing between TSI and CO2 is one of wavelength: In the case of TSI increase, most of the extra incoming energy is in the form of shortwave radiation. In the case of GHGs, it is in the form of long-wave radiation (infrared). So while GHGs "dump heat" efficiently into the system, TSI increases drive a number of other things as well, e.g. chemistry.
  44. Climate time lag
    Falkenherz Hmmh, you are smart but you decline to look into the math ... so ok, I did the math for you, or better say, for your thought experiment: We start with the assumption that the system does have a lagged response between 25 and 50 years. If a perturbation (energy imbalance, I, in energy per time) to it occurs, the response is converted with a rate k (=1/tau) into a temperature, T, increase proportional to the difference in T between the equilibrium response and the current temperature, aka dT/dt = k*(I*cs - T(t)) (eq. 1) with cs = climate sensitivity in K per energy (assumed to be ~0.7 K per W/m2 as in Hansen et al., 2005), and k in per time (so that tau is in time units, say yr^-1) The solution to this (separable) differential equation is T(t) = I*cs *(1-exp(-t/tau)) Let's assume first that we have an instantaneous input of I to the system, a step change so to say. This was explained hetre before in numerous words, and by Riccardo with a graph. The first graph I produced here is the same basically: Image and video hosting by TinyPic It shows the response to the step change for various lag times from 25 to 50 years (in 5 year steps plotted in black to cyan). Note that I alinged the year axis roughly in assumption that the increase occurred in 1750. Let's say this is the hypothetical TSI increase of 1 W/m2, so I am actually strongly overestimating its potential effect on Earth's T. So this is for illustration on how the lag works. Next, let's make it a bit more realistic: The TSI increase could be assumed to be linear (based on your comments) instead of step-change like. So I had it linearly increase from 0 to 1 and then stop (as per your comment again). The differential of that curve gives me the yearly increase in TSI, each year inputing a bit of energy to the system, which can be modelled exactly teh same way as for teh step change illustrated in the above graph. One then needs to simply add up all those changes (integration). The resulting change in T looks like this: Image and video hosting by TinyPic Note that (a) during much of the linear TSI increase, T also increases linearly, hence the close, near linear correlation between TSI and T during the phase of change, and (b) once the forcing is shut off, an exponential decay of the remaining T-increase results. As you can see though, much of the increase had already happened at the time the forcing was shut off (0.5-0.6 of the equilibrium 0.7 K, depending on lag). (more to come)
  45. Climate time lag
    Falkenherz: ""climate lag is the same for all forcings but it is not the same for all forcings" (hi, bob) " What I specifically said above in #356 was "and the TSI increase vs. CO2 increase effects are, to a first approximation, not much different", and I followed that in #369 with "different radiative forcings can have different effects, although many of the differences are subtle." Note the "first approximation", and "not much different" in the first quote, and the "many of the differences are subtle" in the second. If you seem to think that I claimed that "climate lag is the same for all forcings", then you you aren't reading well (or aren't understanding well). If you seem to think that my two statements are in disagreement, then please be explicit is saying how. I'm going to try to rephrase what I (and others have) said earlier. Concepts such as "time lag" are very simple ways of trying to understand one aspect of a system. Although such simple constructs may provide a useful way of visualizing one or a few characteristics, the simple constructs will fail to catch many of the details. Trying to force the details into that simple construct will undoubtedly fail. "It is still not clear to me why an existing climate lag cannot be visualized by displacing cause (TSI) and effect (global temp) accordingly on the time axis." For starters, there isn't a single "existing climate lag". Secondly, what are you trying to show by doing this? The appearance is that you are trying to force observations of the real world to fit a simple model - one that is too simple. As DSL points out, to do it well, you have to start out including other factors. I gave a list in #369 of all (or close to all) of the things that would need to be considered to get a full understanding of the climate system. Depending on the purpose, models can leave some of those things out - but still be useful. Leave the wrong ones out (for a specific purpose), and you'll end up with a bad model. Remember the old saying "as simple as possible, but no simpler". By focusing on a single time lag concept, you are going too far past the "no simpler" point.
  46. 2012 SkS Weekly Digest #40
    With regards to the 'What Say You?' portion of this post: What spoonfuls of sugar do we have in our arsenal that might enable the average person to swallow the "medicine" of climate change mitigation and adaption? I might suggest that babies are a particuarly poignant spoonful. From the evidence, we can be reasonably confident that climate change and ocean acidification is already disrupting present-day food production and will eventually cause severe disruptions in global food production. I personally would go so far as to say that we are at, or near, the point of choosing between the mutually exclusive options of a carbon-based society today or reliable global food production tomorrow (metaphorically speaking). Suffice it to say, small children across the world alive today are the ones who are, at present, going to feel the worst of the climate disruptions to come (to say nothing of their descendents). I have a one-year old son, and the thought of him not having the opportunities afforded to me and my generation due to ongoing climate disruption is not a pleasant one. Suffice to say I do not find appeals to emotion, or appeals to consider the interests of future generations, illegitimate, as long as they are based on a solid foundation of evidence & logic.
  47. Climate time lag
    Falkenherz: "It is still not clear to me why an existing climate lag cannot be visualized by displacing cause (TSI) and effect (global temp) accordingly on the time axis." Who says it can't? However, if you're going to do it well, then you need to isolate the solar signal in the temp series. You need to strip out GHG forcing, aerosols, ENSO, etc., to reveal the solar effect on temp as purely as possible, and then you can go lag hunting. Even then, it's going to be tough, because the effect isn't going to return 100% at one point in time. General circulation is going to spread out the return. The spread may be consistent, but it still confuses the issue.
  48. Climate time lag
    Dear all, thanks for your last comments, but I think most are by now besides my point. I have the impression you sometimes read only half of my arguments and jump on some red flags; answers range from "you have no idea so shut up and read" to "climate lag is the same for all forcings but it is not the same for all forcings" (hi, bob) to "it is too complicated to give a simple answer" to "you cannot do this". (-snip-) I need to be able to understand answers with my limited non-scientific perspective. Especially the link to the discussion of Shapiro et al. offers interesting insight for me. It is still not clear to me why an existing climate lag cannot be visualized by displacing cause (TSI) and effect (global temp) accordingly on the time axis. If I roughly understand the results and the discussion under the "Shapiro article", I should confirm nothing else than what we found out here, anyways: The current rise of global temp is simply too much to be even a concealed trailing off from a raised TSI-end-level from 1960.
    Moderator Response: [DB] Tone-trolling snipped.
  49. Jerry Mitrovica: Current Sea Level Rise is Anomalous. We've Seen Nothing Like it for the Last 10,000 Years
    the gravitational pull effect occurs likely with Antarctica too, so what does that do for sea levels in NH?
  50. Jerry Mitrovica: Current Sea Level Rise is Anomalous. We've Seen Nothing Like it for the Last 10,000 Years
    Rob@4, Yeah, let's say that: Jerry did not draw the complete picture of SL in last 10ka but suggested it would be a hockey stick shape with a blade angle 1.5-2mm/y in XX century and accellerating to 3.5mm/y in satelite era. So there is no doubt which paleo guy from PSU you are talking about. It's so obvious that I don't even think about it, and I'm not even sure if SLR hockey stick can be technically compared with the original from tree rings but the PSU guy deserves every piece of credit, so let's add SLR hockey stick to his "league".

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