A Few Things Ill Considered

A layman's take on the science of Global Warming featuring a guide on How to Talk to a Climate Sceptic.

Sunday, June 04, 2006

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Observations Show Climate Sensitivity Is Not Very High

(Part of the How to Talk to a Climate Sceptic guide)

This article has moved to ScienceBlogs

It has also been updated and this page is still here only to preserve the original comment thread. Please visit A Few Things Ill Considered there. You may also like to view Painting With Water, Coby Beck's original fine art photography.

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56 Comments:

  • At June 05, 2006 1:05 AM, Anonymous Mikel Mariñelarena said…

    Coby:

    Lindzen actually does mention the oceans’ thermal inertia in his recent presentation at Timbro: http://www.timbro.se/pdf/060505_r_lindzen.pdf and his exact figure is not 2/3 but 3/4 of the 2xCO2 forcing already materialized through the current CO2 atmospheric increase.

    But could you please explain how exactly thermal inertia invalidates Lindzen’s reasoning?

    - Has it not been operating in the past century but it will release all the stored heat at some later moment? (My understanding, from Gavin Schmidt at RC, is that there is a lag of 20-30 years for the warming forcing/s to completely realize but not that they will realize all of a sudden).
    - Is the 3/4 figure correct? If not, what figure would be the correct one?
    - How can modeling virtual worlds be a better way of assessing the 2xCO2 sensitivity than working it out directly from empirical evidence, as Lindzen does? The latter includes all feedbacks, known and unknown. Rather than setting aside the whole argument, because he allegedly missed thermal inertia, it would be more productive to correct the possible wrong figures, factor in thermal inertia and work out a better assessment, wouldn’t it?
    - If the 3/4 figure is correct (75% of 2xCO2 has already materialized) and we accept, as you did during our aerosols-SH cooling discussion, that it is very unlikely that all the observed warming in the past century (0.6C +/- 0.15) was due to CO2, arriving at a high 2xCO2 sensitivity through the remaining 25% of the forcing + current thermal inertia seems a very hard task to accomplish, doesn’t it?

    Thanks,

    Mikel

     
  • At June 05, 2006 10:02 AM, Blogger coby said…

    Hi Mikel,

    I will endeavor to get answers for these questions. I had a look through the document (briefly), the URL you provided is not working ATM, but I found a cached google html version to read. I honestly do appreciate the challenges you present, but out of curiosity, do you challenge Lindzen's assertions in the same way? I did not see any numbers, just hand waves and a few clear misrepresentations. In particular he claims most models have a 2x CO2 sensitivity of 4oC. This is incorrect and I don't know why he would think this. The models have generally been showing 1.5-4.5 sensitivities for a decade I believe. I do know that now the model's are converging around a sensitivity of 2.9oC (1.7-4.9 95% confidence interval).

    I will respond further when I have something more sold, thanks.

     
  • At June 05, 2006 12:17 PM, Anonymous Mikel Mariñelarena said…

    Hi Coby,

    You bet I challenge Lindzen's assertions or anyone else's. My questions above are a proof of that, I believe. I don't know where the truth lies in the AGW issue and have a genuine curiosity in finding out as much as possible. After all, this is the planet I'm planning to live in with my children and future grandchildren.

    Thanks for taking the trouble of accepting my challenges (it's part of the deal when you set up a blog, I reckon). I hope that your interest is equally genuine and you find the discussion motivating.

     
  • At June 05, 2006 12:51 PM, Blogger Belette said…

    I doubt the 75% figure is right, even theoretically.

    But observationally, there are many confounding factors. Recent natural forcing is probably -ve, and this has masked some of the CO2. Sulphate aerosol, ditto.

    But the thermal lag thing is probably quite a part of it.

     
  • At June 06, 2006 1:46 PM, Blogger coby said…

    Hi Mikel,

    In terms of hard numbers, James Annan has offered 43% as the theoretical portion of 2xCO2 forcing provided by 1.35xCO2
    - ln(1.35)/ln(2) (details here)

    Thermal intertia just means that we can not use current observations of T rise to determine sensitivity to a forcing that has not been stable long enough. Your suggestion of what is more constructive than setting aside Lindzen's whole argument is a good one, but you have just described how to build a climate model, albeit a simple one. So now, in effect you are just asking if it would not be more useful to use a very simple model rather than a full fledged GCM.

    The models do reproduce the 20th century, and even the last 1000 years globally averaged reasonably well, observational data of forcing factors permitting, and they do this with the same physics that produce 2xCO2 sensitivity as 2.9oC

    There is another essential factor in looking at current T rise vs CO2 forcing and that is the global dimming phenomenon. This is definately counteracting GHG forcing and so needs to be factored out. I didn't see Lindzen do that, or really address thermal inertia, though he waved at both of them.

     
  • At June 07, 2006 3:15 AM, Anonymous Mikel Mariñelarena said…

    Hi Coby,

    Thanks a lot for the infos. It’s very interesting to see how these gentlemen have got themselves into such an ardent dispute. Personal attacks, accusations of dishonesty, alleged use of flawed arguments for failing to mention this or that detail in a presentation for a non-technical audience…difficult to believe that it’s all just about atmospheric physics, isn’t it? But of course Timbro is not a politically neutral institution and of course the RC team are not a group of president Bush supporters. This is in essence what makes the AGW dispute unsolvable, in my view.

    Not being a physicist, there are many things that I miss to judge whether Lindzen’s or Annan’s calculations are more correct. Where does Lindzen get the 75% figure from? What is the precise form of the logarithmic function of radiation increase percentage wrt CO2 in Lindzen’s graph? How do they arrive at such relations? What does 2.4 W/m^2 exactly represent in Crowley’s data set? Why does Annan use these paleoclimatic records to estimate the current GHG forcing?

    In any case, Annan’s reply to your post does provide pretty much an answer to my queries above. Since Lindzen’s argument is that the total man-made GHG forcing accumulated to date is equivalent to 75% of 2xCO2, Annan’s response to that would be that in 1998, according to the source he provides, the real figure was 54% (and I guess slightly more today). Still, if we take this figure we arrive by linear extrapolation at a provisional ~1.1 C temperature increase for a CO2 doubling (including all feedbacks, known and unknown). To this we should add the thermal inertia still in the system. As I understand it, this inertia operates as a ~25 year delay in the total realization of the forcing, so we should add the corresponding fraction of 1.1 C to get the total figure. I don’t see it getting much above 1.5 C.

    What I can’t agree with is further adding to that the alleged negative forcings that would be operating at the moment but would somehow cease to operate in the future. First, as, you know from our anthropogenic aerosols discussion, I have serious doubts as regards the effect of these on global temperatures, seeing the mid-century SH cooling pattern. Second, the uncertainties in these forcings (man-made aerosols, solar, land use change, volcanoes,...) are far too big. Much though I dig in different sources I can’t see an agreement of what they represent at the moment. What we do know more or less is what has happened with global temperatures in the past 120+ years, while all these factors likely operated in both senses. You agreed that most of the early century warming (almost half of that observed) was natural in origin. In the same vein, the IPCC TAR didn’t attribute that warming to human causes. So I think that it’s fair to leave these factors as a discussion point for pushing the final figure upwards or downwards but I wouldn’t compute them in the climate sensitivity calculation. It seems more reasonable to assume that natural and additional human forcings will continue to operate on average as they have done in the past.

    Note that I am not suggesting to create another model. I do appreciate the tremendous effort that goes into generating a modern GCM but the problem is all the assumptions these have to incorporate to make their predictions reliable. We must assume that we know what all the forcings are, quantify them, know how they operate and interoperate in the climate system, further assume that this tends to some equilibrium rather than being in constant imbalance…but in fact modellers ignore much of all this. What I proposed instead was to use, as Lindzen did, the old-fashioned method of relying on little controversial observations and basic relationships. I think that he did a good job at simplifying the problem. We may not get as much detail as in the virtual worlds of the GCMs but it does seem to me that we gain in reliability.

    In any case: ~1.5 C sensitivity (or much less if we take Lindzen’s figures).

    BTW, I see that Tobis is already threatening to “moderate” the only discrepant voice in that thread.

     
  • At June 07, 2006 5:51 AM, Blogger Heiko said…

    Actually I think it's a pretty good presentation in many respects (and the link now works, at least for me).

    I am not sure why he gave 4C rather than 3C, maybe a minor oversight on his part.

    The 75% figure is for all greenhouse gases, not just CO2 (ie all greenhouse gases together are equal to 75% of the forcing in W/m2 of doubled CO2 on its own).

    I'll take your 43% and assume the difference between that and 75% is methane etc... (from memory that seems about right when I recall the picture illustrating relative forcings on the IPCC website).

    The point about aerosols Lindzen makes isn't unreasonable. We have to assume their forcing cancels some of the greenhouse forcing in order to make the models agree with reality, and there's large uncertainty about aerosols. Lindzen clearly believes that there is a fair chance that there are large negative feedbacks in the system (he seems to favour clouds as the reason) and that therefore climate sensitivity may be quite low.

    I accept that's at the gut feel level, but I can't properly judge whether it stacks up that badly against the belief that aerosol forcing is large compared to greenhouse forcing at the moment (large=cancels a sizeable fraction of the forcing).

    My own feeling on the matter is that Lindzen does not represent the majority view on this, and that I tend to favour the majority view, ie aerosols are probably the explanation rather than some "unknown effect" (=eg clouds).

    What I particularly like about the presentation is that he agrees there is a "consensus", but that this consensus isn't that weather will become "worse" in every respect imaginable, largely it'll just grow a little warmer (and slowly on human time scales, not least due to thermal inertia).

     
  • At June 07, 2006 6:01 PM, Blogger coby said…

    Hi Heiko,

    I am curious as to your take on this comment from early in the document referring to some quoted statements of the consensus:
    These references fail to note that there are many sources of
    climate change, and that profound climate change occurred
    many times both before and after man appeared on earth.


    What is he implying by this and is it reasonable and relevant?

    As for the 75% figure, what is the utility of using supposedly observed forcing of all GHG's to then estimate sensitivity to 2xCO2 alone? Seems like a bit of a shell game with numbers to me.

    Re uncertainty and aerosols, I would just like to remind you that uncertainty cuts both ways. "Dimming" may well be overestimated and therefore CO2 sensitivity is lower than thought, but it may also be underestimated meaning CO2 sensitivity is higher than thought.

     
  • At June 07, 2006 7:34 PM, Blogger coby said…

    Alexi is a very difficult person to have a conversation with, he really brings a toxic tone to a discussion. I think he and I have had some success, but I don't have the technical knowledge or the math to properly address his concerns. I understand when those that do are not interested in being taken as contemptuous fools. If he fails to pass moderation it will be because of this attitude and not because anyone is afraid of any substantive point of view.

    On that subject, I apologize for having to turn on moderation here, I hope it won't be for long. It is due to a single individual and I have no intention of blocking anything more than his posts. It has become very tedious deleting well over 100 such comeents in the last two weeks.

     
  • At June 08, 2006 2:34 AM, Blogger Heiko said…

    Coby,

    re moderation, I know which individual you've got in mind, and I agree it's a whole load of spam.

    I didn't actually check the link to James Annan's posting you provided, now that I have done, it seems to me there's something strange about his numbers.

    2.4/3.7 is 65%, not 54%. (I guess it's a harmless oversight, maybe he mistyped?)

    Also, I agree with Mikel, the tone of James Annan's comment is needlessly ad hominem (throwing out an accusation of deliberate dishonesty).

    "As for the 75% figure, what is the utility of using supposedly observed forcing of all GHG's to then estimate sensitivity to 2xCO2 alone?"

    I think it all boils down to the fact that he is trying to talk up the likelihood that aerosols are negligible, and clouds are important, so to speak.

    He's probably just trying to explain why aerosols are needed to make reality and the models fit.

    Yesterday I tried to post something here, but somehow the site wouldn't allow me to. So, I saved the message:

    "Mikel,

    while I think that the ideal carbon dioxide price at this stage is 0 Euros per tonne,

    this is largely because

    1. I think by far the most likely result is a moderate temperature and sea level rise that in my opinion will leave the world better off

    2. I don't see any truely catastrophic outcomes, and for anything coming close, I believe there's plenty of time to change course, if necessary (whether we want to burn lots of coal after 2050, which is the basis for the high end IPCC estimates, well, we can largely decide that after 2050).

    For me, arguments about the low end of the sensitivity range are somewhat less important than making sure we've got a good handle on the high end. Can we exclude 11C climate sensitivity, the kind of thing that might bring sea level rise to 30 m a century? And with what certainty?"

    As happens you bring up something very similar:
    "I would just like to remind you that uncertainty cuts both ways."

    You see I totally agree with this. Lindzen accepts that clouds are poorly understood and aerosols are poorly understood. What I care about is less whether this makes 1.5C 30% likely rather than 10% likely, but what it does to the top end of the range.

    Re the section in Lindzen's presentation you want me to comment on:

    I don't think that point is about science. Of course, I may be reading my own opinion into this, but I think he's referring to the fact that some climate scientists and environmental advocates sound like priests worshipping mother nature and bemoaning our sinfulness and arrogance in the face of nature for which we need to atone. Mother nature is all perfect and will take care of her children, and any change brought about by man, is by definition bad.

    Because of our discussion of aerosols, I came across a section on geoengineering in the IPCC reports (something I want to post on sometime on my own blog, but haven't gotten around to).

    And when I read the kinds of arguments Schneider brings up in a critique of the idea:
    http://stephenschneider.stanford.edu/Publications/PDF_Papers/Ch20ClimatePolicy.pdf
    I do get annoyed by the moralistic/religious tone behind it all.

    Anyways, you wanted to know whether I think Lindzen's comments in that small section you quoted are reasonable and relevant. It depends on what you read into them, and whether you think it's about science, or about values. I think it's about the latter.

    And the values being talked about are complex, so they don't lend themselves to simplification. Few people believe we should reduce world population back to 150,000 and do away with anything more technologically advanced than a stone, and few people think that we should pave over all forests, and blindly implement schemes crying "technological overreach = failure is bound to happen with all of us dying and the planet left behind an ice cube or pulverised altogether".

     
  • At June 08, 2006 8:18 AM, Anonymous Mikel Mariñelarena said…

    I don’t know about Alexi but I see that Annan is further threatening poor Steve in the Lindzen thread, who had already apologized to Tobis even though he hadn’t done anything wrong. I guess Annan would also think that anything I’m saying here is easily refutable by looking on the internet.

    Basically, if you’re not convinced about the seriousness of AGW, there’s hardly any room for you in those threads. You have to stay with your own in some skeptic forum… or come here to Coby’s refuge. Thanks for allowing free discussion here Coby.

    (Sad case, that individual of the spam posts, I kind of feel sorry about him more than anything else).

     
  • At June 08, 2006 3:39 PM, Anonymous Mikel Mariñelarena said…

    ”2.4/3.7 is 65%, not 54%”

    Well spotted, Heiko. Climate scientists seem to be like banks or utilities: if they make a mistake it’s always for their profit.

    That would leave the transient climate response to 2xCO2 at about 0.9C.

    It seems clear that temperature increases seen so far do not provide any evidence for a high climate sensitivity. As Coby said, the key issue here is thermal inertia (and to a lesser extent aerosols).

    I have already given my personal opinion on aerosols and other forcings. As for thermal inertia, I think that a very good guide, as usual, is the IPCC TAR: http://www.grida.no/climate/ipcc_tar/wg1/356.htm The figure shows how much thermal inertia increases the final climate response in various models: it’s the difference between the red and the brown bars. One significant element of this graph is that low transient climate responses (red bars) are associated with low effects of thermal inertia (difference between red and brown bars). Thus the oceans thermal lag is unlikely to increase the final figure very much.

    And one other important element to consider is that, as Lindzen said, we have no basis for assuming that all the warming seen in the past century (0.6 +/- 0.15 C) is due to HGH increases. In fact, we have very good grounds to assume that almost half of it had nothing to do, as GHG concentrations had still not risen much when it took place.

     
  • At June 08, 2006 4:20 PM, Blogger coby said…

    Mikel,

    I don't see where the system's thermal inertia is being accounted for in your calculations. The percentages from forcings will remain decades out of synch with the percentages from warming until the system is in equilibrium again.

    As for providing a refuge, well how can I claim to be a guide for talking to the sceptics if I don't try to do it myself?! :)

     
  • At June 08, 2006 7:32 PM, Blogger coby said…

    Re 2.4/3.7 = 65% not 54%, the 2.4 is for all GHG's whereas 3.7 is for a doubling of CO2 alone. So, there is no mistake (at least not this mistake) but there is some work not shown...

     
  • At June 09, 2006 1:27 AM, Blogger Heiko said…

    Coby,

    maybe I am suffering from poor reading comprehension.

    "The CO2 rise alone will account for ln(1.35)/ln(2) = 43% of the effect
    of a doubling. Crowley gives the total GHG effect at about 2.4W/m^2,
    which would only be 75% of the doubling if a doubling was 3.2W/m^2. In fact it is about 3.7W/m^2, so a 35% increase in CO2 gives 54% of a
    doubling. "

    CO2 alone (35% increase in concentration) = 43% increase in forcing compared to doubling =1.59 W/m2 divided by 3.7 W/m2

    And now what's the 54% for? The way I read the passage it ought to be for

    All GHG / CO2 doubling alone = 2.4/3.7 W/m2.

    What am I missing here?

    At any rate, I don't think it's a big deal to mistype a number in a spreadsheet for a google groups message, should that be the cause for the apparent discrepancy.

     
  • At June 09, 2006 2:31 AM, Blogger Heiko said…

    Mikel,

    I am not a climate scientist, just a chemical engineer with a longstanding interest in the issue.

    Because of that longstanding interest I realise that even the forcing from CO2 (never mind feedbacks) alone is not trivial to determine (from long discussion with a physicist specialised in the physics of absorption and reemission).

    In the end, a lot therefore comes down to trust and I accept the IPCC view as a reasonable representation of our current state of knowledge.

    My understanding of how we arrive at the 1.5-4.5 C range is that this is based on both theory and evidence from past climate.

    The link you give indicates that thermal inertia is a huge factor. At the time of doubled CO2 concentration (after about 70 years of 1% annual increases), actual temperature rise varies from about 1.3C to about 2.2C, while climate sensitivity is 1.5-4.5C.

    IPCC also think that the change in natural forcings is likely close to zero over the period
    http://www.grida.no/climate/ipcc_tar/wg1/figspm-3.htm
    (a tiny bit coming from the sun).

    How do we make all that fit?

    Answer:

    The forcing of greenhouse gases is counteracted by about 1 Watt/m2 of aerosols, leaving us with 1.5 W/m2 or thereabouts, or less than half that of a doubling of CO2 (3.7 W/m2), and thermal inertia cuts that by half again for the high end sensitivities, and not much of a cut is required for the low end sensitivites (1.5C times fraction of forcing 1.5/3.7 giving about 0.6C).

    As I mentioned earlier, the fact that aerosols are already counteracting greenhouse gases does lead to the question, whether we could counteract greenhouse gas forcing through another forcing (increased albedo, aerosols, blocking out part of the sun through space mirrors etc..).

    It seems that not that much mass would be required to do this. Or in other words it's feasible in principle with present technology. It might also bring large ancillary benefits, such as selective scattering of UV.

    Arguments against this means of countering greenhouse gases are:

    1. It mightn't work as intended, and in the mean time disctract from getting the world onto a low emissions path.

    2. It's playing God to even try. (very religious one this)

    Personally, I am no great fan of argument number 2. If we can make the world a better place (more CO2 for plants, less UV for us all, not much change in sea levels) and putting UV scatterers into orbit is a reliable way to do this, then I'd be in favour of using it. As the potential benefits are clearly very large, research funding is appropriate to investigate this option further.

     
  • At June 09, 2006 11:16 AM, Anonymous Mikel Mariñelarena said…

    Coby:

    I don’t think I am close to being able to compute the thermal lag. In my first calculation above, based on Annan’s figures and my understanding of the thermal lag effect, I just offered a “not much above 1.5C”.

    But in fact, after looking for better explanations of this effect and finding nothing better than the IPCC, I think that the thermal lag would actually influence much less the final climate sensitivity. Note in the link I gave that the lower the transient climate response, the lower is the thermal lag effect: for example, in the rightmost model the thermal lag just elevates a TCR of about 1.3C to a final response of about 1.7C.

    If we add to this the fact the TCR I calculated was inflated due to Annan’s typo and, again, a good portion of the observed ~0.6 temp increase cannot be due to GHGs, I think that it’s fair to conclude that the thermal inertia does not change the picture so much. I can understand why Lindzen and others have little faith in global temperatures going from +0.6 C in the past century to +3 C (or much higher!) in the coming decades.

    I second Heiko’s explanation of Annan’s apparent mistake. It doesn’t matter how much CO2 is in the total current radiative effect of all GHGs, as they all operate equally increasing this effect. That was Lindzen’s point, so his 75% figure must be compared to Annan’s 54/65%. Sorry for having given you a false account of Lindzen’s argument myself!

     
  • At June 09, 2006 12:56 PM, Blogger coby said…

    One crude way to put thermal lag into the calculations would be to do it all not with 35% current CO2 increase but, say, 20% from a few decades ago.

    Re geoengineering, I am not against these ideas on any quasi-religious basis even though I am personally uncomfortable with them for quasi-spiritual reasons. However, I think there are very real and serious practical concerns that make it nothing but a last ditch, desperate do or die option.

    Specifically, not having other planets as trial runs or as backups for failure leaves us much too vulnerable. Technology is capable of pretty impressive feats, but mistakes are part of the learning process and we can't afford any.

    Also, depending on our ultimate priorities and moral concerns, any system we chose to put in place should not require continued maintainence or operational efforts, like continuously pumping aerosols into the stratosphere. If we do that for a couple hundred years, and take the free license to raise CO2, the day some major change in human society occurs that prevents continuing this operation, all those chickens will come home to roost in a disasterous way.

    Anyway, whenever a conversation strays far down this path I can't help but stop and think if technolgy really is this powerful and reliable, why don't we just develope a way to live without emitting CO2...?

     
  • At June 09, 2006 3:17 PM, Anonymous Mikel Mariñelarena said…

    Heiko:

    I have a couple of problems with your last post.

    The link you give indicates that thermal inertia is a huge factor.

    That is of course relative but I rather see it the other way around. In this thread we’re talking about thermal inertia being so powerful that it can reconcile the small response in temperatures seen so far with the catastrophic forecasts made for the coming decades. I don’t see that in this link. As you say, the largest thermal lag effect you find in those models is no more than a doubling of the TCR (for very high TCRs that are at odds with current observations and both Lindzen’s and Annan’s figures).

    IPCC also think that the change in natural forcings is likely close to zero over the period http://www.grida.no/climate/ipcc_tar/wg1/figspm-3.htm

    What I see in that link is a relation of all known forcings (except for volcanoes) and rough estimates of their effects. But (a) They recognize upfront that the scientific understanding for most of them, including the most important one (the Sun) is very poor. (b) If the natural forcings have been basically constant the warming of the early 20th century seems difficult to explain, as well as the end of the LIA or the mid-century southern hemisphere cooling. (c) What about the possibility of unknown forcings? Can we already say that we know them all? What about chaotic variability?

    Finally, you say that we arrive at the 1.5-4.5 C range based on both theory and evidence from past climate. I think that we arrive at those figures by relying on computer models that indeed compute theories and evidence but also a lot of questionable and uncertain assumptions that I have mentioned above.

    Much more qualified people than me have already expressed their doubts about GCMs in this very blog. As far as I’m concerned, and looking at those state-of-the-art models from my standpoint as an economist, all I can say is that it’s not for lack of trying that we economists have failed so far to fully explain many elemental questions: Why do business cycles exist? What is the best role of the government (if any) in the economic system?

    Not that I don’t have my own ideas but, whatever you think of economy as a science, I can assure you that some of the finest minds in the past centuries have dedicated their best efforts rather fruitlessly to find responses for a system that is at least as complex and chaotic as climate: ‘humans trying to satisfy their needs and wishes with limited resources’. At least since the 19th century it’s fair to say that economists have also tried to atomize and model mathematically all imaginable aspects of this system but many basic questions remain unanswered.

    And I don’t see powerful computers changing much the scenery in the field of economic forecast.

     
  • At June 09, 2006 6:33 PM, Blogger Heiko said…

    http://www.realclimate.org/index.php?p=115

    http://www.grida.no/climate/ipcc_tar/wg1/255.htm

    Mikel,

    I know that real climate is a rather biased site, but they've got some good material on climate sensitivity (see above link):
    "For instance, total forcings since 1850 are around 1.6+/-1 W/m2, the temperature change is around 0.7+/-0.1 °C and the current rate of warming of the ocean (to correct for the non-equilibrium conditions) is around ~0.75 W/m2. Together, that implies a sensitivity of 0.8 +/- 1 °C/W/m2 or 3.2+/-4°C for 2xCO2."

    And here we've got an actual estimate of thermal inertia in W/m2, and maybe it's not "huge", but at any rate nearly as large an effect as aerosols, together getting us from 2.4 W/m2 to 0.85 W/m2 (+/-1).

    Looking at the IPCC link, they predict forcings on top of year 2000 values of as much as 5.15 W/m2 from CO2 alone.

    My gut feeling, speaking as a chemical engineer (and heat transfer is a core chemical engineering area), is that the uncertainty for thermal inertia is not that large, it ought to depend mainly on the speed of temperature rise and be estimatable based on the temperature rise history to date (if you do doubt that, I am sure Coby, you or me can do some digging to clear that up).

    The radiative forcing is complex, but well understood. So, it's really aerosols that you have to rely on to come up with a low climate sensitivity based on temperature rise to date and present overall forcing (2.4 W/m2 less thermal inertia of 0.75 W/m2 giving 1.65 W/m2 with only 0.7C warming, while 4-5 W/m2 is supposed to give 3C).

    On your point b), well, the fact that natural forcings were say +0.4W/m2 in 1945, and 0W/m2 in 1900, doesn't preclude them being 0 again in 2000. I was referring to the IPCC figure and that's for change between 1750 and 2000 (and I mentioned that there is a small solar forcing, small enough to be off-set by eg albedo).

    On your point c). The system is non-linear, and so I've also got a bit of a conceptual problem with climate sensitivity. Why should a forcing no matter how large, and no matter what the source, always linearly translate into a world average temperature change (eg at 0.6C per W/m2)?

    On paleo-climate, I'll cite real climate:
    "What about paleo-climate? An early attempt to use the Vostok ice core data in a regression analysis (Lorius et al., 1990) resulted in a climate sensitivity of 3-4ºC. The best period for these purposes is the last glacial maximum. This was a relatively stable climate (for several thousand years, 20,000 years ago), and a period where we have reasonable estimates of the radiative forcing (albedo changes from ice sheets and vegetation changes, greenhouse gas concentrations (derived from ice cores) and an increase in the atmospheric dust load) and temperature changes. A reasonable estimate of the forcings is 6.6+/-1.5 W/m2 (roughly half from albedo changes, slightly less than half from greenhouse gases - CO2, CH4, N2O). The global temperature changes were around 5.5 +/-0.5°C (compared to pre-industrial climate). This estimate then gives 0.8 +/- 0.2°C/(W/m2), or ~3+/-1°C for 2xCO2"

     
  • At June 09, 2006 6:55 PM, Blogger Heiko said…

    Coby,

    I know it's not really that important a point, but I am curious whether you now agree that the 54% is likely a typo, or if not, whether you can tell me what Annan actually means?

    On aerosols, I am particularly keen to learn more about the possibility to selectively scatter out UV, something that would have large benefits on top of compensating for the radiative forcing of CO2.

    Teller has argued that the cost of UV scatterers would be low relative to CO2 reduction measures, that the benefit from reduced UV would be substantial, and that a combination of present temperatures, reduced UV and CO2 fertilisation would yield large increases in plant productivity.

    As you know, I believe we already have the technologies to greatly reduce CO2 emissions "at zero cost", and to actually go negative (ie sucking CO2 out of the atmosphere) at modest cost compared to future GDP.

    I am not convinced that there's value in reducing CO2 emissions now, because I think it's likely that the 1.5-3C our present and near term actions (as opposed to burning lots of coal after 2050) will bring are a net positive, and I don't see any way our CO2 emissions could junk our planet. We don't have another one, yes, but CO2 concentrations have been much higher in the past, and there are sound physical reasons why Venus isn't possible.

     
  • At June 09, 2006 8:29 PM, Blogger coby said…

    Heiko,

    I think the 54% is the result of some conversion based on the portion of GHG forcing that is CO2. If I am right it would have to be that CO2 forcing is 83% of the total GHG forcing (65% * .83 = 54%)

    I won't argue with you that eventually a warmer, higher CO2 laden atmosphere might be an all round better place, but as I try to present in this article, the problem is how rapidly we are changing things to get there.

     
  • At June 10, 2006 1:09 AM, Blogger Heiko said…

    I've found a way to get his number:
    35/65*100=54%.
    (trouble is 35 is for carbon dioxide concentration, and 65 is for forcing, so if that's the calculation it was indeed a typo in a spreadsheet)

    Actually CO2 as a percentage of all radiative forcing would be:
    43/65*100=66%

    You messed up the link (I think) so that it actually leads back to this page rather than the FAQ section
    http://illconsidered.blogspot.com/2006/02/whats-wrong-with-warm-weather.html

    Never mind, as you know, I don't think the costs imposed by that change are large, not as long as sea level rise is only 50 cm over a hundred years (and the midpoint for the scenarios I consider most policy relevant, ie those excluding lots of coal burning after 2050, is somewhat lower still) and the change in "weather extremes" largely amounts to nothing more than what would be expected from moving south a few hundred kilometres.

    When I hear people talk about the 2003 heat wave as a 5 sigma event, and tens of thousands of deaths, I cringe. Britons and Germans, including healthy elderly, stream in the millions to the Mediterranean in summer, where 42C (the temperature reached in my parents' locality in Germany) is not a rare event at all. The heat wave was surely largely only a deadly event in the statistics in so far as it affected people already weakened severely by other factors, and even that only because of inadequate air conditioning, which might consume a lot of energy, but would do an awful lot more good than trying to lower Northern European summer temperatures through lower CO2.

    My view about extinctions is largely that the saving of important/cuddly species depends on specific conservation efforts, and that I don't really care if some arctic moss or species of fly doesn't make it from Siberia to Greenland.

    We all like polar bears, televised pictures of coral reefs and pristine landscapes. But that's not the same as caring about species. I think the idea that the preservation of lots of species of slug, or lichen etc. is a worthy moral goal in its own right is highly questionable.

    If 50% of species died, I wouldn't mind, providing that is that they aren't vital in some way (ie without them our life gets demonstrably worse) or at the very least there's a strong esthetic reason to preserve them. As far as I am concerned 50,000 species of insects are just as good as 100,000.
    In fact, the differences between a world with the present number of species and twice or half the number seems to be so marginal that that's the kind of error margin there is on the number of species (because the vast majority of species is represented by ones that are small in most senses of the word, that is have few individual members, a small geographic range etc..).

    That of course is a moral (as opposed to scientific) debate, just like whether abortion or gay marriage should be legal.

     
  • At June 11, 2006 3:12 PM, Anonymous Mikel Mariñelarena said…

    the fact that natural forcings were say +0.4W/m2 in 1945, and 0W/m2 in 1900, doesn't preclude them being 0 again in 2000

    Sure, Heiko. But the thing is that in the 1st part of the 20th century the global average temperature rose at a rate comparable in size and speed to that of the last 30 years. From 1910 to 1944 it rose a full 0.65C, or 0.4C if we take smoothed figures: http://hadobs.metoffice.com/hadcrut3/diagnostics/global/nh+sh/

    - How would you explain this rise? Note that in the hockey stick graph it is as unprecedented as that of the last 3 decades: http://www.grida.no/climate/ipcc_tar/wg1/figts-5.htm

    - How do you explain the fact that the southern hemisphere followed the cooling trend of the northern one in the mid-century in spite of tropospheric aerosols (especially the man-made ones) having a very small impact there?

    My gut feeling, speaking as a chemical engineer (and heat transfer is a core chemical engineering area), is that the uncertainty for thermal inertia is not that large

    My gut feeling, as a complete layman, is that, indeed, if you don’t see temperatures rising much, you can’t count on large amounts of heat being absorbed by the oceans. And vice versa, if temperatures rise a lot, another good portion may possibly be being absorbed by the oceans. This is what the IPCC link I gave above shows.

    On the other hand, and speaking as a simple observer again, I very much doubt that we have the ability to measure the oceans’ heat uptake and figure out with much precision how thermal inertia operates. Note that in the IPCC link the ocean heat flux is taken as a parameter in the models and varies by a factor of about 2.

    As for Dr. Annan’s mysterious words, rather than trying to decipher them, it may be better to work on what’s easily understandable:
    According to Lindzen, current GHGs radiative forcing = 75% radiative forcing of 2xCO2.
    According to Annan, current GHGs radiative forcing = 2.4 W/m^2 and radiative forcing of 2xCO2 = 3.7 W/m^2 => Lindzen’s figure ought to be 2.4/3.7 = 65%.

    I think that in the main Lindzen’s arguments are reasonable enough. But I tend to sympathize with Professor Tenneke’s view that arguing about physics alone will not solve the AGW debate. The uncertainties are too big and this, in turn, makes him be very skeptic as regards the current climate models’ prediction ability.

    I’m not one of the most recognized experts in turbulence like Tennekes. But I’m old enough to remember the cooling scare of the seventies, the NASA “long-term weather forecasts” or the attempts to “seed” rain-generating clouds…

     
  • At June 12, 2006 4:00 AM, Blogger Heiko said…

    1. Natural variability and maybe a little bit of a human contribution. Black soot and methane and land use changes come to mind as possible anthropogenic contributors before 1945.

    Also, don't forget Lindzen's point that the increase in forcing isn't linear with concentration.

    2. I don't think the hockey stick is nearly as important as the heated discussion would suggest.

    I also don't think that we've got good enough proxy data to get a world mean accurate to +/- 0.1 C hundreds of years ago.

    Firstly, because there's uncertainty in the proxies themselves, and secondly because of poor coverage of the globe.

    My gut feeling (there that word again) is that the grey area in the figure is a good representation of the overall error, and that we are therefore only just above the high end for the Northern hemisphere.

    Climate isn't pure randomness, and doesn't closely approximate the normal distribution.

    Clearly, if there was a slight downward trend until 1750 and then a somewhat steeper upward trend until now, even if 2005 was then the warmest year in the record, that wouldn't in and of itself suggest much about human contribution. It would, if temperature was constant with some random noise around it approximating the normal distribution. Then the current high in and of itself would be suggestive of a net human impact.

    As is, the huge uncertainty about aerosols means that in principle net human impact on climate could have always netted out to something close to zero with most of the temperature change due to natural trends.

    The IPCC think this is unlikely though, ie there's a greater than 66% chance that more than half the change to date (ie >0.3C) is a net anthropogenic impact.

    3. Could be co-incidence? It might be that the Northern hemisphere went down due to aerosols and the Southern due to natural variability.

    4. On thermal inertia, maybe my gut feeling is wrong and there's more uncertainty here than my intuition tells me there should be.

    I'd have to look more into why the thermal inertia is greater in models with higher climate sensitivity than in models with lower climate sensitivity.

    "indeed, if you don’t see temperatures rising much, you can’t count on large amounts of heat being absorbed by the oceans. And vice versa, if temperatures rise a lot, another good portion may possibly be being absorbed by the oceans."

    But the link shows more than that. When temperature rises by 6C, or 3C, you might expect the oceans heat uptake to differ by a factor two. The link seems to be suggesting it's more like a factor 5 (ie for double the climate sensitivity thermal inertia keeps the temperature temporarily down by 2C rather than 0.4C).

    The way I interpret that is that the higher climate sensitivity must either involve different heat transfer modes/patterns, or that it involves a different temperature rise path, with more of the increase backloaded (ie if most of the increase for high sensitivity comes after 2070, then there's less time for the oceans to equilibrate than there would be, if most of the temperature increase was done by 2030).

    5. Typing in thermal inertia W/m2 into google gives you these two links:

    http://www.sciscoop.com/story/2005/4/29/64527/5456
    (I'd class Hansen as an alarmist)

    http://www.worldclimatereport.com/index.php/2005/05/16/determining-climate-sensitivity-from-volcanoes-observations-vs-models/
    (I don't like the word skeptical, it's tainted by association with the low hanging fruit that Coby is so busy refuting, but anyway this site is biased like real climate but towards a more positive, less alarmist point of view)
    http://www.worldclimatereport.com/index.php/2006/04/10/dialing-in-your-own-climate/

    Anyway, Patrick Michaels also comes up with 0.5C in the pipeline from thermal inertia.

    6. On Lindzen's figure. It doesn't take that much to reconcile Annan and Lindzen, as 2.7 W/m2 is 73% of 3.7 W/m2. Lindzen may just have used more up to date figures and rounded up a little.

    http://cta.ornl.gov/oilTransitions/Session4/AirPollutionClimateSmith.pdf

    And a quick google seems to confirm that (see page 11 out of 21 of the slide show)

    7. What Coby is dodging somewhat is the debate about solutions. He has this category: "Climate change can't be stopped.",

    but then goes into very little detail as to how it should be stopped.

    After all, people making these "it's too expensive, difficult" type of arguments mean to add the word "now", "it's too expensive, difficult now".

    Few will argue that we can put CO2 into the atmosphere at present rates forever, either we'll run out of fossil fuels, or there'll be a point where adding further CO2 clearly will be the more expensive option, and in the extreme (there's plenty of carbon in the Earth's crust, and failing that the solar system) it'll turn the Earth into Venus eventually, and probably before that the CO2 itself would start getting toxic (at a few ten thousand ppm it ought to get to levels that'll kill us).

    The arguments about "it can't be stopped" are all about it not being worthwhile doing much more than we are doing at the moment. And when Coby refuses to go into detail as to what we should be doing at the moment that we aren't in fact doing, then, well, he isn't exactly addressing the "it can't be stopped" (or as I'd put it, "present climate policies are just fine") type of arguments.

     
  • At June 13, 2006 12:50 PM, Blogger Heiko said…

    Looking at your original posting maybe you could update it, to save people the trouble of going through the many comments?

    In particular, I think links to Lindzen's presentation, and to sources showing the magnitude of thermal inertia and forcings would be good.

    The graph on Pat Michael's website is particularly good for thermal inertia I think.

     
  • At June 13, 2006 4:15 PM, Blogger coby said…

    Hi Heiko, I added a bit of an update, in case you need to refresh your browser's view...

     
  • At June 14, 2006 1:50 AM, Anonymous Mikel Mariñelarena said…

    Thanks for the updates, Coby.

    However, don’t you think that the IPCC link suggests a contradiction with your idea that most of the heat is absorbed and later released by the oceans? Once they release it, only a fraction eventually shows up as surface warming, most especially for low transient responses, like the one we have now, or are likely to have in the future, if we follow both Lindzen’s and Annan’s figures.

    As for aerosols, does anyone know what percentage of tropospheric aerosols are man-made? I have read that in fact, most of them are natural in origin, with the Sahara and other deserts as the main contributors. These aerosols are obviously not going to disappear and can be considered a part of the current climate system. Does the portion of man-made sulphate aerosols have such a huge impact? Has this really been determined to any degree of certainty? (Again, the mid-century SH cooling seems to point to the contrary).

    Actually, I do like the term ‘skeptic’. With the clear uncertainties that still remain and the record we have of climate/weather forecasts or attempts to tweak atmospheric variables, I feel quite comfortable with it.

     
  • At June 14, 2006 7:50 AM, Blogger coby said…

    Mikel,

    The IPCC figure (here) describes the differing projections of ocean heat uptake from model to model. I don't think you are describing it well by saying this heat is later released, it simply stays in the ocean and is manifested as high water temperatures. So I am not sure where you see a contradiction.

    About aerosols, one thing to consider is that any natural background concentration of dust etc will not be forcings, by definition, we need to look only at changes. That may well include increased or decreased natural dust (for natural or unnatural reasons), and definately volcanic aerosols (note that this factor was increasingly negative in the 40's to 60's) along with man-made aerosols. But beyond that attribution link and the GISS model E forcings described here (and links therein) I can't really answer your questions.

    Re SH cooling, I still don't see that very much cooling went on in the south.
    http://data.giss.nasa.gov/gistemp/graphs/Fig.B_lrg.gif
    (two decade pause in a 70 year general warming)
    http://hadobs.metoffice.com/hadcrut3/diagnostics/hemispheric/southern/
    (10 or 15 year spike in the midst of a general 100 year long warming)

    Power to the 'skeptics', but death to the 'septics'! ;-)

     
  • At June 14, 2006 1:06 PM, Anonymous Mikel Mariñelarena said…

    …I don't think you are describing it well by saying this heat is later released, it simply stays in the ocean and is manifested as high water temperatures

    Coby:

    If all that heat stayed in the oceans there wouldn’t be any thermal inertia and your main point in this thread would fall apart. You can have a look at this IPCC link for further details of how the ocean heat flux and final climate response are supposed to operate.

    Re SH cooling, I still don't see that very much cooling went on in the south.

    If you don’t see much cooling in the south you should see even less cooling in the north, where it lasted a bit longer but was much less pronounced, so I’m afraid we’re back to the NH-SH difference page. Do you still disagree with my interpretation of those data?

    Whether you want to call it “cooling” or “interruption of warming”, both hemispheres followed similar trends after the 40s and up to the late 60s-70s (and all along the 20th century, at that), so if you explain the northern one through aerosols how do you explain the concurrent southern one?

     
  • At June 14, 2006 1:41 PM, Blogger Heiko said…

    Thanks for making sure my screen doesn't show marks for always displaying the same page.

    Also, I've tried my own rewrite of this post over on my blog.

     
  • At June 14, 2006 7:30 PM, Blogger coby said…

    That post is here for anyone interested.

     
  • At June 15, 2006 2:18 AM, Blogger Heiko said…

    Hi Mikel,

    on your second point, apart from coincidence, there'll also be heat transport around the globe. A warming arctic will, all else equal, lead to less heat transport from the tropics to the Arctic, and therefore the tropics will be warmer, and that in turn will make the Southern hemisphere warmer.

    Think of a house, where you start heating one room only. That room will experience a rise from ambient (say 5C) to 22C. The room next door will go up a bit then as well, say from 5C to 10C.

    The house example gets me to your other point. When you put a 1 kW fan heater into a room, the air it'll put out will virtually immediately be at 60C, but the room will heat quite slowly, until after maybe an hour it reaches equilibrium, say at 22C.

    The power output of the fan heater is constant at 1 kW for the whole period, but the temperature is not. There is a thermal lag.

    The end temperature will depend on an equilibrium between the heat added to the house, and the heat lost. At equilibrium of 22C, the house will lose as much heat through its walls, as it gains from the heater.

    But as said the heater's output is constant. During the heat up, part of the power is used to bring up the temperature of the air and furniture etc. in the house. It'll gain heat, and there is an imblance between the heat gained by the house and the heat radiated away.

    So, over that hour it takes to get to equilibrium, 0.5 kW might be lost through the walls, and the other 0.5 kW are there to accumulate heat.

    This is very similar for the earth. A forcing of 1 W/m2 will eventually result in a temperature rise and that temperature rise will increase radiation losses to exactly balance the forcing.

    But in the mean time, some of the heat input will accumulate.

    As happens the heat capacity of water is very large, 4.2 kJ/kg. So, 500 m of ocean have around 200 times the heat capacity of the whole depth of the atmosphere (which weighs roughly the same as 10 m of water column, which is therefore equal to 1 bar or 1 atmosphere of pressure).

    To heat the atmosphere by 0.5C over 30 years takes around 0.01 W/m2. To heat 500 m worth of ocean depth by 0.5C over 30 years takes 2 W/m2.

    With the forcing changing by roughly that much (1 W/m2 in 30 years), the heat taken up by the atmosphere is negligible and we've got immediate equilibrium there, that is the extra heat input must be balanced by extra radiation. There isn't enough heat capacity for heat to accumulate, so the only way to reach balance is through extra heat losses from the Earth (to exactly balance the forcing). 1 extra W/m2 of forcing gets balanced by having a higher temperature which then puts up losses by 1 W/m2.

    But for the oceans, there's plenty of heat capacity for heat to accumulate. And a significant fraction of the forcing can go on adding heat to the water. As mentioned above 0.5W is not enough to heat 500 m water column by 0.5C over 30 years, even if all the heat goes into the water, and none of it is lost because all else equal: higher temperature equals greater heat losses.

    In summary then, a change in forcing of 1 W/m2 over 30 years may result in a temperature rise of 0.25C, with that temperature rise increasing radiation losses by 0.5W/m2. The remaining 0.5W/m2 are required to add heat to the ocean. At some stage, the temperature of the earth ocean system will be at equilibrium (if we stop changing the forcing after 30 years and then wait a long time). Then the temperature rise will by 0.5C, and 1 W/m2 of forcing will be exactly counterbalanced by 1 W/m2 of extra radiative losses, and no net heat is then being added to the system.

     
  • At June 15, 2006 3:56 PM, Blogger Heiko said…

    Mikel,

    I have now seen the long discussion you had with Coby on the topic of aerosols and cooling in the Southern hemisphere.

    http://illconsidered.blogspot.com/2006/05/aerosols-should-mean-more-warming-in.html

    http://en.wikipedia.org/wiki/Image:Climate_Change_Attribution.png

    http://data.giss.nasa.gov/gistemp/graphs/Fig.B_lrg.gif

    Looking at the graphs I just don't seem to be seeing what you are claiming.

    The graphs are all terribly noisy, but what's clear is that the North has greater temperature variability than the South. Unsurprisingly so, I should add, as there's much more land in the Northern hemisphere, and therefore much less thermal inertia.

    There is some loose link between movements in the North and the South (also as you'd expect, both because some of the forcings are linked, eg solar, greenhouse gases, and because of heat transfer), but I don't see where you get the idea that in the 1940-1975 period the South cooled more than the North. In the smoothed graphs you preferred cooling was from 1940 to 1952 and around 0.2C in both hemispheres.

    And when looking at the three graphs split into North, Tropics and South, the trends are, 0.3-0.4C cooling in the North (1940-1970), 0.1-0.2C cooling in the Tropics and no cooling in the South.

    Besides, the attribution Wikipedia link of Coby's is suggestive of volcanic forcing having a major role and it doesn't look like sulphate forcing rose faster than greenhouse forcing over any time period of consequence in the 20th century.

     
  • At June 16, 2006 6:14 AM, Anonymous Mikel Mariñelarena said…

    Hi Heiko,

    Let’s go step by step.

    As for point 1 in my previous email (why there was a concurrent mid-century cooling in both hemispheres with negligible aerosol forcing in the southern one), let me see if I’ve got your reasoning right:

    The NH cools down > so do the tropics as they release more heat to the NH > so does the SH as the tropics have cooled down and have less heat to transfer to it > the SH actually cools down more than the NH, even though the cooling initiated in the NH, the SH lacked the anthropogenic aerosols forcing and thermal inertia would tend to make the change smaller…

    Isn’t this all a bit too convoluted? Do you have any reference for that sequence of events (or at least to the inter-hemispheric heat/cooling transfer mechanism)? Aren’t we trying to force anthropogenic causes on all observed climatic events, rather that assuming that we still may not know enough??

    I found your analogy of the house warming up with a fan heater quite useful. But I’d like to know how it all ties in with the discussion we’re having:

    1) Coby first concluded that Lindzen’s argument is flawed because it ignores thermal inertia. I think that if we factor in thermal inertia (based on all figures we’ve been discussing and particularly on the IPCC links I provided), we still don’t get enough warming to support a large sensitivity. Agreed?

    2) Coby later on proposed that all the ocean thermal flux reflected in the first IPCC link I provided stays there and does not get released to the surface. I disagree with that interpretation and provided the second IPCC link. Where do you stand?

    As for your last post, I think that you’re also not getting the facts right. Following the sharp cooling in both hemispheres that started in the 40s (whatever caused that??), there was more cooling in the south than in the north until the late 60s (the SH deviation from the 1960-1991 mean was larger and more consistent). If we can’t agree on this basic fact derived from the HadCRUT3 graphs and datasets, we won’t be able to pursue a fruitful discussion.

    I suggest that if we are to find an agreement on the observational facts it might be useful that we concentrate each time on the same data and period.

     
  • At June 16, 2006 6:45 PM, Blogger Heiko said…

    the SH actually cools down more than the NH

    The most important problem here is that I just don't see that in any of the temperature graphs.

    If it were true, then the reason for most of the cooling in the South ought to be something other than aerosols in the North (and heat transfer linkage to the North should only be responsible for a fraction of the cooling in the South).

    1.) See my blog entry, it works out perfectly when including thermal inertia and the generally accepted range for aerosol forcing, ie it's in agreement with the 1.5C-4.5C climate sensitivity consensus.

    2.) I am confused by what you are saying here.

    My point was that thermal inertia can be measured in W/m2, currently standing at 0.85 W/m2. Once the oceans are at equilibrium that'll drop to zero, and equilibrium precisely means that input (from forcing) equal output (from extra radiation due to the higher temperature). Before equilibrium is established, the input is larger than the output and there is an imbalance, ie accumulation of heat (currently standing at 0.85 W/m2 as mentioned above).

    Heat is measured in Joules, not Kelvin. It's temperature that's measured in Kelvin. And heat and temperature are not the same thing in physics (this may be blindingly obvious to you, but I mention it anyway just in case that's the reason for why we don't seem to be able to understand each other's points).

     
  • At June 17, 2006 4:21 AM, Anonymous Mikel Mariñelarena said…

    Heiko,

    Let’s see if we can return to the same wavelength. At some point during the thread we seem to have tuned in different directions.

    The most important problem here is that I just don't see that in any of the temperature graphs.

    One thing I very much like about HadCRUT is that you can actually see the actual data the graphs are made from. Shall we have a look for a moment at the annual data for each hemisphere:

    Northern hemisphere:
    http://hadobs.metoffice.com/hadcrut3/diagnostics/hemispheric/northern/annual

    Southern hemisphere:
    http://hadobs.metoffice.com/hadcrut3/diagnostics/hemispheric/southern/annual

    Now, in the period 1945-1968 can you find a single year where the NH was cooler than the SH (its deviation from the average was more negative than that of the SH)?

    There isn’t any. And this is what is expressed by a positive value in the NH-SH difference graphs for that period:

    http://hadobs.metoffice.com/hadcrut3/diagnostics/hemispheric/difference/

    If we agree so far, the question remains: why did the SH cool down so much in this period relative to the NH? If we still don’t agree, can you explain why?

    1) In this point I wasn’t challenging your calculations (I will do later on) but Coby’s initial notion that thermal inertia alone explains why observations show much less warming than predictions.

    2) Again, in this point I’m challenging Coby’s (contradictory) assertion that the heat taken up by the oceans in the following IPCC link stays there and does not get (partially) released to the atmosphere:
    http://www.grida.no/climate/ipcc_tar/wg1/356.htm

    My questions were what your opinion on both points was.

     
  • At June 17, 2006 3:08 PM, Blogger Heiko said…

    Just lost the post, because my 14 month old baby son decided to hit the off switch while sitting on my lap.

    why did the SH cool down so much in this period relative to the NH? If we still don’t agree, can you explain why?

    Maybe one reason is that we are talking about different time periods. The temperature deviation peaks in 1944 in both series, and drops a bit more in the North than the South (0.45C and 0.4C respectively measured from peak to trough or thereabouts, too lazy to look the numbers up a second time), with most of the Southern cooling over in the 60's.

    Looking at Coby's attribution link a major reason for the drop off after 1944 would seem to be volcanic forcing.

    Now, in the period 1945-1968 can you find a single year where the NH was cooler than the SH (its deviation from the average was more negative than that of the SH)?

    As you say this series is for NH deviation minus SH deviation, it's not the temperature difference between SH and NH.

    The NH-SH series goes positive in 1920. Or in other words in the warming phase between 1917 (don't remember whether the -0.6C for that year were for both hemispheres or just the North) and 1944, the North heats a lot more than the South.

    Between 1944 and the late sixties the North and South cool by similarish quantities and the NH-SH series stays roughly constant, and then in the 70's the NH-SH series turns negative with more warming in the South than the North.

    why did the SH cool down so much in this period relative to the NH?

    Because up to 1944 the NH warmed by a greater amount than the SH.

    http://en.wikipedia.org/wiki/Image:Climate_Change_Attribution.png

    This stacks up reasonably well against the attribution graph. Volcanic forcing depends on where the volcanoes are, not on industry.

    This also limits the utility of the attribution graph for explaining the NH-SH series a bit. We'd have to check where the volcanoes had an impact.

    As a guess, it might be that between 1944-1960's volcanoes depressed the South, and sulphates depressed the North between 1944-1970's.

    If Coby is reading this, one remark on the attribution graph. Where's thermal inertia in there???

    1) Ok, but in all fairness Coby's corrected that and now includes sulphate aerosols in his explanation.

    2) I’m challenging Coby’s (contradictory) assertion that the heat taken up by the oceans in the following IPCC link stays there and does not get (partially) released to the atmosphere

    I just don't see what's contradictory here. I am somewhat straining to guess why you find it contradictory. Could you explain why you think there's a contradiction?

    Coby is saying that the oceans are taking up heat and eventually will stop doing so. At that point, world and ocean temperatures will be higher and the oceans will neither be releasing heat nor taking any up.

     
  • At June 17, 2006 7:43 PM, Anonymous Mikel Mariñelarena said…

    Heiko,

    I know very well that taking part in internet debates can disrupt one’s family life. I bet my wife doesn’t feel any happier about this pastime of mine than your baby…

    Anyways, it sounds like we are pretty much in agreement on the NH-SH mid-century cooling now. No need to stir the pot with minor points or with Coby’s words’ real meaning. He can clarify them himself if he so wishes.

    Making Lindzen’s argumentation compatible with a high climate sensibility, as you have managed to do with your calculations, is no trivial task, surely. But you’ve had to make some assumptions and rely on some figures that I don’t think are all that well established at all.

    First of all, you’re using Coby’s Wikipedia link as a source of scientific information (also for the mid century SH cooling). A couple of thoughts on this:

    - Would you trust Wikipedia very much if you knew that climate change related issues were authored by a prominent AGW skeptic (say Pat Michaels, for example)? As it happens, the prominent AGW activist William Connolley, who is also a Wikipedia administrator, authors most Wikipedia articles pertaining to this topic. I’m not sure about that being right or wrong but it would be naïve not to expect some bias, especially when you read the kinds of arguments he’s been engaged in to defend his Wikipedia articles. This particular chart was made by a physics student, also known for his activism on the climate change issue: http://www.globalwarmingart.com/wiki/User:Robert_A._Rohde

    - I don’t see anything in that link that could explain the abrupt mid-forties trend shift. The PCM model itself does not manage to simulate it.

    - I cannot find the volcanic explanation you have proposed for the SH cooling very convincing. Volcanoes are supposed to cool the temperature of the atmosphere through stratospheric aerosols on a global basis, not on a hemispheric one. Moreover the effect wouldn’t last for decades.

    - In spite of the remarkable “fit” they’ve achieved between model and observations, I continue seeing some major problems. For example, the 1910-1945 warming, which explains half the 20th century temperature increase, is based on solar and volcanic (natural) forcings over that period plus a small GHG increase. So far so good. But, as stated above, this ~0.5 C temperature increase is assumed to be unprecedented on at least a millennial scale: http://www.grida.no/climate/ipcc_tar/wg1/figts-5.htm Did this combination of natural events never take place in the past 1-2 millennia??

    - What does a “positive volcano forcing” exactly mean? Is there any such thing as a “normal” volcanic behavior?

    - Once again, we have the whole history of the 20th century “world temperatures” explained through the combination of five (no more no less) forcings. Is this credible? If that’s all there is to it, how come we still lack an explanation (let alone reliable predictions) for El Niño events, hurricane seasons or the very glacial episodes?

     
  • At June 18, 2006 1:40 AM, Blogger Heiko said…

    Mikel,

    I know there's a lot of bias out there. Real climate claims to be about presenting the science, but they do show aplenty that they are leftwing, alarmist, unduely friendly and credulous towards environmentalist activists and paranoid about industry.

    After reading 15 or so of Pat Michael's articles I think the quality of the science he presents is similarish to real climate, the only major issue I have is that he seems to unduely emphasise low end climate sensitivities (of course I may have overlooked some whoppers there or indeed over on real climate - in both cases I have to base my opinion on less than 10% of what's on their sites).

    He's clearly biased as well, and appears much more suspicious of environmental activists than of industry. Like me I'd think he'd give environmental activists like Greenpeace very little credit for improving our environment, and technology/industry plenty for changing our lives from short/brutish/nasty to something much better.

    Anyways, I do tend to look at articles based on the merit of the argument largely, and when information like the wikipedia climate attribution graph is presented I do take it with a bit of a grain of salt.

    Thermal inertia isn't in there. There's no component for things like El Nino as you say and none of the forcings can be expressed in degrees C with much confidence. It's bad enough for W/m2, but with climate sensitivity having an uncertainty range from 1.5-4.5C, putting in a line for greenhouse gas forcing measured in degrees C without any uncertainty band is a bit heroic.

    Be that as it may, I still find the graph helpful.

    It boils down to there being a lot of noise from things like solar and volcanoes, and superimposed on that greenhouse gases and within the existing uncertainty it's not that hard to pick and choose your forcings and climate sensitivity to come up with something that fits the actual temperature curve quite well.

    You say that the warming between 1900 and 1944 appears unprecedented based on the hockey stick and that that seems strange.

    My rejoinder is firstly that the error band for the hockey stick is somethink like +/-0.5C (if not +/-1C) and that therefore the hockey stick isn't sufficient proof that it is unprecedented.

    Secondly, climate isn't purely random. It's not entirely long term trends either. But still, if there was a natural trend heading down from year 1000 to year 1750 and then up a bit more steeply, then having say the warmest year in the past millennium in the 1940's wouldn't be all that strange.

    And thirdly, greenhouse gas forcing was significant between 1900 and 1944. You probably have heard the argument "But before 1944 we had hardly emitted any CO2". Yet as Lindzen points out, greenhous gas forcing isn't linear and it's not all CO2.

    I'd really like to see the greenhouse gas forcing change between 1900 and 1944 expressed in W/m2, though to get a better feel for it.

    You talk about an "abrupt mid forties shift". Well yes, but I don't find that particularly troubling. The explanation could be something like El Nino, it could be volcanic forcing. The relevant question for me, is that sudden drop-off an argument for a lower climate sensitivity, and I don't see why it would be.

    On volcanic forcing: I am unsure how well volcanic aerosols distribute across the stratosphere, and whether there's an imbalance between SH and NH there. I also don't know how the wikipedia article gets its baseline for volcanic forcing.

     
  • At June 18, 2006 4:05 AM, Anonymous Mikel Mariñelarena said…

    Ok, taking advantage of my wife’s benign mood this rainy morning, a small follow-up on my last post.

    I think it is safe to conclude that:

    1) A good portion of the 20th century temperature increase (perhaps half of it) was natural in origin.
    2) Attribution is a very uncertain task and should be approached with care (i.e. scepticism).
    3) There is a very low scientific understanding of some of the forcings evaluated, according to the IPCC.

    Now, bearing all this in mind, let’s analyse Heiko’s exercise to conciliate Lindzen’s figures with ‘the models’: http://heikoheiko.blogspot.com/2006/06/how-do-observations-fit-in-with.html

    To be honest, I don’t remember where the 0.85 W/m2 thermal inertia estimate came from. I can’t seem to find the source now. But let us not forget that the goal is to find climate sensitivity to 2xCO2. That’s what the 1.4-4.5C consensus (?) refers to, not to a prediction of actual temperature increases. Therefore, the figure to compute would be the part of thermal inertia attributable to the temperature increase caused by GHGs. According to point 1 above, this would be a fraction –perhaps half- of 0.85 W/m2 (assuming this figure to be correct).

    I cannot give precise numbers but I think that a good orientation to quantify thermal inertia for different transient climate responses must be the 1st IPCC link I gave: http://www.grida.no/climate/ipcc_tar/wg1/356.htm

    It is clear that for low transient responses the thermal inertia produces low increases in the final response. For example, a TCR of ~1.3 translates to an effective climate response of ~1.7. If, following, the reasoning above, we assume current TCR derived from GHGs to be 0.3C-0.4C, we arrive again to figures very well below the 1.4-4.5C sensitivity.

    So we’re back to the "Observations Show Climate Sensitivity Is Not Very High" conclusion.

     
  • At June 18, 2006 9:51 AM, Blogger Heiko said…

    http://www.nasa.gov/vision/earth/environment/earth_energy.html

    They confirmed the energy imbalance by using precise measurements of increasing ocean heat content over the past 10 years. ...The imbalance is 0.85 watts per meter squared.

    Jim Hansen is the lead author.

    In my calculation I actually put in a value of 0 for natural forcings.

    The calculation:

    Greenhouse gas forcing: 2.7 W/m2
    Aerosols: 1 W/2
    Ocean heat uptake: 0.85 W/m2

    Total forcing: 2.7-1-0.85=0.85 W/m2

    Temperature change: 0.7 K

    Climate sensitivity: 0.7/0.85=0.82 K /(W/m2)

    Or scaling to 3.7 W/m2: 0.82*3.7=3.05K for a doubling of CO2

    http://www.grida.no/climate/ipcc_tar/wg1/figspm-3.htm

    Based on the IPCC estimates for what's possible the sum of all forcings could also brush 4 W/m2, in which case the sensitivity would be below 0.7C, and with the uncertainty in the temperature (+/- 0.2 C) could even be as low as 0.5C.

    The forcings could also add up to something close to zero, in which case the calculated climate sensitivity would approach infinity.

    How much of the forcing is natural is actually irrelevant for the calculation of the climate sensitivity. The only thing that matters is the sum of all forcings. So, suppose aerosols and greenhouse gases exactly cancel and natural forcings (including thermal inertia) were to add up to 0.85 W/m2 (a tall feat given our knowledge of these forcings, but just for illustration let's assume it anyway). That'll also give 3.05 K for a doubling of CO2, even though 100% of climate change to date would be natural.

    To make climate sensitivity small you've got to assume some combination of forcings that is high and temperature increase that is low (ie take the maximum for greenhouse gases, negligible aerosol forcing, maximum solar forcing and the bottom of the temperature range).

    And looking at the uncertainties, it seems quite hard to do that without, in particular, essentially assuming away the aerosol forcing.

    As for thermal inertia, it's also entirely irrelevant how much is due to natural forcing and how much to anthropogenic forcing. That simply does not impact the calculation.

    The IPCC link you gave actually gives ocean heat uptake after 70 years, around 0.8 W/m2 in the case of the lowest climate sensitivity of 1.7C, with 1.3C actual warming.

    That's about twice the warming so far (more warming equals greater ocean uptake all else equal), and also about twice the time period for the oceans to warm (more time equals less ocen heat uptake, all else equal). So there's no contradiction with Hansen's figure of 0.85 W/m2 today.

     
  • At June 18, 2006 10:31 AM, Blogger Heiko said…

    http://pubs.giss.nasa.gov/docs/2005/2005_Hansen_etal_1.pdf

    That's the actual paper. They give an uncertainty for thermal inertia of 0.85 +/- 0.15 W/m2 and for total forcings of 1.8 +/- 0.85 W/m2. They say greenhouse gases added up to 2.75 W/m2 in 2003 (ie the same as Lindzen).

    One thing I utterly disagree with in their conclusions is this paragraph:
    Before action to counter this trend could be effective, it would be necessary to eliminate the positive planetary energy imbalance, now ~0.85 W/m2, which exists as a result of the ocean's thermal inertia. Given energy infrastructurre inertia and trends in energy use, that task could require on the order of a century to complete.

    What energy infrastructure is meant to last 100 years? Cars last maybe 20, power plants maybe 40.

    France got from zero to 80% nuclear in less than two decades and that without noticeable economic disruption.

    I think Hansen heavily understates what we could do, if we truely needed to.

    For that matter, if 400PPM had to be avoided to save humanity from certain extinction, it could be done. 1/3 of world electricity is already CO2 emissions free. 90% of transportation is discretionary. People don't have to commute. They can rent a tiny flat within walking distance of their place of work and head home for the weekend in buses filled with 100 people. And so forth, we could slash fossil fuel use by 90% within days without many people having to die.

    And within 20 years without an actual reduction in GDP, but maybe something like 1% annual growth instead of the historical 3%.

    A hundred years ago biomass and coal burning supplied most energy, there was next to no electricity, petroleum, natural gas.

    In a hundred years emissions can drop to zero merely from advances in technology making fossil fuels obsolete.

     
  • At June 18, 2006 12:17 PM, Blogger coby said…

    Sorry I have not been keeping up well with this thread. Here are a couple of isolated responses, if I missed a specific point someone wanted me to try to address, please just restate it and I'll try again.

    [Heiko] I'd really like to see the greenhouse gas forcing change between 1900 and 1944 expressed in W/m2, though to get a better feel for it.

    This may be what you are looking for.

    [Heiko] Where's thermal inertia in [the attribution graph]”

    The forcings shown in that chart are the inputs to the model, whereas thermal inertia is a property of the system so would not be appropriatley grouped with things like changes in aerosols, solar or GHG’s. I take your point that thermal inertia can be expressed as W/m^2 but don’t think it fits the defintion of a forcing.

    [Mikel] On trusting Wikipedia, while selection of references is clearly an oppurtunity for injecting ones bias, at least all of the material there is in fact well referenced. In the case of that climate attribution chart it is based on a clearly identified paper, so I don’t think it is too much of a leap of faith to accept it at face value. Other sources are of course welcome in this discussion.

    [Mikel] Volcanoes are supposed to cool the temperature of the atmosphere through stratospheric aerosols on a global basis, not on a hemispheric one.

    I don’t think this is quite correct. Similar to anthropogenic aerosols, volcanic influences tend to remain by and large in their own hemispheres.

    [Mikel] I think that GHG forcing in the early 20th was as big an influence as solar. This is enough to explain it being exceptional in the last 1000 years, if indeed it was.

    [Mikel] we have the whole history of the 20th century “world temperatures” explained through the combination of five (no more no less) forcings. Is this credible?

    There are of course many more forcings, but these are the major ones. The IPCC and the GISS model E identify many more. The study from that attribution chart surely has more forcings involved and the graph merely presents the major ones.

    [Heiko] There's no component for things like El Nino

    El ninos effect individual years, so I don’t think belong in a discussion of climate forcing. Changes in El Nino patterns are of course interesting to the general field of climate change.

    Thanks for all the interesting discussion!

     
  • At June 18, 2006 1:21 PM, Blogger Heiko said…

    Coby,

    nice link. So, in 1944 greenhouse gas forcing was about 0.81 W/m2 or a third of its 1998 value of 2.43 W/m2.

    On the attribution graph, you are right I think that thermal inertia isn't a forcing. But, the graph has forcings in Celsius and modelled response in Celsius and it looks like you just add up.

    I see two problems with that graph. Firstly, even if it's not a forcing, thermal inertia needs to be included to calculate the response to all forcings. And secondly, it should really be made much clearer that there are wide error margins, not least the uncertainty in the climate sensitivity. The agreement between modelled and actual temperature history is therefore way overstated.

    I don't know that much about El Ninos, and I am no longer sure why I actually mentioned them.

     
  • At June 18, 2006 1:23 PM, Blogger coby said…

    Further in response to Heiko's last post which crossed in cyber space:
    Given energy infrastructure inertia and trends in energy use, that task could require on the order of a century to complete.

    I have no personal insight into how Hansen arrives at this time frame, nor any particular knowledge of the issue to provide my own, however I think you are overly optimistic and need to consider the time required for research and development and not merely implementation. Not to mention political inertia.

    In general, I share your positive outlook on what is indeed possible given the will to do it. I just wanted to make one orthoganal point:

    A hundred years ago biomass and coal burning supplied most energy, there was next to no electricity, petroleum, natural gas.

    Don’t forget simple human labor, a very large component of the economic view of energy 100 years ago. Also work animals.

     
  • At June 18, 2006 1:55 PM, Blogger coby said…

    I see two problems with that graph. Firstly, even if it's not a forcing, thermal inertia needs to be included to calculate the response to all forcings.

    It certainly must be included in the model, along with atmosphere and ocean convection and many other factors, but the output is a representation of the climate response at a given time. What you want to know is what will be the equilibrium response, which is a different question. What this representation is trying to show is how modeled climate compares to observed climate over the 20th century, and how much change at any given moment is attributable to what factor.

    And secondly, it should really be made much clearer that there are wide error margins, not least the uncertainty in the climate sensitivity. The agreement between modelled and actual temperature history is therefore way overstated.

    This is a poorly framed question, IMO. The topic came up with a troll on sci.environment but I am afraid I am probably not able to explain it enough. Uncertainty and error margins are properties of measurements and statistical results. But the uncertainty in a model is a different thing and is really just a question of how likely is it that the model is “correct”. Consider a simpler physics model, say one that predicts the change in the speed of time from one frame of reference to another. Before there were any experiments, this was a theory and a model based on mathematical equations. If Einstein presented you with his prediction of how much time would slow in a given trip around the moon and back, would it come with error margins?

    Do you get what I mean? Climate sensitivity is like that, it is an output of a model and the result of all the physics built into it. How certain it is, is a question of how complete and confident is our knowledge of the system.

     
  • At June 18, 2006 3:42 PM, Blogger Heiko said…

    Ok, it's probably just a matter of preference. One could add all the forcings and the ocean uptake (which constitutes most of the thermal inertia) to get a figure in W/m2, which then translates into a temperature deviation, and then say x degrees C is due to greenhouse gases, y degrees C to thermal inertia etc..., or do it as done in the graph. As you say the forcing in degree C could be defined as a percentage of the total modelled response.

    I suppose even the second point (on error bands) comes down to preference, but it's one where I don't accept your argument as readily as on the first point (that thermal inertia might as well be excluded).

    This graph can be interpreted as showing much better agreement between modelled and actual temperature developments than is actually justified. This is something Lindzen dwells extensively on in his presentation (it's not the same graph, but also a comparison between model and actual) and I think he's got a strong argument there. The fact is that within the uncertainty we've got, all sorts of combinations of particular forcings and climate sensitivity will give a similarly good fit.

    We could halve the contribution of greenhouse gases say, and compensate by less aerosol cooling.

     
  • At June 18, 2006 5:07 PM, Anonymous Mikel Mariñelarena said…

    Heiko:

    Lindzen’s argument is definitely in contradiction with a high climate sensitivity. That’s the whole point of his presentation.

    Let’s try to make things as simple as possible.

    Climate sensitivity (for a doubled CO2) = equilibrium temperature change on the surface of the earth caused by this CO2 (or equivalent GHG) forcing.

    For further details on this definition see the IPCC glossary: http://www.grida.no/climate/ipcc_tar/wg1/518.htm

    This definition includes feedbacks but clearly excludes other concurrent forcings so let’s forget about them for a moment.

    Current GHGs forcing, according to Lindzen = 75% of 2xCO2 forcing.
    Current GHGs forcing, according to Annan = 2.4 W/m2 = 65% of 2xCO2 forcing.
    Let’s assume a central 70% value.

    Observed temperature increase since late 19th century = 0.6C +/- 1.5C

    Now, if we are to follow Lindzen’s argument, this is where we do have to guesstimate how much of this temperature increase is due to the above GHGs forcing. This is in part circular, as that’s precisely what we are trying to estimate, but we do know, from observations (not models or uncertain estimates) that not all of it can be due to GHGs since roughly half of that warming (~0.35C) took place before GHGs could play a significant role. As you said, opting to believe in aerosols’ importance or not is the key of the analysis. As long as the SH mid-century cooling remains unexplained I think it’s safer to leave them out. In any case, let’s assume a rather generous 0.5C value.

    The transient climate response to 2xCO2 (T) would thus be:

    T = 0.5C + 0.3 T => T = 0.71C

    And the climate sensitivity T’ would be:

    T’ = 0.71C + thermal inertia

    Where this thermal inertia is solely the one that would be generated by this 0.71 temperature increase. As you said yourself, climate sensitivity needs to be the same, by definition, irrespective of what factors other than CO2 are in play at any given moment.

    For the reasons already stated in my posts above, even when we add thermal inertia, T’ would still fall well below the 1.5-4.5C range.

     
  • At June 19, 2006 3:05 AM, Blogger Heiko said…

    Mikel,

    Annan's said that his value is out of date. Hansen gives 2.75 W/m2 for 2003.

    The temperature increase is also out of date though. 0.6C +/- 0.2C comes from the last IPCC report and it seems (picking a figure used at real climate) that it's now closer to 0.7C.

    The transient climate response to 2xCO2 (T) would thus be:

    T = 0.5C + 0.3 T => T = 0.71C


    Yes, assuming as said that aerosols are zero, add the thermal inertia and climate sensitivity is something like 1.5C.

    And yes if you assume large natural forcing, no aerosol forcing, and make it 0.3C for 2.75 W/m2 of greenhouse gas forcing, then we'd go to 0.5C.

    This is completely unrealistic, because we've got other ways to estimate climate sensitivity, notably the temperature and albedo, dust, greenhouse gas induced forcings of the last ice age, and those independently make it quite hard for sensitivity to be less than 1.5C or more than 4.5C.

    As long as the SH mid-century cooling remains unexplained I think it’s safer to leave them out.

    The aerosol cooling isn't estimated based on the shape of the temperature curve over the 20th century. The fact that the NH rose faster than the SH up to 1944 is easily explained by there being more land in the North. SH and NH fell by similar amounts from 1944 to 1960's, the NH then stayed down in the 1970's, and since then has warmed faster than the SH.

    That's quite consistent with sulfates being a major factor in the NH (particularly depressing the 70's) and not in the SH, and anyway there's a lot of noise in the data. I don't see anything there justifying a belief that aerosol forcing must be 0 rather than 1 W/m2, if other evidence suggests that 1 W/m2 is much more likely than 0.

     
  • At June 19, 2006 10:27 AM, Anonymous Mikel Mariñelarena said…

    Yes, assuming as said that aerosols are zero, add the thermal inertia and climate sensitivity is something like 1.5C

    Nope. Assuming aerosols are zero (and updating temp increase to 0.7C and current GHG forcing to 75%, as you suggest), we’d have something like:

    T = 0.4C + 0.25 T => T = 0.53C

    And climate sensitivity T’ = 0.53C + thermal inertia.

    No way thermal inertia can triple such a low transient climate response. This is Lindzen’s argument, I believe.

    This is completely unrealistic

    I don’t know if Lindzen is right. But I surely like the simplicity of his reasoning and the economy of uncertain assumptions in comparison to other estimates. Other than direct observations and commonly accepted relationships, we only have to assume what part of the observed warming is GHG-induced.

    What is more unlikely, just from a commonsensical point of view, that a huge amount of the GHG-induced warming is being “masked” by aerosols, volcanoes, thermal lags, etc but will soon appear in full force if we don’t repent and abandon our capitalistic ways or that after 120 years releasing GHGs and ¾ of the way to a CO2 doubling we should be seeing most of its effects?

    The reason why the SH mid-century cooling speaks to me very strongly against man-made aerosols having such a large effect is because they are the reason commonly alleged for the global mid-century cooling, in spite of the rapidly rising GHGs. However they hardly affected the SH and yet it cooled parallel to the NH.

     
  • At June 19, 2006 10:45 AM, Blogger Heiko said…

    It would about double your figure of 0.71C getting us quite close to the bottom of the range. Lindzen accepts that aerosols might be 1 W/m2, he tends to favour 0 and the consequently smaller climate sensitivity.

    To get 0.3C from natural forcings you've got to assume quite a bit of forcing in 2003. As mentioned earlier, natural forcings may be lower today than in 1944 and also there was already 0.81 W/m2 of greenhouse gas forcing then, or about a quarter of 2*CO2.

    I don't accept what you call a commonsensical view, because as mentioned, we've got other evidence indicating that aerosol forcing is not 0 (I trust the IPCC over Lindzen here), and also other evidence that climate sensitivity is unlikely to be much below 1.5C.

    Aerosols are maybe commonly alleged to be the reason for mid century cooling, but what's the problem with accepting that they are just one reason, and one that comes through particularly clearly in the 1970's temperature record?

     
  • At June 20, 2006 8:42 AM, Anonymous Mikel Mariñelarena said…

    Heiko:

    Given the uncertainties, it will always be possible to find plausible explanations and keep supporting an alarmist scenario. I recall this was one of Lindzen’s points in the presentation we’ve been discussing: how can you disprove the possibility of this scenario being true?

    We could argue on all the above ad infinitum without ever being able to conclude if the 1.5-4.5 range is correct. However I do think that there a number of arguments that speak against an important anthropogenic contribution to observed temperatures changes in the past century:

    - The 1910-1945 allegedly unprecedented warming, in spite of the small impact of GHGs at the time.
    - The SH mid-century cooling, in spite of the absence of sulphates forcing.
    - The abrupt regime change in the 40s on both hemispheres, that finds no match in the behavior of the forcings commonly considered.
    - The spatial distribution of the observed warming, both on the surface regional level and on the atmospheric vertical level.
    - The small warming observed so far (relative to the projected predictions).

    I generally find that the IPCC papers are the best source of information on climate issues. Indeed some of them have been signed by prominent “skeptic” scientists. And in spite of being compatible with certain alarmist positions, the IPCC conclusions do not support a major anthropogenic attribution to temperature changes prior to ~30 years ago.

    With all this said, one can never forget that the IPCC itself is very likely to have an unavoidable built-in bias. In fact, it was created under the assumption that a problem existed, long before any strong evidence had been gathered in support of that assumption. It was a political act and, were the IPCC ever to proclaim that no such problem exists, we’d have what has been termed a “walking army” of researchers and bureaucrats literally out of work. Just a small digression…

     
  • At June 27, 2006 11:36 PM, Blogger Peter K. Anderson said…

    There is not a case of 'Climate sensitivity'; there is simply NOT a 'greenhouse effect' linking CO2 to 'temperature'. The Land Surface median rise oft mentioned as ~0.7 degree C is just that, a rise in median Land Surface temperature. This is produced within and by the actions of Humanity in altering the materials of the surface, and thus the abilities of that overall surface in its interactions with the energy presented by incident Radiation. This activity is a match for the 400 year (so far) explosion in Human Population. This is outlined with slides at http://hartlod.blogspot.com ...(*)
    Even the 'great discovery' of the 1950s 'warming' is only showing the impact of the spread post WWII of that technology developed within the previous decade along with the upsurge of Human population, spreading 'its' productions of surface materialing alteration.

    The Ocean surface median surface temperature is seemingly on a ~15 year lag (seen in many plots of surface temperatures), trailing that trend of the Land surface but in a muted manner. There is not enough energy penetrating the atmosphere within the Infrared Region to directly warm water significantly. That Energy that is surface incident with sufficient Energy and that can interact with Water is only within the lower Visible Spectrum (see slides in *). The land surface is however being increasingly warmed (i.e. unnaturally so) by increasing alterations to the material of the surface, these increasing kinetic induction from Energy within the surface incident UV Radiation, which can penetrate the atmosphere. Overall Energy interaction and Kinetic Energy (KE) inductance is increasing from the 'new' surface. This KE is moved into the processes of Conduction and Convection where in as 'powering' the processes of Turbulence, it is NOT all measurable as a 'Temperature' of those masses being moved by the processes of Turbulence. The KE moving the involved masses is infact separate from that measured as the Temperature of the involved masses. The actual measured rise IN the Land surface Temperature (of ~0.7 degrees C) is infact only the residual KE remaining after the actions of Conduction and Convection begin the distribution of this KE. Thus the increase in overall KE being induced within the biosphere is far greater than could ever be produced by any actual 'greenhouse effect'.

    The existence of Humanity as it is seen NOW bio-formed has been 'bio-forming' as such for at least now ~7 million years (it seems). Life as Humanity IS would not have formed as it has with over 90% saline water within a cellular structure if EVER there had been sufficient Energy within surface incident Radiation within the Infrared Region to actually produce the HEAT that the 'greenhouse platform' is 'suggestive of'. The present cellular processes would NOT function in that 'environment', would not have evolved 'as is' even. This is just ONE example of the paucity within 'greenhouse issues' in relation to SCIENCE.
    It is the surface alterations that are beneath the presently observed alterations in weather patterning. The situation with the rematerialing of the surface is that the energy incident is of a distribution that would seem unaltered over Millions of years when notice is made of processes that should be sensitive to such and already show sensitivity to Radiation by protective reactions. There is then no warming process related to CO2 from any REAL 'greenhouse process' or any REAL relevance involving a 'CO2 quantity' and such 'warming processes' at all. There is not either evidenced any alteration to the irregular Natural Climate alterations process and its observed progression within the last 400 years, let alone in the last few decades.

    What the rematerialing produced by modern Humanity is doing is opening up the potential for increased Kinetic Induction to occur within Interactions by such Human materialing with Energy in the surface incident UV spectrum especially. I have outlined a Global split plot model in other places at other times to indicate the potential for study of variation of a natural surface to a surface rematerialed by Humanity. It is not that complex and only needs notice of what is Kinetic Energy, and how Kinetic Inductance produces such within the material that ARE present in the manner they DO behave, rather than by opinioning such and then proceeding to process 'opinions'. The general belligerence of a few is all that prevents more PUBLIC discussion of this.
    The first thing to realise is that it is NOT at all that ["a whole additional component of energy will be induced'] in any manner. What is happening is that the Radiation that is surface incident is having MORE of the energy available, that presented as the Photons involved, inducing a Kinetic gain within the materials interacted with. The ENERGY as a total is unaltered, the BALANCE tween Photonic Remittance and Kinetic Induction is all that is altering and this is due to the materials being changed by the actions of Humanity.
    So the surface materials will reemit LESS energy within a secondary Photon for the interactions that occur and become hotter (the measure of the kinetic inductance) than the 'natural' terrain that was replaced. Turbulence, from the actions of the processes of Conduction and Convection, will remove such kinetic gains from the surface materials and then the general motions of thermodynamic gradients will be noticed. The secondary photons will be 'processed' within the atmospheric cascade and be slowly removed, again however the previously made calculations indicate a 12 month average life for Photons within this cascade effect.

    The major issue with present climate models is that they are based on misinterpretations of SCIENCE and misuse ENERGY, the effort to 'minimise error' or 'improve correlation' would be vastly assisted if notice was made to what WAS happening rather than attempting to opinion 'a fix' (or trying to add another 'new component') whilst maintaining the base of that 'model' with the flawed 'greenhouse premises'. The situation IS that a 'greenhouse model' is NOT representing the world that is observed about us. The reason that present 'climate models' are 'bulky' is that they are trying to work around being basically 'wrong' by adding in 'enough' to begin to 'look right'.
    Realise that the natural trend of temperature at present IS 'upwards' as we continue to climb from that last Glaciation and that the irregular periodicity in natural Climate behavior is all that is seen demonstrated by present 'climate observations' .

    Your's,
    Peter K. Anderson a.k.a. Hartlod(tm)
    From the PC of Peter K Anderson
    E-Mail: Hartlod@bigpond.com

     
  • At February 20, 2007 6:51 PM, Anonymous Anonymous said…

    "...climate system does not respond instantly to forcings. Shouldn't he know that?"

    ___________________

    Pretty bold statement from someone who initially openly admited to no formal training.

     
  • At July 11, 2008 11:14 PM, Blogger yezi said…

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